IN-VITRO HYDROCORTISONE RELEASE FROM OINTMENTS IN PRESENCE OF CYCLODEXTRINS

The influence on hydrocortisone (1) release from 1% HC containing oinm ents by beta-cyclodextrin (beta CD) and hydroxypropyl-beta-cyclodextri n (HP beta CD) is described using the oinment release model according to Loth. White petrolatum, an o/w cream (Aqueous Hydrophilic Ointment DAB 10), a w/o cream (Aqueous Wool Alcohol Ointment DAB 10) and a hydr ogel (Aqueous Polyacrylic Acid Gel DAB 9) are used as vehicles. It is shown that after 7h the smallest amounts of 1 are released from white petrolatum and the w/o cream. Incorporation of 1 as an inclusion compo und has only a relatively small effect. Quite larger amounts of 1 are released with all formulations (1, physical mixtures, inclusion compou nds with beta CD and HP beta CD) from the o/w cream and the hydrogel. Incorporation of both inclusion compounds offers no advantages with th e hydrogel compared with noncomplexed 1, the release from beta CD incl usion compound is smaller. A clear improvement of 1-release by using i nclusion compounds from the same vehicle is obtained only from the o/w cream: here HP beta CD is more effective than beta CD. Reasons for th e different CD influences on 1-release in various vehicles are differe nt solubilities of HC and of the CD complexes in the vehicles, differe nt complex stability constants, varying water amounts in the vehicles, and possible interactions of the complexes with constituents of the v ehicles.