SOME FACTORS AFFECTING THE VAGINAL ABSORPTION OF HUMAN CALCITONIN IN RATS

We studied the absorption of human calcitonin (HCT) from rat vaginal mucosa. The absorption of HCT was affected by pH, but scarcely by the osmotic pressure of the HCT solution. The pharmacological availability of HCT after vaginal administration without any additives and at pH 7.4 was low. However, vaginal absorption of HCT was promoted by coadministration of sodium deoxycholate, and by the peptidase inhibitors bestatin, leupeptin and pepstatin A. The effects of peptidase inhibitors on the rate of degradation of HCT in a 9000 X g supernatant of vaginal mucosa homogenate were determined in order to clarify why peptidase inhibitors promoted the absorption of HCT. The promotion of vaginal absorption of HCT was correlated with the inhibition of HCT degradation by peptidase inhibitors.