The widely used acne drug isotretinoin can cause severe birth defects and miscarriage, yet only about a third of women who use it are taking effective measures to avoid pregnancy, Canadian researchers say.

“When I first prescribed the drug in the 1980s we were quite afraid of the drug and very cautious,” Dr. David Henry from the Institute for Clinical Evaluative Sciences in Toronto told Reuters Health. “I fear some of that has been lost through familiarity.”

Numerous studies from several countries have shown that women taking isotretinoin aren’t aware of - or simply ignore - the pregnancy prevention guidelines.

Henry and colleagues used prescription records from 1996 to 2011 to estimate how often pregnancy occurred during and after treatment with isotretinoin. They also looked at how many women taking isotretinoin also had prescriptions for oral contraceptives before and while using isotretinoin.

Of the nearly 60,000 women who received isotretinoin, as many as 55 percent had not tried other, less dangerous acne drugs first (a clear violation of prescribing guidelines).

In the year before their isotretinoin treatment, 28 to 36 percent of women (depending on where they lived) used oral contraceptives - and the percentage did not go up during isotretinoin treatment.

As reported in CMAJ, about four to six of every thousand women using the medication got pregnant. And four times that many got pregnant within 42 weeks of taking it.

Of the 1473 pregnancies recorded during this study period, 118 (8 percent) resulted in live births, 290 (20 percent) resulted in miscarriages, and 1041 (71 percent) were ended by abortions.

Eleven (9 percent) of the live babies had birth defects.

“Medical practitioners and patients must be constantly reminded of the risks of isotretinoin to the fetus and must adhere to the policy that mandates effective contraceptive measures,” the researchers say.

“There is persistent incomplete adherence to very clear requirements for prescribing and dispensing the drug to young females,” Henry said. “And this will be an underestimate as it is based only on publicly funded insurance programs and does not include privately purchased drug and online supplies (which are cheap).”

Henry emphasized that women and their doctors need to “undertake the necessary steps to exclude pregnancy before commencement, to minimize risk during pregnancy, and to monitor for pregnancy during and after treatment. It’s quite an intensive process when done properly.”

Dr. Bruno Stricker from Erasmus University Medical Center, Rotterdam, The Netherlands found similar risky behavior during isotretinoin use there. He told Reuters Health, “Basically, there are three options, i.e., not being pregnant, not prescribing isotretinoin, or prescribing isotretinoin only after strict written informed consent and a pregnancy test. Of course, even then things may go wrong, unfortunately, but the risk for that will be smallest.”

In the U.S., the Food and Drug Administration requires women to register at iPLEDGE , complete an informed consent form and receive counseling about the risks associated with the drug, and it requires women of childbearing age to comply with pregnancy testing. Only registered prescribers and pharmacists are permitted to prescribe and dispense isotretinoin.

Despite this requirement, studies in the U.S. have documented similarly low use of effective contraception, low compliance with pregnancy prevention programs, and high rates of birth defects and abortion after maternal isotretinoin use.

Source: Reuters