When clinicians prescribe the acne medication isotretinoin, they advise reproductive-age women to avoid pregnancy through two different contraceptives and an online iPledge app.

Since the drug causes severe birth defects, it is important young women do not become pregnant while taking the drug, says Aaron Lazorwitz, MD, MSCS, assistant professor of obstetrics and gynecology at the University of Colorado Anschutz Medical Campus division of family planning in Aurora, CO.

Etonogestrel contraceptive implants could be one contraceptive option for women taking isotretinoin, but there are concerns the acne drug would decrease the effectiveness of hormonal contraceptives.

“What’s interesting about this drug [isotretinoin] is there’s some data in the literature that it can promote enzymes in the liver that break down other drugs,” Lazorwitz says.

For this reason, the Food and Drug Administration states in prescribing information for isotretinoin that a “drug interaction that decreases effectiveness for hormonal contraceptives has not been entirely ruled out for isotretinoin.”1

Investigators conducted a prospective study of women, ages 18-45 years, who planned to take isotretinoin while using an etonogestrel contraceptive implant. They collected participants’ blood samples before starting the acne medication to measure their baseline serum etonogestrel concentration.1

“We took women who had an implant for birth control and take isotretinoin for acne and measured the hormone released before and during treatment to see if we could see a similar effect. Fortunately, we did,” Lazorwitz says. “We didn’t find that it caused the levels to drop.”

The cutoff for etonogestrel contraceptive implants to effectively prevent pregnancy is 90 picograms per milliliter (90 pg/mL) of serum etonogestrel concentration, he says.

“Below 90 pg/mL, women might ovulate, and the contraceptive might not work as well,” Lazorwitz explains. “We didn’t find that problem; all eight participants kept their levels above 90.”

The study participants used the implant for varying amounts of time. Some had it implanted for a month, while the longest one had been in place for 27 months. Despite these differences, the amount of serum etonogestrel concentration was consistent.

“You’d be worried the longer it is implanted, it runs out of the drug more, but we didn’t see that at all,” Lazorwitz says.

None of the participants became pregnant. “We were happy to see that,” Lazorwitz says. “We don’t want adolescents and young women using this medication to get pregnant.”

The results should reassure clinicians and women that the drug interaction between etonogestrel implants and isotretinoin will not be significant, he adds. “We only looked at implant users and can’t generalize beyond the implant,” Lazorwitz says.

The three-year implant is a highly effective contraceptive with a 99.7% success rate, he adds. “It goes in the arm over the triceps muscle,” Lazorwitz says. “Like an IUD [intrauterine device], it works without the person having to do anything, which is why those are the most effective methods.”

This pilot study suggests it is safe for clinicians to prescribe etonogestrel contraceptive implants for women on the acne drug.

“We can reassure people, when talking about options for birth control and when they want to take isotretinoin, that the implant works great,” Lazorwitz says. “Their second birth control method could be a barrier method: a condom, diaphragm, or spermicide.”

REFERENCE

  1. Lazorwitz A, Seale R, Davis A, et al. A pilot study on the effect of isotretinoin on serum etonogestrel concentrations in contraceptive implant users. Contraception 2020. doi:10.1016/j.contraception.2020.04.011. [Epub ahead of print].