DRUG-RELEASE AND RELEASE MECHANISM OF PREDNISOLONE LOADED SOLID LIPIDNANOPARTICLES

Solid lipid nanoparticles (SLN) are a colloidal carrier system for the controlled delivery of drugs. To study the potential of SLN to achiev e prolonged drug release prednisolone was chosen as a lipophilic model drug. The cold and the hot homogenisation method were used to produce prednisolone loaded SLN. To investigate the drug release from SLN the USP XXII paddle method was employed. Atomic force microscopy (AFM) wa s applied for the characterisation of the shape and the surface of SLN . By applying the cold homogenisation technique SLN dispersions were o btained which show in vitro only a minor burst and a prolonged drug re lease over a monitored period up to 5 weeks. In contrast, the release profile of SLN produced by the hot homogenisation technique is charact erised by a pronounced fast initial drug release (burst effect) in the first five minutes which is followed by a prolonged drug release. The biphasic release profile is generated by the heterogeneous particle s tructure and by partitioning processing during and after the productio n. The partitioning mechanism is strongly affected by the solubility o f the drug in the water phase. Thus by applying low production tempera tures and surfactant concentrations the burst effect can be minimised. In conclusion, choosing appropriate production temperatures and surfa ctant concentrations a desired in vitro release profile can be obtaine d. These result show that SLN are suitable as carriers for prolonged d rug release.