Sulfasalazine-induced abnormal sperm penetration assay reversed on changing to 5-aminosalicylic acid enemas

Sulfasalazine, a drug used in the treatment of inflammatory bowel disease, has been associated with male infertility, an effect attributed to sulfapyridine rather than to 5-aminosalicylic acid (5-ASA), the presumed therapeutically active component of sulfasalazine. Recently, the sperm penetration assay (SPA) has been found to be an accurate method of quantitating male fertilization potential. We report the case of a man with ulcerative colitis in whom infertility and a markedly abnormal SPA were demonstrated while he was taking sulfasalazine. Shortly after discontinuing sulfasalazine and initiating treatment with 5-ASA enemas, his SPA became normal and his wife became pregnant. The SPA is a useful screening test for sulfasalazine-induced male infertility. On the other hand, 5-ASA enemas do not appear to be associated with an abnormal SPA.