Simple and rapid high-performance liquid chromatographic assay for esmolol.

A procedure for determining esmolol concentrations in blood is described. Dichloromethane was used to extract esmolol from the blood and to inhibit the activity of blood esterases. Blood esmolol concentrations were determined by high-performance liquid chromatography using 3-methoxy-O-demethylencainide as the internal standard. The limit of detection of this assay was 5 ng/ml. The relationship between the peak-height ratio of esmolol and the internal standard was linear in the concentration ranges 10-30,000 ng/ml. The mean absolute and relative recoveries of esmolol from blood were 84 and 89%, with coefficients of variation less than 3%. This method has been used in our laboratory for pharmacokinetic and pharmacodynamic studies.