The Effect of Different Surfactants on Dissolution Rate of Recrystallized Indomethacin

The effects of crystallization of indomethacin as a poorly water-soluble drug in aqueous surfactant solutions (using the basket method), on the drug dissolution behavior was investigated.A significant enhancement of drug dissolution was observed for for the dissolution rates of crystals treated with hydrophilic surfactants, Tween 80 and sodium lauryl sulfate (SLS). However, asing Arlacel 60 as a hydrophobic surfactant incrystallization medium decreased the indomethacin dissolution rate. Differential scanning calorimetry (DSC) and Fourier Transform Infrared Spectroscopy (FT-IR) indicated the existence of both α and γ- polymorphs of indomethacin (with different percentages). The FT-IR results also showed that, only the α- form could be detected in indomethacin crystals without any surfactant. These results were also confirmed by X-ray powder diffraction and scanning electron microscopy (SEM). The nuclear magnetic resonance (NMR) studies demonstrate the presence of a small amount of Tween 80 and the absence of SLS in the treated crystals. In this study, we concluded that, the presence of small amounts of surfactant, adsorption of surfactant onto the crystal surface and the decrease in powder bulk density could be the possible mechanisms of alteration in the dissolution rate of crystals treated with Tween 80, Arlacel 60 and SLS respectively Antioxidant.