Serum prolactin response to acute and chronic cimetidine administration in man.

Unlabelled: The effects of cimetidine administration on the serum prolactin (PRL) response has been studied in twenty healthy volunteers and 46 duodenal ulcer patients. Cimetidine acute administration in two different doses (200 or 400 mg i.v.) induced a similar conspicuous rise of PRL while CB154, a dopaminergic drug, inhibited said increase. No high PRL level was observed when the drug was administered per os in a single acute dose (800 mg), nor in the chronic short-term treatment (1 g/die/28 days) for duodenal ulcer.

Conclusions: 1. Cimetidine has no antidopaminergic activity or this hypothetic action is very slight; 2. serum PRL increase after the drug is probably ascribable to the H2-receptor blocking, 3. this effect is observable only with the bolus i.v. of cimetidine, but not during or after acute and chronic oral administration.