ON THE EMPLOYMENT OF LAMBDA-CARRAGEENAN IN A MATRIX SYSTEM - III - OPTIMIZATION OF A LAMBDA CARRAGEENAN-HPMC HYDROPHILIC MATRIX

The lambda carrageenan/HPMC ratio in matrix tablets has been optimized in order to obtain pH-independent release profiles of chlorpheniramin e maleate, a freely soluble drug. Release profiles in acidic (pH 1.2) and neutral (pH 6.8) media were fitted according to the Weibull and th e power law models. Model independent parameters (t(50%) and the perce ntage of drug released after 2 h) were also calculated. The Weibull pa rameters were found suitable to describe the dependence of the release profiles on matrix composition. Preparation and testing of the optimi zed formulation showed linear and pH-independent release profiles last ing about 24 h, in good accordance with the values predicted by the op timization procedure. (C) 1998 Elsevier Science B.V.