Solid lipid microparticles of lamotrigine: an injectable controlled release system for local delivery in nerve injuries

Designing an injectable controlled release system containing lamotrigine loaded solid lipid microparticles (SLMs) for repairing nerve injuries was considered. Lamotrigine was loaded in mixture of stearic acid and cholesterol by melt dispersion method in the presence of surfactant. The mixture was cooled under stirring and SLMs were freeze-dried. Effect of cholesterol content, surfactant percentage and duration of mixing on particle size was studied by Taguchi design. Morphology, stability, entrapment efficiency and release behavior of SLMs were also examined. Results showed that higher levels of surfactant provided smaller SLMs. Increasing amount of cholesterol resulted in decreasing size distribution. Formulation containing higher level of cholesterol released the drug faster than others. SLMs containing mannitol as cryoprotectant presented higher stability in freeze drying and showed lower change in size distribution. Drug release was controlled by this system and it seems that SLMs would be a promising system for local controlled delivery of lamotrigine.