Dioxopromethazine and phenylephrine were determined simultaneously in eye drops using the method of capillary isotachophoresis. Two elektrolyte systems with different compositions and pH were examinated. Prior to analysis, the eye drops are diluted with water in a ratio 1:50. Precision, correctness, linearity, robustness, and selectivity of the ITP method were evaluated for both electrolyte sytems.

        Key words: isotachophoresis – dioxopromethazine – phenylephrine – eye drops – validation