Embryotoxic effects of thalidomide derivatives on the non-human primate Callithrix jacchus; 3. Teratogenic potency of the EM 12 enantiomers.

The teratogenic potencies of the enantiomers of 2-(2,6-dioxopiperidine-3-yl)-phthalimidine ( = EM 12), a teratogenic thalidomide analogue, were investigated in Callithrix jacchus, a primate very sensitive to the teratogenic action of this thalidomide analogue. The results indicate that the S-(-)-form of EM 12 is clearly more teratogenic than the R-(+)-form. The interpretation of the studies designed to evaluate stereo-selective differences in the teratogenicity of the enantiomers becomes difficult, since both enantiomers racemise in vivo with appreciable rates (Schmahl et al. 1988a, b). Therefore, it cannot be concluded as yet that the R-(+)-form lacks all teratogenic potential.