Novel vaginal delivery systems for calcitonin: I. Evaluation of HYAFF/calcitonin microspheres in rats

Abstract The vaginal absorption of salmon calcitonin (sCT) from a solution and after incorporation into microspheres of hyaluronane esters (HYAFF) was studied in rats. Hypocalcaemic responses were markedly enhanced by the use of HYAFF microspheres. Microscopic examination showed good adhesion of microspheres to the vaginal epithelium. The performance of various pessary bases for the vaginal administration of HYAFF and sCT microspheres was evaluated. Vaginal pessaries based on Suppocire BS 2 X were the most suitable of those tested, maintaining the bioadhesion of HYAFF microspheres and absorption of sCT. Changes in plasma calcium levels were similar after vaginal administration of this formulation (100 IU/kg sCT) and s.c. injection of sCT solution (10 IU/kg).