Inclusion complex of trimethoprim with beta-cyclodextrin.

The complexation of trimethoprim (TMP) with beta-cyclodextrin (beta-CD) was studied. UV-spectrophotometry and phase-solubility techniques were employed to investigate the complexation behaviour in liquid medium, and to demonstrate that the aqueous solubility of TMP increased 2.2-fold due to complexation with beta-CD. Solid samples prepared by co-evaporation (in 2 wt% acetic acid solution) have also been studied, using differential scanning calorimetry (DSC) and powder X-ray diffraction (XRD), to assess the formation of the inclusion complex. The water content of the complex and beta-CD was determined using thermo gravimetric analysis (TGA). In vitro dissolution analysis indicated that dissolution properties of TMP/beta-CD complex were superior compared to both pure TMP and the corresponding physical mixture of TMP and beta-CD.