Mineral and electrolyte metabolism vol:17 issue:6 pages:353-6
This study was performed to assess whether the 1,25(OH)2 vitamin D3 stimulation test for osteoblastic function is influenced by a prostaglandin synthesis inhibitor (piroxicam). Thirty-four healthy male young adults had a 1,25(OH)2 vitamin D3 (Rocaltrol) stimulation test. After a baseline day, the subjects received 2 micrograms Rocaltrol every 12 h for 4 days. Serum and urinary parameters of bone turnover were assessed before and after stimulation. The subjects were randomly allocated to placebo or piroxicam 5-, 10- and 20-mg treatment groups. After stimulation, serum and urinary calcium increased significantly, and immunoreactive PTH decreased significantly in the control group. In the piroxicam group, serum calcium, phosphate, osteocalcin and urinary calcium increased significantly, and PTH and glycosaminoglycan excretion significantly decreased. The piroxicam treatment group did not differ from controls, except for a nonsignificant minor increase in serum calcium and phosphorus after calcitriol stimulation. Since the major effect of nonsteroidal anti-inflammatory drugs is to decrease prostaglandin synthesis, these data suggest that prostaglandins do not mediate the effects of calcitriol on bone and other target tissues, because no alteration in intestinal calcium absorption, calcium-phosphorus-PTH interaction, bone turnover and renal handling of calcium and phosphorus in normal subjects was found.