Rapid liquid chromatographic assay for the determination of amiodarone and its N-deethyl metabolite in plasma, urine, and bile

Article abstract of DOI:10.1002/jps.2600740418

A rapid high-performance liquid chromatographic assay was developed for the determination of amiodarone (1) and its N-deethyl metabolite (desethylamiodarone, 2) in plasma, urine, and bile. Analysis was performed on a C₁₈ reversed-phase column and precolumn using a mobile phase consisting of methanol:water:58% ammonium hydroxide (94:4:2) delivered at a flow rate of 1.5 mL/min. The eluant was monitored at 244 nm. Under these conditions, 1, 2, and the internal standard eluted with retention times of 5.5, 4.6, and 6.8 min, respectively. Samples (100 μL) of plasma were prepared by precipitating the plasma proteins with acetonitrile containing the internal standard and injecting an aliquot of the supernatant directly onto the column. Samples (100 μL) of urine and bile were prepared for injection by acidifying the sample with concentrated HCl and then extracting the mixture with six volumes of 2,2-dimethoxyproprane. The recovery of 1 and 2 from plasma was virtually complete. The recovery from urine and bile was 80-90% for 1 and 60-65% for 2. The limit of sensitivity of both compounds in plasma was 100 ng/mL. For urine and bile, the detection limits were 1 and 5 μg/mL, respectively. Over the plasma concentration range of 0.1-10.0 μg/mL, the within-day CV ranged from 1 to 10% for 1 and from 1 to 8% for 2. The between-day CV ranged from 2 to 12% and from 1 to 17% for 1 and 2, respectively. Of 44 drugs tested for potential assay interference, four interfered with the determination of 2 and one with the analysis of 1. The assay has been used for pharmacokinetic studies in rats and routine monitoring of concentrations of 1 and 2 in human plasma.