Formulation and evaluation of zidovudine sustained release matrix tablets
ABSTRACT The objective of the study was to design oral sustained release matrix tablets of zidovudine using Hydroxy Propyl Methyl Cellulose (HPMC) K4M, Guar Gum and Ethyl Cellulose as the retardant polymers and study the effect of various formulation factors such as polymer proportion, polymer type and effect of filler type on the in vitro release of the drug. Matrix tablets were prepared by wet granulation method and prepared tablets were evaluated for weight variation percentage friability, hardness thickness and in vitro dissolution studies. All the granules and formulations showed compliance with pharmacopieal standards .In vitro release studies revealed that the release rate decreased with increase polymer proportion and hydrophobic polymers retard the drug release more than hydrophilic polymers .The formulations F2 and F8 sustained release of drug for 12 hrs with 96%, 98% release but F5 (15% of HPMC) using MCC as diluent drug releases 10 hours only. Because of swelling property of MCC increased the drug release profile to a small extent due to change in swelling at the tablet surface. The kinetic treatment showed that the mechanism of drug release non-Fickian for HPMC and Ficikian–Diffusion process for guar gum. The developed sustained release matrix tablets of zidovudine with good initial release for first 2hrs(20-25%) and extended the release up to 12hrs can over come the disadvantages of conventional zidovudine tablets.