Related Experiment Videos
Prolactin responses to cimetidine
British Journal of Clinical Pharmacology
|January 1, 1979
Summary
Intravenous cimetidine significantly increases prolactin levels in men, an effect blocked by bromocriptine. Oral cimetidine did not raise prolactin, suggesting dose-dependent effects and potential idiosyncratic responses.
Area of Science:
- Pharmacology
- Endocrinology
Background:
- Cimetidine, a histamine H2 receptor antagonist, is widely used.
- Elevated prolactin (hyperprolactinemia) can cause endocrine disturbances.
Purpose of the Study:
- To investigate the effect of intravenous and oral cimetidine on serum prolactin levels in healthy males.
- To explore the role of prolactin in cimetidine-associated side effects like gynecomastia.
Main Methods:
- Four healthy males received a 400 mg intravenous injection of cimetidine.
- A separate group of healthy males received an 800 mg oral dose of cimetidine.
- Serum prolactin levels were measured, and bromocriptine pretreatment was used in one experiment.
Main Results:
- Intravenous cimetidine caused a threefold increase in serum prolactin.
- Bromocriptine pretreatment prevented the prolactin increase induced by intravenous cimetidine.
- Oral cimetidine (800 mg) did not elevate prolactin levels, with peak concentrations less than 20% of IV dose.
- Hyperprolactinemia was observed in 3 of 7 patients experiencing gynecomastia or galactorrhea during cimetidine treatment.
Conclusions:
- Intravenous cimetidine can acutely increase prolactin levels in healthy males.
- The prolactin-elevating effect of cimetidine appears to be dose-dependent.
- Hyperprolactinemia may contribute to idiosyncratic side effects like gynecomastia and galactorrhea at therapeutic oral doses.