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In-vitro studies of diclofenac sodium controlled-release from biopolymeric hydrophilic matrices.

PURPOSE
The objective of this study was to develop uncoated HPMC matrix tablets, evaluating the relationship and influence of different content levels of microcrystalline cellulose (MCC), starch, and lactose, in order to achieve a zero-order release of Diclofenac Sodium.


METHODS
HPMC matrix tablets of Diclofenac Sodium using microcrystalline cellulose (MCC), starch, and lactose were prepared by wet granulation process. The USP paddle method was selected to perform the dissolution profiles carried out in 900 mL 0.1 N HCl, and phosphate buffer.


RESULTS
There was no significant difference in drug release between the hydrophilic matrices when the HPMC concentration was modified in low percentage. Release kinetics of Diclofenac Sodium from these swollen matrices was principally regulated by starch (17 percent) or lactose (17 percent), even on the presence of MCC. When starch (8.5 percent) and lactose (8.5 percent) were mixed at lower concentration in a ratio 1:1, MCC (5 percent or 7,5 percent) appeared to control the drug release. The release profile remained unchanged after three months storage of tablets. The best-fit release kinetics was achieved with the zero-order plot, followed by the Higuchi and first-order equations. The data obtained proved that the formulations are useful for a sustained release of Diclofenac, due to the percentage released after 8 hours is nearly to 70 percent.


CONCLUSIONS
The release of Diclofenac Sodium was influenced by the presence of MCC, and by the different concentrations of starch and lactose. Drug release kinetics from these formulations corresponded best to the zero-order kinetics. Compared to conventional tablets, release of the model drug from these HPMC matrix tablets was prolonged; as a result, an oral release dosage form to avoid the gastrointestinal adverse effects was achieved.