Formulation and Optimization of Controlled Release of Olanzapine by Glycerol Monooleate

In situ gel formation of Glycerol Monooleate (GMO) has been utilized to release many drugs. The aim of this research was to optimize, and in-vitro characterization of the controlled release and formulation of the matrices containing Olanzapine (OZ), GMO and Polyethylene glycol (PEG 300). Methods and Materials: Response surface methodology (RSM) is a combination of mathematical and statistical techniques. In this study, Design-Expert® software with Box-Behnken response surface methodology has been used to determine the relationships between variables and responses. GMO/water weight ratio (w/w) different and PEG 300/GMO (w/w) were in the range of 2-4% and 2-6% respectively. Percentage of loading; and release at 12th and 168th hr were calculated. In-vitro release studies of OZ from prepared gels were conducted in PBS (pH 6.8) and then analyzed by spectrophotometer at 265 nm. The optimum formulation was obtained at weight ratio of water/GMO (w/w) and PEG (300)/GMO (w/w) at 0.28 and 0.2 respectively, and percentage of OZ was at 4%. The observed and predicted values for EE % were 86.8 %, 90.31% respectively those parameters for release at 12th hr were 16.1% and 15% and for release at 168th hr, were 59.8 % and 63.56% respectively. In this study we performed kinetic release profile of OZ with several models, from which Higuchi model showed the best fitting and correlation.