Key Parameters for the Development of Long Term Delivery of Antipsychotic Drug

Use of biodegradable polymers as drug carriers mainly depends on desired degradation mechanisms and mechanical properties. Schizophrenia requires medication for months to years. Presently, all the existing atypical preparations have to be given daily. Non-compliance is a major problem in these patients. Risperidone is an atypical antipsychotic and drug of choice for the treatment of schizophrenia. In the present study, risperidone (RSP) long acting microspheres were prepared by emulsion solvent evaporation method using biodegradable polymer i.e. poly-(lactic-co-glycolic acid) (PLGA) 50:50(Mw- 18,27and 66 Kda) and 75:25(Mw-18,27and 67 Kda). Various formulation and process parameters, which play a pivotal role, are drug polymer ratio, PVA concentration, stirring rate and time, temperature of external phase, solvent removal time and o/w phase ratio were optimized. Microspheres were characterized for particle size, encapsulation efficiency, surface morphology and in-vitro drug release. The optimized formulations exhibited initial drug release followed by sustained release up to 28 days time period. Microspheres containing PLGA(50:50, Mw 27Kda) had shown maximum percent of drug release (94.54±2.54), whereas the formulation containing PLGA(75:25, Mw 67Kda) had released 69.23±2.53 percent of drug in 28 days time period. Formulation containing PLGA (75:25, Mw 67Kda) was found to be the best among all the formulations of risperidone, in terms of drug release profile for 28 days. Results of this study suggest that biodegradable microspheres of PLGA can be used for long term delivery of atypical antipsychotic drug for 4 weeks, which may lead to improvement in the patient compliance, therapeutic efficacy and results in cost- effective treatment of schizophrenia. Keyword - Biodegradable microspheres, Long acting injection, Psychosis Risperidone, Solvent evaporation method.