Methyldopa, an anti-hypertensive drug having a half life of less than 2 hours, and given with a dose of 250 mg 3-4
times daily.
Objective: The present study was for objective of developing a sustained release (SR) matrix tablets of methyldopa
usin
g hydroxypropyl methylcellulose(HPMC) as release controlling factor, and to study the effect of some formulation
factors on drug release from tablets.
Methods: Hydrophilic SR matrix tablets containing 250 mg of methyldopa were prepared using wet granulation
method. Granules were evaluated for moisture content, loose bulk density, tapped bulk density, compressibility index
and hausner’s ratio. Tablets were subjected to physiochemical studies and in vitro dissolution study. Effect of
concentration and viscosity grade of HPMC, both binder and lubricant concentration on drug release from matrix
tablets was evaluated .
Results: All formulations showed physiochemical properties which appear to be in compliance with pharmacopeial
standards. From the in vitro dissolution studies, it was clear that as the concentration or viscosity of polymer increased,
the rate of drug release was found to be decreased. Higher concentration of binder (PVP K30) showed slower release
of drug, while the level of lubricant(magnesium stearate and talc) appeared to insignificantly affect release rates. Drug
release kinetics of about all formulations correspond best to Korsemeyer-Peppas model and drug release mechanism
was found to be anomalous (non-Fickian) diffusion based on release exponent value. The formulation F6 (containing
15% HPMC K100M ) was selected as the optimized formulation as it sustained the release over 24 hrs.
Conclusion: The results of this study showed that the drug release from HPMC based matrix tablets using methyldopa
as a drug model could be modulated by varying the polymer concentration, the polymer viscosity and the binder
concentration with no significant effect of varying the lubricant concentration.
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.
The objective of the present study was to formulate methyldopa sustained release
matrix tablets using hydrophilic hydroxypropyl methylcellulose (HPMC) alone or in
combination with hydrophobic ethyl cellulose polymer(EC). Matrix tablets were prepare
d
by wet granulation method, and subjected to physiochemical studies. All formulations
showed physiochemical properties which appear to be in compliance with pharmacopeial
standards. The in-vitro dissolution studies showed that increase in concentration or
viscosity of HPMC polymer led to decrease in the rate of drug release decreased. The
results also revealed that Combination of HPMC K4M and EC slower drug release more
than using HPMC K4M alone. Drug release kinetics of about all formulations correspond
best to Korsemeyer-Peppas model and drug release mechanism was anomalous diffusion
based on release exponent value.
Nifedipine is one of the most used calcium channel blocking agents. Due to its low aqueous solubility, it often shows low and irregular bioavailability after oral administration. Nifedipine has short half-life so it has to be administered many times
a day. Immediate-release formulations increase the risk of myocardial infarction and mortality. This research aims to prepare dual-function drug delivery system to enhance nifedipine solubility using solid dispersion technique, and extend its release by incorporating these dispersions in matrix tablets. 32 Factorial design was employed; two independent variables, Poloxamer 188 and Ethyl cellulose, to improve solubility and extend release respectively, were used in 3 levels. The prepared tablets were examined, and succeeded in extending nifedipine release up to 12 hrs. The equations that link the dependent and independent variables were obtained, through which tablet hardness and the released amount after 1, 4 and 6 hours could be predicted.