INFLUENCE OF COATING AGENTS ON THE DEGRADATION OF POLY(D,L-LACTIC-ACID) NANOPARTICLES IN MODEL DIGESTIVE FLUIDS (USP-XXII)

Biodegradable poly(D,L-lactic acid) (PLA(50)) nanoparticles coated wit h either a readily digestible protein, albumin, or a non-digestible po lymer, polyvinyl alcohol, were prepared by the solvent evaporation tec hnique. Their degradative properties were investigated in simulated ga stric and intestinal fluids (USP XXII). PLA(50) degradation was determ ined using size exclusion chromatography as well as the enzymatic dete ction of lactate in bulk solution. In pepsin-rich simulated gastric fl uid, similar behaviour was observed for both nanoparticle systems: no degradation of the PLA(50) matrix was observed over an eight hour incu bation time, either for albumin coated PLA(50) nanoparticles. In pancr eatin-rich simulated intestinal fluid, however, the degradation of the PLA(50) matrix was different, depending on the agent coating the nano particles: the PLA(50) matrix of polyvinyl alcohol coated PLA(50) nano particles was virtually not degraded whereas the PLA(50) matrix of alb umin coated PLA(50) nanoparticles was rapidly converted into lactate f ollowing enzymatic degradation kinetics. Thus, a direct relationship b etween degradability of the coating agent and subsequent PLA(50) degra dation in simulated intestinal fluid was established.