Abstract
Aminopyrine and its molecular compounds with barbiturates were commonly used in humans as analgesics and antipyretics. These compounds showed potent teratogenicity. Pregnant ICR/Jcl mice received 3 s.c. injections of pyrabital (2 molecules of aminopyrine and 1 molecule of barbital) daily on days 9, 10 and 11 of gestation. Significant yields of late deaths and malformations were induced at doses more than 0.2 mg/g body weight, and clear dose-relationship was observed. Most malformations were ruptured omphaloceles (eventration of the abdominal viscera), which are extremely rare in mice. Equivalent doses of aminopyrine contained in pyrabital also induced late deaths and malformations. However, in each case, the incidence of malformations was significantly lower than that by pyrabital. When aminopyrine (0.21 mg/g) and barbital (0.09 mg/g) were given separately to pregnant mice on days 9, 10 and 11 of gestation, teratogenicity was approximately equal to that by the equivalent dose of molecular compound (0.3 mg/g). Consequently, potent teratogenicity of pyrabital is independant of the molecular compound, but depends only on the presence of baibital with aminopyrine.
