NOVEL METHYLDOPA EXTENDED RELEASE MATRIX TABLETS

The objective of the present study was to develop extended release (ER) matrix tablets of methyldopa using hydrophilic hydroxypropyl methylcellulose (HPMC) alone and in combination with hydrophobic ethylcellulose (EC), and to study the effect of some formulation variables (HPMC viscosity grade and combination with hydrophobic polymer in different ratio) 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. The in-vitro dissolution studies showed that formulation F1 containing 15% of HPMC K100M and formulation F6 containing EC:HPMC K4M (5%:10%) were selected as optimized formulations as they were able to sustain the release of methyldopa up to 24 hours. Drug release kinetics show that drug release mechanism from these two formulations was found to be anomalous diffusion in acidic medium, while in phosphate buffer medium methyldopa release mechanism was case ІІ transport in formulation F1 and anomalous diffusion in formulation F6.