Investigation of ibuprofen release from ethylcellulose matrix compacts

Abstract

A comprehensive study of ethylcellulose powder and ethylcellulose compacts (of different ethylcellulose viscosity grades) was undertaken. Studies showed that the lower viscosity grade ethylcellulose (4 cP) was more compressible than the higher ethylcellulose viscosity grades, resulting in compacts of higher tensile strength and lower compact porosity. These differences, in addition to differences such as surface roughness, water uptake and contact angle (with phosphate buffer) affected the release of ibuprofen from ethylcellulose:ibuprofen compacts prepared with different ethylcellulose viscosity grades. The effect of ethylcellulose viscosity grade and polymer-to-drug weight ratio on ibuprofen release from ethylcellulose:ibuprofen compacts was investigated. Results showed that the higher the ethylcellulose viscosity grade used during formulation the greater the percentage drug release. Experiments also found that as the level of drug concentration in the ethylcellulose ; ibuprofen matrix formulation increased, the drug release rate also increased. It was thought that the increase in drug concentration resulted in an increase in compact porosity and a concomitant decrease in the tortuosity of the matrix. Percolation theory was also used to explain the change in dissolution kinetics of the matrix controlled release system over the range of drug loadings examined.