The Effects of Acute and Chronic Administration of Salmon Calcitonin as Nasal Spray in Ovariectomized Women

Estrogen replacement is highly effective in the prevention of postmenopausal osteoporosis. l ,* However, estrogen treatment is unsuitable for many postmenopausal women, mainly in the elderly when contraindications to steroid administration are often p r e ~ e n t . ~ Therefore, alternative therapeutic strategies are needed for the treatment and the prevention of this disease. It is well known that calcitonin exerts a potent and direct inhibitory action on osteoclast activity, recruitment, and n ~ m b e r . ~ Among the different types of calcitonins so far described, salmon calcitonin (sCT) seems to show the most potent biological activity in human^.^ Although sCT has been successfully used in the treatment of postmenopausal osteoporosis,6 the high incidence of side effects and the necessity for daily intramuscular injections resulted in an high rate of discontinuation of treatment.’ Therefore, chronic parenteral sCT administration is unsuitable for long-term treatment, mainly in the prevention of postmenopausal osteoporosis. Recently, sCT has been proposed in a new formulation as nasal spray.&-’O Preliminary data suggest that nasal sCT can exert potent biological actions, and, at variance from parenteral forms, it is virtually deprived of side effects.&’O Accordingly, the aim of the present investigation was to further evaluate the acute and chronic effects of intranasal administration of sCT on bone turnover in ovariectomized women.