Dissolution rate enhancement of Alprazolam by Solid Dispersion

Solid dispersions were prepared by both solvent evaporation and physical mixing method for poorly water soluble model drug Alprazolam using carriers such as polyethylene glycol-6000 (PEG-6000) and polyvinylpyrrolidone-K30 (PVP-K30) at different proportions (Drug:carriers-1:1, 1:2, 1:4). The solid dispersions were characterized by solubility, drug content uniformity, dissolution rate, similarity factor analysis and stability after 2 months at 30 degrees C/75%RH and 40 degrees C/75%RH. More than 80% of Alprazolam was released within 30 minutes of dissolution and the release was more with PVP-K30 when prepared by solvent evaporation method than prepared by physical mixing. The dissolution data's were fitted in Zero order, First order, Higuchi model and Korsmeyer-peppas equation. All the formulations followed Higuchi model (r(2)>0.96) and the 'n' values were within 0.5 to 0.95, which indicates anomalous transport. The formulations containing drug and PEG-6000 and PVP-K30 at 1:1 revealed similar dissolution profile with theoretical dissolution. The stability study indicates condition of 30 degrees C/75%RH as suitable for solid dispersion storage. Tablets were prepared from selected solid dispersions and subjected to various quality control tests.