Powdered solution technology: principles and mechanism.

The concept of powdered solutions can be used to formulate liquid medications in dry, nonadherent, free-flowing, and readily compressible powders. The technique is based on simple admixture of drug solution or liquid drug with selected carrier and coating materials. Improved drug release profiles are exhibited by such delivery systems even for poorly water-soluble drugs. Previous work using this method has rendered its industrial application impractical because of the unsatisfactory flow properties of the powder admixtures. This article presents a theoretical model based on the principles and mechanism of powdered solutions and introduces a new physical property of powders termed the flowable liquid-retention potential (phi value). Mathematical expressions are derived that can be used to calculate the optimum amount of excipients required to yield powder admixtures with acceptable flowability. The validity and applicability of these expressions have been verified experimentally using clofibrate and prednisolone as test materials. The proposed model is shown to be superior to previously reported studies in optimizing the amount of excipients needed to prepare powdered solutions with acceptable flow properties.