Sulfaethylthiadiazole (SETD) release from synthetic wax prolonged-release particles. I. Effect of dispersant concentration

Application of factorial design in the examination of Tofizopam microcapsules

The authors studied the parameters of sustained released Tofizopam microcapsules, prepared by a melt-dispersion method. The parameters examined were the flowing rate, strength and dissolution characteristics. Dissolution curves were linearized by the RRSBW distribution. The factorial design method proved to be very useful for examination of microcapsules.

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).

Influence of wax coatings on release rate of anions from ion-exchange resin beads

Ion-exchange resin beads were coated with various waxes to improve and control their release. The in vitro release rates of benzoate ions from the coated-resin beads were then investigated using a rotating sieve basket technique. The dramatic differences in release rates observed with the different waxes can be discussed in terms of the wax to resin ration and the solubility characteristics of the waxes. The initial release rates can be expressed in terms of a mathematical expression previously reported for the diffusion of ions in ion-exchange resins, thereby aiding in the elucidation of the effect of the waxes on release.