Purpose: To show and underline specific character of influence of the mixture of 10% L-lysine.2HC1.2H2O in 0.005% latanoprost on physiological levels of IOP. Methods: The mixture of 10% L-lysine.2HC1.2H2O in 0.005 % latanoprost (Xalatan), or separately 0.005 % latanoprost and 10% L-lysine.2HC1.2H2O respectively were in weekly intervals instilled into the conjunctival sac of the left eye of five rabbits (females of "New Zealand white" bred). The IOP levels and the size of the pupil were measured in minuté 5, 15, 30, 60, 120, 180, and 240 after the instillation. The right eye was considered as a control. Results: The amino acid L-lysine.2HC1.2H2O by itself did not influence the IOP or the size of the pupil; latanoprost until minuté 30 lowered the IOP, in minuté 55 exceeds the IOP the level of the control eye. Since minuté 60 until 240, the IOP changed irregularly and insignificantly. The mixture of 10% solution of L- lysine.2HC1.2H2O in latanoprost 0.005% insignificantly lowered the IOP until min. 30, after rapid elevation in min. 50 exceeds the IOP of the control eye, and since min. 60, the IOP remains above the control eye's IOP with the samé course oflevels. Summary: The amino acid L-lysine.2HC1.2H2O alone did not change the physiological IOP. Latanoprost 0.005% significantly lowered the IOP until min. 30. High level of interactive specificity as well as duration of influence of the mixture of respective amino acid with respective antiglaucomatic drug was established.

        Key words: influence upon the IOP in rabbits, impact of the mixture of solution of L-lysine.2HC1.2H2O in latanoprost 0.005 % on IOP in rabbits