Pfizer said Wednesday it will conduct two studies of hormone-replacement drugs for postmenopausal women after a US Food and Drug Administration panel voted 10-2 to recommend against its use as a nutritional supplement for premenopausal women.

A short analysis of the committee’s advice found that panel members “strongly agreed with their colleagues on the benefits” of hormone replacement therapy for women with endometriosis, who have low levels of estrogen, who have endometrial cancer, who are at high risk of osteoporosis or estrogen-related cancer, who have biological daughters or teenage daughters, or who are breastfeeding. They voted unanimously against an expansion to include all premenopausal women, based on conclusions drawn from a medical evaluation, according to the analysis.

“I think the interesting thing is that women were focused on the benefits,” Dr. Susan Love, an endocrinologist and the founder of Clinical Endocrinology Associates in California, said. “There was not much opportunity for the committee to look at any potential issues, such as side effects.”

Love is one of the nation’s foremost experts on hormone therapy. She has also published multiple studies that found that the vast majority of women who take hormones suffer few side effects.

When FDA health advisers cast their votes on Wednesday, they were responding to advice from a panel convened by Pfizer, which asked the agency in July to determine the safety and efficacy of its Menopaquito supplement, which it sells under the brand name Premarin. Both the FDA and Pfizer didn’t comment on the substance of Wednesday’s meeting, but FDA commissioner Dr. Scott Gottlieb indicated publicly in October that the agency would likely vote against Premarin and other versions of Premarin.

A spokeswoman for Pfizer said the company respects the FDA’s decision.

“The questions that the advisory committee raised were not based on our clinical trials, but rather on the detailed work we’ve done in response to the advisory committee’s recommendations,” the spokeswoman, Pamela Eisele, said in a statement. “While the votes were split, the panel made a significant number of recommendations that, if followed, will allow continued development of the Restorative Health Network (RLN) franchise, including both Premarin and Prempro.”

The FDA has called these other versions of the pills Premarin, and they were previously approved to treat endometriosis and reproductive and hormonal disorders in women.

The EU and Canada already prevent women from using these medicines as supplements, but there is no ban in the US. The panel’s decision means that only new patients, not the existing base of US women who have used them, can now buy the pills as dietary supplements.

Women’s health advocates argued that the FDA should apply the same restrictions to these pills as it does to other supplements, but Love said Pfizer appears to have agreed to drop the prescription pill from the market and not make any additional pills available to treat postmenopausal women who are breast-feeding or having children.

The FDA needs to prohibit women from obtaining these kinds of medicines without a prescription, Love said.

“They just removed the prescription component, and I don’t see why they can’t take that same kind of line with these supplements,” Love said. “We need to get the information out so that we can make the right health choices for ourselves.”

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