Antifertility effect of sulfasalazine in the male rat.

Sulfasalazine, which has been used for treatment of ulcerative colitis in man, caused a dose-dependent and reversible reduction in fertility of the male rat. By five weeks after forced feeding with sulfasalazine in corn oil at daily doses of 300, 450 and 600 mg/kg, the fertility decreased to 60.9, 35.5 and 26.8% of the control rats, respectively. Besides, the number of cohabited female being successfully inseminated was significantly reduced especially at high dose. However, complete recoveries of the mating behavior and fertility were evident by three weeks after drug withdrawal. Number of spermatozoa in the caput, the corpus and the cauda epididymides were not changed, but motility of spermatozoa collected from the cauda epididymides was significantly decreased. The body weight and the weights of testes, epididymides, seminal vesicles, prostate glands and coagulating glands as well as the concentration of plasma testosterone were not altered by five weeks after drug treatment at a dose of 450 mg/kg. This study shows that sulfasalazine also has an antifertility action in the male rat without affecting the blood androgens as previously reported in male patients.