Effects of short- and long-term administrations of famotidine and ranitidine on some pituitary, sexual and thyroid hormones.

The endocrine effects of short-term (4 weeks) and long-term (6 months) oral administration of famotidine (40 and 20 mg nocte, respectively) and ranitidine (300 and 150 mg nocte, respectively), were investigated in 20 male patients with duodenal ulcers. Basal PRL, LH, FSH and TSH serum levels were evaluated and their response to specific releasing factors, and basal blood levels of some sexual (E2, P, T) and thyroid (T3, T4) hormones. None of the treatments modified basal and RH-stimulated levels of PRL, LH, FSH and TSH, nor basal levels of sexual hormones. Regarding the thyroid hormones, no effect was observed during the administration of famotidine. On the contrary, short-term treatment with ranitidine induced a significant decrease in thyroxine serum levels, while no effect was observed during maintenance treatment.