Effect of nasal salmon calcitonin on calcium and bone metabolism

We have investigated the pharmacokinetics and pharmacodynamics of nasal SCT in the dose range of 50-200 IU. When evaluated by AUC, it appeared that the absorption through the nasal mucosa was dose dependent. The resulting plasma levels of SCT were highly variable between individuals. A hypocalcemic effect accompanied by an increase of s-PTH was seen 2-3 hours after administration of a single dose of 200 IU to healthy male adults, but not after administration to postmenopausal women. When evaluated by changes in biochemical markers of bone remodeling nasal SCT 200 IU decreased bone resorption in the magnitude of 15% after a single dose as well as after a multiple daily dosing regimen. No tachyphylaxis of the antiresorptive effect of nasal SCT was noted. The histomorphometric analysis revealed a decrease of erosion depth as the major antiresorptive action on the bone remodeling system of nasal SCT. We were unable to demonstrate an anabolic effect of nasal SCT on bone formation. There was a tendency towards a dose dependent increase in lumbar BMD, but not even in the group receiving 200 IU daily did the increase reach statistical significance when compared to placebo. BMD in the distal forearm as well as in the hip was unaffected by nasal SCT.