Biodegradation of solid lipid nanoparticles as a function of lipase incubation time

The in vitro degradation of solid lipid nanoparticles (SLN) was studied in solutions of pancreatic lipase/colipase. Degradation was followed by turbidity measurements of SLN suspensions and by the determination of the formed free fatty acids (FFA). The degradation velocity was found to depend on the nature of the lipid matrix, being highest for Dynasan 114, medium for cetylpalmitate and relatively slow for lipids with longer fatty acid chains (Compritol ATO 888). The surfactant used for SLN stabilization had a dominating effect on degradation velocity. Use of the sterically stabilizing poloxamer 188 could prevent the in vitro degradation of well-degradable Dynasan 114 particles. This was attributed to the lack of anchoring of the lipase to the particle surface-prerequisite for enzymatic degradation. The dominating effect of the surfactant be exploited to design SLN with optimum degradation velocity and matrix-controlled drug release-independent on the nature of the lipid matrix.