Formulation of methyldopa sustained release matrix tablets using hydrophilic polymers

The present study aims to develop sustained release (SR) matrix tablets of methyldopa using hydrophilic hydroxypropyl methylcellulose (HPMC), and to study the effect of some formulation variables (HPMC concentration and viscosity grade, combination with hydrophobic Ethylcellulose (EC) in different ratio, binder and lubricants concentrations) on the properties of prepared tablets. Matrix tablets were prepared by wet granulation method, and prepared granules and tablets were subjected to suitable physiochemical studies. Drug release kinetics showed that drug release mechanism for about all formulations was found to fit best to Higuchi model and drug release mechanism was anomalous diffusion based on release exponent value. The in-vitro dissolution studies showed that formulation F6 containing 15% of HPMC K100M and formulation F11 containing EC:HPMC K4M (5%:10%) were able to sustain the release of methyldopa up to 24 hours so these two formulations were selected as suitable formulations.