Abstract

The aim of this study was to enhance the solubility and dissolution rate of sulfamethoxazole (SMZ) by preparing the inclusion complexes with β-cyclodextrin (β-CD), hydroxypropyl-β-cyclodextrin (HPβ-CD) and γ-cyclodextrin (γ-CD). The effect of the type of cyclodextrins used for the preparation of complexes, on the in vitro dissolution profiles and solubilities in different mediums (pH 4.5 and 7.0) was also evaluated. The interaction between SMZ and cyclodextrins in solution was studied by the phase-solubility method. Inclusion complexation was confirmed by the results from the studies of infrared spectoroscopy (IR) and differential scanning calorimetry (DSC). The effect of water-soluble polymers, that is, polyethylene glycols 4000, 10000, 20000 and non-ionic surfactants, that is, polysorbate 20, 40 and 60 on the complexation of SMZ with CDs were also investigated by the same methods. The rates of release of the active material from the complexes were determined from dissolution studies using USP XXII paddle method. As a result of this study, it was found that the solubility of SMZ was significantly enhanced by inclusion of β-CD, especially when the water soluble additives are added (from 0.086 to 0.377 mg/ml with SMZ:β-CD:PEG20000).

Key words: Cyclodextrins, sulfamethoxazole, solubility, dissolution rate.