In vitro evaluation of emulgel formulation for topical application of diclofenac potassium

Purpose: For superficial pain, nonsteroidal antiinflammatory medications (NSAIDs) offer sufficient analgesia, particularly in cases of mild to severe dull pain. Diclofenac potassium is one of the most preferred drugs in this group, but its low water solubility and high permeability due to its BCS II class classification makes it a challenging active substance in the formulation process. The aim of this study was to develop and evaluate in vitro of emulgel formulations containing diclofenac potassium. Materials and Methods: All substances used in the formulation development process were substances in conformity with pharmacope specifications. Emulgel formulations containing diclofenac potassium were prepared and evaluated in terms of pH, conductivity, rheological properties, viscosity, drug release rate and stability. Results: The method developed and validated for the determination of the active ingredient resulted in a good linear relationship that was established between the peak areas and the concentrations (2.5-40 mu g /mL) of diclofenac potassium with the determination coefficient (R2) which equals to 0.9999. F1, F2, F3 and F4 formulations were found to be stable at the end of the 1st and 3rd month when evaluated with the amount of active substance, pH and rheological properties at different temperatures and conditions. Formulations F2 and F4 are more viscous than other formulations F1 and F3. The initial pH values of all prepared formulations were found to be compatible with the skin. When the reological properties of the formulations were studied, they were determined by examining the calculated R2 values of the HerschelBulkley reological type (R2 values of F1, F2, F3 and F4 formulations respectively were 0.999045, 0.999301, 0.999650, 0.999631). In the drug release rate studies, the release of active substance from F2 and F4 formulations continued until the 6th hour and reached plateau values. Conclusion: Diclofenac potassium emulgel can be used as an antiinflammatory analgesic agent for topical drug delivery.