Abstract: In this study sustained release Phenylpropanolamine Hydrochloride (PPA(HCl) hydrophilic matrix tablets containing HPMC K100M and Carbopol 971P were prepared by direct compression method, and the release tests were performed. In all cases the plot of cumulative drug release percentage against t1/2 produced a straight line (r>0.98, P<0.01). The composition of polymers was selected employing orthogonal design. The chosen formulation showed consistent performance. The release profiles of the test and reference preparation were similar in 0.1 mol·L^-1 HCl, distilled water, phosphate buffer pH 5.0, 6.8, 7.4 and in 0.1 mol·L^-1 HCl for 2 h followed by release in phosphate buffer pH 6.8 for 10 h, for in these cases, the values of "similarity factor, f2" varied within the range of 63~74. The rate of PPA(HCl released in 0.1 mol·L^-1 HCl was significantly higher than in other four media (P<0.05). It was found that in the ranges examined, the rate of PPA(HCl released in distilled water decreased with the content of HPMC K100M or Carbopol 971P increased (P<0.05), but variations of the polymers ratio (using the same total content of polymers), the content of magnesium stearate or hardness of matrices appeared to insignificantly affect release rates (P>0.05).

Key words: Hydroxypropylmethylcellulose HPMC, K100M, Hydroxypropylmethylcellulose HPMC, K100M, Carbopol 971P, Carbopol 971P, Phenylpropanolamine Hydrochloride, Phenylpropanolamine Hydrochloride, Hydrophilic sustained release matrix tablets, Hydrophilic sustained release matrix tablets, Similarity factor, Similarity factor