Prolactin secretion in man following acute and long-term cimetidine administration

Abstract

In 20 patients with duodenal ulcer we measured serum prolactin levels following acute and long-term cimetidine administration. In addition, in 20 healthy volunteers we studied the effect of pre-treatment with bromocriptine, metergoline, nomifensine and cyproheptadine on cimetidine-induced prolactin release. Intravenous cimetidine stimulated prolactin secretion in patients and in normal subjects. In the latter, bromocriptine and metergoline pre-administration blunted the release of prolactin in response to iv cimetidine whereas nomifensine and cyproheptadine were ineffective. Long-term treatment with cimetidine (1.2 g daily for 3 months) had no effect on prolactin secretion in the 20 patients studied. No incidence of gynaecomastia, galactorrhoea or disorders of the menstual cycle was observed.It has been shown that cimetidine, an H2 receptor blocking agent, releases prolactin in man (Carlson & Ippoliti 1977; Bohnet et al. 1978). Moreover, side effects such as gynaecomastia and galactorrhoea have been reported in patients treated with the drug (Hall 1976; Delle Faveetal. 1977; Bateson etal. 1977).We studied the effects of both acute and chronic cimetidine treatment on serum prolactin levels in 20 patients with duodenal ulcers. Additional stu¬ dies were carried out on 20 normal subjects in order to elucidate the mechanism(s) responsible for cimetidine-induced prolactin secretion. Materials and MethodsStudies were performed on 20 healthy volunteers, medi¬ cal students and technicians, aged 19 to 36 years and 20 patients with duodenal ulcer, aged 23 to 38 years. In each group 50 per cent were male. All the patients had an endoscopie diagnosis of duodenal ulcer requiring treat¬ ment with cimetidine. An informed consent was obtained prior to the study. The experiments started at 08.00 h after an overnight fast with the subjects in a recumbent position. A venous cannula was inserted in a forearm vein at least 45 min prior to beginning the study; patency was maintained by a slow infusion of normal saline. After collection of three baseline samples (-30, -15 and 0 min) all subjects received an iv bolus of 200 mg cimetidine (Tagamet®; Smith Kline 8c French, Milan, Italy). Blood was collected 15, 30, 60 and 120 min later. In the volunteers, cimetidine administration was repeated 60 min after giving the following drugs: bromocriptine (2.5 mg p.o.), metergoline (2 mg p.o.), nomifensine (200 mg p.o.) and cyproheptadine (8 mg p.o.). A 3 day interval elapsed between each test which was performed exactly as described above. The patients were treated with cimetidine, 400 mg p.o., t.i.d. for 3 months. Blood samples were obtained weekly from each patient, at 08.00 h, prior to the administration of the first daily dose.Blood samples for hormone assay were centrifuged and serum specimens stored at -20°C until assayed. All samples from each subject were processed in duplicate in the same assay. Serum prolactin was measured by a specific double-antibody radioimmunoassay (McNeilly 1973). Standard, antiserum and 125I-labelled human pro¬...

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

“…The present investigation confirms previous stu¬ dies showing that Cim, when administered iv in doses varying from 200 to 400 mg, provokes a significant rise in serum Prl (Burland et al 1979;Carlson & Ippoliti 1977;Ferrari et al 1979;Másala et al 1980;Pontiroli et al 1981;Rolandi et al 1979), but leaves serum TSH unaffected (Carlson & Ippoliti 1977). It also demonstrates that acute hypercalcaemia blunts the Prl response, which fol¬ lows upon a rapid iv injection of 400 mg Cim, by approximately 35%.…”

Histamine-Induced Prolactin Release: Pharmacological Characterization of Receptors in Male Rats

“…However, these views are mostly based on experiments with antihistamines. Regarding this, cimetidine, a potent H2-antagonist, was found to evoke an acute massive prolactin-releasing re sponse [6,16,23,26]. Recent studies with ranitidine, a more potent H2-antihistamine [4], show a minimal increase of plasma prolactin levels in man, even when the drug was in jected intravenously in high doses [19].…”

Αντιμετώπιση Και Μακροχρόνια Παρακολούθηση Προλακτινωμάτων

“…[164] Ισταµίνη Η ισταµίνη έχει ασαφή ρόλο στη ρύθµιση της προλακτίνης, [165] κι αυτό γιατί ενώ η χορήγηση ενδοφλέβιων ανταγωνιστών των υποδοχέων Η 2 έχει φανεί να προκαλεί αύξηση της προλακτίνης, [166] η παρατεταµένη χορήγηση p.os ανάλογων ουσιών δεν µπορεί να προκαλέσει εµµένουσα αύξηση της προλακτίνης. [167]…”