Verapamil increases serum alkaline phosphatase in hypertensive patients.

Abstract

In rats, verapamil decreases intestinal absorption of calcium, increases serum parathyroid hormone (PTH), and induces osteopenia. In this prospective study, verapamil 80-120 mg three times daily was given for 2 months to 20 patients with hypertension, and the effects on calcium homeostasis were recorded. This dose of verapamil significantly reduced supine systolic and diastolic blood pressure (+/- SD) from 158/100 +/- 9/8 mmHg to 146/89 +/- 14/8 mmHg (P = 0.001). Serum alkaline phosphatase (ALP) increased significantly from 2.77 +/- 1.06 mu kat l-1 to 3.19 +/- 1.22 mu kat l-1 (P = 0.004), and isoenzymes of ALP of skeletal origin appeared after verapamil treatment. The excretion of sodium in the urine increased (Na/creatinine ratio 8.95 +/- 6.01 before and 13.16 +/- 8.26 after verapamil; P = 0.04), while the excretion of calcium, phosphate and potassium was not changed. PTH was slightly increased at the end of verapamil treatment (1.09 +/- 0.54 vs. 0.98 +/- 0.74 microgram l-1; P = 0.07), and s-1,25(OH)2D3 was also somewhat increased (22.3 +/- 14.4 vs. 17.6 +/- 4.9 ng l-1; P = 0.26). Serum Ca was not affected by verapamil (before verapamil 2.43 +/- 0.11 mmol l-1, after verapamil 2.40 +/- 0.12 mmol l-1; P = 0.28). The increase in serum ALP demonstrates that verapamil affects bone cell metabolism in man. This effect could be secondary to the enhancement of PTH secretion.