Sildenafil Tablets

Sildenafil is a vasoactive agent that is commonly prescribed to treat erectile dysfunction (impotence) in men, and to reduce symptoms in patients with pulmonary arterial hypertension (PAH). By decreasing vascular resistance and relaxing muscles, sildenafil increases blood flow to particular areas of the body including the penis. Sildenafil is generally taken 30 to 60 minutes prior to sexual intercourse, sildenafil troche may be taken up to 10 minutes before intercourse.

Sildenafil is regarded as the most popular erectile dysfunction drug. Sildenafil was developed by a group of pharmaceutical chemists at Pfizer’s facility in Kent, England who worked together to synthesize sildenafil. The medication was initially formulated to treat hypertension (a symptom of ischaemic heart disease) and chest pains caused from the inadequacy of the blood circulation to the heart. The drug was tried on men in Morriston Hospital (Swansea), in 1991 and 1992. Its clinical trials were conducted under the supervision of Ian Osterloh, who suggested that the drug had very little effects on treating angina, but effected significant changes in penile erections. Pfizer decided to commercialize the drug as a treatment for erectile dysfunction.

Sildenafil belongs to the phosphodiesterase type 5 (PDE5) inhibitors drug class. Sildenafil was originally developed as an antianginal agent but was found to be more effective in treating erectile dysfunction (ED). Sildenafil continues to be studied clinically to assess its utility in treating sexual dysfunction in females, but initial studies have found sildenafil to provide results similar to placebo in women. In regard to ED, sildenafil was tested in more than 4000 men in 21 clinical trials. The average age of these men was 55 years and they had ED for an average of 5 years before entering the study. Sildenafil was effective in roughly 70% of subjects. Response rates of 90% have been achieved in trials of male patients with psychogenic ED. Sildenafil may also be effective in male patients with ED related to diabetes mellitus1 or due to pelvic fracture urethral disruption.2 Sildenafil has been shown to be effective and well tolerated in patients on multidrug antihypertensive regimens and not associated with additional safety risks in these patients.3 According to ED treatment guidelines, oral phosphodiesterase type 5 inhibitors (PDE5 inhibitors) are considered first-line therapy.4 Final FDA approval for sildenafil for the treatment of ED was granted in March 1998.

Shortly after approval for ED, studies showed sildenafil was effective in treating patients with pulmonary arterial hypertension (PAH). Sildenafil improved exercise capacity as well as mean pulmonary artery pressure and other measures of cardiac function in patients with PAH. Sildenafil is the first oral therapy approved for treating early stages of PAH. Although preliminary data from 12 patients with sickle cell anemia showed a decrease in PAH, a larger clinical trial (n = 134) investigating the use of sildenafil for pulmonary hypertension in adults with sickle cell anemia was stopped early due to an increased risk of severe adverse effects, especially sickle cell pain crises, compared to placebo (38% vs. 8%, respectively). The reason for the increased risk of pain is unknown; however, in the initial trial, patients were aggressively treated with transfusions and hydroxyurea to control crises; the larger trial offered no intervention for crises. Sildenafil has also shown efficacy in treating altitude sickness.568 The oral formulation of sildenafil (Revatio) was approved by the FDA for treatment of pulmonary arterial hypertension (PAH) in June 2005; the injectable formulation was approved in November 2009.