Drug Loading into and In Vitro Release from Nanosized Drug Delivery Systems

Abstract

Drug loading during preparation and subsequent release after administration are two important properties that have to be built into a drug delivery system during their development as they largely determine the efficiency of such systems. Drug loading is the process of incorporation of the drug into a polymer matrix or capsule. Drug release is the reverse process by which the drugmolecules are liberated from the solid phase and become available for absorption and pharmacological action. Therefore, in addition, in vitro drug release can be a quality control of the drug delivery system, provide information about the internal structure of the carrier, the interaction between the drug and carrier, and can be used to predict in vivo behavior (Chorny, Fishbein, Danenberg, & Golomb, 2002; Washington, 1990a). Drug loading and release are related to each other because both depend on the physicochemical properties of the matrix, the physicochemical properties of the drug and the interaction between the matrix, drug and the environment. This chapter describes the various processes involved with drug loading into nanosized drug delivery systems and how it influences the subsequent release of the drug from these systems.