Amiloride: biological fluid analysis by reverse-phase HPLC

Amiloride is an effective anti-kaliuretic-diuretic which has been used clinically since 1965. Because of a lack of sensitivity in reported analytical methods, useful pharmacokinetic data have been sparse. This publication describes a sensitive (1 ng/ml), rapid, and reproducible reverse-phase HPLC technique for the quantitative measurement of amiloride levels in both serum and urine specimens. Sample clean-up is based on the adsorption of amiloride to commercially available silica cartridges and its selective elution with perchloric acid. The eluted drug is further resolved from endogenous interferences on a Waters' C-18 µBondapak analytical column with a mobile phase consisting of methanol:sodium perchlorate (0.1 M, pH 4.0) 40:60 v/v and fluorescence detection (λex = 368 nm, λem = 417 nm). This method has been applied to the analysis of human serum and urine samples.