Sildenafil

Generic Name
Sildenafil
Brand Names
Liqrev, Revatio, Viagra, Vizarsin, Sildenafil Actavis, Sildenafil ratiopharm, Granpidam, Sildenafil Teva, Mysildecard
Drug Type
Small Molecule
Chemical Formula
C22H30N6O4S
CAS Number
139755-83-2
Unique Ingredient Identifier
3M7OB98Y7H
Background

In eliciting its mechanism of action, sildenafil ultimately prevents or minimizes the breakdown of cyclic guanosine monophosphate (cGMP) by inhibiting cGMP specific phosphodiesterase type 5 (PDE5) . The result of doing so allows cGMP present in both the penis and pulmonary vasculature to elicit smooth muscle relaxation and vasodilation that subsequently facilitates relief in pulmonary arterial hypertension and the increased flow of blood into the spongy erectile tissue of the penis that consequently allows it to grow in size and become erect and rigid .

Interestingly enough, it is precisely via this mechanism why sildenafil was at first researched as a potential treatment for angina - or chest pain associated with inadequate blood flow to the heart - before being serendipitously indicated for treating erectile dysfunction in the late 1980s . Nevertheless, it is because of this mechanism that sildenafil is also indicated for treating pulmonary arterial hypertension but is also additionally notorious for interacting with various anti-anginal or anti-hypertensive agents to develop potentially rapid, excessive, and/or fatal hypotensive crises .

Regardless, sildenafil, among a variety of other similar or related PDE5 inhibitors, has become a common and effective treatment for erectile dysfunction and since its formal approval for medical use in the public in 1998 , continues to see millions of prescriptions written for it internationally. Although the medication has historically been most popularly recognized as Pfizer's brand name Viagra, sildenafil is currently available generically and even as a non-prescription over the counter medication in some countries .

Indication

Sildenafil is a phosphodiesterase-5 (PDE5) inhibitor that is predominantly employed for two primary indications:

(1) the treatment of erectile dysfunction ; and

(2) treatment of pulmonary hypertension, where:

a) the US FDA specifically indicates sildenafil for the treatment of pulmonary arterial hypertension (PAH) (WHO Group I) in adults to improve exercise ability and delay clinical worsening . The delay in clinical worsening was demonstrated when sildenafil was added to background epoprostenol therapy . Studies establishing effectiveness were short-term (12 to 16 weeks), and included predominately patients with New York Heart Association (NYHA) Functional Class II-III symptoms and idiopathic etiology (71%) or associated with connective tissue disease (CTD) (25%) ;

b) the Canadian product monograph specifically indicates sildenafil for the treatment of primary pulmonary arterial hypertension (PPH) or pulmonary hypertension secondary to connective tissue disease (CTD) in adult patients with WHO functional class II or III who have not responded to conventional therapy . In addition, improvement in exercise ability and delay in clinical worsening was demonstrated in adult patients who were already stabilized on background epoprostenol therapy ; and

c) the EMA product information specifically indicates sildenafil for the treatment of adult patients with pulmonary arterial hypertension classified as WHO functional class II and III, to improve exercise capacity . Efficacy has been shown in primary pulmonary hypertension and pulmonary hypertension associated with connective tissue disease . The EMA label also indicates sildenafil for the treatment of pediatric patients aged 1 year to 17 years old with pulmonary arterial hypertension . Efficacy in terms of improvement of exercise capacity or pulmonary hemodynamics has been shown in primary pulmonary hypertension and pulmonary hypertension associated with congenital heart disease .

Associated Conditions
Erectile Dysfunction, NYHA Functional Class II-III Pulmonary arterial hypertension, Premature Ejaculation, Pulmonary Arterial Hypertension (PAH)
Associated Therapies
-

Sildenafil for Chronic Obstructive Pulmonary Disease (COPD) Associated Pulmonary Hypertension

Phase 4
Withdrawn
Conditions
Interventions
First Posted Date
2008-08-08
Last Posted Date
2012-08-23
Lead Sponsor
University of Aarhus
Registration Number
NCT00730067
Locations
🇩🇰

Department of Cardiology, Skejby sygehus, Århus N, Denmark

🇩🇰

Department of Pulmonary Diseases, Århus Sygehus, Århus, Denmark

Effect of Oral Sildenafil With Digital Therapeutic Iontophoresis of Sodium Nitroprussiate in Healthy Volunteers

Not Applicable
Completed
Conditions
Interventions
First Posted Date
2008-07-04
Last Posted Date
2011-10-06
Lead Sponsor
University Hospital, Grenoble
Target Recruit Count
40
Registration Number
NCT00710099
Locations
🇫🇷

Clinical Researsh Centre, Grenoble, Isere, France

Cardiovascular Effects of Chronic Sildenafil in Men With Type 2 Diabetes

First Posted Date
2008-06-06
Last Posted Date
2013-05-08
Lead Sponsor
University of Roma La Sapienza
Target Recruit Count
59
Registration Number
NCT00692237
Locations
🇮🇹

Dipartimento di Fisiopatologia Medica - Policlinico Umberto I, Rome, Italy

Special Investigation For Long-Term Use Of Sildenafil (Regulatory Post Marketing Commitment Plan)

Completed
Conditions
Interventions
First Posted Date
2008-04-24
Last Posted Date
2021-02-01
Lead Sponsor
Pfizer's Upjohn has merged with Mylan to form Viatris Inc.
Target Recruit Count
3337
Registration Number
NCT00666198

Safety and Efficacy of Sildenafil in Cystic Fibrosis (CF) Lung Disease

Phase 1
Completed
Conditions
Interventions
First Posted Date
2008-04-16
Last Posted Date
2020-10-19
Lead Sponsor
National Jewish Health
Target Recruit Count
36
Registration Number
NCT00659529
Locations
🇺🇸

National Jewish Health, Denver, Colorado, United States

Assess the Effect of Daily Treatment of Vardenafil 20mg or Sildenafil 100mg and Placebo on Sperm Function

First Posted Date
2008-04-10
Last Posted Date
2014-12-30
Lead Sponsor
Bayer
Target Recruit Count
200
Registration Number
NCT00655590

A Study Evaluating the Efficacy and Safety of Sildenafil in Patients With Erectile Dysfunction Receiving Hemodialysis

First Posted Date
2008-04-07
Last Posted Date
2021-02-01
Lead Sponsor
Pfizer's Upjohn has merged with Mylan to form Viatris Inc.
Target Recruit Count
100
Registration Number
NCT00654017
Locations
🇧🇷

Pfizer Investigational Site, Sao Paulo, Brazil

A Study Evaluating the Efficacy and Safety of Sildenafil in Men With Traumatic Spinal Cord Injury and Erectile Dysfunction

First Posted Date
2008-04-07
Last Posted Date
2021-02-01
Lead Sponsor
Pfizer's Upjohn has merged with Mylan to form Viatris Inc.
Target Recruit Count
88
Registration Number
NCT00654082
Locations
🇹🇷

Pfizer Investigational Site, Konya, Turkey

A Study to Evaluate Self-esteem and Relationships in Males With Erectile Dysfuntion

Phase 4
Completed
Conditions
Interventions
First Posted Date
2008-04-01
Last Posted Date
2021-02-01
Lead Sponsor
Pfizer's Upjohn has merged with Mylan to form Viatris Inc.
Target Recruit Count
780
Registration Number
NCT00648596
Locations
🇬🇧

Pfizer Investigational Site, Taunton, Ta1 5da, United Kingdom

A Study to Investigate the Effects on Blood Pressure and Pulse Rate of a Single 100mg Dose of Sildenafil in Patients With Benign Prostatic Hyperplasia Who Are Being Treated With Doxazosin

Phase 2
Completed
Conditions
Interventions
First Posted Date
2008-03-27
Last Posted Date
2021-02-01
Lead Sponsor
Pfizer's Upjohn has merged with Mylan to form Viatris Inc.
Target Recruit Count
20
Registration Number
NCT00645034
Locations
🇺🇸

Pfizer Investigational Site, Newport Beach, California, United States

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