Carbamazepine‐Induced Brain Weight Reduction in Chick Embryos

Abstract The antiepileptic drug carbamazepine (CBZ) had been considered to be relatively safe for the fetus. We examined the teratogenicity of CBZ using chick embryos, with particular focus on the brain. A single dose of 5 mg was injected into the yolk sac of White Leghorn chick embryos at 24, 72, 120, 168 or 216 hours of incubation. On day 19 of incubation, embryos were removed, and counted and recorded as either live or dead. Each live embryo was inspected for the presence of external abnormalities, and body and brain weight were measured. There was no statistically significant difference between treated groups and control groups at all hours of incubation for mean body weight and incidence of embryo death. Mean brain weight was significantly lighter in treated groups at 120 and 168 hours of incubation. A significant difference in mean brain/body weight ratio was observed only at 120 hours of incubation. External abnormalities in treated embryos were not found with any consistency and these incidences were not significantly higher compared to those in the control groups. This experiment provides evidence regarding the risk of teratogenesis due to CBZ in the brain of chick embryo. The 120 hours of incubation in chick embryos corresponds to the 34-36th day after conception in humans.