Formulation and evaluation of a bilayer tablet comprising of diclofenac potassium as orodispersible layer and diclofenac sodium as sustained release core
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Diclofenac a phenylacetic acid derivative has long been used as an anti-inflammatory and analgesic drug to treat certain conditions however its sustained release formulation with immediate release loading dose is desirable. The rationale of the current work was to develop and evaluate bilayer tablets with diclofenac potassium as orodispersible layer and diclofenac sodium as sustained release core. The diclofenac sodium core was prepared by wet granulation method while the orodispersible outer layer was prepared by direct compression method using super disintegrant sodium starch glycolate. The powder blends were then evaluated for both pre- compressional and post compressional properties. The physical parameters of both powders and tablets were in accordance with the compendial standards. The orodispersible portion disintegrated in less than 30sec releasing diclofenac potassium as the loading dose while the core was able to sustain the release of diclofenac sodium up to 10hrs in simulated intestinal fluid (pH 6.8). The kinetic data revealed that the release pattern was best fitted into Korsmeyer-Peppas model with non-fickian release. The outer orodispersible layer of diclofenac potassium and sustained release inner core of diclofenac sodium in a single tablet was successfully formulated while sodium starch glycolate showed to have good super disintegrant properties.