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Estrogen Product Approved, But Firm Delays Launch

Cheryl A. Thompson

A new product containing synthetic conjugated estrogens, including an essential component of the best-selling competitor, was approved Monday by the Food and Drug Administration (FDA), but the drug company has decided not to make the tablets available until it can also sell low-strength versions.

Barr Pharmaceuticals Inc. announced Tuesday that it had received approval to market the 0.625- and 1.25-mg strengths of Enjuvia, known by the generic name synthetic conjugated estrogens B, for the treatment of moderate to severe vasomotor symptoms associated with menopause. The company also announced that it would continue to seek approval of the 0.3- and 0.45-mg tablets, for which FDA had issued a "non-approvable" letter a year ago.

According to the company, the conjugated estrogens in Enjuvia are derived from plants and include delta 8,9-dehydroestrone sulfate.

Delta 8,9-dehydroestrone sulfate is the component of Premarin that Wyeth, then known as Wyeth-Ayerst Laboratories, convinced FDA must be present in any generic version of the equine-derived conjugated estrogens product. FDA agreed with the company that delta 8,9-dehydroestrone sulfate contributes to the estrogenic potency of Premarin. In that 1997 decision, the agency also stated that it could not approve the marketing of a synthetic generic version of Premarin until the complex product's active ingredients were defined.

Barr spokeswoman Carol A. Cox said the company probably will not launch the Enjuvia product line until sometime in 2005, when approval of the low-strength tablets is expected. She said FDA declined to approve marketing of the 0.3- and 0.45-mg tablets because they had "not shown efficacy for vasomotor symptoms."

In announcing FDA's approval of the high-strength tablets, Barr explained that the new drug application for all strengths of Enjuvia had been submitted in April 2003 by the product's original owner, Endeavor Pharmaceuticals. Barr bought Enjuvia eight months later.

Barr, through its subsidiary Duramed Pharmaceuticals Inc., also markets synthetic conjugated estrogens A, known as Cenestin. The product contains nine synthetic estrogen substances but not delta 8,9-dehydroestrone sulfate.