Medications · Sexual health

Compounded Sildenafil

PDE-5 inhibitor at custom strengths or rapid-dissolve preparations.

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Compounded Sildenafil molecular structure (PDE-5 inhibitor)

Why this needs to be personal

Why Personalized Compounded Sildenafil

Viagra was approved at 25, 50, and 100 mg because those three tablets covered the bell curve of trial responders well enough for a manufactured product. The pivotal trials did not pick a dose for your absorption rate, your nitric-oxide baseline, the SSRI or alpha-blocker you also take, how quickly you metabolize the drug, or whether onset speed or duration matters more for your situation. Revatio's PAH schedule was set the same way, calibrated for the average pulmonary-hypertension adult, with a separate weight-banded suspension added for children only after STARTS-1 and STARTS-2 forced the FDA to address pediatric dosing as a distinct problem.

A compounding pharmacy fills the gaps that fixed tablet strengths leave behind. A prescriber can ask for a strength between 25 and 50 mg or between 50 and 100 mg for patients who need finer titration, a sublingual troche that bypasses first-pass metabolism for faster, more predictable onset, a preservative-free oral suspension for a child or an adult who cannot swallow tablets, or an individualized blend that pairs sildenafil with tadalafil and a low dose of oxytocin under a doctor's protocol when the single-agent FDA products have not produced an adequate response. The molecule is the same one the FDA reviewed in 1998. The strength, the route, and any combination are written for one named patient.

This is the older arrangement that pre-dates mass-produced tablets. A doctor writes the prescription, a pharmacist prepares it for that patient, and the label carries the patient's name. Modern state-board inspection and 503A oversight keep that arrangement honest.

In brief

Compounded Sildenafil Explained

Sildenafil is a prescription pill that improves blood flow to specific tissues by relaxing the smooth muscle in small blood vessels. The original brand is Viagra, approved by the FDA in 1998 for erectile dysfunction 1. A second brand, Revatio, was approved in 2005 for a different problem, pulmonary arterial hypertension, a serious lung-blood-pressure disease, and a children's liquid version followed 57.

Generic sildenafil tablets are inexpensive and widely available. RonanRx only makes a compounded version when the standard tablet doesn't work for a specific patient, for example, when a patient needs a strength that's not manufactured, can't swallow tablets, needs a faster-onset sublingual troche under a doctor's direction, or when a child with pulmonary hypertension needs a custom liquid dose 27.

At a glance

Quick Facts About Compounded Sildenafil

Category
Selective PDE5 (phosphodiesterase type 5) inhibitor
Active ingredient
Sildenafil citrate
FDA-approved branded forms
Viagra (erectile dysfunction, approved 1998); Revatio (pulmonary arterial hypertension, approved 2005; pediatric oral suspension subsequently approved). Generic sildenafil widely available.
Routes studied in humans
Oral tablet, oral suspension, intravenous (Revatio), orodispersible film, sublingual troche (compounded), topical cream (investigational)
Evidence posture
Pivotal phase III evidence supports the manufactured tablets (Viagra for ED, Revatio/SUPER-1 for PAH, STARTS-1/STARTS-2 for pediatric PAH). Compounded preparations have no separate efficacy program.
Compounded under
503A, patient-specific prescription only, where the manufactured FDA-approved product is not clinically appropriate (excipient sensitivity, non-tablet dose form needed, off-label dose, pediatric weight-banded liquid)
Absolute contraindication
Concomitant nitrate therapy (any form, any indication), life-threatening hypotension. Also contraindicated with riociguat (soluble guanylate cyclase stimulator).
Important compounding caution
Per FDA guidance, compounded versions of an FDA-approved drug are restricted to documented patient-specific clinical needs that the manufactured product cannot meet. Generic sildenafil tablets are inexpensive and widely available, so routine compounding as an essentially-a-copy substitute is not appropriate.

Prescription review

Patient-Specific Prescription Only

Compounded Sildenafil on this page is a 503A compounded preparation. Every dose is made on a prescription, for a named patient, by a licensed pharmacist. It is not a stocked, mass-manufactured product.

  • Made to order, not off a shelf. No batch sits in a warehouse waiting for buyers. Your prescription is what triggers the prep.
  • Named-patient label. The bottle carries your name. The batch records carry your prescription.
  • Dose, strength, and route chosen for you. A prescriber who knows your chart decides what gets compounded, not a manufacturer who set the strength for a trial population.
  • Licensed pharmacist on the hook. A real person, with a license that can be pulled, signs off on every prep. State inspectors check the facility.
  • Compounded drugs are not FDA-approved. They should not be evaluated using branded-drug trial data. Availability varies by state and prescribed medication.
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Real medicine, not gray market

How This Differs from a Research-Use-Only Website

A research-use-only website ships a vial from a warehouse. There is no prescription, no pharmacist, no facility inspection, and no way to recall the product if something is wrong with it. If the vial is mislabeled, contaminated, or under-potent, there is nobody whose license is at stake.

A 503A compounding pharmacy is the other thing. Your doctor writes the prescription. A licensed pharmacist, whose name is on the label, prepares the medicine in a facility the state inspects. If something goes wrong, there is a person and a license on the hook, and a documented chain of custody on every lot. That accountability is what makes it safe.

What it is

What is Compounded Sildenafil?

Sildenafil citrate is a small-molecule selective inhibitor of phosphodiesterase type 5 (PDE5), the cyclic-GMP-specific phosphodiesterase that predominates in penile corpus cavernosum smooth muscle and in the pulmonary vasculature 2. The molecule emerged from Pfizer's UK-92,480 cardiovascular discovery program originally targeting angina, where it underperformed but produced an unexpected, durable improvement in erectile function in early trials, leading to the redirected development program that culminated in Viagra 1.

Sildenafil was the first oral PDE5 inhibitor approved (Viagra, 1998), creating a new pharmacologic category 3. The same molecule was later developed for pulmonary arterial hypertension as Revatio (2005), where chronic PDE5 inhibition reduces pulmonary vascular resistance 458. Pediatric PAH labeling for Revatio (oral suspension) followed the STARTS program 7.

Generic sildenafil citrate tablets are widely available since US patent expiry 5. The molecule is one of the most-studied drugs in clinical pharmacology, with thousands of trial-years of safety data across both ED and PAH indications.

How it works

How Compounded Sildenafil Works

Class
PDE-5 inhibitor
First studied
FDA-approved 1998
Common forms
Compounded sublingual troche, capsule
Compounding category
503A, patient-specific prescription

Sexual stimulation triggers release of nitric oxide (NO) from neuronal and endothelial sources in the corpus cavernosum. NO activates soluble guanylate cyclase, which converts GTP to cyclic GMP (cGMP). cGMP relaxes vascular smooth muscle, allowing blood inflow that produces an erection. PDE5 is the dominant enzyme that breaks cGMP down to inactive GMP, terminating the response.

Sildenafil is a selective competitive inhibitor of PDE5 2. By slowing cGMP breakdown it amplifies and prolongs the local effect of any NO that the patient's own nervous system releases. It does not initiate an erection in the absence of sexual stimulation, there must be NO release first. The same mechanism in pulmonary vascular smooth muscle reduces pulmonary vascular resistance, the rationale for the PAH indication 4.

Selectivity for PDE5 over the other 10 PDE isoforms is high but not absolute. Modest cross-inhibition of PDE6 (retinal photoreceptors) accounts for the dose-related blue-tinted-vision adverse effect; weak cross-inhibition of PDE1 has been characterized but is not clinically prominent.

Research history

Compounded Sildenafil Research History

Sildenafil (UK-92,480) was synthesized in Pfizer's Sandwich, UK laboratories in 1989 as a candidate for stable angina pectoris and hypertension 42067. Early-phase studies in coronary artery disease were disappointing, but volunteers consistently reported penile erections as a side effect 5092. Boolell and colleagues at Pfizer published the first peer-reviewed characterization of sildenafil's PDE5-inhibitor mechanism and its erectogenic effect in 1996 (Int J Impot Res; Br J Urol), and Ballard 1998 worked out the relaxation profile in human corpus cavernosum tissue 234 55. The Goldstein 1998 NEJM trial established efficacy and safety in a 21-center US program of 532 men with ED and underpinned FDA approval of Viagra in March 1998 126821. Open-label long-term follow-up 77 and replication in special populations followed quickly: diabetes 76, spinal cord injury 78, and elderly subgroups 79.

Cardiovascular safety became a regulatory and clinical priority shortly after launch as case reports of cardiovascular events with concomitant nitrate use accumulated 45. The hemodynamic mechanism was rigorously characterized in dedicated interaction studies, Webb 1999 (organic nitrate and calcium-antagonist drug-interaction studies), Webb 2000 (NO donor potentiation in stable-angina patients), and Oliver/Webb 2009 (time-dependent attenuation of the sublingual nitroglycerin, sildenafil interaction) 303132. Parker 2007 demonstrated that IV nitroglycerin could be safely administered after an 8-hour washout 134648. The ACC/AHA expert consensus document 10 codified the absolute nitrate contraindication and the alpha-blocker caution; Kloner 2004 quantified the doxazosin/tamsulosin interaction 91 42. A 4-year safety review (Padma-Nathan 2002), updated reviews 11, and a large modern systematic review and meta-analysis of long-term PDE5-inhibitor cardiovascular outcomes 89 supported the cardiovascular safety profile when contraindications were observed; Vlachopoulos 2004 even demonstrated acute reversal of smoking-induced endothelial dysfunction by sildenafil 1.

Pulmonary hypertension development followed the same mechanism logic 62. The SUPER-1 trial 5 supported FDA approval of Revatio for PAH; SUPER-2 6 extended the safety record to two years. SERAPH 57 was an early head-to-head against an endothelin-receptor antagonist (bosentan), and combination-therapy programs followed: COMPASS-1 94, PACES 59, COMPASS-2 58, and AMBITION 61. Singh 2006 reported a placebo-controlled crossover trial of oral sildenafil specifically in severe pulmonary arterial hypertension including Eisenmenger physiology 3351 56. PHIRST 60 established the tadalafil-PAH labeling that broadened the class 4443. Pediatric development through STARTS-1 7 and STARTS-2 8 established pediatric PAH dosing, and produced an unexpected mortality signal at the highest dose that informed FDA's pediatric labeling restriction 65. A pediatric oral suspension formulation was subsequently approved for Revatio 73314. Neonatal PPHN evidence comes from the Baquero 2006 pilot RCT in infants and the Pierce 2021 multicenter trial of IV sildenafil in PPHN 6364 75.

Heart-failure indications were tested next: Bocchi 2002 (sildenafil in advanced systolic heart failure), Lewis 2007 (sildenafil improves exercise capacity in systolic HF with secondary pulmonary hypertension), Guazzi 2011 (1-year sildenafil in HFpEF with pulmonary hypertension), and the negative RELAX trial 54 that ultimately argued against sildenafil for unselected HFpEF 5253.

Beyond labeled use, sildenafil has been investigated for Raynaud phenomenon 18, high-altitude pulmonary hypertension and exercise capacity 17, female sexual arousal disorder 19, and pregnancy-related growth restriction 66. Network and systematic meta-analyses comparing PDE5 inhibitors (Tsertsvadze 2009 AHRQ Ann Intern Med review and harms meta-analysis; Yuan 2013 European Urology network meta-analysis) confirm broadly comparable efficacy across the class with distinct PK and AE profiles 746970.

Rare but recognized post-marketing adverse events include nonarteritic anterior ischemic optic neuropathy (NAION; Pomeranz 2005, Pomeranz 2017; case-control work by McGwin 2006, Gorkin 2006, Margo 2007; the modern US claims-database cohort by Etminan 2022; meta-analysis by Penedones 2020), sudden sensorineural hearing loss 15, and priapism (rare and reported especially in sickle-cell physiology, Burnett 2006 reported that long-term low-dose oral PDE5 inhibitor therapy paradoxically alleviates recurrent priapism in selected men) 7172. Wang 2024 published a comprehensive FAERS pharmacovigilance review 16 4749. Counterfeit and unregulated sildenafil represents a separate quality-and-safety axis: Veronin 2014 quantified active ingredient and impurity content in Internet-sourced sildenafil, and Venhuis 2014 documented dose-to-dose variability in counterfeit packages 8788 90.

Timeline

Compounded Sildenafil Timeline

  1. 1989 Sildenafil (UK-92,480) synthesized at Pfizer's Sandwich, UK laboratories as an angina/hypertension candidate 4
  2. 1996 Boolell et al 23. publish the mechanism-of-action and first clinical erectogenic data, sildenafil as an orally active PDE5 inhibitor for male erectile dysfunction
  3. 1998 Goldstein et al 134. publish the pivotal NEJM trial of oral sildenafil for ED; FDA approves Viagra (March 27, 1998); Ballard characterizes the relaxation profile of human corpus cavernosum and the PDE-isoenzyme selectivity profile in vitro
  4. 1998 Murthy & Makhlouf work out cGMP/cAMP differential regulation of PLA2 in smooth muscle, foundational signaling biology underlying PDE5 inhibition 38
  5. 1999 ACC/AHA expert consensus document (Cheitlin) codifies the absolute nitrate contraindication and cardiovascular caution profile; Webb publishes the formal drug-interaction studies of sildenafil with organic nitrate and a calcium-channel antagonist; Rendell publishes JAMA RCT in diabetic men; Goldstein publishes 36-week open-label long-term safety 10307677
  6. 2000 Webb publishes JACC nitrate-donor interaction data, sildenafil potentiates the hypotensive effect of NO donors in stable-angina patients; Hultling reports Spinal Cord QoL data for sildenafil in SCI; Muirhead reports the sildenafil, ritonavir/saquinavir PK interaction 317882
  7. 2001 Caruso publishes first placebo-controlled RCT of sildenafil for female sexual arousal disorder in premenopausal women; Boulton reports the T2DM RCT; Wagner publishes the elderly-subgroup analysis 197579
  8. 2002 Nichols publishes definitive single-dose human PK (absolute bioavailability, food effect, dose proportionality); Muirhead publishes age/renal/hepatic PK and the erythromycin interaction; Padma-Nathan publishes 4-year cumulative safety update; Bocchi publishes the sildenafil-in-CHF Circulation trial 980811252
  9. 2003 Basson and Berman publish parallel RCTs of sildenafil for female sexual arousal disorder (BJOG and J Urol) 6768
  10. 2004 Ghofrani publishes Ann Intern Med RCT of sildenafil for exercise capacity at altitude, proof of concept for hypoxia-induced pulmonary vasoconstriction; Kloner publishes the doxazosin/tamsulosin alpha-blocker interaction study; Vlachopoulos demonstrates reversal of smoking-induced endothelial dysfunction 179190
  11. 2005 SUPER-1 trial (Galiè, NEJM) supports FDA approval of Revatio for pulmonary arterial hypertension; SERAPH (Wilkins) compares sildenafil to an endothelin-receptor antagonist; Pomeranz & Bhavsar report NAION case series; Fries publishes Raynaud phenomenon RCT in Circulation; Weeks characterizes high biochemical selectivity for PDE5 over PDE11 557131835
  12. 2006 Ghofrani, Osterloh, and Grimminger publish the comprehensive Nature Reviews Drug Discovery review; Jackson publishes updated cardiovascular safety perspective; Maggiorini reports the tadalafil/dexamethasone HAPE-prevention trial; Singh publishes the placebo-controlled crossover trial in severe PAH (including Eisenmenger physiology); Baquero reports the PPHN pilot; McGwin and Gorkin publish NAION case-control / incidence data; Burnett reports paradoxical relief of recurrent priapism with long-term low-dose PDE5 inhibition 411625163424492
  13. 2007 Margo reports the VA-cohort NAION ophthalmology data; Lewis publishes sildenafil-in-systolic-HF Circulation trials (exercise capacity and hemodynamics in HF with secondary pulmonary hypertension); Mehrotra reviews the role of PK/PD in PDE5-inhibitor therapy; Parker demonstrates safety of IV nitroglycerin 8 hours after sildenafil pretreatment 43539333
  14. 2008 PACES (Simonneau, Ann Intern Med) demonstrates clinical benefit of sildenafil added to long-term IV epoprostenol 59
  15. 2009 PHIRST (Galiè, Circulation) tests tadalafil in PAH, class-extension data informing PDE5-inhibitor practice; COMPASS-1 (Gruenig) reports acute hemodynamic effects of adding sildenafil to bosentan; Oliver/Webb characterize time-dependent attenuation of the sildenafil, nitroglycerin interaction; Maddox proposes a cellular-stress etiology for sudden hearing loss; Laties reviews PDE5-related vision disorders; Lin reviews PDE5 in the corpora cavernosa; Marmor's group publishes ERG data on daily high-dose sildenafil; Tsertsvadze publishes the AHRQ systematic review and harms meta-analysis 609432484137407172
  16. 2011 SUPER-2 long-term extension (Rubin, Chest) reports 2-year survival and safety with sildenafil monotherapy in adult PAH; Khan reports 'Viagra deafness' case-series in Laryngoscope; Guazzi reports 1-year sildenafil in HFpEF with pulmonary hypertension; Corbin/Francis describe allosteric conformational regulation of PDE5 6475636
  17. 2012 STARTS-1 (Barst, Circulation), randomized dose-ranging study of oral sildenafil in treatment-naive children with PAH 7
  18. 2013 Barreto & Bahmad review PDE5 inhibitors and sudden sensorineural hearing loss; FDA pediatric labeling warning issued following STARTS-2 mortality signal (Abman editorial summarizes implications); Redfield publishes the negative RELAX HFpEF JAMA trial; Roustit publishes the Raynaud meta-analysis; Yuan publishes the PDE5-inhibitor network meta-analysis in European Urology 1565546973
  19. 2014 STARTS-2 (Barst, Circulation), long-term pediatric survival data; higher mortality observed at the highest dose, informing dosing restriction; Damle publishes PK of a novel orodispersible tablet of sildenafil; Veronin and Venhuis publish quality/impurity and counterfeit-variability data on Internet-sourced sildenafil 8838788
  20. 2015 Sae Yoon publishes physicochemical and microbiological stability data for an extemporaneously compounded sildenafil oral suspension; AMBITION (Galiè, NEJM) demonstrates initial-combination superiority of ambrisentan + tadalafil, class-level evidence informing PDE5-inhibitor combination strategy; COMPASS-2 (McLaughlin, Eur Respir J) tests bosentan added to sildenafil; Borlaug publishes the RELAX ventricular/vascular function ancillary analysis 22615855
  21. 2016 Nahata publishes extended stability data for oral sildenafil for use in infants and young children 85
  22. 2017 Pomeranz publishes comprehensive review of erectile dysfunction agents and NAION in Neurologic Clinics 14
  23. 2018 Liu publishes a Taiwan population-based cohort study of sudden sensorineural hearing loss in PDE5-inhibitor users 49
  24. 2019 Liao publishes a Bayesian network meta-analysis of PDE5 inhibitors specifically in diabetic men with ED; Khouri publishes the secondary-Raynaud network meta-analysis 7470
  25. 2020 Penedones publishes the NAION meta-analysis across PDE5 inhibitors 46
  26. 2021 Pierce reports the multicenter trial of IV sildenafil in neonatal PPHN; Cheung publishes physical-chemical stability data for compounded sildenafil 100-mg rapid-dissolving tablets 6486
  27. 2022 Etminan publishes a JAMA Ophthalmology US claims-database cohort of ocular adverse events with PDE5 inhibitors 45
  28. 2023 Pels et al 66. publish the Cochrane review of nitric-oxide-pathway interventions (including sildenafil) for fetal growth restriction in pregnancy, net negative
  29. 2024 Thurman publishes phase 3 safety RCT of 3.6% topical sildenafil cream for female sexual arousal disorder; Wang publishes FAERS real-world pharmacovigilance analysis; Soulaidopoulos publishes the modern long-term cardiovascular outcomes meta-analysis; Burnett revisits NO physiology in the penis; Mewada publishes a taste-masked ODF formulation study 2116893984
  30. 2025 Jannini reviews sildenafil orodispersible film as a next-generation rapid-onset oral formulation; Luo publishes FAERS-based PDE5/hearing-impairment analysis 2350

Natural role

Biological Role of Compounded Sildenafil

Sildenafil is not endogenous. It engages the endogenous nitric-oxide / cGMP signaling pathway that governs vascular smooth-muscle tone in the corpus cavernosum, pulmonary vasculature, systemic vasculature, and other tissues. PDE5 is the predominant cGMP-hydrolyzing enzyme in those tissues, making it a clean pharmacologic target.

Because the mechanism requires upstream NO release, sildenafil's effect is conditional on the integrity of the patient's nitrergic and endothelial signaling 24. In severe diabetic or post-prostatectomy nerve damage, NO supply is limited and PDE5 inhibition alone may not restore function, a common reason for partial response.

Clinical contexts studied

Clinical Contexts for Compounded Sildenafil

Erectile dysfunction in adult men fda approved

FDA-approved indication for Viagra (and generic sildenafil tablets).

Goldstein 1998 NEJM RCT in 532 men across 21 US centers demonstrated dose-dependent improvement in erectile function (mean IIEF score 22 vs 12 at 100 mg vs placebo) with successful intercourse attempt rates of 69% vs 22% 1. FDA approved Viagra in March 1998. Generic sildenafil 25/50/100 mg tablets are widely available; standard dosing is 50 mg taken approximately one hour before sexual activity, adjustable to 25 or 100 mg by response and tolerability 2.

Branded product: Viagra (sildenafil citrate tablets, Pfizer; multiple generic manufacturers)

Pulmonary arterial hypertension (PAH) in adults fda approved

FDA-approved indication for Revatio (and generic sildenafil).

SUPER-1 5 randomized adults with PAH (WHO Group 1, Functional Class II, IV) to placebo or sildenafil 20, 40, or 80 mg TID for 12 weeks 4. Placebo-adjusted 6-minute walk distance improvement was 45, 50 m across active arms. SUPER-2 6 extended follow-up to 2 years and reported sustained walk-distance benefit with acceptable tolerability. Approved adult dose is 20 mg TID.

Branded product: Revatio (sildenafil citrate, Pfizer; generic available)

Pediatric pulmonary arterial hypertension fda approved

Studied in pivotal pediatric trials; pediatric oral suspension approved for Revatio. Dosing requires caution due to STARTS-2 mortality signal at highest doses.

STARTS-1 7 was a randomized dose-ranging study of low/medium/high-dose oral sildenafil in treatment-naive children 1, 17 years old with PAH over 16 weeks. STARTS-2 8 reported long-term survival in extension follow-up, with higher mortality observed at the highest weight-banded dose. FDA issued a labeling caution discouraging chronic use of higher doses in pediatric PAH on the basis of STARTS-2; the manufactured oral suspension is available for weight-banded pediatric dosing.

Branded product: Revatio (sildenafil citrate oral suspension, Pfizer)

Raynaud phenomenon (secondary to systemic sclerosis or resistant primary) well studied

Studied in small RCTs; off-label use with reasonable supportive evidence.

Fries 2005 (Circulation) randomized 16 patients with Raynaud phenomenon resistant to vasodilatory therapy to sildenafil 50 mg BID vs placebo crossover; the active arm showed reduced attack frequency, reduced cumulative attack duration, and improved capillary flow on nailfold capillaroscopy 18.

Hypoxia-related pulmonary vasoconstriction / high-altitude exercise capacity emerging

Studied in placebo-controlled crossover RCT; remains exploratory off-label use.

Ghofrani 2004 (Ann Intern Med) randomized healthy mountaineers to sildenafil vs placebo in a double-blind crossover at low altitude under hypoxia and at Mt 17. Everest base camp. Sildenafil 40 mg or 80 mg improved exercise capacity and reduced pulmonary vascular resistance under hypoxic conditions. This trial established mechanistic plausibility for altitude use but does not constitute regulatory or routine clinical recommendation.

Female sexual arousal disorder emerging

Studied in small RCTs and a recent topical-cream phase 3 program. Evidence remains limited; no FDA-approved oral sildenafil indication in women.

Caruso 2001 (BJOG) and Caruso 2006 (Fertil Steril, in premenopausal women with type 1 diabetes) reported modest improvements in arousal-domain measures with oral sildenafil vs placebo in double-blind crossover designs 1920. More recently, Thurman 2024 (J Sex Med) reported phase 3 safety data for a 3.6% topical sildenafil cream formulation; efficacy results are reported in companion publications 21. No FDA-approved sildenafil product for FSAD exists at the time of writing.

Post-prostatectomy erectile rehabilitation well studied

Studied in dedicated RCTs; on-demand use after surgery is broadly accepted, but nightly prophylactic rehabilitation showed limited benefit.

Padma-Nathan 2008 (Int J Impot Res) randomized 76 men after bilateral nerve-sparing radical prostatectomy to nightly sildenafil 50 or 100 mg vs placebo for 36 weeks 24. The active arm showed improvement in spontaneous erectile function vs placebo at the post-treatment evaluation, though absolute response rates remained modest and the trial has been a touchstone in subsequent debate over rehabilitation strategies.

Erectile dysfunction in diabetes mellitus fda approved

FDA-approved indication overall; specific evidence supporting diabetic-ED efficacy from dedicated trials.

Rendell 1999 (JAMA, N=268) demonstrated successful intercourse rates of 56% on sildenafil vs 10% on placebo in men with diabetes-related ED 76. Boulton 2001 (Diabetologia, N=219) confirmed efficacy in type 2 diabetes 75. Liao 2019 (World J Urol) network meta-analysis confirmed broadly comparable efficacy of sildenafil, tadalafil, vardenafil, avanafil, and udenafil in diabetic men 74.

Branded product: Viagra and generic sildenafil

Erectile dysfunction after spinal cord injury fda approved

FDA-approved indication overall; specific quality-of-life and efficacy data from dedicated SCI trials.

Hultling 2000 (Spinal Cord, N=178) reported significant improvement in successful intercourse and quality-of-life endpoints with sildenafil in men with spinal cord injury, providing the dedicated-population evidence for routine use of sildenafil in SCI-related ED 78.

Branded product: Viagra and generic sildenafil

Pulmonary arterial hypertension combination therapy well studied

Sildenafil + endothelin-receptor antagonist or + prostacyclin: evidence base for sequential and initial-combination strategies.

PACES 59 showed improvement in 6MWD and time-to-clinical-worsening when sildenafil was added to long-term IV epoprostenol. COMPASS-1 94 characterized acute hemodynamic effects of adding sildenafil to bosentan. COMPASS-2 58 did not show event-driven benefit of adding bosentan to sildenafil. AMBITION 61 demonstrated superiority of initial combination ambrisentan + tadalafil vs monotherapy, class precedent for upfront combination PDE5i + ERA. SERAPH 57 was an early head-to-head of sildenafil vs bosentan.

Branded product: Revatio and generic sildenafil

Heart failure with preserved or reduced ejection fraction well studied

Studied but not FDA-approved; multicenter HFpEF evidence is negative.

Single-center HFrEF and HFpEF trials with secondary pulmonary hypertension 52 reported short-term improvements in exercise capacity and pulmonary hemodynamics 5356. The multicenter RELAX trial in unselected HFpEF 54 was negative for the primary endpoint of peak VO2; the Borlaug 2015 ancillary analysis confirmed no benefit on ventricular or vascular function 55. Current guidance does not support routine sildenafil for HFpEF.

Persistent pulmonary hypertension of the newborn (PPHN) emerging

Off-label in many settings; off-label in centers without iNO/ECMO; multicenter trial of IV sildenafil added to iNO is negative for accelerated weaning.

Baquero 2006 (Pediatrics) pilot RCT in 13 neonates without iNO/ECMO availability showed oxygenation improvement and survival benefit with oral sildenafil 63. The Pierce 2021 multicenter trial (J Pediatr, N=59) of IV sildenafil added to inhaled NO did not significantly accelerate iNO weaning or reduce treatment failure but established acceptable safety 64. Use is restricted to PPHN-experienced centers.

Off-label use

Off-Label Uses of Compounded Sildenafil

Raynaud phenomenon well studied

Off-label use with small RCT support; appropriate as a clinician-directed trial in patients with severe disease resistant to standard vasodilators.

See clinical context above 18. Off-label use is established in rheumatology practice for severe or refractory cases.

High-altitude pulmonary hypertension / exercise capacity emerging

Off-label, exploratory. Evidence is mechanistic and short-term.

Ghofrani 2004 demonstrated short-term exercise-capacity improvement under hypoxia, but routine prophylactic use for altitude illness is not established 17.

Female sexual arousal disorder emerging

Off-label for oral sildenafil; topical 3.6% cream is investigational.

Small RCTs 19 suggested modest oral effects; recent work 21 is evaluating a 3.6% topical cream formulation 20.

FDA-approved use

FDA-Approved Uses of Compounded Sildenafil

BrandIndicationYearRoute
Viagra Erectile dysfunction in adult men 1998 Oral tablet (25 mg, 50 mg, 100 mg)
Revatio Pulmonary arterial hypertension (WHO Group 1) to improve exercise ability and delay clinical worsening, adults 2005 Oral tablet (20 mg), oral suspension, intravenous
Revatio (pediatric oral suspension) Pediatric PAH dosing in children 1, 17 years (with FDA labeling caution against chronic use of higher doses based on STARTS-2 mortality signal) — Oral suspension

Viagra (sildenafil citrate, 25/50/100 mg oral tablets) was FDA-approved March 27, 1998 for erectile dysfunction in adult men 1. Approval was supported by the Goldstein 1998 NEJM trial and a broader phase III program in 3,000+ men. Generic sildenafil citrate tablets are widely available since US patent expiry.

Revatio (sildenafil citrate, 20 mg oral tablet TID; oral suspension; intravenous) was FDA-approved June 3, 2005 for pulmonary arterial hypertension in adults, on the basis of SUPER-1 5 with extension support from SUPER-2 6 72526. A pediatric oral suspension was subsequently labeled, with an FDA caution following STARTS-2 8 regarding chronic high-dose use in children.

The label carries an absolute contraindication with nitrates (any form, any indication, risk of life-threatening hypotension) and with the soluble guanylate cyclase stimulator riociguat. Cardiovascular caution applies to alpha-blocker co-administration and to severe baseline hypotension or unstable cardiovascular disease 10.

Compounded use

Compounded Compounded Sildenafil (503A)

Generic sildenafil citrate tablets are commercially available at low cost in all FDA-approved strengths (25/50/100 mg for Viagra-equivalent; 20 mg for Revatio-equivalent), and Revatio is available as a manufactured oral suspension for pediatric weight-banded dosing 22. RonanRx dispenses compounded sildenafil under 503A only when the prescribing clinician documents a patient-specific clinical reason that the manufactured product cannot meet.

Legitimate compounded use cases include: (1) sublingual troches or rapid-dissolve preparations for patients who require faster onset than the oral tablet, who have swallowing difficulty, or who cannot tolerate the tablet's excipients; (2) custom dose strengths for partial responders who do not benefit from the available manufactured strengths; (3) pediatric oral suspensions when the manufactured Revatio suspension is not appropriate or available; and (4) combination preparations where a single formulation simplifies adherence for a specific patient.

Per FDA guidance for industry on compounding under 503A, a compound that is essentially a copy of a commercially available drug is generally restricted unless the prescriber has determined a clinical difference for the identified patient 2728. Because generic sildenafil tablets are inexpensive and widely available, the bar for compounded sildenafil is the documentation of a specific clinical need, RonanRx does not fill prescriptions for compounded sildenafil that read as routine substitution for generic Viagra or Revatio.

Formulations and routes

Compounded Sildenafil Formulations and Routes

FormConcentrationDescription
Sublingual troche (compounded) Custom (commonly 25, 100 mg per troche) Slow-dissolve buccal/sublingual matrix designed for partial pre-gastric absorption. Used when patients require faster perceived onset than the oral tablet or cannot use oral tablets. PK profile differs from the manufactured tablet and has not been characterized in head-to-head bioequivalence studies.
Oral capsule (compounded) Custom strengths (e.g., 10, 15, 35, 60 mg) Custom-strength capsules for patients who require a dose between or below manufactured tablet strengths. Prepared per USP <795> non-sterile compounding standards.
Oral suspension (compounded, pediatric) Commonly 2.5 mg/mL or 10 mg/mL Weight-banded liquid preparation for pediatric PAH dosing when the manufactured Revatio suspension is not appropriate or available. Sae Yoon 2015 published physicochemical and microbiological stability data for an extemporaneously compounded sildenafil citrate oral suspension.22
Topical cream (investigational) 3.6% (per Thurman 2024 program) Topical formulation studied in a phase 3 program for female sexual arousal disorder. Not FDA-approved. Mentioned here as the published literature context; not a routine RonanRx compounded preparation.21
Orodispersible film (manufactured / investigational) 50 mg, 100 mg Manufactured rapid-dissolve oral film studied as a next-generation formulation; reviewed by Jannini 2025. Listed here as the literature reference for comparative formulation discussion; not a RonanRx compounded preparation.23

Routes used in published literature: oral, sublingual, troche, intravenous.

Dosing

Compounded Sildenafil Dosing

RoutePopulationRangeDurationStudy type
Oral (tablet) Adults with erectile dysfunction (FDA-label population) 50 mg approximately 1 hour before sexual activity; adjustable to 25 mg or 100 mg by response and tolerability; maximum once daily On-demand FDA-approved labeled regimen; mirrored by generic sildenafil1
Oral (tablet) Adults with pulmonary arterial hypertension (FDA-label population) 20 mg three times daily, approximately 4, 6 hours apart Chronic FDA-approved labeled regimen based on SUPER-156
Intravenous Adults with PAH unable to take oral therapy temporarily 10 mg IV three times daily (label-equivalent to 20 mg oral TID) Bridging while oral route unavailable FDA-approved labeled regimen5
Oral suspension Pediatric PAH, ages 1, 17 years Weight-banded per Revatio label; FDA labeling cautions against chronic use of higher doses in children based on STARTS-2 Chronic FDA-labeled pediatric regimen informed by STARTS-1 and STARTS-278
Oral (tablet) Adults with severe renal impairment, severe hepatic impairment, or on strong CYP3A4 inhibitors Reduced starting dose (e.g., 25 mg for ED) and slower up-titration; consult product labeling for indication-specific reductions Per indication FDA-label population-specific guidance9
Sublingual troche (compounded) Adults for whom manufactured tablet is not appropriate (per prescriber-documented reason) Custom strength selected by the prescribing clinician; on-demand or as directed On-demand or as directed Compounded formulation under 503A; PK not bioequivalent to manufactured tablet27

Doctor-prescribed and titrated. The Viagra label-defined starting dose of 50 mg for ED can be adjusted to 25 or 100 mg by response and tolerability. The Revatio label specifies 20 mg three times daily for adult PAH. Pediatric PAH dosing is weight-banded per the Revatio oral suspension label, with an FDA-mandated caution against chronic use of higher pediatric doses based on STARTS-2 mortality data 8 9.

Dose reductions are required with strong CYP3A4 inhibitors (ketoconazole, itraconazole, ritonavir, clarithromycin), sildenafil exposure can rise multifold 5910. Avoid concomitant nitrates absolutely. Caution with alpha-blockers (additive hypotension), particularly within 4 hours of dosing.

Compounded preparations should not exceed the FDA-label maximum daily exposure equivalents in routine prescribing. Sublingual troche dosing requires clinical judgment because the PK is not bioequivalent to the oral tablet 1.

Doses listed are literature context, not patient instructions. Dosing decisions are made by the prescribing doctor and tailored to the individual patient.

Safety

Compounded Sildenafil Safety

Safety overview

Sildenafil's safety profile is one of the most extensively characterized in modern pharmacology, with thousands of trial-years across ED and PAH indications and 25+ years of post-marketing surveillance 16. Modern syntheses include Wang 2024 (FAERS pharmacovigilance), Soulaidopoulos 2024 (long-term cardiovascular outcomes meta-analysis), and Tsertsvadze 2009 (AHRQ harms meta-analysis) 8972 49. Common adverse events are headache, flushing, dyspepsia, nasal congestion, mild visual disturbance (blue-tinged vision, increased light sensitivity, attributable to weak PDE6 cross-inhibition characterized by Marmor's ERG work [Zoumalan 2009] and reviewed by Laties 2009), and back pain 4041 95. The majority are mild to moderate and dose-related.

Serious but rare adverse events: nonarteritic anterior ischemic optic neuropathy (NAION), Pomeranz 2005 (case series), Pomeranz 2017 (review), case-control work by McGwin 2006, Gorkin 2006, and Margo 2007, claims-database cohort by Etminan 2022, and meta-analysis by Penedones 2020 501314. Patients with small optic disc cup-to-disc ratio, hypertension, diabetes, or hypercholesterolemia are at higher baseline risk 444345. Sudden sensorineural hearing loss, case-series by Khan 2011, mechanistic hypothesis by Maddox 2009, population cohort by Liu 2018, and FAERS analyses by Barreto 2013, Zhang 2024, and Luo 2025 154748. Priapism (erection >4 hours) is rare and requires emergent urologic evaluation; paradoxically, long-term low-dose oral PDE5 inhibition has been used to alleviate recurrent stuttering priapism in selected patients 92.

Cardiovascular safety is dominated by the absolute nitrate contraindication. Sildenafil-nitrate coadministration produces profound additive hypotension that can be fatal, characterized hemodynamically by Webb 1999, Webb 2000, Oliver/Webb 2009 (time-course), and Parker 2007 (8-hour washout supports IV nitroglycerin safety in coronary disease) 3233. The ACC/AHA expert consensus document 10 codified the contraindication and the alpha-blocker caution (quantified by Kloner 2004 in healthy normotensives) 91. Subsequent updates (Padma-Nathan 2002 4-year safety, Jackson 2006 updated perspective, Soulaidopoulos 2024 long-term meta) confirmed an acceptable-to-favorable cardiovascular profile in patients without contraindications 1211. Vlachopoulos 2004 even demonstrated acute reversal of smoking-induced endothelial dysfunction 90 4246. In pregnancy, the Pels 2023 Cochrane review and the discontinued Dutch STRIDER trial argued against routine antenatal sildenafil for fetal growth restriction following an adverse-events signal 303166.

Contraindications

Absolute contraindications: concomitant use of any nitrate in any form (organic nitrate, nitrite, nitric oxide donor; for cardiac, recreational, or other indication), risk of life-threatening additive hypotension; concomitant use of riociguat (soluble guanylate cyclase stimulator); known hypersensitivity to sildenafil or excipients 10.

Relative contraindications and cautions: severe baseline hypotension; unstable angina or recent myocardial infarction; severe hepatic impairment; severe renal impairment (initial dose reduction); concomitant strong CYP3A4 inhibitors (dose reduction); concomitant alpha-blocker therapy (initiate at lowest sildenafil dose, separate dosing by ~4 hours); known history of NAION (relative contraindication, the second eye is at risk); known retinitis pigmentosa (theoretical concern via PDE6) 1011.

Pediatric PAH: FDA labeling cautions against chronic use of higher doses in children based on the STARTS-2 mortality signal 8 14.

Drug interactions

Absolute interaction: nitrates and nitric-oxide donors in any form, additive cGMP accumulation and profound hypotension. Includes nitroglycerin, isosorbide mono- and dinitrate, amyl nitrite (poppers), and sodium nitroprusside. Webb 1999 and Webb 2000 quantified the additive hypotensive effect with organic nitrate and NO donors respectively; Oliver/Webb 2009 showed that the interaction is most severe within 4 hours of sildenafil and substantially attenuated by 8 hours, and Parker 2007 demonstrated that IV nitroglycerin can be safely administered to men with coronary disease at least 8 hours after sildenafil, basis for the conservative 24-hour washout convention 103031. Riociguat (a soluble guanylate cyclase stimulator) is similarly contraindicated.

Pharmacokinetic interactions: sildenafil is metabolized predominantly by CYP3A4 (major pathway) with minor contribution from CYP2C9 9 32. Strong CYP3A4 inhibitors substantially elevate exposure, ritonavir/saquinavir produces ~11-fold AUC increase 82; erythromycin and azithromycin produce smaller but clinically meaningful increases (Muirhead 2002 erythromycin/azithromycin study) 81. Dose reductions are required (e.g., starting dose 25 mg with ritonavir, lower limits in PAH). Strong CYP3A4 inducers (rifampin, carbamazepine, St John's wort) reduce sildenafil exposure 33.

Pharmacodynamic interactions: alpha-blockers (doxazosin, tamsulosin) produce additive hypotension, Kloner 2004 quantified the interaction in healthy normotensive men 91. Sildenafil should be initiated at the lowest dose with established alpha-blocker therapy, ideally with at least 4 hours separation 1193. Antihypertensives in general produce a small additive blood-pressure effect that is usually clinically tolerable.

Wang 2024 FAERS pharmacovigilance analysis and Soulaidopoulos 2024 long-term outcomes meta-analysis summarize real-world post-marketing interaction signals 1689.

Adverse events

Common (>5%): headache (incidence ~16% in ED trials), flushing (~10%), dyspepsia (~7%), nasal congestion (~4, 10%), visual disturbance (blue tinge, light sensitivity, dose-related, ~3, 11% at 100 mg), back pain, myalgia. Most are mild to moderate and resolve with drug clearance over 4, 8 hours 30. The Tsertsvadze 2009 AHRQ harms meta-analysis pooled the AE landscape across class 72.

Rare but serious: nonarteritic anterior ischemic optic neuropathy (NAION) 424346. Pomeranz 2005 reported a case series of seven patients developing NAION soon after sildenafil use 13 31. Case-control and cohort follow-ups 44 and the modern claims-database cohort 45 consistently identified a small but real signal, summarized in the Penedones 2020 meta-analysis 95. Patients with small optic disc cup-to-disc ratio, hypertension, diabetes, or hyperlipidemia have higher baseline NAION risk 14. Vision biology is grounded in PDE6 cross-inhibition characterized by the Marmor group (Zoumalan 2009 ERG study) and reviewed by Laties 2009 4041 12.

Sudden sensorineural hearing loss (often unilateral) has been reported as a post-marketing signal across all PDE5 inhibitors 474849. Case-series by Khan 2011 popularized the 'Viagra deafness' label; Maddox 2009 proposed a cellular-stress etiology; Liu 2018 produced the strongest population-cohort evidence (Taiwan NHI), and modern FAERS analyses 15 confirm the disproportionality signal at the class level 50.

Priapism (erection >4 hours) is rare and requires emergent urologic evaluation. Burnett 2006 reported the paradoxical use of low-dose long-term oral PDE5 inhibition to alleviate recurrent stuttering priapism in selected sickle-cell and other susceptible men 92.

Cardiovascular: sildenafil produces a small (~8/5 mmHg) transient blood-pressure reduction at therapeutic doses 9; clinically important hypotension is uncommon in patients without contraindications 11. Modern long-term outcomes meta-analysis 89 suggests neutral-to-favorable cardiovascular signal. Real-world FAERS pharmacovigilance 16 catalogs the post-marketing AE landscape.

Monitoring

Monitoring Compounded Sildenafil Therapy

ED indication: no routine laboratory monitoring is required for healthy adult men starting sildenafil 5. Cardiovascular risk should be screened at baseline (per the Princeton consensus framework, patients with active cardiac symptoms should be evaluated before sexual activity is resumed) 11. Re-assess response at 4, 6 weeks; adjust dose by response and tolerability.

PAH indication: baseline and on-therapy monitoring includes 6-minute walk distance, WHO functional class, BNP/NT-proBNP, echocardiogram, and (per center practice) periodic right-heart catheterization. Liver function should be checked if hepatic impairment is suspected.

Patients should be counseled to seek prompt evaluation for sudden visual change (NAION risk), sudden hearing loss, or erection lasting more than 4 hours 14.

Special populations

Compounded Sildenafil in Special Populations

Pregnancy

Sildenafil is not approved for use in pregnancy. The Pels 2023 Cochrane systematic review of nitric-oxide-pathway interventions (including sildenafil) for fetal growth restriction found no benefit on perinatal mortality or morbidity 66. The Dutch STRIDER trial was halted early after a signal of higher rates of pulmonary hypertension among neonates in the sildenafil arm. Current recommendation is against routine antenatal sildenafil for FGR. Treatment of PAH that predates or arises during pregnancy is managed individually by experienced multidisciplinary teams.

Pediatric

Pediatric PAH (ages 1, 17) is the only FDA-approved pediatric indication, supported by STARTS-1 7 and STARTS-2 8. STARTS-2 found higher mortality at the highest weight-banded dose, prompting an FDA labeling caution against chronic high-dose pediatric use 65. Compounded oral suspensions are dispensed only when the manufactured Revatio suspension is not appropriate or available, on a patient-specific prescription with documented clinical reason. Pharmacy-grade extended stability is supported by Sae Yoon 2015 and Nahata 2016 2285.

Neonatal persistent pulmonary hypertension (PPHN) is a separate context: the Baquero 2006 pilot in low-resource settings reported a survival benefit, but the Pierce 2021 multicenter trial of IV sildenafil added to inhaled NO did not significantly accelerate iNO weaning or reduce treatment failure 6364. Use is therefore reserved for centers with PPHN expertise and is typically off-label.

Sildenafil is not approved for pediatric ED or other non-PAH indications 22.

Geriatric

Sildenafil clearance is reduced in adults over 65 years, Muirhead 2002 (Br J Clin Pharmacol) quantified an approximately 50% reduction in elderly subjects vs young volunteers 807912. The ED label recommends consideration of a 25 mg starting dose 9. Wagner 2001 published the elderly-subgroup analysis from the phase III ED program demonstrating preserved efficacy. Cardiovascular comorbidity and nitrate use are more common in this population and must be screened. PAH dosing is not formally age-adjusted but caution is warranted.

Renal impairment

Severe renal impairment (CrCl <30 mL/min) reduces sildenafil clearance approximately 2-fold per Muirhead 2002; starting dose reductions are recommended for the ED indication (25 mg) 809. Revatio PAH dosing does not require routine adjustment in renal impairment per the manufacturer label, but caution is appropriate given the chronic nature of treatment.

Hepatic impairment

Moderate hepatic impairment (Child-Pugh class B) reduces sildenafil clearance approximately 47% per Muirhead 2002; dose reduction is recommended for the ED indication 809. Severe hepatic impairment (Child-Pugh class C) has not been adequately studied; the Revatio label notes caution and consideration of dose reduction in moderate impairment for PAH.

Evidence quality

Compounded Sildenafil Evidence Quality

Evidence for the manufactured products is strong 757879. ED indication: Goldstein 1998 (NEJM, N=532) plus the broader phase III program 77 120. Adult PAH indication: SUPER-1 5 and SUPER-2 extension 6, with class-extension data from SERAPH 57, PHIRST 60, AMBITION 61, and combination trials PACES 59, COMPASS-1 94, and COMPASS-2 58. Severe PAH including Eisenmenger physiology: Singh 2006 745152. Pediatric PAH: STARTS-1 7 and STARTS-2 8 45. Neonatal PPHN: Baquero 2006 pilot and Pierce 2021 multicenter RCT 565543. Twenty-five-plus years of post-marketing surveillance (Padma-Nathan 2002 4-year update; Jackson 2006; Wang 2024 FAERS; Soulaidopoulos 2024 long-term CV meta-analysis) confirm the cardiovascular safety profile when contraindications are observed and characterize the rare-event landscape (NAION, Pomeranz 2005/2017, McGwin 2006, Gorkin 2006, Margo 2007, Etminan 2022, Penedones 2020 meta; sudden hearing loss, Barreto 2013, Maddox 2009, Khan 2011, Liu 2018, Zhang 2024, Luo 2025; priapism, Burnett 2006) 121189.

Class-level network meta-analyses (Tsertsvadze 2009 AHRQ Ann Intern Med, Yuan 2013 European Urology, Liao 2019 in diabetic ED) confirm broadly comparable within-class efficacy of PDE5 inhibitors 461548. Heart-failure evidence is mixed: Bocchi 2002, Lewis 2007, and Guazzi 2011 reported single-center benefit in HFrEF/HFpEF with secondary pulmonary hypertension, but the multicenter RELAX trial 54 and the Borlaug 2015 ventricular-function ancillary analysis were negative in unselected HFpEF, argues against routine sildenafil for HFpEF 6364.

Off-label evidence is heterogeneous 161344. Raynaud phenomenon has RCT support 18 plus meta-analysis 69, clinically useful as a second-line option 70. Altitude exercise capacity has crossover RCT support 17 with class confirmation from Maggiorini 2006 (tadalafil/dexamethasone HAPE prevention) 62 53. Female sexual arousal disorder has small placebo-controlled trials of oral sildenafil 19 and a recent topical-cream phase 3 program 21, evidence remains preliminary in all cases 92. Pregnancy: the Pels 2023 Cochrane review and the discontinued Dutch STRIDER trial argue against antenatal sildenafil for fetal growth restriction 66 5073.

Evidence specifically supporting compounded preparations is limited 676876. Sae Yoon 2015, Nahata 2016, and Cheung 2021 published physicochemical stability data for compounded oral suspensions and rapid-dissolving tablets respectively 228586. PK data for the manufactured orodispersible tablet 83 and a novel taste-masked ODF 84 are the closest comparator literature for compounded rapid-onset forms, though compounded troches and ODFs are not bioequivalent to either the manufactured tablet or the manufactured ODT 71. There is no parallel efficacy program for compounded troches, custom-strength capsules, or topical preparations; compounded use is therefore an extrapolation from the manufactured-product evidence base, justified case by case by patient-specific clinical factors 474995. Counterfeit and Internet-sourced sildenafil shows substantial API and impurity variability 87, arguing for licensed-pharmacy sourcing 144288.

Major studies

Major Compounded Sildenafil Clinical Studies

StudyDesignParticipantsDurationFinding
Goldstein 1998, Oral sildenafil in the treatment of erectile dysfunction (NEJM) Multicenter randomized double-blind placebo-controlled 532 24 weeks Sildenafil 25/50/100 mg produced dose-dependent improvement in erectile function (IIEF Q3 and Q4) and successful intercourse attempts (69% vs 22% placebo at 100 mg); foundational evidence for FDA approval of Viagra 1.
Boolell 1996, Sildenafil PDE5 mechanism (Int J Impot Res) and first clinical erectogenic data (Br J Urol) Mechanistic + early clinical — Early-phase Established sildenafil as an orally active, selective PDE5 inhibitor and reported its erectogenic effect in men, motivating the phase III program 23.
SUPER-1 (Galiè 2005, NEJM) Phase III randomized double-blind placebo-controlled 278 12 weeks Sildenafil 20/40/80 mg TID improved 6-minute walk distance by 45, 50 m placebo-adjusted in adults with PAH (WHO Group 1, FC II, IV); supported FDA approval of Revatio 5.
SUPER-2 (Rubin 2011, Chest) Open-label long-term extension 259 (of SUPER-1 enrollees continuing) Up to 3 years Sustained walk-distance benefit and acceptable tolerability with long-term sildenafil monotherapy in adult PAH 6.
STARTS-1 (Barst 2012, Circulation) Randomized double-blind placebo-controlled dose-ranging 235 16 weeks Oral sildenafil at low, medium, and high weight-banded doses improved exercise capacity and hemodynamics in treatment-naive children 1, 17 years old with PAH 7.
STARTS-2 (Barst 2014, Circulation) Long-term extension of STARTS-1 234 Up to ~7 years Long-term survival data showed higher mortality at the highest weight-banded dose vs lower doses, prompting FDA pediatric labeling caution against chronic high-dose use 8.
Nichols 2002 (Br J Clin Pharmacol) Single-dose human PK Healthy male volunteers Single dose Absolute oral bioavailability ~41%, Tmax ~1 h fasting, dose proportionality across studied range, food (especially high-fat meal) delays absorption 9.
Fries 2005 (Circulation), Sildenafil for Raynaud phenomenon Randomized double-blind placebo-controlled crossover 16 4 weeks per arm Sildenafil 50 mg BID reduced attack frequency and cumulative duration vs placebo in patients with Raynaud refractory to standard vasodilators 18.
Ghofrani 2004 (Ann Intern Med), Sildenafil at altitude Randomized double-blind placebo-controlled crossover 14 Single dose under hypoxia and at Mt. Everest base camp Sildenafil 40/80 mg improved exercise capacity and reduced pulmonary vascular resistance under hypoxia 17.
Caruso 2001 (BJOG) and Caruso 2006 (Fertil Steril), Sildenafil for female sexual arousal disorder Randomized double-blind placebo-controlled crossover varied (small) weeks Modest improvements in arousal-domain measures with oral sildenafil vs placebo in premenopausal women with FSAD; trial sizes are small and the FDA has not approved sildenafil for FSAD 1920.
Thurman 2024 (J Sex Med), Topical 3.6% sildenafil cream for FSAD safety Randomized placebo-controlled phase 3 safety study Phase 3 safety population 12 weeks Demonstrated safety profile of 3.6% topical sildenafil cream in women with FSAD; efficacy reported in companion papers 21. Not FDA-approved.
Wang 2024 (Andrology), FAERS pharmacovigilance analysis Disproportionality analysis of FDA Adverse Event Reporting System — Cumulative post-marketing Catalogs real-world AE signals for sildenafil including cardiovascular, ocular, otologic, and priapism events; consistent with the established label 16.
Padma-Nathan 2008 (Int J Impot Res), Nightly sildenafil for post-prostatectomy rehabilitation Randomized double-blind placebo-controlled 76 36 weeks treatment, post-treatment evaluation Nightly sildenafil 50 or 100 mg improved spontaneous erectile function vs placebo after bilateral nerve-sparing radical prostatectomy 24.
Sae Yoon 2015 (Sci Pharm), Compounded sildenafil oral suspension stability Physicochemical and microbiological stability study — Up to 90 days Established stability parameters for an extemporaneously compounded sildenafil citrate oral suspension; supports pharmacy-prepared pediatric liquid use 22.
Ghofrani 2006 (Nat Rev Drug Discov), Sildenafil from angina to ED to PAH Comprehensive narrative review — N/A Reviews the discovery program, mechanism, clinical-development trajectory across indications, and the cardiovascular safety framework 4.
Rendell 1999 (JAMA), Sildenafil for erectile dysfunction in diabetic men Multicenter randomized double-blind placebo-controlled 268 12 weeks Successful intercourse rates 56% on sildenafil vs 10% on placebo in men with diabetes-related ED; foundational evidence for routine ED treatment in this difficult-to-treat subgroup 76.
Hultling 2000 (Spinal Cord), Sildenafil for ED in spinal cord injury Multicenter randomized double-blind placebo-controlled 178 Crossover and open-label extension Significant improvement in successful intercourse and QoL endpoints with sildenafil in men with spinal cord injury 78.
Boulton 2001 (Diabetologia), Sildenafil in T2DM-related ED Multicenter randomized double-blind placebo-controlled 219 12 weeks Sildenafil produced significant improvement in IIEF erectile function vs placebo in men with type 2 diabetes; safety profile comparable to general ED trials 75.
Webb 1999/2000 (Am J Cardiol; JACC), Sildenafil, nitrate hemodynamic interaction studies Controlled crossover human PK/PD studies — Single dose Sildenafil substantially potentiates the hypotensive effects of organic nitrates and NO donors; basis for the absolute nitrate contraindication 3031.
Oliver 2009 (Br J Clin Pharmacol), Time-dependent sildenafil, GTN interaction Double-blind randomized human crossover — Single dose with time-staggered nitrate The blood-pressure interaction is most severe within 4 hours of sildenafil dosing and is substantially attenuated by 8 hours, basis for the 24-hour washout convention 32.
Kloner 2004 (J Urol), PDE5 inhibitor + alpha-blocker interaction Randomized double-blind placebo-controlled crossover in healthy normotensive men — Single dose Quantifies the additive hypotensive effect of PDE5 inhibition added to doxazosin or tamsulosin; informs label-recommended dose-staggering of PDE5i with alpha-blockers 91.
Singh 2006 (Am Heart J), Sildenafil in severe PAH including Eisenmenger physiology Randomized placebo-controlled double-blind crossover 20 6 weeks each phase Oral sildenafil improved 6-minute walk distance and reduced pulmonary vascular resistance vs placebo in severe PAH 51.
Wilkins 2005 (Am J Respir Crit Care Med), SERAPH (sildenafil vs bosentan) Open-label randomized comparator 26 16 weeks Sildenafil and bosentan produced broadly comparable improvements in exercise capacity and hemodynamics in adult PAH; sildenafil reduced right-ventricular mass on cardiac MRI 57.
Simonneau 2008 (Ann Intern Med), PACES (sildenafil added to epoprostenol) Randomized double-blind placebo-controlled 267 16 weeks Adding sildenafil to long-term IV epoprostenol significantly improved 6MWD, hemodynamics, and time-to-clinical-worsening in adult PAH 59.
McLaughlin 2015 (Eur Respir J), COMPASS-2 (bosentan added to sildenafil) Event-driven randomized double-blind placebo-controlled 334 Median ~3 years Adding bosentan to sildenafil did not significantly reduce time to first morbidity/mortality event vs sildenafil alone, informs combination-therapy sequencing 58.
Galiè 2015 (NEJM), AMBITION Randomized double-blind active-comparator 500 Event-driven (median ~520 days) Initial combination of ambrisentan + tadalafil reduced clinical-failure events vs monotherapy with either drug, class-level evidence for upfront combination PDE5i + ERA strategy that informs sildenafil practice 61.
Galiè 2009 (Circulation), PHIRST tadalafil in PAH Phase III randomized double-blind placebo-controlled 405 16 weeks Tadalafil 40 mg daily improved 6MWD and time-to-clinical-worsening, establishes class-level PDE5-inhibitor labeling for PAH 60.
Maggiorini 2006 (Ann Intern Med), Tadalafil/dexamethasone HAPE prevention Randomized double-blind placebo-controlled 29 Rapid ascent to 4,559 m Both tadalafil and dexamethasone reduced HAPE incidence vs placebo, class-level support for PDE5 inhibition in altitude pulmonary edema, consistent with sildenafil data from Ghofrani 2004 62.
Baquero 2006 (Pediatrics), Sildenafil in PPHN Pilot randomized blinded 13 Up to 72 h Oral sildenafil improved oxygenation and survival vs placebo in neonates with PPHN where inhaled NO and ECMO were unavailable 63.
Pierce 2021 (J Pediatr), IV sildenafil for PPHN (SPED-3) Multicenter randomized double-blind placebo-controlled 59 Up to 14 days IV sildenafil added to inhaled NO did not significantly accelerate iNO weaning or reduce treatment failure in neonates with PPHN; safety was acceptable 64.
Bocchi 2002 (Circulation), Sildenafil in advanced systolic heart failure Double-blind placebo-controlled randomized 23 Single dose plus open-label extension Sildenafil improved exercise capacity and reduced sympathoneural activation in advanced CHF; foundational signal motivating subsequent HF programs 52.
Lewis 2007 (Circulation), Sildenafil in systolic HF with secondary PH Randomized double-blind placebo-controlled 34 12 weeks Sildenafil 50 mg TID improved peak VO2, 6MWD, and QoL in HFrEF with pulmonary hypertension 53.
Guazzi 2011 (Circulation), 1-year sildenafil in HFpEF with PH Randomized double-blind placebo-controlled 44 12 months Long-term sildenafil improved pulmonary hemodynamics, RV function, and exercise capacity in HFpEF with pulmonary hypertension, single-center, contrasts with multicenter RELAX 56.
Redfield 2013 (JAMA), RELAX in HFpEF Multicenter randomized double-blind placebo-controlled 216 24 weeks Sildenafil did not improve exercise capacity or clinical status vs placebo in unselected HFpEF; argues against routine PDE5 inhibition in this population 54. Borlaug 2015 ancillary analysis confirmed no benefit on ventricular or vascular function 55.
Etminan 2022 (JAMA Ophthalmol), Ocular AE cohort in US men Retrospective claims-database cohort 213,033 PDE5i users Up to 7 years PDE5 inhibitor use was associated with an increased rate of serous retinal detachment, retinal vascular occlusion, and ischemic optic neuropathy vs non-users, incident rate ~15.5 per 10,000 person-years for any of the three combined 45.
Penedones 2020 (Acta Ophthalmol), NAION systematic review and meta-analysis Systematic review and meta-analysis of observational studies — Cumulative Significantly increased risk of NAION with PDE5 inhibitor use (pooled OR consistent across studies), particularly in men with predisposing optic-disc anatomy or vascular risk factors 46.
Liu 2018 (Pharmacoepidemiol Drug Saf), PDE5 inhibitors and SSNHL cohort Population-based cohort (Taiwan NHI) >25,000 users 5-year follow-up Increased adjusted hazard of sudden sensorineural hearing loss in PDE5-inhibitor users vs matched non-users; consistent with FAERS analyses by Zhang 2024 and Luo 2025 499550.
Soulaidopoulos 2024 (Eur Heart J Cardiovasc Pharmacother), Long-term CV outcomes meta-analysis Systematic review and meta-analysis of long-term PDE5-inhibitor studies — Cumulative PDE5 inhibitor use was associated with reduced cardiovascular events and all-cause mortality vs non-use across pooled analyses; supports neutral-to-favorable CV profile in patients without absolute contraindications 89.
Tsertsvadze 2009 (Ann Intern Med + Urology), AHRQ systematic review and harms meta-analysis Systematic review and meta-analysis — Cumulative Confirms efficacy of oral PDE5 inhibitors across populations; characterizes harm profile including headache, flushing, dyspepsia, visual disturbance, and serious-but-rare AEs 7172.
Yuan 2013 (Eur Urol), PDE5 inhibitor network meta-analysis for ED Network meta-analysis 82 RCTs, 47,626 men Cumulative Sildenafil, tadalafil, vardenafil, avanafil, and udenafil produce comparable efficacy with distinct PK and AE profiles, informs class selection rather than within-class 73.
Liao 2019 (World J Urol), PDE5 inhibitors in diabetic ED network meta-analysis Bayesian network meta-analysis of RCTs — Cumulative All PDE5 inhibitors improved IIEF and intercourse success vs placebo in diabetic men, with broadly comparable within-class efficacy 74.
Roustit 2013 / Khouri 2019, Secondary Raynaud meta-analyses Systematic review and meta-analysis (Roustit); network meta-analysis (Khouri) — Cumulative PDE5 inhibitors reduce attack frequency and duration in secondary Raynaud phenomenon; effect sizes are modest and clinically useful as a second-line option after standard vasodilators 6970.
Pels 2023 (Cochrane), NO-pathway interventions for fetal growth restriction Cochrane systematic review — Cumulative Sildenafil and other NO-pathway interventions did not improve perinatal mortality or morbidity in pregnancies with fetal growth restriction; the Dutch STRIDER trial was halted early for safety signal, current recommendation is against routine antenatal sildenafil for FGR 66.
Muirhead 2002 (Br J Clin Pharmacol), Age, renal, hepatic PK Open-label PK in healthy and impaired-organ-function adults — Single dose Sildenafil clearance is reduced ~50% in adults >65, in severe renal impairment (CrCl <30 mL/min), and in moderate hepatic impairment, quantitative basis for label starting-dose reductions 80.
Muirhead 2000 / 2002 (Br J Clin Pharmacol), CYP3A4 interaction studies Open-label PK with strong/moderate CYP3A4 inhibitors — Steady-state Ritonavir/saquinavir and erythromycin substantially elevate sildenafil exposure (multifold AUC increase with ritonavir); foundation for label dose reduction with strong CYP3A4 inhibitors 8281.
Damle 2014 / Mewada 2024, Sildenafil orodispersible tablet/film PK PK / bioequivalence studies — Single dose Manufactured ODT (Damle) is bioequivalent to the conventional tablet; novel taste-masked ODF (Mewada) improves measured bioavailability, pharmacy context for the rapid-dissolve form 8384.
Nahata 2016 / Cheung 2021, Compounded sildenafil stability Physicochemical stability studies — Up to 91 days Nahata characterized extended stability of oral sildenafil for infants/young children; Cheung reported stability of compounded sildenafil 100 mg rapid-dissolving tablets, pharmacy-grade BUDs supported by data 8586.
Veronin 2014 / Venhuis 2014, Internet-sourced and counterfeit sildenafil quality Analytical chemistry of marketed samples — N/A Internet-sourced and counterfeit sildenafil products show substantial dose-to-dose API variability and impurity content; argues for licensed-pharmacy sourcing of compounded preparations 8788.

Mechanism detail

Detailed Mechanism of Compounded Sildenafil

PDE5 hydrolyzes cGMP to 5'-GMP. Sildenafil is a structural analog of cGMP that occupies the catalytic site competitively, with an IC50 in the low nanomolar range against PDE5 34. In tissues without NO-driven cGMP generation, sildenafil has minimal effect, this is why the drug does not produce an erection without sexual stimulation, and why it has limited cardiovascular impact at rest in healthy individuals 36 10.

Isoform selectivity is high but not absolute. Sildenafil has substantial selectivity for PDE5 over PDE1, PDE2, PDE3, PDE4, PDE7, PDE8, PDE9, PDE10, and PDE11 35. Modest cross-inhibition of PDE6 in retinal photoreceptors underlies the dose-related blue-tinge / increased light-sensitivity adverse effect, characterized electroretinographically by Marmor and colleagues (Zoumalan/Marmor 2009 ERG study of daily high-dose sildenafil) and reviewed by Laties 2009 4041.

Allosteric regulation of PDE5 itself is dynamic: Corbin and Francis 2011 showed that incubation of PDE5 with sildenafil or with metal ions drives a conformational change that further stimulates allosteric cGMP binding, suggesting a positive-feedback loop that contributes to sustained activity 36. The cGMP downstream effector is cGMP-dependent protein kinase (PKG), which phosphorylates targets including phospholipase A2 38, myosin light chain phosphatase, and various ion channels, net effect is reduced cytosolic Ca2+ and smooth-muscle relaxation. Lin and colleagues 37 have characterized PDE5 expression and regulation specifically within the penile corpora cavernosa; Burnett 2024 revisited the central role of NO in penile erection physiology 39.

In the pulmonary circulation, chronic PDE5 inhibition amplifies endogenous NO-mediated vasodilation, reducing pulmonary vascular resistance and right-ventricular afterload over weeks of treatment 65. The clinical signal in SUPER-1 was improvement in 6-minute walk distance and hemodynamics in WHO Functional Class II, IV patients with PAH 5; long-term survival data came from SUPER-2 6 and, in children, from STARTS-2 8.

The combination of PDE5 inhibition with nitric oxide donors (nitrates) causes profound, additive cGMP accumulation in vascular smooth muscle and is the basis for the absolute nitrate contraindication, quantified hemodynamically by Webb 1999 (organic nitrate plus calcium antagonist drug-interaction studies), Webb 2000 (NO donors potentiated by sildenafil in stable-angina patients), and time-course-characterized by Oliver/Webb 2009 (the hypotensive effect of sublingual glyceryl trinitrate combined with sildenafil is most severe within 4 hours of sildenafil dosing and substantially attenuated by 8 hours) 303132. Parker 2007 demonstrated that IV nitroglycerin can be safely administered to men with coronary disease pretreated with sildenafil if at least 8 hours have elapsed, supporting the operational 24-hour washout rule 2433.

Pharmacology

Compounded Sildenafil Pharmacokinetics & Pharmacodynamics

Pharmacokinetics

Oral sildenafil is rapidly absorbed. Tmax is approximately 60 minutes in the fasted state; absolute oral bioavailability is approximately 41% due to first-pass metabolism 9. A high-fat meal delays Tmax by about 1 hour and reduces Cmax by ~29% but does not meaningfully change AUC. Mehrotra 2007 reviewed PK/PD across the PDE5 inhibitor class with attention to onset, duration, and food effects 93.

Sildenafil is metabolized predominantly by hepatic CYP3A4, with minor contribution from CYP2C9, to an active N-desmethyl metabolite (UK-103,320) that has ~50% the in-vitro PDE5 potency of parent and ~20% of plasma exposure, meaning the metabolite contributes meaningfully to net pharmacodynamics. Terminal half-life is approximately 3, 4 hours for both parent and metabolite. Clearance is reduced ~50% in adults >65, in severe renal impairment (CrCl <30 mL/min), and in moderate hepatic impairment (Muirhead 2002 age/renal/hepatic study), dose reductions are required in each 80. Ritonavir/saquinavir produces ~11-fold AUC increase 82, and erythromycin/azithromycin produce smaller but clinically meaningful increases (Muirhead 2002) 81.

Manufactured orodispersible tablet PK has been formally characterized: Damle 2014 reported bioequivalence of a novel ODT to the conventional film-coated tablet 83. Mewada 2024 reported a taste-masked orodispersible film with improved measured bioavailability vs comparator film 84. Jannini 2025 reviews the ODF landscape for ED.

Compounded sublingual troches and oral suspensions are not bioequivalent to the manufactured oral tablet or to the manufactured ODT. Sublingual partial pre-gastric absorption may produce a faster perceived onset but has not been characterized in head-to-head bioequivalence studies. Compounded oral suspensions have published stability data (Sae Yoon 2015, Nahata 2016) and rapid-dissolving compounded tablets have stability data from Cheung 2021, but PK should be assumed similar to (not identical to) the manufactured Revatio oral suspension 228586. Counterfeit and Internet-sourced sildenafil shows substantial API/impurity variability 87, additional argument for licensed-pharmacy sourcing 2388.

Pharmacodynamics

Pharmacodynamic effect requires upstream NO release. In the corpus cavernosum, this means sexual stimulation must occur for sildenafil to produce an erection. In the pulmonary vasculature, sildenafil reduces vascular resistance via amplification of endogenous NO-driven cGMP signaling, onset over hours acutely, with longer-term hemodynamic remodeling over weeks of chronic dosing 115.

Systemic hemodynamic effect at therapeutic doses is modest: a small transient reduction in blood pressure (~8/5 mmHg) is typical in healthy adults 9. Reflex tachycardia is mild. The drug does not have meaningful direct inotropic or chronotropic effect.

Comparative formulations

Comparing Compounded Sildenafil Formulations

The manufactured oral tablet (Viagra, Revatio, and generic equivalents) is the formulation studied in all pivotal ED and adult PAH trials. The manufactured Revatio oral suspension is the formulation labeled for pediatric PAH dosing 22.

Compounded sublingual troches differ pharmacokinetically, partial pre-gastric absorption can produce a faster perceived onset, but the route has not been characterized in head-to-head bioequivalence studies and exposure profiles vary by troche base, pH, and patient salivation. Compounded oral suspensions have published stability data (Sae Yoon 2015) but should be assumed similar (not identical) to the manufactured suspension 22.

An orally disintegrating film (ODF) formulation is reviewed in Jannini 2025 as a next-generation rapid-onset oral pathway; this is a manufactured formulation context, not a RonanRx compounded preparation 23. A topical sildenafil cream (3.6%) was studied in a phase 3 program for female sexual arousal disorder 21 and is not FDA-approved.

RonanRx-compounded preparations are dispensed only when the manufactured product is not appropriate for the identified patient. The pharmacist review documents the patient-specific clinical reason, and the resulting formulation difference (PK, onset, dose accuracy) is noted on dispensing 9.

Storage

Compounded Sildenafil Storage and Handling

Manufactured sildenafil tablets are stored at controlled room temperature (USP definition: 20, 25 °C, with excursions permitted 15, 30 °C) in tightly closed containers. The manufactured Revatio oral suspension is reconstituted by the dispensing pharmacy per label instructions and is stable for 60 days at room temperature or refrigerated after reconstitution.

Compounded oral capsules, troches, and suspensions are stored per USP <795> beyond-use-date conventions and specific stability data for the formulation. Sae Yoon 2015 characterized stability for an extemporaneously compounded oral suspension; specific beyond-use dates are set by the dispensing pharmacy based on its formulation record 2922.

RonanRx operations

Compounded Sildenafil Compounding & Operations

503A compounding

Compounded sildenafil is prepared under 503A on patient-specific prescriptions in state-licensed compounding pharmacies 2827. RonanRx prepares non-sterile oral capsules, sublingual troches, and oral suspensions per USP General Chapter <795>, with documented active-ingredient sourcing (USP/NF grade where available), gravimetric verification, and finished-product quality checks per the pharmacy's quality-management system 29.

Because generic sildenafil tablets are widely available at low cost, the threshold for compounded preparation is the documented patient-specific clinical reason that the manufactured product cannot meet, excipient sensitivity, dose individualization outside available strengths, non-tablet dose form needed (sublingual, liquid), pediatric weight-banding when manufactured suspension is not appropriate, or documented supply gap. RonanRx applies the FDA essentially-a-copy guidance criterion and does not fill prescriptions that read as routine substitution for generic Viagra or Revatio.

Pharmacist review

Each prescription for compounded sildenafil undergoes pharmacist review prior to dispensing. The review confirms: a documented patient-specific clinical reason that the manufactured Viagra/Revatio/generic is not appropriate (excipient sensitivity, dose individualization, non-tablet form needed, pediatric weight-banding, supply gap); absence of absolute contraindications (concomitant nitrate therapy, riociguat use); presence of relative contraindications (alpha-blocker use, strong CYP3A4 inhibitor therapy, severe hepatic or renal impairment, history of NAION) addressed in the prescription; and that the prescribed regimen aligns with label-equivalent dose ceilings where relevant 10.

RonanRx does not fill prescriptions that read as routine substitution of compounded for manufactured product without documented clinical rationale, consistent with FDA guidance on compounded copies of commercially available drugs 27.

Quality and traceability

Active pharmaceutical ingredient (sildenafil citrate) is sourced from FDA-registered facilities with documented certificates of analysis. Each batch is recorded with lot numbers traceable to API source, compounding date, beyond-use date, and dispensing pharmacist of record. Finished product lot records are retained per state board of pharmacy retention requirements.

Cold chain

Compounded sildenafil oral capsules and troches are not cold-chain products. They are stable at controlled room temperature and shipped in standard pharmacy-grade packaging. Compounded oral suspensions may be refrigerated based on the specific formulation's stability data; patients should follow the dispensing label.

FAQ

Frequently Asked Questions About Compounded Sildenafil

Is compounded sildenafil the same as Viagra or generic sildenafil tablets?

No. Viagra (and generic sildenafil tablets) are FDA-approved manufactured products with extensive pivotal-trial evidence. Compounded sildenafil is a pharmacy-prepared preparation on a patient-specific prescription and is not bioequivalent to the manufactured tablet 1. Compounded drugs are not FDA-approved 28.

When is a compounded version appropriate?

Per FDA guidance, a compounded version is generally restricted unless the prescriber documents a patient-specific clinical need the manufactured product cannot meet 27. Common documented reasons include excipient sensitivity, a non-tablet dose form (sublingual troche or liquid), a dose strength not available commercially, pediatric weight-banding when the manufactured suspension is not appropriate or available, or a documented supply gap. Because generic sildenafil tablets are inexpensive and widely available, the bar is documentation of a specific clinical need.

Can I take sildenafil if I'm on a nitrate?

No, this is an absolute contraindication. Combining sildenafil with any nitrate (nitroglycerin, isosorbide mono- or dinitrate, amyl nitrite/'poppers', sodium nitroprusside) can cause life-threatening low blood pressure. Sildenafil should not be taken within 24 hours of any nitrate, and nitrates should not be started within 24 hours of sildenafil 1011. This applies to all PDE5 inhibitors.

How well does sildenafil work for erectile dysfunction?

In the Goldstein 1998 NEJM trial, sildenafil 100 mg produced successful intercourse attempts in 69% of attempts vs 22% on placebo, with mean IIEF erectile-function scores of 22 vs 12 1. Effect is conditional on sexual stimulation, sildenafil amplifies the body's own nitric-oxide-driven erection signal rather than initiating one independently.

What are the most common side effects?

Headache, flushing, dyspepsia, nasal congestion, mild visual disturbance (blue tinge or increased light sensitivity at higher doses), and back pain. Most are mild to moderate and resolve as the drug clears over a few hours. Rare but serious adverse events include nonarteritic anterior ischemic optic neuropathy (NAION), sudden hearing loss, and priapism (erection lasting more than 4 hours, which requires emergency urologic evaluation) 141516.

What is sildenafil approved for besides erectile dysfunction?

Sildenafil is also FDA-approved as Revatio for pulmonary arterial hypertension (PAH), a serious lung-vascular disease 567. Revatio is available as a 20 mg oral tablet (taken three times daily), an oral suspension (used for pediatric PAH dosing), and an intravenous form 8. Pivotal evidence comes from the SUPER-1 trial (adults) and the STARTS-1 and STARTS-2 trials (children).

Does RonanRx sell compounded sildenafil directly to patients?

No. Compounded sildenafil requires a patient-specific prescription written by a licensed doctor for an identified patient with a documented clinical reason that the manufactured Viagra, Revatio, or generic sildenafil is not appropriate, plus pharmacist review before dispensing 27. RonanRx is not a direct-to-consumer storefront 28.

Clinician resource

Download the Compounded Sildenafil Clinical Monograph (PDF)

The full white paper covers every section on this page plus chemical identity, evidence grading, indication-by-indication summaries, research gaps, and reference appendix. Suitable for sharing with prescribing doctors and pharmacist reviewers.

Download information packet ↓

References

References

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