A double-masked multicenter comparative study between alendronate and alfacalcidol in Japanese patients with osteoporosis

To evaluate the efficacy and safety of alendronate, a double-masked, active (alfacalcidol) controlled comparative study for 48 weeks was carried out i n a total of 210 Japanese patients with osteoporosis. The doses of alendron ate and alfacalcidol were 5 mg/day and 1 mu g/day, respectively. The lumbar bone mineral density (LBMD) values observed at 12, 24, 36 and 48 weeks aft er the initiation of alendronate treatment were 3.53 +/- 0.53%, 5.37 +/- 0. 62%, 5.87 +/- 0.74% and 6.21 +/- 0.59% (mean +/- SE), respectively, higher than the baseline value. Corresponding values in the alfacalcidol group wer e 1.50 +/- 0.43%, 0.69 +/- 0.63%, 1.12 +/- 0.60% and 1.36 +/- 0.63%, respec tively. There was a significant difference between the two groups at each t ime point (p<0.05 or p<0.001). The bone turnover markers were depressed dur ing treatment in the alendronate group: -32.2% for alkaline phosphatase, -5 3.7% for N-terminal osteocalcin and -45.0% for urinary deoxypyridinoline co mpared with the corresponding baseline values. On the contrary, no notable changes in these parameters were observed in the alfacalcidol group. Treatm ent with alendronate caused a transient decrease in serum calcium concentra tions associated with an increase in the serum level of intact parathyroid hormone. In contrast, treatment with alfacalcidol resulted in a tendency of these parameters to change in the opposite direction. No difference in fra cture incidence between the two groups was observed. The overall safety of alendronate was comparable to that of alfacalcidol, In conclusion, although it was a relatively short-term study of 48 weeks, the results of the prese nt study indicate that alendronate at the daily dose of 5 mg was effective in increasing LBMD and that no serious drug-related adverse events were obs erved in the alendronate-treated patients. Alendronate is more efficacious than alfacalcidol in increasing bone mineral density, although the mechanis ms of the actions of the two drugs are apparently different.