An estimated 1.4 million U.S. women take custom-compounded bioidentical hormone therapy (CBHT) for menopausal symptoms, and most are unaware that these drugs are not FDA-approved, according to late-breaking research presented this week at the North American Menopause Society (NAMS) annual meeting.

This “important knowledge gap” represents a substantial educational opportunity for clinicians who “play a significant role” in guiding women’s choice of menopausal hormone therapy (MHT), the investigators say in a meeting abstract.

“Even though there are times when a woman might need custom-compounding because she might be sensitive to an approved drug's ingredients, we think that it's important to educate women about the risks and that they are not FDA-approved,” JoAnn Pinkerton, of the University of Virginia, Charlottesville, who led the study and presented the data, told Reuters Health by phone.

To see how many U.S. menopausal women were using CBHT and to explore how much women knew about it versus FDA-approved MHT, two Internet surveys were conducted among women aged 40 and older. One was done by Rose Research in April 2014 and the other was done by Harris Interactive in July 2013.

In the Rose survey, 5 percent of respondents (883 out of 17,825) were current MHT users. Extrapolating to the general population suggests that at least 3.6 million U.S. women per year use MHT, the researchers say.

“Multiplying 3.6 million by the average number of drugs current MHT users in Rose were taking per year indicates 57 million prescriptions for MHT may be filled annually,” they report.

Subtracting the roughly 36 million FDA-approved MHT prescriptions filled annually from the estimated 57 million annual MHT prescriptions suggests 21 million CBHT prescriptions may be filled annually, they estimate.

“Further, dividing the roughly 21 million annual CBHT prescriptions by mean duration of use by number of products being used suggests at least 1.4 million women use CBHT," they say.

The cost of CBHT prescriptions filled annually in the U.S. “may exceed $1 billion,” the researchers say.

In the Harris survey, 86 percent of the menopausal women appeared to be unaware that these drugs were not FDA-approved, Pinkerton noted.

“Three-quarters (76 percent) of the Harris completers didn't know whether bioidentical hormone therapies were compounded, if they were FDA-approved or not, and 10 percent believed incorrectly that they were FDA-approved,” she told Reuters Health. “That makes us really concerned because it means that we as providers are not doing a good job about talking about the risks.”

She added, “If you think back to the deaths with the fungal meningitis cases, we learned a lot about the unique risks with custom-compounding, that they aren't FDA-approved, monitored or regulated, that there is concern about under dosing or over dosing and there haven't been any large clinical trials to test safety and effectiveness of these products.”

Dr. Pinkerton said that once she looked at this survey data and realized how many women were actually using CBHT, she felt it was important to present it at NAMS and “get the message out” in the hope that more health providers will talk to their patients about the potential risks of using non-FDA-approved compounded products.