Formulation and evaluation of injectable in situ forming microparticles for sustained delivery of lornoxicam.

The objective of this study is to formulate biodegradable in situ microparticles (ISM) containing lornoxicam for post-operative and arthritic pain management. ISM emulsions were prepared according to 2 full factorial experimental design to investigate the influence of formulation variables on the release profile of the drug. The independent variables studied are the polymer type, polymer inherent viscosity, polymer concentration, oil type and polymer:oil ratio. In vitro drug release, microscopical examination, particle size determination and syringeability measurement were selected as dependent variables. The effect of γ-sterilization on the prepared formulae was also examined. The prepared formulae showed extended drug release over two weeks, and flow time below 5 s/ml. Scanning electron microscope revealed that the prepared microparticles were spherical in shape, with diameter ranging from 3.45 to 22.78 µm. In vivo pharmacokinetic evaluation of two selected optimum formulations in rabbits showed prolonged drug absorption indicated by delayed T and the extended mean residence time. In conclusion, the prepared injectable ISM could be a promising approach for providing extended delivery of lornoxicam with low initial burst effect.