THE EFFECT OF HYDROXYPROPYL METHYLCELLULOSE ON THE RELEASE OF DEXAMETHASONE FROM AQUEOUS 2-HYDROXYPROPYL-BETA-CYCLODEXTRIN FORMULATIONS

The effect of hydroxypropyl methylcellulose on the complexation of dex amethasone with 2-hydroxypropyl-beta-cyclodextrin (HP beta CD) was inv estigated. The aqueous solubility of dexamethasone was significantly i ncreased by formation of a water-soluble dexamethasone-HP beta CD (1:1 ) inclusion complex. The complexation was increased when hydroxypropyl methylcellulose was added to the aqueous complexation medium. Additio n of 0.1% (w/v) hydroxy propyl methylcellulose resulted in a 26% incre ase in the stability constant of the complex. The release of dexametha sone from aqueous HP beta CD vehicles was affected by the hydroxypropy l methylcellulose induced complexation increase. Also, the effect of H P beta CD on the permeability of dexamethasone from an aqueous solutio n through the cornea into the aqueous humor was investigated in vivo i n rabbits.