During the past four decades, the solid dispersion technology has been successfully used to increase the dissolution rate and bioavailability of poorly water soluble drugs. Recently, the attempts are being made to develop the sustained-release drug delivery systems with simple carrier polymers using the solid dispersion techniques.

The objective of the study was to formulate a single controlled release solid dispersion powder of Propranolol Hydrochloride that can be used for the development of multiple strength dosage forms of the drug. Also, to study the physical characterizations of the formulation using sophisticated analyzing techniques. Various solid dispersions formulations were made using the solvent evaporation method and screened for their in-vitro dissolution profiles according the USP. The formulation with an optimum sustained-release profile was then further evaluated on multiple strength basis containing 40mg, 60mg and 80mg of drug. In addition, this formulation was stability tested on a limited basis and enlarged to study its suitability for commercial use. The dissolution profiles from all samples were then individually evaluated and compared with the Control using these data.

Among all the formulations studied, the dispersion containing Eudragit ^®S100: Eudragit^®L100 (1:3.5:4) produced desirable controlled release dissolution profile over a 24 hour period. The dissolution profile from this sample was then compared with the pure drug and the physical mixture, and the data indicate that neither the pure drug nor its physical mixture with the polymers were able to control the drug release. This proved that it was the solid dispersion technology that enabled the polymer materials to effectively sustain the release of drug from such formulations. Even though, the release of drug from the formulations was proportional to the amount of drug in the samples, the percent drug release vs. time from all samples remained the same. This strongly supports the fact that a single formulation powder can be encapsulated to produce the suitable multiple strength dosage forms of the drug.

The physicochemical properties of the solid dispersion were studied using X-ray Diffraction, Differential Scanning Calorimetric and Fourier Transformed Infra Red method. The results confirmed that the drug exists in the amorphous form and there are no chemical interactions among the drug and polymer.