Formulation and Evaluation of Extended Release Matrix Tablet of Zidovudine Using Hydrophilic and Hydrophobic Matrix Formers

Abstract:

Background: Zidovudine is a virustatic drug has a very short half life and undergoes consider¬able first-pass metabolism thus necessitating an adequate zero order delivery. Objectives: The aim of the present study was to prepare and characterize extended release matrix tablets of Zidovudine (ZID) using hydrophilic (HPMC K4M) and hydrophobic olibanum gum resin polymers separately. Methods: The matrix forming resin was extracted from a naturally available olibanum gum and evaluated as a matrix former. The FTIR and DSC studies confirmed that no chemical interaction took place in the final formulations. The scanning electron microscopy was used to visualize the effect of dissolution medium on matrix tablet surface. Release kinetics was evaluated by using United States Pharmacopoeia (USP)-23 type I dissolution apparatus. Results: The in-vitro drug release study of formulation with HPMC K4M revealed that the controlled release was only for 12 h. The effect of polymeric resin on release profile of drug from matrix tablet was slow over 24 h. Drug release was by non-fickian diffusion mechanism. Resin encapsulated matrix tablet of ZID exhibited good controlled release characteristics and were found suitable for once a day oral controlled release products. Fitting the in-vitro drug release data to Korsmeyer equation indicated that diffusion along with erosion could be the mechanism of drug release. Conclusion: In conclusion, the results suggest that the developed controlled release tablets of ZID with olibanum resin matrix could perform therapeutically better than tablets prepared with HPMC K4M, leading to improved efficacy and better patient compliance.

Key words: Olibanum gum resin, matrix tablet, controlled release, zidovudine.