The invention comprises pharmaceutical preparations consisting generally of a drug with a substantially low water solubility and an amorphous, water-soluble cyclodextrin-based mixtures. In these preparations a stable amorphous state can be achieved. This improves the dissolution properties of the drug and hence its absorption by the body. The required cyclodextrin-based mixtures were prepared from .alpha.-, .beta.-, or .gamma.-cyclodextrin which were rendered amorphous through non-selective alkylation. The alkylation agents suitable for that purposes are exemplified by propylene oxide, glycidol, iodoacetamide, chloroacetate, or 2-diethylaminoethylchloride; their reactions with cyclodextrins were performed in a manner to yield mixtures containing many components, a circumstance which effectively prevents crystallization processes within the above pharmaceutical preparation.