Amorphous –state Characterization and Dissolution Behaviour of Efavirenz- Tocopheryl Polyethylene Glycol Succinate (TPGS)-1000 Solid Dispersions

Abstract

The aim of the present investigation was to enhance the aqueous solubility and dissolution rate of a poorly soluble drug, efavirenz, by preparation of solid dispersions with tocopheryl polyethylene glycol succinate (TPGS)-1000, a non - ionic surfactant. Phase solubility studies suggested that the solubility of efavirenz increased with the increase in TPGS concentration.1 absorption. Gibbs free energy (ΔG) were negative, indicatingthe spontaneous nature of efavirenz solubilization. Dispersions in different ratios were prepared using the fusion method and their physicochemical characteristics were investigated using Fourier Transform Infrared Spectroscopy(FTIR), X-ray Powder Diffraction studies(XRPD) and Scanning Electron Microscopy(SEM).A drug: carrier ratio of 1:1.5 w/w prepared by cooling the fused mixtures at 5° C showed the highest drug release of 33.27%.It was demonstrated that decrease in crystallinity of the drug and H-bonding between efavirenz and TPGS-1000 might be responsible for the enhanced dissolution rate. Analysis of dissolution data showed the best fitting with Higuchi model.