IMPROVEMENT OF SOME PHARMACEUTICAL PROPERTIES OF DRUGS BY CYCLODEXTRIN COMPLEXATION .7. TRIMETHOPRIM

Inclusion complexation of trimethoprim (TMP) with 3 cyclodextrins (alp ha-, beta-, and gamma-CyDs) in water and solid phase were studied by t he solubility method, spectroscopy (UV, IR), X-ray diffractometry, the rmal analysis and their modes of interactions were assessed. A spacial relationship between host and guest molecules was clearly reflected i n the magnitude of the stability constant (gamma- > beta- > alpha-CyD) . The investigated cyclodextrins were found to increase the solubility of the drug in water to a marked extent. Calculating the amount of dr ug in free and complexed forms revealed that solubilization is totally due to complex formation. The solid complexes of TMP with alpha-, bet a- and gamma-CyDs were prepared in molar ratios of 1:1 and their disso lution behavior was examined. The results indicated that the CyD compl exes may have great utility as a rapidly dissolving form of TMP in wat er especially gamma-CyD.