To evaluate a possible utility of γ-cyclodextrin (γ-CyD) in an injecting agent, various pharmaceutical properties of inclusion complex such as dissolution, membrane permeation, chemical stability, protein binding, and biological fate were investigated using thiopental (TP) as a test drug. Inclusion complex formation of TP with γ-CyD in aqueous solution and in solid state was assesed by solubility method, spectroscopies, thermal analysis, and X-ray diffractometry. The 1 : 1 TP-γ-CyD complex exhibited a rapid dissolution in water, resulting in the net increase in the fraction of free TP available for membrane permeation. The TP in γ-CyD complex was significantly stable compared with sodium salt of TP during the accelerated storage conditions (40°C, RH 75%). The binding capacity of TP to rabbit serum albumin was found to be reduced by CyDs. Because of the small stability constant of TP-γ-CyD complex, no significant effect of γ-CyD was observed on the pharmacokinetic parameters of TP after the intravenous administration to rabbits. Many advantages obtained for TP-γ-CyD complex suggested great utility of γ-CyD in parenteral preparations without change in the biological fate of the drug.