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Purpose: To compare the effect of amino acids mixtures to a double combination of antiglaucomatics on the physiologic intraocular pressure (IOP) in rabbits., Methods: Experimental evaluations were performed on 5 female rabbits of the New Zealand White species., Results: 1) After instillation of 10 % L-arginine. HCl in the double combination of antiglaucomatics: a) 0.5 % Timolol with 0.005 % Xalatan mixture, the biphasic IOP decrease was measured. The mean decrease in 24 hours was - 2.9 torr; b) 2 % Trusopt with 0.005 % Xalatane mixture in 24 hours, the biphasic decrease of the IOP was measured. The mean decrease in 24 hours was - 4.2 torr; c) Fixed combination COSOPT the mean IOP value decrease was - 1.8 torr. 2) The IOP decrease achieved during 24 hours by instillation of the amino acid 10 % L-taurine.HCl and the double combination of antiglaucomatics: 0.5% Timolol with 0.005% Xalatane mixture was in average - 2.8 torr. The pupilar diameter was not changed., Conclusions: We assume that after the interaction of the selected amino acids 10 % L-arginin or 10 % L-taurin with the double combination of antiglaucomatics (Trusopt and Xalatan, COSOPT or Timoptol and Xalatan) a new substance was formed. The effect of this substance is not separate or additive but acts as a newly formed substance. In vivo, it is only a weak interaction with the free amino acids of the conjunctival sac and the antiglaucomatics. The amino acids interacted in vitro with the double combination of antiglaucomatics resulting in a new "bio-antiglaucomatic" better penetrating into the target area. This new substance was responsible for a more significant decrease and regulation IOP after the mixture application compared to the antiglaucomatics alone (Fig. 1, Ref. 23).

Aim: Presented experimental work was aimed to examine a pharmacokinetic efficiency of 0.5% Timolol mixtures with 4 free amino acids, present in conjunctival sac: lysine, arginine, glycine or taurine on the IOP physiological values in rabbits., Methods: The experimental work was performed on 5 female rabbits of the New Zealand White species. After instillation at 8.00 a.m. into the left conjunctival sac: a) the 10% L-lysine x 2HCl x 2H2O in 0.5% Timolol; b) the 10% L-arginine x HCl in 0.5% Timolol; c) the 10% L-glycine x HCl in 0.5% Timolol; d) the 10% L-taurine x HCl in 0.5% Timolol, the IOP was measured before and in 5th, 15th, 30th, 60th, 120th, 180th and 240th min and in 24 hours. The right eye of the same rabbit was used as control with the instillation of both 0.5% Timolol and amino acids alone into the conjunctival sac., Results: a) The IOP has decreased after mixture of 10% lysine in 0.5% Timolol with two spikes--not significant decrease up to 60th min and a high significant decrease between 120th to 240th min; b) The mixture of 10% arginine in 0.5% Timolol decreased the IOP values with a high significance (from 2.1 to 4 torr); c) The 10% glycine in 0.5% Timolol showed a significant IOP decrease (excluding measurement in 5th min) in all measured times, the biggest IOP decrease was observed in 60th min (mean value 8.5 torr), the decrease was 3.3 torr also in 24th hours; d) The 10% taurine in 0.5% Timolol showed also a significant IOP decrease (excluding measurement in 5th min) in all measured times with maximum in 180th min (with a decrease to 6.7 torr) and the decrease showed a significantly low level--3.3 torr--also in 24 hours., Conclusions: The results proved that the mixture of antiglaucomatic 0.5% Timolol and amino acid (lysine, arginine, glycine or taurine) contains a new biologically active substance, the "specific bioantiglaucomatic" created by interaction. Compared to the substances alone, mixture of amino acid in the antiglaucomatic decreased the physiologic IOP in rabbits with a high significance. The effect on IOP based on the interaction of the mixture of amino acid with antiglaucomatic is specific and its efficacy together with time was changed depending on the type of amino acid. Our in vitro produced bioantiglaucomatic fulfilled the physiological criteria for the IOP reduction (Fig. 4, Ref 12). Full Text (Free, PDF) www.bmj.sk.

Authors present comparison of the previous results on the influence of free amino acids of the aqueous humor in rabbits and human on the pH of the aqueous humor in vitro. Four clinically used antiglaucomatics were added (2% Trusopt--pH 5.33; 0,005% Xalatan--pH 6.4; 0.5% Timoptol--pH 6.80 and 1% Pilocarpine--pH 5.87) into the aquired aqueous humor of rabbits (pH 7.59) and human (pH 7.11 +/- 0.11). After their instillation pH of the aqueous humor immediately decreased towards acid levels. The pH changes after Timoptol, Xalatan and Pilocarpine showed a similar time pattern and after return to the baseline values the pH shifted to alkaline levels. In case of Trusopt instillation the pH value reached the baseline of the aqueous humor after 240 min. Almost no pH changes were recorded from 240 min up to 24 hours after all tested antiglaucomatics. From the wiev on the speed of activity and effectivity depending on time required to reach the initial pH value of the aqueous humor we to make this order: Pilocarpine>Timoptol>Xalatan>Trusopt. Comparing our results the effect of antiglaucomatics is connected with different composition and also with shift of the aqueous humor pH towards slightly alkaline level (similar effect in rabbits and human). Results presented in this work are theoretical but also practical contribution to the treatment of glaucoma. (Fig. 1, Ref. 38.).