Evaluation of Properties of Dexamethasone Eye Drops

During the development of medicinal forms (eye drops), it is necessary to consider several parameters, so that the medicine is nonirritating to the eye and, at the same time, has the desired effect. We prepared eye drops containing dexamethasone or its water-soluble salt in a 0.1% concentration. We compared suspension eye drops (with dexamethasone) and solution eye drops (with dexamethasone sodium phosphate) without viscosity adjustment as well as with viscosity adjustment by adding chitosan low molecular weight (LMW) with the mass-produced product Unidexa 1%. Acidity (pH), surface tension, density, viscosity, and irritability were evaluated. An in vitro or ex vivo test on human erythrocytes (red blood cells [RBCs]) was used to test irritability. Hemolysis of RBC was monitored by determining hemoglobin spectrophotometrically at a wavelength of 550 nm. The addition of chitosan 0.1% as a viscosity-increasing agent reduced the irritation potential of the experimental eye drops.