Acute effect of cimetidine and pirenzepine on plasma parathyroid hormone and calcitonin in haemodialyzed patients.

The acute effects of intravenous injection of cimetidine and pirenzepine on plasma iPTH and CT were studied in seven patients on chronic haemodialysis and seven healthy controls. As expected, the resting iPTH and CT levels were significantly higher in patients on RDT than in the healthy subjects. Both drugs decreased to a similar extent the increased plasma iPTH in the patients, but neither was able entirely to normalize the elevated level. The CT concentration in the patients on haemodialysis was significantly decreased by cimetidine but was only moderately reduced by pirenzepine. As neither drug was able to normalize the elevated PTH level in patients on chronic dialysis, it can be assumed that neither used alone would improve signs and symptoms of secondary hyperparathyroidism.