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. The effect on CT was only significant after cimetidine.