Studies on Formulation and Characterization of Acyclovir Sustained Release Matrix Tablets by using Natural Polymers

The goal of a sustained release dosage form is to maintain therapeutic blood or tissue levels of the drug for an extended and specified period of time. This is generally accomplished by attempting to obtain "zero-order" release from the dosage form. Zeroorder release constitutes drug release from the dosage form which is independent of the amount of drug in the delivery system (i.e. a constant release rate). Sustained-release systems generally do not attain this type of release and usually try to mimic zero-order release by providing drug in a slow first-order fashion (i.e., concentration release dependent). Systems that are designated as prolonged release can also be considered as attempts at achieving sustained-release delivery. In the present study the effect of types and concentration of polymer were studied on In-Vitro drug release. It shows that increase in concentration of polymer results in the sustained drug released at 11 hours. The study has revealed that by increasing concentration of polymer, release rate of drug was retarded and results confirmed that the released rate from hydrophilic matrix tablets depends on type and concentration of polymer. In present studies, matrix formulation containing Chitosan was probably showed better drug released up to 95.98 % within 11 hours, which was the average gastrointestinal residence time. According to stability study it was found that there was no significant change in hardness, drug content and in vitro dissolution of optimized formulation (F9). So the formulation F9 was concluded best formulation among the formulations F1 to F9 were prepared