[Profile of a new calcitonin: carbocalcitonin-(Asu1,7) E-CT].

(Asu1,7) E-CT (carbocalcitonin-elcatonin) is the aminoasuberic analogue of eel calcitonin differing from the natural hormone in that an ethylene bridge replaces the disulphide bridge in position 1-7. This modification preserves the conformation of natural calcitonin but enhances the physical, chemical and biological stability of the molecule. This in its turn facilitates maximum purification of the product as well as enhancing its resistance to degradation both in vitro and in vivo. The specific activity of carbocalcitonin is equivalent to 5000 U.MRC/mg and it possesses all the pharmacological and clinical properties of natural calcitonins. It has the same hypocalcemic potency of eel or salmon calcitonin, superior to the human and porcine types. Carbocalcitonin has the typical pharmacological effects of the natural hormone on the kidneys, bone and gastrointestinal tract, the target organs of calcitonins. When injected into the cerebral ventricle of laboratory animals it was found to have an analgesic effect. In clinical terms (Asu1,7) E-CT gave good results when used in the treatment of hypercalcaemia and senile osteoporosis. Carbocalcitonin was also employed in conditions characterised by a high bone metabolism turnover such as Paget's disease, Sudeck's atrophy and immobilisation osteoporosis. Experiments to date have shown carbocalcitonin to be extremely interesting in terms of tolerability with very few side effects being noted. This may well be attributable to the greater stability conferred by the absence of the S-S bridge.