Purpose: To evaluate the effect of locally instilled 10 % L-arginine.HCl and 10 % L-lysine.2HCl.2H2O in 0.005% Latanoprost (Xalatane) mixture on the physiological IOP in rabbits. Methods: After instillation of the arginine and lysine in 0.005% latanoprost mixture into the left conjunctival sac of 5 female rabbits of the New Zealand White species the, IOP was measured at the time of instillation, and 5, 15, 30, 60, 120, 180, 240 min. and 24 hours after the instillation. The right eye was used as the control. Results: The mixture of arginine with lysine in 0.005% latanoprost decreased significantly the IOP value. The decrease had two peaks. The major decrease of the IOP was observed after 30 min. (3.1 mmHg) and after 24 h (5.0 mmHg) after instillation of this mixture. Between 120 min. and to 240 min., the mild decrease of the mean value of the IOP was found at the control eye as well. Conclusions: The mixture of arginine with lysine in 10 % concentration in 0.005 % latanoprost (Xalatane) decreased significantly the physiological IOP values in rabbits during the whole experiment. The decrease was significant in comparison both to the IOP of the control eye and to the effect of the amino acids arginine and lysine alone.

        Key words: 10% L-arginine.HCl with 10% L-lysine.2HCl.2H2O in 0.005% latanoprost, intraocular pressure