Preparation of spherical matrixes of prolonged-release drugs from liquid suspension

A simple and less expensive method for the preparation of spherical matrixes of prolonged-release drugs was developed from liquid suspension. The drugs dispersed in distilled water were agglomerated with a small amount of organic solution or melt of matrix material. The process, called a "solution" or "melting" method, depended on the state of matrix material. In the present study, sulfamethoxazole and sulfanilamide were agglomerated with white beeswax and ethylcellulose. Furthermore, the parameters affecting the average size and release behavior of the resultant matrixes were investigated. Increasing the amount of matrix material used yielded large matrixes and prolonged-release action. The drugs rendered hydrophobic by surface treatment produced larger matrixes that released drug more slowly than untreated drugs. The sizes of the matrixes decreased and became uniform with increasing agitation speed. The sulfamethoxazole matrixes with wax proved to be enteric coated since the release rate was fast in the alkaline test solution (pH 7.5) but slow in the acidic one (pH 1.2).