Correlation between particle size and dissolution profile of carisoprodol in a solid pharmaceutical form

Carisoprodol is a myorelaxant drug with CNS action, whose effect causes decrease in polysynaptic reflexes and the blockade of interneuronal activity, causing muscle relaxation. It has low solubility characteristics (BCS class II), which may negatively influence its bioavailability.
Dissolution is a determining fator for drug absorption and then for therapeutic effects. Several factors influence it, such as physicochemical properties of: solubility, crystallinity, particle size, molecular structure, ionization degree, dissolution diffusion,and hygroscopicity.
The purpose of this work was to evaluate the impact of particle size on the dissolution profile of carisoprodol in tablets. For this, carisoprodol with particle size D90 = 235 µm was micronized to D90 = 63 µm and then, both were compressed.
Dissolution profile studies were conducted with both formulations in order to evaluate invitro dissolution rates. As a result, a significant improvement in drug dissolution was observed after the micronization process.