Effects of two histamine H2-receptor blocking drugs on basal levels of gonadotrophins, prolactin, testosterone and oestradiol-17 beta during treatment of duodenal ulcer in male patients.

In a study of 51 male patients with duodenal ulcer, treatment with cimetidine was accompanied by an increase in basal levels of serum testosterone. Treatment with ranitidine, a new histamine H2-receptor antagonist, produced no such effect. It is concluded that cimetidine had antiandrogenic activity in man which is separate from the histamine H2-receptor blocking activity.