Development and Evaluation of Efavirenz Solid Dispersion by Solvent Evaporation and Fusion Methods

Background

The bioavailability of the drug is influenced by the solubility of the drug in the biological fluids. Solubility and dissolution are the rate-limiting steps for the absorption and bioavailability of BCS class II drugs.

Materials and Methods

In the current work, Efavirenz (EFV) has been selected as a model drug for the development and assessment of Solid Dispersion (SD) by solvent evaporation and fusion methods using sugar-based carriers like xylitol, Sorbitol, lactulose, and one nonsugar carrier surplus. First, the drug was assessed for solubility in various solvents. EFV Solid Dispersions (S.D.s) have been produced by solvent evaporation and fusion at different carrier ratios (1:0.5, 1:1, 1:1.5, 1:2, and 1:3). The prepared SDs were subjected to drug content uniformity, saturation solubility studies, and in vitro dissolution studies.

Results

Preformulation investigations, such as FT-IR, proved that the excipient and drug molecules are binding with intermolecular hydrogen bonds. EFV was found to be more soluble in 7.4 pH phosphate buffer than in the other solvents. The saturation solubility of EFV was affected by carrier concentration and %yield, and in vitro drug dissolution studies were performed on the S.D.s. Pure EFV released 54.78% of the drug, whereas SDs by solvent evaporation method released 85.28± 1.84%-100.74±1.69% drug, and SDs prepared by fusion method released 76.65±0.98%- 99.28±1.95% of the drug in 60 min.

Conclusion

SDs of EFV prepared by solvent evaporation and fusion methods have improved the aqueous solubility of EFV, and, in turn, improved the in vitro drug release, and formulation with 1:1.5 drug-to-carrier ratio has been selected as an optimized formulation.