Development And Evaluation Of A Sustained Release Dosage Form : Microencapsulation Of Drug-Pectin Complex
Diclofenac sodium-pectin complexes were prepared by physical mixture and solvent deposition techniques. Microcapsules of drug and drug-pectin complex were prepared by coacervation phase separation method using ethylcellulose as coating material. The stability of the drug in the formulations were confirmed by TLC and IR studies. Different sizes in a batch of dried microcapsules were separated by sieving. Scanning electron microscopy revealed the morphology of microcapsules. In vitro release from complexes and mirocapsules in distilled water and mechanism of drug release are identified. The dissolution rate decreased with an increase in the concentration of pectin and ethylcellulose added in complexes and microcapsules respectively. Dissolution data were fitted into a double log plot equation, a Fickian release (n=0.5) was obtained for all the complexes and microcapsules. The data demonstrates that controlled release formulation of diclofenac sodium can be developed using a combination of two techniques like complexation and microencapsulation. The binding of drug to pectin was investigated using equilibrium dialysis. The binding data were expressed in the form of Scatchard plot, which indicated two classes of binding sites.