- Associated Press - Tuesday, August 17, 2010

WASHINGTON (AP) - Shire PLC said Tuesday it will pull a blood-pressure drug off the market following warnings from federal regulators who said the drug has not been proven effective.

The Irish drugmaker said in a statement it will withdraw ProAmatine by the end of September. The announcement came one day after the Food and Drug Administration threatened to pull the drug because of missing data on its effectiveness.

The FDA approved ProAmatine in 1996 based on promising early results in treating low blood pressure. But the FDA said Shire never established the long-term benefits of the drug, as required under the agency’s so-called accelerated approval system.

Shire said in a statement it completed the studies required by the FDA, but the agency “viewed these trials as inconclusive.”

The company also said it notified the FDA and physicians last year that it would pull the drug from the market effective Sept. 30.

On Monday the FDA issued a letter to Shire and several drugmakers that market generic versions of ProAmatine, proposing a withdrawal of the drug from the market. FDA spokespeople said the letter marked the first time the agency threatened to pull a drug off the market due to missing follow-up data, though it has long held that power.

“This proposal is necessitated by Shire’s failure to conduct postmarketing clinical trials that verify and describe the clinical benefit” of ProAmatine, the agency stated.

Generic manufacturers of the drug include Mylan Pharmaceuticals and Sandoz Inc. Those generic products would also be subject to a market withdrawal, unless their manufacturers complete the studies requested by the FDA.

Roughly 100,000 U.S. patients received prescriptions for ProAmatine or generic versions last year, according to the FDA. The drug is approved to treat orthostatic hypotension, a type of low blood pressure that causes patients to become dizzy or faint when standing upright.

Shares of Shire PLC fell 17 cents Tuesday to $68.84 in afternoon trading.