Terbinafine Formulations Likely Safe During Pregnancy

Both oral and topical forms of the antifungal agent terbinafine seem safe to use during pregnancy, a large registry study shows.

There was no increase in fetal malformations or spontaneous abortion with terbinafine, researchers found.

"Our results may provide reassurance for pregnancies exposed to terbinafine, as well as help inform clinicians, patients, and drug regulatory authorities," Dr. Niklas Worm Andersson of University Hospital Bispebjerg and Frederiksberg in Copenhagen told Reuters Health by email. "However, given that this is the first published observational study to examine the association between terbinafine use in pregnancy and fetal safety outcomes, additional studies are needed to confirm and expand on these findings."

As reported in JAMA Dermatology, Dr. Andersson and colleagues analyzed data from more than a million and a half pregnancies in Denmark from 1997-2016. Pregnancies were matched on propensity scores comparing oral terbinafine-exposed vs unexposed women (1:10 ratio); topical terbinafine vs unexposed (1:10); and oral vs topical terbinafine (1:1).

A total of 891 pregnant women (mean age, 30.4) took oral terbinafine and 3,174 (mean age, 29.5) used topical terbinafine; 40,650 unexposed (to either formulation) were included for the matched outcome analyses.

With regard to major malformations risk, the prevalence odds ratios were 1.01 for oral terbinafine-exposed vs unexposed pregnancies (absolute risk difference, 0.04%); 1.08 for topical terbinafine vs unexposed (ARD, 0.26%); and 1.18 for oral vs topical terbinafine (ARD, 0.59%)

With respect to the risk of spontaneous abortion, the hazard ratios were 1.06 for oral terbinafine vs unexposed pregnancies (ARD, 0.13%); 1.04 for topical terbinafine vs unexposed (ARD, 0.17%); and 1.19 for oral vs topical terbinafine (ARD, 1.13%).

No statistically significant associations were seen in sensitivity analyses of any of the comparisons.

Dr. Jenny Murase of the Palo Alto Foundation Medical Group in Mountain View, CA, coauthor of a related editorial, commented in an email to Reuters Health that although terbinafine is likely the safest anti-fungal medication to use during pregnancy, "it is always important to question the appropriateness of treating non-life-threatening issues during pregnancy and lactation."

—Marilynn Larkin

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