Assessment of once daily sustained release hydrophilic matrix tablet of carvedilol

Abstract

The objective of the present study was to design and evaluate once daily sustained release tablet of
carvedilol, using two molecular weight grades of hydrophilic polymers (methocel® K4M CR and methocel®K15M
CR) as release retarding materials. Two sets of formulations were prepared, where first set of four formulations (F1-
F4) contained variable ratios of methocel® K4M CR and methocel® K15M CR (15% : 15%, 15% : 13%, 15% : 11%
and 15% : 9%) to optimize the composition of polymers in the tablet matrices such that the drug and polymer
interaction was sufficient for sustaining release up to 24 hours and second set of five formulations (F5-F9) contained
variable percentages of sodium lauryl sulfate (SLS) (1.0, 1.25, 1.5, 1.75 and 2.0%) to enhance the dissolution rate of
the drug from the tablet matrices because of its poor aqueous solubility. The tablets were prepared by direct
compression method and evaluated for hardness, thickness, friability, weight variation and in vitro drug release. The
in vitro dissolution studies were carried out in simulated gastric fluid (900 ml, pH 1.2) for 24 hours using USP type II
apparatus operated at 100 rpm and 37 ± 0.05°C. The release profiles were explored and explained by zero order, first
order, Higuchi, Korsmeyer-Peppas and Hixson-Crowell models. From this study, the drug release profiles for
formulations F6 to F9 were found to be satisfactory and the release mechanism followed both diffusion and erosion.
Due to lower percentage of SLS used, F6 was considered as the best formulation.