PREPARATION AND IN VITRO EVALUATION OF SUSTAINED RELEASE BILAYERED MATRIX TABLETS OF VALSARTAN
Rama Rao Tadikonda* and Srilatha Ade
ABSTRACT
The purpose of the present investigation was to prepare sustained release bilayered matrix tablets (MF1 to MF7) of valsartan by direct compression method using Hydroxypropyl cellulose, Xanthan gum, guar gum and to evaluate for various tests such as thickness, hardness, weight variation, friability, drug content and in vitro drug release studies. All the physico-chemical parameters of matrix formulations of valsartan were found to be within limits and all the matrix formulations provided the drug release up to 24 hrs in a controlled manner without changing their physical integrity in dissolution medium. The drug release data of all the matrix tablets fit well to the Higuchi expression clearly indicating that the drug release mechanism was predominantly diffusion controlled. The diffusional exponent values obtained from korsmeyer’s plot(n<0.5) showed that all the matrix tablets followed Fickian diffusion. The results of studies indicated that formulations
MF1, MF3 and MF5 are better formulations as they released the total amount of drug in a sustained manner upto 24 hours and their ƒ2 value is also high(˃60) indicating that dissolution profiles are similar to theoretical release profile. Stability studies of hydrophilic matrix tablets MF1, MF3 and MF5 showed no change in physical appearance, drug content and dissolution studies after storage period indicating that valsartan formulations are stable. FTIR studies and DSC studies clearly proved that there is no drug polymer interaction.
Keywords: Valsartan, Sustained release, Bilayered matrix tablets, HPC, Xanthan gum, Guar gum.
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