ABSTRACT:
Solid dispersion can be defined as “The dispersion of one or more active ingredients in an inert carrier or matrix at solid state”. Solid dispersions are prepared with an aim to improve the solubility and dissolution rate. Polyethylene Glycols (PEG4000, PEG6000and PEG8000), Polyvinyl pyrrolidone (PVP) used as polymers in the preparation of solid dispersions. Chloroform, Ethanol, Methanol is used as the solvents. The method of preparation of solid dispersions include Fusion method, hot melt extrusion, Solvent evaporation method, super critical fluid method, Dielectrostatic spinning process. Solid dispersions are divided into six types based on their molecular arrangement. They are Eutectics (crystalline drug in crystalline matrix), Amorphous precipitations in crystalline matrix (crystalline drug in amorphous matrix), Solid solutions (crystalline drug molecularly dispersed in matrix), Glass suspensions (crystalline drug in amorphous matrix), Glass suspensions (amorphous drug in amorphous matrix), Glass solutions (amorphous drug molecularly dispersed in matrix). Thin Layer Chromatography and Infra Red spectral analysis confirms the absence of interaction between the drug and the carriers. A marked improvement in the dissolution rate was observed in all the solid dispersions compared with the pure drug.900ml of 0.1M pH 7.4 phosphate buffer used as dissolution medium. The stirrer is adjusted to 75 rpm at 37oC and absorbance is measured by using UV-vis spectrophotometer.