Risk Summary

There are no adequate data on the developmental risk associated with the use of NOURIANZ in pregnant women. In animal studies (see Data), oral administration of istradefylline during pregnancy resulted in teratogenicity (increased incidences of fetal structural abnormalities, embryofetal and offspring mortality and growth deficits) at clinically relevant exposures and in the absence of maternal toxicity. The teratogenic effects of istradefylline in pregnant rabbits were substantially greater when administered in combination with levodopa/carbidopa than when administered alone.

The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. In the U.S. general population, the estimated background risks of major birth defects and miscarriage in clinically recognized pregnancies are 2-4% and 15-20%, respectively.

Data

Animal Data

Oral administration of istradefylline (0, 40, 200, or 1000 mg/kg/day) to pregnant rats throughout organogenesis resulted in decreased fetal body weight and increased fetal skeletal and visceral variations at the highest dose tested. Plasma exposure (AUC) at the no-effect dose for adverse effects on embryofetal development in rats (200 mg/kg/day) is approximately 4 times that in humans at the maximum recommended human dose (MRHD) of 40 mg.

Oral administration of istradefylline (0, 50, 200, or 800 mg/kg/day) to pregnant rabbits throughout organogenesis resulted in increased embryofetal mortality at the mid and high doses, increased fetal malformations (external, visceral, skeletal) at all doses, and reduced fetal body weight at the highest dose tested. A no-effect dose for adverse effects on embryofetal development in rabbits was not identified. Plasma exposure (AUC) at the lowest dose tested (50 mg/kg/day) is less than that in humans at the MRHD.

In pregnant rabbits, oral administration of istradefylline (0, 50, 200, or 400 mg/kg/day) alone or in combination with oral levodopa/carbidopa (80/20 mg/kg/day) throughout the period of organogenesis resulted in an increase in embryofetal mortality and an increase (marked at the high dose) in malformations (including limb reduction, craniofacial, and cardiovascular) in fetuses from rats administered istradefylline at all doses in combination with levodopa/carbidopa. Istradefylline alone resulted in an increase in embryofetal mortality and visceral malformations; no increase in fetal malformations was observed with levodopa/carbidopa alone. Fetal body weight was reduced by istradefylline alone (400 mg/kg/day) and in combination (200 and 400 mg/kg/day) with levodopa/carbidopa. A no-effect dose for adverse effects on embryofetal development in rabbits when istradefylline was administered in combination with levodopa/carbidopa was not identified. Plasma exposure (AUC) at the lowest dose of istradefylline tested (50 mg/kg/day) in combination with levodopa/carbidopa is less than that in humans at the MRHD.

Oral administration of istradefylline (0, 6, 25, 100, or 400 mg/kg/day) to female rats throughout gestation and lactation resulted in decreased pup survival and reduced pup body weight (which persisted into adulthood) at all but the lowest dose tested. Exposure to drug in the milk may have contributed to these effects, as demonstrated in pups of untreated (control) dams reared by dams receiving istradefylline (400 mg/kg/day). No adverse effects were observed on physical or neurobehavioral development, or reproductive function. Plasma exposure at the no-effect dose for adverse effects on pre- and postnatal development in rats (6 mg/kg/day) is less than that in humans at the MRHD.