HYPOTHALAMIC-PITUITARY-GONADAL DYSFUNCTION IN MEN USING CIMETIDINE

We studied the effect of cimetidine therapy (1200 mg per day by mouth for nine weeks) on the hypothalamic-pituitary-gonadal axis of seven men. There was a 43 per cent mean reduction in sperm count after therapy. The luteinizing hormone response to luteinizing hormone releasing factor was also reduced, and a statistically significant rise in plasma testosterone occurred, although it was less than that before therapy. Gonadotropin responses to provocative clomiphene stimulation were inadequate when compared with those of controls. Cimetidine did not affect the responses of thyroid-stimulating hormone, prolactin, growth hormone and thyroxine to thyrotropin releasing factor. Caution is advisable in administration of cimetidine for prolonged periods to young men. (N Engl J Med 300:1012–1015, 1979) THE histamine H2 receptor antagonist, cimetidine, has been shown to be an effective drug in the management of peptic-ulcer disease.1 2 3 4 5 In early clinical trials, few side effects of clinical importance, except for gynecomastia, have been recognized.6,16 Early toxicologic studies, however, have shown a decrease in prostate and seminal-vesicle weight in rats and dogs treated with this drug. Recently, these studies have been confirmed in rats.17 Moreover, they have been extended; cimetidine has been shown to compete for binding to androgen cytosol receptors in the rat ventral prostate and to block nuclear uptake of dihydrotestosterone.17 The present study was initiated. © 1979, Massachusetts Medical Society. All rights reserved.