FDA Panel Verdict On Premarin Inconclusive

The US Food and Drug Administration's advisory panel for Fertility and Maternal Health Drugs has failed to deliver a verdict on whether a constituent of Wyeth-Ayerst's hormone replacement drug Premarin (conjugated estrogens) is an active component or a contaminant (Marketletter July 31).

At its meeting on July 27-28, the panel concluded that there was insufficient clinical evidence to determine whether delta-8,9 dehydroestrone sulfate is essential to the efficacy of Premarin. The FDA convened the meeting in response to applications for approval of generic versions of Premarin from Duramed and Barr Laboratories, and a Wyeth petition seeking to affirm that these generic forms should not be considered equivalent.

Duramed and Barr have developed generic forms which contain the five forms of estrogen stipulated as active ingredients of Premarin in the US Pharmacopeia. Delta- 8,9 DHES is not included on that list; rather, the USP considers it an impurity. At the meeting, Wyeth sought to persuade the panel that delta-8,9 DHES was in fact an active component of conjugated estrogen and should be included in generic forms of the product.