HealthDay News — Under the Risk Evaluation and Mitigation Strategy (REMS), prenatal exposure to phentermine-topiramate is lower than topiramate and other antiobesity medications (AOMs), according to a study published online March 21 in the Annals of Internal Medicine.
Noting that the US Food and Drug Administration approval of phentermine-topiramate for obesity required a REMS to prevent prenatal exposure, Amir Sarayani, PharmD, MPH, PhD, from the University of Florida in Gainesville, and colleagues conducted a retrospective cohort study involving females aged 12 to 55 years to examine the rate of prenatal exposure, contraceptive use, and pregnancy testing with phentermine-topiramate compared to topiramate or other AOMs. Overall, 156,280 treatment episodes were included.
The researchers found that at treatment initiation, the adjusted prevalence of pregnancy was 0.9 vs 1.6 per 1000 episodes for phentermine-topiramate vs topiramate (prevalence ratio, 0.54). For phentermine-topiramate vs topiramate, the incidence rate of conception during treatment was 9.1 vs 15.0 per 1000 person-years (rate ratio, 0.61). Compared with AOMs, for phentermine-topiramate, both outcomes were similarly lower. Prenatal exposure was slightly lower in topiramate vs AOM users. In all cohorts, approximately 20% of patients had at least 50% of treatment days covered by contraceptives. Furthermore, 5% or less of patients had pregnancy tests before treatment, but this was more common among phentermine-topiramate users.
“Potential exposures were detected, suggesting the need for further clinical vigilance and risk mitigation,” the authors write.
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