The effect of polyvinylpyrrolidone on cyclodextrin complexation of hydrocortisone and its diffusion through hairless mouse skin

The effect of nine different cyclodextrin derivatives on the aqueous solubility of hydrocortisone was investigated. Three of these derivatives were selected for further investigation. The effect of methyl-beta-cyclodextrin, carboxymethyl-beta-cyclodextrin and maltosyl-beta-cyclodextrin on the flux of hydrocortisone, from an aqueous suspension or solution, through hairless mouse skin was investigated in vitro. When the hydrocortisone concentration was kept constant and the cyclodextrin concentration was gradually increased, the flux through the skin was increased up to a point when all the hydrocortisone molecules were in solution, then the flux decreased with increasing cyclodextrin concentration. Polyvinylpyrrolidone (PVP) increased the complexation of hydrocortisone which increased solubility of the drug in the aqueous cyclodextrin solutions. Also, the flux of hydrocortisone through hairless mouse skin was increased by addition of small amount of PVP to the cyclodextrin vehicle. The flux of hydrocortisone could be increased even further by addition of oleic acid to the aqueous cyclodextrin PVP vehicle systems.