[Effect of phenobarbital on the embryotoxic action of 2-methyl-4-chlorophenoxyacetic acid]

Single administration of 2-methyl-4-chlorophenoxyacetic acid (2M-4C) to albino rats on the 9th and 10th day of gestation produces a teratogenic and embryotoxic action. A preliminary administration of phenobarbital in a dose of 80 mg/kg for 3 days largely reduced the embryotoxic effect of the drug, this manifesting itself in a lower general embryonal and post-implantation mortality, greater size and mass of the fetuses. It is suggested that the stimulation of the microsomal oxidation with phenobarbital led to a higher speed of the 2M-4C molecule decomposition and, consequently, to its lessened embryotoxic effect.