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.
