Sulphasalazine and male infertility: reversibility and possible mechanism.

Earlier observations on infertility related to sulphasalazine treatment were extended and semen samples obtained from 28 patients with inflammatory bowel disease on treatment with sulphasalazine at 2-4 g per day. Semen was examined for changes in density, motility, and morphology before, during, and after withdrawal of sulphasalazine. Gross semen abnormalities were seen in 18 patients on this drug for more than two months. Semen quality improved after sulphasalazine had been withdrawn for more than two months and 10 pregnancies are reported after sulphasalazine withdrawal. Preliminary endocrine and acetylator phenotype studies do not elucidate the mechanism of this important new side-effect of this drug. The time course of the drug's effect on semen quality is consistent with the hypothesis that sulphasalazine or a metabolite, possibly sulphapyridine, is directly toxic to developing spermatozoa. These studies confirmed the preliminary report and suggest that prolonged treatment with sulphasalazine may universally depress semen quality and cause reversible infertility.