FORMULATION AND EVALUATION OF ZIDOVUDINE FLOATING TABLETS
Ch. Taraka Ramarao* and K. Bhavyasri
ABSTRACT
Floating Drug Delivery Systems (FDDS) or hydro dynamically balanced systems (HBS) have a bulk density lower than gastric fluids and hence remain floating in the stomach for a prolonged period of time. The drug is slowly released from the floating system at a desired rate without fluctuations in plasma drug concentration thus leading to an increase in the gastric residence time (GRT). After complete release of drug from the delivery system, the residual is expelled from the stomach. It is a low density approach which has a bulk density lower than gastric fluids and hence remains buoyant in the stomach, releasing the drug slowly without affecting the gastric emptying rate for a prolonged period of time. The present investigation includes zidovudine floating tablets optimization and release controlled
employing xanthane gum, HPMC, Carbapol. The basic idea behind the development of gastro retentive drug delivery systems is to maintain a constant level of drug in the blood plasma in spite of the fact that the drug does not undergo disintegration. The drug usually keeps floating in the gastric fluid and slowly dissolves at a predetermined rate to release the drug from the dosage form and maintain constant drug levels in the blood. It also has an advantage of minimizing the fluctuations in plasma drug concentration by delivering the drug in a controlled and reproducible manner.
Keywords: Floating, Buoyancy, Floating lag time, Swelling index and Zidovudine.
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