Effect of crystallinity on the percutaneous absorption of corticosteroid. I. Determination of the degree of crystallinity of hydrocortisone acetate in ground mixtures with crystalline cellulose.

Abstract
The effect of the crystallinity of a topically applied drug on its percutaneous absorption was investigated with hydrocortisone acetate as a model drug. To decrease the degree of crystallinity, the drug was ground with crystalline cellulose. The X-ray diffraction method for determining the degree of crystallinity was valid in the range of amorphous cellulose ratio of 0 to .apprx. 50% by using simple mixtures of glutathione and amorphous cellulose. The dissolution rate of hydrocortisone acetate was confirmed to increase quantitatively with decreasing cystallinity.