1986 Volume 34 Issue 3 Pages 1235-1241
The physicochemical properties of the solid state of hydrocortisone butyrate propionate (HBP) were determined by thermal analysis of the solid phase. In addition, the solubility of HBP was measured in a wide variety of solvents. The physicochemical properties and solubility of HBP obtained experimentally were compared with those reported for hydrocortisone (HC).The solid phase of HBP showed a lower melting point (122°C) and heat of fusion (4.98kcal/mol) than those of HC. The activity of the solid phase of HBP was significantly higher than that of HC. The solubility parameter of HBP estimated from the solubility in various solvents was 11.2 (cal/ml)1/2. This value is lower than that of HC, which was reported as 12.4 (cal/ml)1/2. Further, the solubility parameter of HBP was closer to that of skin, which was reported as 9.7-10.0 (cal/ml)1/2.Consequently, it is considered that the high release ability from topical preparations and the high percutaneous absorption of HBP are due to the high activity of solid phase and the fact that the solubility parameter is close to that of skin.
