Formulation by Design (FbD) approach to develop pharmaceutically amended Diclofenac Sodium hydrogel as compared to marketed gel

The aim of the present study was to develop pharmaceutically better performing Diclofenac Sodium hydrogel through FbD approaches as compared to marketed gel. The quality target product profile was set for the critical quality attributes of the gel. The key material variables like Carbopol 934P, propylene glycol and Triethanolamine (TEA) were optimized using design of experiments. A response surface central composite design was used considering viscosity, pH and cumulative percentage permeation of the drug up to 120 min as responses. TEA had a significant effect on the pH at concentrations of 0.3182-3.6818% (w/w). The applicability of the optimized formulations was influenced by both Carbopol 934P (0.6591-2.3409%; w/w) and propylene glycol (PG; 6.591-23.409%; w/w) content due to their ability to alter the formulation viscosity. The optimized formulation, determined mathematically, contained 1.5% (w/w) Carbopol 934P. 2.0% (w/w) TEA and 15% (w/w) PG. The optimized hydrogel and marketed gel were evaluated for viscosity, spreadability, skin irritation, homogeneity and grittiness, texture analysis, in vitro release and ex vivo permeation studies. When these evaluation parameters were compared with a marketed gel in respect of all the evaluating tests, the optimized hydrogel was found to be far better formulation than the marketed one.