Effect of guest drug character encapsulated in the cavity and intermolecular spaces of γ-cyclodextrins on the dissolution property of ternary γ-cyclodextrin complex
Various ternary Guest 2/(Guest 1/γ-cyclodextrin (CD)) complexes were prepared using a cogrinding and subsequent heating method, wherein Guest 1 was incorporated in the cavity of γ-CD and Guest 2 was incorporated into the intermolecular spaces between γ-CD columns. Dissolution fluxes of Guest 1 and Guest 2 from all ternary complexes were almost identical. The dissolution flux of flurbiprofen (Guest 1) from the ternary complexes depended on the solubility of Guest 2 drugs (naproxen < ketoprofen < ethenzamide) in the dissolution medium of pH 1.2. It is noteworthy that the dissolution flux of flurbiprofen from the ternary complexes with ketoprofen and ethenzamide as Guest 2 drugs was further enhanced compared with that from the flurbiprofen/γ-CD inclusion complex. The ternary complex of the acidic drug ketoprofen as Guest 1 and the neutral drug hydrocortisone as Guest 2 showed an increased dissolution flux, which was dependent on the increase in pH of the dissolution medium. The pH-dependent dissolution should reflect the solubility of ketoprofen/γ-CD inclusion complex in each dissolution medium. These results indicated that the dissolution flux of the ternary γ-CD complexes could be controlled by selecting the appropriate Guest 1 and Guest 2 species.