Pregnancy
Pregnancy Exposure Registry: There is a pregnancy exposure registry that monitors pregnancy outcomes in women exposed to bictegravir sodium, emtricitabine, and tenofovir alafenamide fumarate during pregnancy. Healthcare providers are encouraged to register patients by calling the Antiretroviral Pregnancy Registry (APR) at 1-800-258-4263.
Risk Summary: There are insufficient human data on the use of bictegravir sodium, emtricitabine, and tenofovir alafenamide fumarate during pregnancy to inform a drug-associated risk of birth defects and miscarriage. Bictegravir (BIC) and tenofovir alafenamide (TAF) use in women during pregnancy has not been evaluated; however, emtricitabine (FTC) use during pregnancy has been evaluated in a limited number of women reported to the APR. Available data from the APR show no difference in the overall risk of major birth defects for FTC compared with the background rate for major birth defects of 2.7% in a US reference population of the Metropolitan Atlanta Congenital Defects Program (MACDP). The rate of miscarriage is not reported in the APR. The estimated background rate of miscarriage in the clinically recognized pregnancies in the US general population is 15-20%. Methodological limitations of the APR include the use of MACDP as the external comparator group. The MACDP population is not disease-specific, evaluates women and infants from a limited geographic area, and does not include outcomes for births that occurred at less than 20 weeks gestation. In animal reproduction studies, no evidence of adverse developmental outcomes was observed with the components of bictegravir sodium, emtricitabine, and tenofovir alafenamide fumarate at exposures that were either not maternally toxic (rabbits) or greater than (rats and mice) those in humans at the recommended human dose (RHD). During organogenesis, systemic exposures (AUC) to BIC were approximately 36 (rats) and 0.6 times (rabbits), to FTC were approximately 60 (mice) and 108 times (rabbits), and to TAF were approximately 2 (rats) and 78 times (rabbits) the exposure at the RHD of bictegravir sodium, emtricitabine, and tenofovir alafenamide fumarate. In rat pre/postnatal development studies, maternal systemic exposures (AUC) were 30 times (BIC), 60 times (FTC), and 19 times (TDF) the exposures of each component in humans at the RHD.
Emtricitabine Human Data: Based on prospective reports to the APR of 3,406 exposures to FTC-containing regimens during pregnancy resulting in live births (including 2,326 exposed in the first trimester and 1,080 exposed in the second/third trimester), there was no difference between FTC and overall birth defects compared with the background birth defect rate of 2.7% in the US reference population of the MACDP. The prevalence of birth defects in live births was 2.3% (95% CI: 1.7% to 3.0%) with first trimester exposure to FTC-containing regimens and 2.0% (95% CI: 1.3% to 3.1%) with the second/third trimester exposure to FTC-containing regimens.
Bictegravir Animal Data: BIC was administered orally to pregnant rats (5, 30, or 300 mg/kg/day) and rabbits (100, 300, or 1000 mg/kg/day) on gestation days 7 through 17, and 7 through 19, respectively. No adverse embryo-fetal effects were observed in rats and rabbits at BIC exposures (AUC) of up to approximately 36 (rats) and 0.6 (rabbits) times the exposure in humans at the RHD of bictegravir sodium, emtricitabine, and tenofovir alafenamide fumarate. Spontaneous abortion, increased clinical signs [fecal changes, thin body, and cold-to-touch], and decreased body weight were observed at a maternally toxic dose in rabbits (1000 mg/kg/day; approximately 1.4 times higher than human exposure at the RHD). In a pre/postnatal development study, BIC was administered orally to pregnant rats (up to 300 mg/kg/day) from gestation days 6 to lactation/post-partum day 24. No significant adverse effects were observed in the offspring exposed daily from before birth (in utero) through lactation at maternal and pup exposures (AUC) of approximately 30 and 11 times higher, respectively, than human exposures at the RHD.
Emtricitabine Animal Data: FTC was administered orally to pregnant mice (250, 500, or 1000 mg/kg/day) and rabbits (100, 300, or 1000 mg/kg/day) through organogenesis (on gestation days 6 through 15, and 7 through 19, respectively). No significant toxicological effects were observed in embryo-fetal toxicity studies performed with emtricitabine in mice at exposures approximately 60 times higher and in rabbits at approximately 108 times higher than human exposures at the RHD. In a pre/postnatal development study with FTC, mice were administered doses up to 1000 mg/kg/day; no significant adverse effects directly related to drug were observed in the offspring exposed daily from before birth (in utero) through sexual maturity at daily exposures (AUC) of approximately 60 times higher than human exposures at the RHD.
Tenofovir Alafenamide Animal Data: TAF was administered orally to pregnant rats (25, 100, or 250 mg/kg/day) and rabbits (10, 30, or 100 mg/kg/day) through organogenesis (on gestation days 6 through 17, and 7 through 20, respectively). No adverse embryo-fetal effects were observed in rats and rabbits at TAF exposures of approximately 2 (rats) and 78 (rabbits) times higher than the exposure in humans at the recommended daily dose of bictegravir sodium, emtricitabine, and tenofovir alafenamide fumarate. TAF is rapidly converted to tenofovir; the observed tenofovir exposure in rats and rabbits were 55 (rats) and 86 (rabbits) times higher than human tenofovir exposures at the RHD. Since TAF is rapidly converted to tenofovir and lower tenofovir exposures in rats and mice were observed after TAF administration compared to TDF administration, a pre/postnatal development study in rats was conducted only with TDF. Doses up to 600 mg/kg/day were administered through lactation; no adverse effects were observed in the offspring on gestation day 7 [and lactation day 20] at tenofovir exposures of approximately 12 [19] times higher than the exposures in humans at the RHD of bictegravir sodium, emtricitabine, and tenofovir alafenamide fumarate.