PHASE-I CLINICAL-TRIAL OF AN INJECTABLE CONTRACEPTIVE FOR THE MALE

Earlier studies on the rat and the monkey had demonstrated that an inj ection of styrene maleic anhydride (SMA) in a solvent vehicle of dimet hyl sulphoxide (DMSO) into the lumen of the vas deferens is toxicologi cally safe and has contraceptive action. Phase I clinical trial was th erefore undertaken on 38 male volunteers giving varying doses of SMA, ranging between 5 mg and 140 mg, into each vas deferens. A dose of 70 mg is the predicted therapeutic dose based on animal data. That the co mpound is within the vas deferens lumen during the period of the safet y assessment is inferred from the effect on the spermatozoa count in e jaculates which reach azoospermic levels in the higher dose ranges. Th e treatment is well tolerated with only minimal side effects in a few cases and no long-term adverse effects.