The European Medicines Agency (EMEA) has approved Pfizer's Revatio (sildenafil citrate) for the treatment of pulmonary arterial hypertension (PAH), a rare, aggressive and life-shortening vascular disease. Sildenafil citrate is the active ingredient in Viagra, Pfizer's erectile dysfunction medication, which has been used by more than 27 million men worldwide.

"The company is pleased with the European regulatory decision and looks forward to making Revatio available to patients in all member states of the European Union. Pfizer's six-year clinical program for Revatio demonstrates our continuing commitment to develop medications for unmet medical conditions, including those that affect small numbers of patients," said Michael Berelowitz, Pfizer vice president worldwide medical

Revatio is classified by the EMEA as an orphan drug. The drug was approved for the treatment of patients with PAH classified as WHO functional class III, to improve exercise capacity. Efficacy has been shown in primary pulmonary hypertension and pulmonary hypertension associated with connective tissue disease, claims a company release.

The EMEA approval was based on the results of a double-blind, placebo- controlled study of 278 patients with PAH. Patients were randomised to three different dosages of Revatio (20 mg, 40 mg, or 80 mg) three times a day or placebo. All three-treatment groups showed statistically significant improvements in the primary endpoint of six-minute walk distance. No significant differences were observed between the three dosages in six-minute walk distance, thus the approved dose is limited to 20 mg three times daily. Patients taking Revatio also showed statistically significant improvements in other important measures of cardiac function.

Patients were followed for an additional year as part of an open-label extension trial. Improvements in walk distance and cardiac function were preserved, with Revatio patients showing a 96 per cent survival rate, compared to an expected survival rate of 71 per cent.

Revatio will be distributed as a white, round 20mg pill to distinguish it from Viagra's blue diamond-shaped pill for erectile dysfunction. It was approved for the treatment of PAH by the United States Food and Drug Administration in June of 2005.

PAH is a blood vessel disorder of the lungs in which pressure in the pulmonary artery rises above normal levels. It affects approximately 100,000 people worldwide and is seen most commonly in women between the ages of 20 and 40.