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Revatio (Sildenafil Citrate)
Sildenafil inhibits phosphodiesterase type 5 (PDE5), increasing cGMP levels and enabling penile smooth muscle relaxation.
Sildenafil is a PDE5 inhibitor indicated for treatment of erectile dysfunction, enhancing nitric oxide-mediated cGMP signaling in penile tissue. The drug demonstrates rapid oral absorption with 41% bioavailability, hepatic metabolism via CYP3A4, and approximately 4-hour half-life. Major contraindications include concurrent use of nitrates, guanylate cyclase stimulators, and hypersensitivity; significant drug interactions exist with alpha-blockers, antihypertensives, and CYP3A4 inhibitors requiring dose adjustments. Sildenafil remains a well-established therapeutic option for erectile dysfunction with manageable safety profile when used appropriately and avoiding contraindicated combinations.
At a glance
| Generic name | Sildenafil Citrate |
|---|---|
| Sponsor | Pfizer Inc. |
| Drug class | PDE5 inhibitor |
| Target | Phosphodiesterase type 5 (PDE5) |
| Modality | Small molecule |
| Therapeutic area | Cardiovascular |
| Phase | FDA-approved |
Mechanism of action
Sildenafil enhances the effect of nitric oxide (NO) by inhibiting phosphodiesterase type 5 (PDE5), which is responsible for degradation of cyclic guanosine monophosphate (cGMP) in the corpus cavernosum. When sexual stimulation causes local release of NO, inhibition of PDE5 by sildenafil causes increased levels of cGMP, resulting in smooth muscle relaxation and inflow of blood to the corpus cavernosum. Sildenafil has no direct relaxant effect on isolated human corpus cavernosum and has no effect in the absence of sexual stimulation at recommended doses. Sildenafil demonstrates high selectivity for PDE5 compared to other phosphodiesterases, with approximately 4,000-fold selectivity over PDE3 (involved in cardiac contractility). However, it is only about 10-fold more potent for PDE5 compared to PDE6, an enzyme found in the retina involved in the phototransduction pathway, which is thought to be the basis for abnormalities related to color vision. Beyond the corpus cavernosum, PDE5 is found in other tissues including platelets, vascular and visceral smooth muscle, skeletal muscle, brain, heart, liver, kidney, lung, pancreas, prostate, bladder, testis, and seminal vesicle. The inhibition of PDE5 in these tissues by sildenafil may contribute to additional pharmacologic effects.
Approved indications
- Impotence
- Pulmonary arterial hypertension
Common side effects
- Headache
- Headache
- Flushing
- Flushing
- Dyspepsia
- Dyspepsia
- Nasal Congestion
- Nasal congestion
- Abnormal Vision
- Abnormal vision
- Back pain
- Back pain
Drug interactions
- Nitrates (organic nitrates or organic nitrites)
- Alpha-blockers
- Amlodipine
- Ritonavir (strong CYP3A4 inhibitor)
- Erythromycin or strong CYP3A4 inhibitors (ketoconazole, itraconazole, saquinavir)
Patents
| Patent | Expiry | Type |
|---|---|---|
| 11123287 | 2033-12-16 | Formulation |
Primary sources
Every claim on this page is sourced from regulatory or scientific primary sources. See our editorial policy for full methodology.
| Source | Used for |
|---|---|
| FDA Orange Book | Patents + exclusivity |
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