EFFECT OF ANTIBODIES TO CALCITONIN ON THE PHARMACOKINETICS AND THE PHARMACODYNAMICS OF THE HORMONE

Calcitonin pharmacokinetics and pharmacodynamics were studied in two g roups of patients with postmenopausal osteoporosis, who, treated for o ne year with intranasal Asu(1,7)-eel calcitonin (eCT), had (Ab+) and h ad not (Ab-) developed a specific immune response to the drug. The tre atment consisted of daily intranasal administrations of eCT (80 IU/die ) with 1 g supplemental calcium. Eight women who had developed specifi c antibodies and 5 who had not, were given 50 IU of CT i.m., in order to assess the pharmacokinetics and pharmacodynamics of the drug. The r ise of serum levels of the hormone was significantly greater in Ab+ th an in Ab- patients. At the end of the study, no significant difference s in mineral bone loss between the two groups were found. In conclusio n, the presence of antibodies to eCT does not represent a negative eve nt in the therapy of osteoporosis, but significantly affects the pharm acokinetics of the drug.