The invention provides a number of methods for enhancing the aqueous solubility of an active ingredient which is insoluble or sparingly soluble in water. In one preferred embodiment, solubilization of the active ingredient is enhanced by combining it with .beta.-cyclodextrin in an aqueous complexation medium comprising .beta.-cyclodextrin and a negatively- or positively-charged compound which forms an inclusion or non-inclusion complex with .beta.-cyclodextrin and its inclusion complexes.