Effects of mesalazine substitution on salicylazosulfapyridine-induced seminal abnormalities in men with ulcerative colitis.

Some semen characteristics of eight male patients with clinically inactive ulcerative colitis were investigated. Semen analysis was carried out twice during salicylazosulfapyridine (SASP) treatment and repeated twice after at least 3 months' treatment with mesalazine. The motility variables all showed significant improvement during mesalazine treatment: the graded motility (p less than 0.05), motility in percentage (p less than 0.01), and the penetration in egg white (p less than 0.05). The semen plasma was analyzed for mesalazine and the metabolite Ac-mesalazine during both regimens. There was no difference in the semen plasma concentration of mesalazine during the two regimens, whereas Ac-mesalazine was significantly higher during mesalazine treatment than during SASP treatment, indicating that other SASP metabolites, most likely sulfapyridine, are the agent causing the abnormal sperm characteristics. We suggest that pure mesalazine preparations are a safer alternative in young men with chronic inflammatory bowel disease.