Formulation and Stability Evaluation of Diclofenac Potassium Microemulsion Formulation Using Tween 80 : Span 80 as Surfactant

Diclofenac potassium is a nonsteroidal anti-inflammatory drug (NSAID) that exhibits hydrophobic properties and causes gastrointestinal side effects, necessitating its formulation as a topical microemulsion. This study aimed to investigate the physical stability of diclofenac potassium microemulsions prepared using a Tween 80:Span 80 surfactant mixture (9:1) at varying surfactant concentrations of 30%, 35%, and 40%. The microemulsions contained oleic acid as the oil phase and propylene glycol as the cosurfactant. Physical stability of the diclofenac potassium microemulsions was assessed using a cycling test in a climatic chamber at 40°C ± 2°C and 4°C ± 2°C for six cycles and centrifugation stability test. Additionally, organoleptic properties, pH, viscosity, density, and globule size were evaluated. The results revealed no significant changes in organoleptic properties, pH, and viscosity during the six cycles for all three formulations. The pH measurements indicated that the formulations had a pH range of 5.8 to 6. The microemulsions exhibited low viscosity, did not exhibit phase separation, and had a density of 1.031-1.037. These findings suggest that all three formulations possess satisfactory physical stability.