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Viagra (sildenafil)
Selectively inhibits phosphodiesterase type 5 (PDE5), increasing cGMP levels to relax smooth muscle in the corpus cavernosum and pulmonary vasculature.
Sildenafil (Viagra/Revatio) was the first PDE5 inhibitor, developed serendipitously by Pfizer and approved in 1998. One of the most recognizable drugs in history, it treats both erectile dysfunction and pulmonary arterial hypertension. Available generically since 2017.
At a glance
| Generic name | sildenafil |
|---|---|
| Also known as | Viagra, Revatio |
| Sponsor | Pfizer Inc. |
| Drug class | PDE5 inhibitor |
| Target | Dual 3',5'-cyclic-AMP and -GMP phosphodiesterase 11A, High affinity cGMP-specific 3',5'-cyclic phosphodiesterase 9A, Multidrug resistance-associated protein 5 |
| Modality | Small molecule |
| Therapeutic area | Cardiovascular |
| Phase | FDA-approved |
| First approval | 1998-03-27 (United States) |
Mechanism of action
Sildenafil was originally developed by Pfizer for angina, but clinical trials revealed its remarkable effect on erectile function as a side effect. It inhibits PDE5, the enzyme that breaks down cGMP in smooth muscle, prolonging the vasodilatory effect of nitric oxide signaling. As Viagra, it became a cultural phenomenon. As Revatio, it treats pulmonary arterial hypertension. Now available generically.
Approved indications
- Impotence
- Pulmonary arterial hypertension
Common side effects
- Headache
- Dyspepsia
- Flushing
- Pain in limb
- Myalgia
- Back pain
- Diarrhea
- Edema
Serious adverse events
- Myocardial infarction
- Sudden cardiac death
- Ventricular arrhythmia
- Cerebrovascular hemorrhage
- Transient ischemic attack
- Pulmonary hemorrhage
- Subarachnoid hemorrhage
- Intracerebral hemorrhage
- NAION (Nonarteritic anterior ischemic optic neuropathy)
- Seizure
Key clinical trials
- A Randomized, Double-blind, Placebo-Controlled Study to Evaluate the Safety and Efficacy of the Addition of Inhaled Iloprost in Patients With Pulmonary Arterial Hypertension Receiving Oral Sildenafil (Phase 3)
- A Double Blind, Placebo Controlled 2-way Cross-over Study to Assess the Clitoral Engorgement Response as Measured by Non-contrast Magnetic Resonance Imaging (MRI) in Women With Female Sexual Arousal D (Phase 2)
- Association Between Premature Birth and Its Comorbidities With NO and the HPG Activation at Minipuberty (N/A)
- SIDAMI - Sildenafil and Diastolic Dysfunction After AMI (Phase 4)
- Study to Assess the Pharmacodynamic Effects of Repeated Oral Doses of SAR247799 on Endothelial Function in Male and Female Patients With Type 2 Diabetes Mellitus (Phase 1)
- A Phase II, Double Blind Randomized Controlled Trial to Determine the Safety and Efficacy of 12.5mg of Oral Sildenafil (Viagra) Compared to Placebo to Decrease Pulmonary Hypertension in Cardiac Patien (Phase 2)
- Intérêt de la rééducation érectile précoce Par Sildénafil après radiothérapie et Proctectomie Pour Cancer du Rectum : Essai contrôlé randomisé (Phase 3)
- A Phase 2a, Randomized, Double Blind, Placebo-controlled, Parallel Group Study Investigating The Dose-response Of Pf-00489791 On Acute Hemodynamics In Subjects With Idiopathic And Familial Pulmonary A (Phase 2)
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 label | Mechanism, indications, dosing, boxed warnings, drug interactions |
| ClinicalTrials.gov | Trial enrolment, design, endpoints, results |
Competitive intelligence
For the full competitive landscape — auto-detected comparators, recent regulatory actions across the set, upcoming PDUFA, patent timeline, sponsor landscape:
- Viagra CI brief — competitive landscape report
- Viagra updates RSS · CI watch RSS
- Pfizer Inc. portfolio CI