The effect of bile salts on the oral mucosal absorption of human calcitonin in rats.

The relationship between the inhibition of the degradation of human calcitonin (HCT) in the supernatant of the rat's oral mucosa homogenate and the promoting effect on the rat's oral mucosal absorption of HCT was investigated by using ten kinds of sodium bile salts. The promoting effects and the inhibition of the degradation by the dihydroxy bile salts were related to the hydrophobicity, respectively. The inhibition of the degradation of HCT was related to the promoting effect on the oral mucosal absorption of HCT in the presence of the dihydroxy bile salts and to the concentration of the bile salts. Furthermore, the micelle formed by the bile salts would be concerned with the inhibition of the degradation of HCT.