An ophthalmic emulsion of retinoic acid

An oil-in-water emulsion of 0.01 % retinoic acid was prepared as a tear. su bstitute to be effective for ocular surface disorders. The ophthalmic emuls ion was composed of 10% arachis oil and 90%Carbopol 940 hydrogel. The physi cal stability of the preparation was assessed by I,measuring the particle s ize distribution, viscosity and flow property. The chemical stability of re tinoic acid in the emulsion was examined by reversed-phase high-performance liquid chromatography. The ophthalmic emulsion of retinoic acid showed pse udoplastic flow with the highest viscosity of 232 cP .s at 60 r/min, and th e mean particle diameter was 2.34 mu m. The drug content (90% of the initia l concentration) did not change during two months of storage at 4 degrees C .