Effects of Cimetidine on the Secretion of Some Pituitary Hormones

Abstract

Cimetidine infused intravenously into 6 healthy volunteers did not induce significant changes in plasma levels of prolactin (hPRL), thyreotropin (hTSH), gonadotropin (hLH and hFSH) and growth hormone (hGH). Conversely it caused a significant increase in prolactin response to TRH without modifying the hTSH response to thyreotropin-releasing hormone (TRH) and gonadotropin response to gonadotropin-releasing hormone (GnRH). Data obtained in these experiments, together with data reported in the literature, suggest that the amplified prolactin response to TRH observed during cimetidine infusion, is likely to be connected with a blockade of H₂-receptors rather than to unspecific actions of cimetidine.

Prolactin release in man: influence of cimetidine, thyrotrophin-releasing hormone and acute hypercalcaemia

“…By contrast, 400 mg Cim, administered iv together with TRH, more than doubled the above men¬ tioned TRH-induced Prl response. However, when other investigators stimulated the Prl release by use of a much higher TRH dose (200 pg), simultaneous iv infusion of Cim, either failed to influence the TRH-induced Prl response (Delitala et al 1979b), or augmented this response only slightly (Scarpignato et al 1979). The Prl response is clearly dose-dependent, showing a progressive increase for TRH doses ranging between 6.25 and 100 pg.…”

Failure of Drugs Acting on H(2)-Receptors to Modify Plasma Prolactin Levels in Pituitary Adenomas: Evidence for a Suprapituitary Locus of Action

“…This response is more pro nounced in women than in men [2] and is dose-related [4]. In addition, we have shown that intravenous infusion of this drug also increases the prolac tin response to exogenous thyrotropin-releasing hormone (TRH) [17]. The site at which cimetidine stimulates prolactin release is, at present, a matter of speculation.…”

Effect of Acute and Chronic Cimetidine Administration on Glucose Tolerance and Insulin Secretion in Man

“…Cimetidine was shown to affect, in some experimental conditions, the endocrine secretions in animals and in man [19,21,23,24], However, conflicting results have been reported in the literature concerning the effect of this H2-antagonist on glucose tolerance. While a deterioration of glucose handling after long-term treatment was observed by Jefferys and Vale [16], an improvement of glucose tolerance was reported [14] after acute admin istration of this drug.…”