Physicopharmaceutical characteristics of an oil-in-water emulsion-type ointment containing diclofenac sodium.

The oil-in-water (o/w) emulsion-type ointment was prepared with food additives containing diclofenac sodium. The oil phase and the emulsifier used were 1,2,3- propanetriyl trioctanoate (caprylic acid glyceryl ester) and sugar wax, and sugar ester, respectively. The emulsion stability of the o/w emulsion-type ointment as well as the diclofenac sodium release profile were investigated and compared with those from conventional ointments. The emulsion stability was evaluated in terms of the viscosity of the emulsion product, the particle size distribution of oil droplets, and the zeta potential of the droplets. It was found that sugar esters have excellent properties as emulsifiers, based on the results of viscosity and zeta potential measurements. The in vitro release test revealed that the amount of diclofenac sodium released from o/w emulsion-type ointment was greater than from the hydrophilic and absorptive ointment. Accordingly, it was concluded that o/w emulsion-type bases are suitable for pharmaceutical use in ointment products.