Preparation of solid dispersion for ethenzamide-carbopol and theophylline-carbopol systems using a twin screw extruder.

In the present study, we prepared solid dispersions of water-insoluble and soluble drugs (ethenzamide (ETZ) and theophylline (THEO)) by the twin screw extruder method, which made it possible to control both kneading and heating at the same time under the fusion point of each drug, using three types of the controlled-release high-molecular-weight substance Carbopol (CAR) as the carrier. The solid dispersions obtained were evaluated and compared with those prepared by the organic solvent method. These products showed significantly increased solubility of ETZ, but the solubility of THEO was reduced indicating that CAR slows the release of THEO. It is important not only to simply knead under high pressure but to select the optimal operation temperature to bring these drugs into a semi-fusion state. Solid dispersions obtained by this method showed X-ray diffraction and differential scanning calorimetry (DSC) patterns similar to those obtained by the organic solvent method indicating that the former can be used as a simple and effective method for preparation of solid dispersions.