Estrogen-dependent differences in the acetylation of sulfadimidine in the rat

The influence of sex hormones on the acetylation of sulfadimidine was investigated in male and female rats, both intact and castrated. Sulfadimidine was administered intravenously in the dose of 40 mg/kg body weight, and unchanged and acetylated sulfadimidine (Ac-S) were then determined in urine and blood. It was found that the percentage of Ac-S was significantly higher in the urine of females than males. The concentration of sulfadimidine in blood was also higher in females than in males. While estrogenization raised the percentage of Ac-S in the urine of males and the concentration of unchanged sulfadimidine in blood, treatment with an androgen had no significant effect in females. The long-lasting stimulatory influence of estrogen in males and a normal percentage of Ac-S in gonadectomized females suggest an indirect action of estrogen. Possible mechanisms are discussed.