One way or another, time may finally be running out for ProAmatine, a drug that became a case study for the US Food and Drug Administration’s (FDA) failure to enforce clinical trial requirements after drugs come to market.

ProAmatine (midodrine) was approved in 1996 to treat patients whose blood pressure plummets when they stand up, making them dizzy or faint. The drug was approved because it increased 1-minute standing blood pressure, but the FDA told Shire, ProAmatine’s Dublin-based developer, to conduct additional clinical trials to verify that the drug actually made patients feel better.

Those studies were never completed, at least not to the FDA’s satisfaction. In September 2009, ProAmatine was prominently featured in a Government Accountability Office report that criticized the FDA for not keeping track of postmarketing commitments. The report noted that in the intervening 13 years, Shire had enjoyed 7 years of market exclusivity. After that the FDA approved five generic versions of the drug, despite the missing data.

Yesterday, the FDA proposed yanking ProAmatine off the market. It would have been an unprecedented move — the FDA has never pulled a drug for failure to fulfill postmarketing requirements — perhaps heralding a new, tougher regulatory stance. But today, Shire countered with a revelation of its own: the company had already decided to stop selling the drug rather than face the costs of additional clinical trials (WSJ). Shire said it was only making $500,000 a year on ProAmatine, hardly enough to cover the cost of the two double-blind, randomized, placebo-controlled trials requested by the FDA.

In fact, Shire notified the FDA of its decision last November, a company spokesperson told the Wall Street Journal, and “Monday’s communique was the first response we received from the FDA on this after that submission.”

Ah, well. Perhaps the five generic midodrine makers stuck around for their reprimand.

Image:Joey Parsons via Flckr, some rights reserved