Design and Characterization of Bilayered Floating Tablets of Clopidogrel Bisulfate and Aspirin using Natural Gums

Objectives: In present investigation, an attempt was made to develop bilayered floating tablets of clopidogrel bisulfate and aspirin using natural gums as release retarded material. Clopidogrel bisulfate and aspirin are anti-platelet agents. Methodology: Clopidogrel bisulfate is a suitable candidate for formulating as gastro retentive dosage form as it has absorption window in stomach and solubility in the acidic pH. Sodium bicarbonate and citric acid were used to get desired floating properties. The effect of formulation variables on floating properties and drug release were investigated. Results: The tablets so designed were evaluated and found to have acceptable physicochemical properties, floating lag time, floating time and drug release. Among all the bilayered formulations, CBXA with susutained.release layer containing xanthan gum (2 ratio with drug), sodium bicarbonate (15% w/w) and citric acid (1.2% w/w) and immediate release layer containing sodium bicarbonate (10% w/w) and guar gum (4% w/w) has shown optimum results. Sustained release layer has shown dissolution of 99.03±0.42 % in 12 hrs whereas immediate release layer has shown 99.4±0.44 % in 30mins.CBXA has shown optimum floating properties with in vitro floating lag time of 4 min and floating time of >12 hr. In vivo buoyancy study revealed that the floating time of CBXA was greater than 6 hr. The in vitro release data of optimized formulation was treated with mathematical equations and was evident that drug release followed zero order kinetics with case II transport mechanism. Conclusion: Based on the results it can be found that bilayered floating tablets of clopidogrel bisulfate and aspirin containing xanthan gum provides a better approach for sustained release and improved bioavailability.