EFFECT OF INTRANASAL SALMON-CALCITONIN THERAPY ON BONE MASS AND BONE TURNOVER IN EARLY POSTMENOPAUSAL WOMEN - A DOSE-RESPONSE STUDY

We examine the dose-related effect of intranasal salmon calcitonin (sCT) on the early postmenopausal bone loss and bone turnover; a 2-year, prospective, randomized, double-blind, placebo-controlled study was carried out with 134 healthy women who had passed a natural menopause within 6 months to 3 years. The women were allocated randomly to 2 years of treatment with either 100, 200, or 400 IU of sCT given intranasally or placebo. All groups received a calcium supplement of 500 mg. Twenty-one women left the study before its end and 91 complied with the study criteria throughout. Bone mineral content/density of the distal forearm and lumbar spine and biochemical parameters of bone turnover were measured. Although the measurements after 24 months revealed no significant difference between groups in bone mineral density of the lumbar spine, the average changes over time revealed prevention of bone loss in the groups treated with 200 and 400 IU of sCT (0.2 to -0.6%) and declines of 0.8-1.7% in the groups treated with 100 IU of sCT and placebo (P < 0.05-0.01; within-group testing). There was no dose-related response to sCT but there was a significant difference between the pooled groups treated with 200 plus 400 IU of sCT versus the 100 IU sCT and placebo-treated groups (P = 0.03-0.005). The same difference between groups was seen for biochemical parameters of bone turnover (P = 0.022-0.003). The biochemical parameters of bone turnover revealed decreases of 10-20% (P < 0.001; within group testing) in the groups treated with the two highest sCT doses. It was concluded that nasal sCT in doses of 200 and 400 IU has some effect in women soon after the menopause-preventing the bone loss in the spine throughout the first year of therapy and lowering the bone turnover. It may be used as an alternative to hormone replacement when estrogens are contraindicated. The present data indicate that discontinuous strategies should be preferred.