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The investigation was concerned with design and characterization of oral controlled release matrix tablets of Zidovudine (AZT) in
order to improve efficacy and better patient compliance. Tablets were prepared by direct compression method using various proportion
of hydrophilic polymer viz; Eudragit RS100 and RL100 along or in combination with hydrophobic polymer ethyl cellulose. In vitro
release studies were performed using USP type I apparatus (rotary basket type). The release kinetics were analysed using Zero-order
model equation, Higuchi¡¯s square root equation and Korsmeyer and Peppas¡¯ emphirical equation. Compatibility of drug with
various formulations excipients was also studied. Dissolution study revealed that either Eudragit RS100 or RL100 10%,20% w/w
of tablet preparations were able to sustain the drug release up to 9 hours, but 30%, 40% as well as ethyl cellulose combination with
20% and 25% w/w of Eudragit RS100 and RL100 were able to sustaining the drug release for 12 hour. Mathematical analysis of the
release kinetics indicated that the nature of drug release from the matrix tablets followed non-Fickian diffusion mechanism. No
compatibility was observed between the drug and excipients used in the formulation of matrix tablets. The optimized formulation
(F13) showed insignificant difference in release mechanism as well as release kinetics (P>0.05) when stability study was done for six
months at 40¡À2
0
C and 75¡À5% RH.
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