Revatio, a Viagra Spinoff, Okayed for Pulmonary Arterial Hypertension

WASHINGTON, June 7-The FDA has approved Revatio, a new formulation of Viagra (sildenafil), for treatment of pulmonary arterial hypertension (PAH).

In the pivotal trial of the Pfizer drug reported last fall, patients taking 20 mg of Revatio three times daily, which became the FDA-approved dose, increased six-minute walk distance by 45 meters, which was significantly better than patients in the placebo group (P <0.001).

That study enrolled 277 patients with PAH, 38% of whom were New York Heart Association (NYHA) functional class II and 58% were NYHA class III.

Hoissein A. Ghofrani, M.D. of the University of Giessen in Germany, said Revatio improved outcome irrespective of functional class. Dr. Ghofrani was principal investigator of the pivotal trial and he presented the results last October at CHEST 2004.

Joe Feczko, M.D., Pfizer's chief medical officer, said Revatio is the first oral treatment for PAH to be approved for patients with early stage disease.

In addition to improved six-minute walk test results, 35% of patients treated with Revatio improved functional class compared with 7% of patients in the placebo group. Moreover, mean pulmonary arterial pressure (mPAP) decreased by an average of 5.1 mm Hg among Revatio-treated patients, but this was not statistically significant.

Revatio, which the company says will be available next month, is the second oral medication approved for PAH. The first, Trocleer (bosentan), which is manufactured by Actelion Pharmaceuticals, costs about $40,000 for a year of treatment.

The drugs differ in mechanism of action. Trocleer is a novel, nonselective endothelin-receptor antagonist. Revatio is a cyclic GMP phosphodiesterase (PDE) type 5 inhibitor that prolongs the vasodilatory effect of nitric oxide.

Pfizer has not released price estimates for Revatio, but a company statement noted that since only about 100,000 patients worldwide are diagnosed with PAH, the company does not view Revatio as a potential profit center. "Revatio demonstrates our commitment to developing treatments for unmet medical needs, including rare conditions such as PAH, regardless of commercial potential," said Dr. Feczko.

Dr. Feczko also noted that Revatio has not been tested in patients currently treated with Trocleer.

Anticipating the potential for confusion, Pfizer said Revatio 20 mg will be marketed as a white round pill to distinguish it from Viagra, which is a blue diamond-shaped pill. Moreover, since the lowest available dose of Viagra is 25 mg, there is no Viagra dose equivalent to the 20 mg Revatio dose.