Protection from the embryopathic effects of 7-hydroxymethyl-12-methylbenz(a)anthracene by 2-methyl-1,2-bis-(3-pyridyl)1-propanone(metopirone, Ciba) and beta-diethylaminoethyldiphenyl-n-propyl acetate (SKF 525-A).

Pretreatment with Metopirone (40 mg.) or SKF 525-A (2 mg./100 g. maternal body weight) protected aganist the embryotoxic and teratogenic actions of7-OHM-12-MBA) (2.5 mg/100 g. maternal body weight) in the Sprague-Dawley rat. At the doses administered SKF-525-A was a more efficient protector than Metopirone. The adrenocorticolytic actions of 7-OHM-12-MBA in the maternal adrenal glands were also prevented by these compounds and a close correlation existed between the degree of protection of the maternal adrenals and of the foetuses. It is suggested that the ultimate embryopathic substance is a metabolite of 7-OHM-12-MBA.