Adverse effects of the salazopyrine metabolite sulphapyridine on female fertility in the rat.

Salazopyrine, a common therapy for inflammatory bowel disease, is known to have a reversible antifertility effect in men and male rats via its metabolite, sulphapyridine. To determine if there is an adverse effect in females, 20 mature Sprague-Dawley rats were assigned to a treatment (400 mg/kg sulphapyridine daily), or a control group. After three estrous cycles of treatment, the rats were bred to males of proven fertility. When killed at 10 days gestation, there was a significant reduction in the proportion of fertilized oocytes between control (112/174) and treatment (81/212) groups (chi-square = 26.16, d.f. = 1, P less than .00001). These findings suggest an adverse effect of sulphapyridine on female fertility.