Teratological evaluation of an injectable male antifertility agent, styrene maleic anhydride, in rats.

Polymer styrene Maleic anhydride (SMA) dissolved in dimethylsulphoxide (DMSO) was injected into the lumen in each vas deferens of male rats at dose levels of 0.25 mg, 0.50 mg, 1.0 mg, 2.5 mg, and 5.0 mg, while control rats (groups 1) received 0.03 mL DMSO in each vas deferens. After 4 weeks, the lumen was flushed with 0.1 mL DMSO and the animals were left for another 6 weeks to regain fertility. These rats were mated with virgin and coeval females. No anomaly was observed which could be related to teratogenic action of the polymer in pregnant mothers or fetuses.