Abstract
Controlled release phenylpropanolamine hydrochloride (PPA) tablets were prepared using different ratios of ethylcellulose-stearic acid matrix. The matrices were prepared by 3 different techniques. The medicated matrices containing 50 % w/w drug, each alone was directly compressed into tablets for the study of drug dissolution from constant surface. Also, the medicated matrices, prepared by the solvent method were mixed with di-calcium phosphate and directly compressed into tablets. The prepared tablets were subjected to physical and release studies. Drug release from constant surface tablet revealed that, in-vitro availability of PPA was found to be dependent on the ethylcellulose-stearic acid ratio in the tablet matrix. As ethylcellulose content increased in the matrix the release rate of the drug was enhanced. Also, the release rate of the drug was found to be affected by the method of the preparation of the matrix and in the following decreasing order melt-physical > solvent > melt-solvent method. The release rates of the drug from constant tablet surface followed the square root relationship of Higuchi model All tablet formulations exhibited acceptable mechanical properties regarding, hardness and friability according to USP requirements. The prepared tablets show no evidence of disintegration for a period of 4 h. The release rates of the drug from the whole tablets were similar to that from constant tablet surface regarding the effect of ethylcellulose concentration in the matrices and the mechanism of the drug release So the proposed ethylcellulose-stearic acid matrices could be useful for the reparation of PPA controlled release tablets.