Preparation, release, rheology and stability of piroxicam emulgel

Abstract

Objective: The purpose of this work was to develop and optimize the emulgel formulation of piroxicam with two types of gelling agent chitosan and xanthan gum. The release profiles of prepared formulas were investigated. In addition, the rheology and stability of the best formula were investigated. Methods: Emulsified piroxicam was prepared to use oleic acid, tween 80 and PG with a ratio (3:10:10). In xanthan based emulgel, the xanthan gum (1% and 1.5%) was spread as powder on emulsified piroxicam with stirring until emulgel was formed. In chitosan-based emgels, Chitosan gel was added to emulsified piroxicam and stirring until the Emulgel was constructed. Chitosan gels were prepared by incorporating different concentration, 2%, 3%, 6% w/v of chitosan in 1% v/v of glacial acetic acid in distilled water. In vitro release of piroxicam from different formulas was conducted in 300 ml phosphate buffer pH 7.4, at a speed of 120 rpm at 37±2°C. The amount of the drug released from the bases was determined spectrophotometrically at 504 nm. Viscometer Myr. Vr 3000 was used to measure the viscosity of the prepared formulas. The prepared formulas were stored in well-stoppered polyvinyl chloride (PVC) plastic containers in the dark for 6 mo at room temperature. They were checked for drug content, viscosity, and pH change bimonthly throughout the period. Results: The results showed that the dissolution increases significantly with increasing the concentration of xanthan. Chitosan has significant synergized the enhancements of xanthan gum in the release. Rheological behaviour of the selected formula containing chitosan (2%) and xanthan gum (1.5) had shear thinning in nature showing a decrease in viscosity at the increasing shear rates. The selected formula was stable 6 mo at 40°C/75% RH and 4°C. The formula found was yellow viscous creamy preparation with the smooth homogenous appearance. The pH and the drug release was also found to be stable under storage conditions. Conclusion: Piroxicam release can be improved by preparing emulgel which stable and have good rheologic properties.