The effect of nicardipine on pituitary hormone release in normal volunteers.

Abstract

Summary 1 In a double-blind, placebo-controlled, randomised, cross-over study of six healthy male subjects, the effect of nicardipine (5 mg h-1 for 3 h) on basal and stimulated pituitary hormone release was examined. 2 Statistically significant differences between nicardipine and placebo were seen occasionally for follicle-stimulating hormone, luteinising hormone and prolactin, but not for thyroidstimulating hormone. These differences were always within the between-batch coefficient of variation of the assay. 3 The overall differences in both basal and stimulated results for all four pituitary hormones were not statistically significantly different. 4 It is concluded, therefore, that nicardipine has no significant effect on either basal or stimulated pituitary hormone release in healthy male subjects.

Effect of Nifedipine on Thyrotropin, Prolactin, and Thyroid Hormone Release in Man: A Placebo‐controlled Study

“…This short-term controlled study confirms a previous open clinical study of thyroid hormone secretion (Zofkova et al, 1983), but disagrees with other studies demonstrating the lack of effect on TSH of 2 dihydropyridines, nifedipine (Zofkova et al, 1983;Teba et al, 1985) and nicardipine (Isles et al, 1985). We found an effect on peak values and on the release constant and no significant effect on the AUCs; the rate constant of TSH elimination was unaffected.…”

“…Although in vitro experimental studies (Eto et d , 1974; Takahara et al, 1975 ;Conn et al, 1983) have clearly shown the depressant effect of calcium ion channel antagonists on pituitary hormone secretion, in vivo clinical studies have generally failed to demonstrate any effect with calcium ion channel antagonists belonging to the dihydropyridine derivatives, such as nifedipine (Zofkova, 1983 ;Struthers et al, 1983 ;Joffe, 1983, Teba et al, 1985 and nicardipine (Isles et al, 1985). However, these clinical studies were open uncontrolled trials which must, therefore, be confirmed by controlled studies.…”

Glucoregulatory hormone response to insulin-induced hypoglycaemia following long-term calcium antagonism with felodipine in patients with essential hypertension

“…Unchanged basal serum levels of TSH, T3 and T4 following felodipine are in accordance with the findings following acute and long-term admini¬ stration of nifedipine and nicardipine (Struthers et al 1983;Isles et al 1985;D'Armiento et al 1984). …”

Nimodipine block of calcium channels in rat anterior pituitary cells.

“…Likewise, therapeutic doses of dihydropyridines have little effect on the secretion of prolactin or growth hormone in vivo (Struthers, Millar, Beastall, McIntosh & Reid, 1983;Abadie, Gauville & Brisson, 1984;Isles, Baty & Dow, 1985). Numerous studies have substantiated the importance of Ca channels in mediating both basal and stimulated hormone secretion in GH cells (see Taraskevich & Douglas (1984), Tan & Tashjian (1984b) and Enyeart et al (1985) for reviews of the literature), so the selectivity of nimodipine action has not been accounted for.…”