MEASUREMENT OF AMILORIDE IN AIRWAY SURFACE LIQUID UTILIZING HPLC AND FLUORESCENCE DETECTION

A high-performance liquid chromatographic method for the determination of amiloride in airway surface liquid is described. It involves extra ction of the drug with methanol from filter paper on which the sample is absorbed and chromatography on a Zorbax Rx column; the mobile phase is 25% acetonitrile in 0.05 M phosphate buffer; detection by fluoresc ence at 360/420 nm. Triamterene is used as an internal standard. The r ange of the assay is 2.0-2033.4 ng/sample, with adequate precision and accuracy. A power curve y = ax(b) best describes the relationship bet ween the peak-height ratio and concentration. Recovery of amiloride is non-linear, probably due to an adsorption process. Accuracy of the as say at lower amounts may be affected by the choice of filter paper a w ell as by presence of endogenous plasma components. The assay was used to measure amiloride amount in airway surface liquid after administra tion of 2.5 and 4.5 mg of nebulized amiloride.