Toxicity and Teratogenicity of Optical Isomers of Thalidomide

Abstract

THE thalidomide molecule contains an asymmetric carbon atom, but the form of the drug which has been used therapeutically and which has produced congenital malformations in man is the optically inactive form, that is (±)-thalidomide. The optical antipodes of thalidomide have been synthesized^1,2, and Dr A. M. Creighton has supplied samples of both (+)- and (−)-thalidomide. The (+)-isomer, melting point 240°–241° C, showed [α]_D²⁰+60° (c = 2 in dimethylformamide) and the (−)-isomer, melting point 241°–242° C; showed [α]_D²⁰−58° (c = 2 in dimethylformamide). (±)-Thalidomide has a melting point of 271° C and, of course, is optically inactive. With these samples, we have determined the acute oral toxicities of the three forms in mice, their teratogenic activity in the New Zealand white rabbit and their effect on the hypnosis induced by hexobarbitone in mice.