Abstract
Malabsorption of calcium is a common finding in patients with postmenopausal osteoporosis (1, 2). In a number of studies serum 1,25 dihydroxyvitamin D levels were found to be significantly lower in osteoporotic patients, which could account for the calcium absorptive defect (3–6). Based on these findings, we studied the effects of synthetic calcitriol (Rocaltrol) in women with osteoporosis. We showed that calcitriol, 0.25 μg twice daily, improved and normalized the absorption of calcium in all patients and improved calcium balance (7). Urine hydroxyproline, which is a measure of bone resorption, decreased significantly after 2 years of treatment with Rocaltrol. Because of these preliminary findings, further clinical studies were carried out at two centers using a variable dose of Rocaltrol. In these studies we focused on the effectiveness of Rocaltrol in preventing vertebral fractures in patients with spinal osteoporosis.
Methods
The results from two centers have been analyzed both as separate groups and as one combined group. One study was performed at the Mayo Clinic (Protocol 861) and the other at Creighton University (Protocol 860). In both centers the studies performed were double blind and randomized, and compared the effect of placebo against Rocaltrol for a period of 1 year. At the end of 1 year all patients on placebo were crossed over to treatment with Rocaltrol and followed for 2 more years. Patients initially treated with Rocaltrol were followed for an additional 2 years, thus yielding treatment data extending to 3 years in a number of patients. In the study design, patients were given Rocaltrol at a starting dose of 0.25 μg twice daily, if hypercalcemia and hypercalciuria did not occur the dose then was increased to 0.75 μg or 1.0 μg daily at the discretion of the investigator.
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