Specific Hydrophobic Nonpolymeric Biomaterials

Use of lipids and other natural hydrophobic substances for sustained delivery of protein dmgs has been the subject of both investigative and developmental activities for several years. Biodegradation of matrices of such materials can be viewed as a process of in situ dissolution by endogenous solvents and surfactants with subsequent normal metabolism of the dispersed material. 

Use of cholesterol pellets for sustained release of protein antigens was recently examined by Opdebeeck and Tucker (1993). Utilizing matrices 

Erodible synthetic hydrogels have been studied as delivery systems for proteins that are stable, or can be stabilized, in an aqueous environment. A number ofsystems have been described (Torchilin etal, 1977 Edman etal, 1980 Heller eta/., 1983 Singh, 1991b). The reader is referred to an excellent and comprehensive review of degradable hydrogels for drug deliveiy by Park eta/. (1993). 

Recently, synthesis of a novel polyphosphazene (9) has been reported 

The development of peptides and proteins as commercially viable therapeutic agents has presented some unique challenges to the drug delivery scientist. Areas where expanded research efforts are important include development of delivery systems with precisely controlled release kinetics—with a particular emphasis on a fundamental understanding of the mechanism of drug release (Shah et ah, 1992) —and further development of pulsatile (e.g., for vaccine delivery), and temporal release systems where the release of drug is consistent with the biochemistry of the disease state. 

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