The effect of histamine2 and muscarine receptor antagonists on plasma levels of parathyroid hormone and calcitonin.

Long-term administration of cimetidine, a histamine2 receptor antagonist, has been reported to normalize elevated parathyroid hormone (PTH) concentrations in patients with secondary [1] and primary hyperparathyroidism [2] and even to improve the clinical symptoms. We have compared the effect of cimetidine and pirenzepine on PTH and calcitonin (CT) plasma levels in a short-term trial on patients with secondary hyperparathyroidism. After cimetidine a significant effect on PTH was seen within 30 min lasting 30 min and after pirenzepine, within 60 min and lasting 60 min.