[Does the calcium antagonist verapamil modify calcium metabolism?]

In 11 healthy volunteers the effects of oral verapamil administration (4 X 80 mg/d) on plasma or serum concentrations of ionized, pH-corrected ionized and total calcium, on intact and midregional parathyroid hormone and on 24 h urinary excretion of calcium were investigated at rest. In addition the concentrations of ionized, pH-corrected ionized and total serum calcium were analyzed under bicycle exercise. Verapamil resulted in an increase of total serum calcium (p less than 0.02) and a fall in midregional parathyroid hormone concentrations (p less than 0.02) at rest. There was also found a statistically significant elevation of both ionized (p less than 0.05) and pH-corrected ionized (p less than 0.05) plasma calcium, and a slight increase in the total calcium under exercise (p less than 0.1). Before verapamil a significant negative correlation between total calcium and midregional parathyroid hormone was evident (r = -0.618; p less than 0.05), which however could not be clearly discerned after verapamil.