3] Incorporation of water-soluble drugs in albumin microspheres

Abstract

This chapter presents the nature and extent of incorporation of water-soluble compounds into albumin microspheres. Physical characteristics with incorporated drug are discussed. It includes appearance, swelling, surface charge and microsphere size. Use of a water-in-oil technique for producing drug-bearing albumin microspheres leads to constrictions on the maximal amount of drug which may be incorporated. The chapter examines the relationship between drug physicochemical structure and its incorporation into albumin microspheres. It is shown that incorporation of water-soluble compounds can have an effect on the size of microspheres formed, their eventual swelling in water, their physical appearance, and their microelectrophoretic mobility. It is also shown that drug associated with the microspheres is probably entrapped within the matrix of the sphere, and that nonspecific protein binding has little effect on the incorporation of water-soluble compounds. The release of water-soluble drugs from albumin microspheres is briefly discussed.