Abstract: A powdered, dispersible composition having stable dispersibility over time is provided. The composition exhibits a characteristic glass transition temperature (Tg) and a recommended storage temperature (Ts), wherein the difference between Tg and Ts is at least about 10° C. (i.e. Tg−Ts is greater than 10° C.). The composition comprises a mixture of a pharmaceutically-acceptable glassy matrix and at least one pharmacologically active material within the glassy matrix. It may be further mixed with a powdered, pharmaceutically-acceptable carrier. It is particularly valuable in unit dosage form having a moisture barrier, in combination with appropriate labelling instructions.