Sensitive Analysis of Idarubicin in Human Urine and Plasma by Liquid Chromatography with Fluorescence Detection: An Application in Drug Monitoring.

A new approach for the sensitive, robust and rapid determination of idarubicin (IDA) in human plasma and urine samples based on liquid chromatography with fluorescence detection (LC-FL) was developed. Satisfactory chromatographic separation of the analyte after solid-phase extraction (SPE) was performed on a Discovery HS C18 analytical column using a mixture of acetonitrile and 0.1% formic acid in water as the mobile phase in isocratic mode. IDA and daunorubicin hydrochloride used as an internal standard (I.S.) were monitored at the excitation and emission wavelengths of 487 and 547 nm, respectively. The method was validated according to the FDA and ICH guidelines. The linearity was confirmed in the range of 0.1-50 ng/mL and 0.25-200 ng/mL, while the limit of detection (LOD) was 0.05 and 0.125 ng/mL in plasma and urine samples, respectively. The developed LC-FL method was successfully applied for drug determinations in human plasma and urine after oral administration of IDA at a dose of 10 mg to a patient with highly advanced alveolar rhabdomyosarcoma (RMA). Moreover, the potential exposure to IDA present in both fluids for healthcare workers and the caregivers of patients has been evaluated. The present LC-FL method can be a useful tool in pharmacokinetic and clinical investigations, in the monitoring of chemotherapy containing IDA, as well as for sensitive and reliable IDA quantitation in biological fluids.

Determination of idarubicin in human urine by capillary zone electrophoresis with amperometric detection.

A simple, reliable and reproducible method, based on capillary zone electrophoresis with amperometric detection, has been developed for the determination of idarubicin in human urine. A carbon disk electrode was used as working electrode. The optimal conditions of separation and detection were pH 5.6 phosphate buffer (0.20 mol/L), 22 kV for the separation voltage and 1.00 V (vs. Ag/AgCl, 3 mol/L KCl) for the detection potential. The linear range was from 4.0 x 10(-7) to 2.0 x 10(-5) mol/L with a regression coefficient of 0.9986, and the detection limit was 8.0 x 10(-8) mol/L. The method was directly applied to the determination of idarubicin in spiked human urine without any other sample pretreatment except filtration, and the assay results were satisfactory.

High-performance liquid chromatographic analysis of idarubicin and fluorescent metabolites in biological fluids.

A specific, sensitive, and reliable high-performance liquid chromatographic (HPLC) method for the determination of idarubicin (IDA) and its known fluorescent metabolites idarubicinol (IDAol) and 4-demethoxy-daunomycinone (AG1) in biological fluids (human plasma and urine) was developed and tested. Plasma samples were solid-phase-extracted (C18 bonded silica cartridges). Complete separation of unchanged drugs and metabolites was achieved on a Cyanopropyl chromatographic column (25 cm x 4.6 mm inside diameter; particle size, 5 microns) using fluorescence detection (excitation wavelength, 470 nm; emission wavelength, 580 nm). Sensitivity was better than 0.2 ng/ml for all analytes; rates of recovery of unchanged drug and metabolites were better than 84.5% (IDA), 80.3% (IDAol), and 83.9% (AG1). The interassay coefficient of variation was 6.5% for IDA, 5.8% for IDAol, and 9.8% for AG1. Mean intra-assay precision was 4.6% for IDA, 5.9% for IDAol, and 5.0% for AG1 at sample concentrations of above 1 ng/ml and 12.1% for IDA, 10.8% for IDAol, and 14.1% for AG1 at sample concentrations of below 1 ng/ml.

Stereoselectivity of idarubicin reduction in various animal species and humans.

1. The (13S)-dihydro derivative of idarubicin, (13S)-idarubicinol, is the major urinary metabolite of idarubicin in humans. Idarubicinol epimers were quantified by h.p.l.c. in urine from rats, mice, rabbits, dogs and man after i.v. administration of idarubicin, and in man after oral dosing. The (13R)- and (13S)-epimers of idarubicinol were determined in rat bile. 2. After i.v. injection of idarubicin. (13R)-idarubicinol was not detectable in mice and rabbit urine and no more than 0.5% of the dose was present in the urine of other species. In man, the proportion of (13R)-idarubicinol in total idarubicinol was similar after i.v. (4.1%) and oral (3.8-5.0%) administration of idarubicin; the same applies to rat bile and urine. 3. Reduction of idarubicin in vivo is dependent upon ketone reductases, and proceeds more stereoselectively than that of most ketones giving rise to the (13S)-epimer almost exclusively. The high stereospecificity in idarubicin reduction might result from chiral induction due to the presence of asymmetric centres near to the carbonyl group in idarubicin.

Hepatobiliary metabolism and urinary excretion of 4-demethoxydaunorubicin as compared to daunorubicin in rats.

The hepatic metabolism and biliary excretion of 4-demethoxydaunorubicin (4DDM) was studied in Crl: CD(SD) BR rats by the liver perfusion technique. In the same strains of rats urinary excretion was investigated in vivo. Daunorubicin (DM) was always included for comparison. The drugs and their metabolites were determined in the perfusion medium, in the bile and liver and in the urine by high-performance liquid chromatography with fluorimetric detection. Compared to its analogue DM, 4DDM markedly differed in the metabolic and excretory profile. The cumulative biliary and urinary excretion of 4DDM and the metabolites was quantitatively lower than that of DM (18% vs 36% of the dose) and was consistent with prolonged persistence of 4DDM in plasma in vivo. The extensive carbonyl reduction of 4DDM and DM observed in previous in vivo pharmacokinetic studies was also evident in this study. 13-hydroxy metabolites, daunorubicinol (DMol) and 4-demethoxydaunorubicinol (4DDMol), either as such or after glycosidic cleavage, i.e. 4DDMol aglycone, were present in appreciable amounts in the perfusion medium, bile, liver and urine. In the hepatobiliary system, however, the 13-hydroxy derivative of DM amounted to a much lower fraction than the DM aglycone (17% vs 50% of the total dose), 80% of the total 4DDM dose was accounted for by 4DDMol aglycone. In urine uncleaved DMol or 4DDMol represented more than 75% of the total amount excreted for both drugs. Conjugation, a major step in the excretion of aglycones, seems to play a minor role in the biliary and urinary excretion of 4DDM and 4DDMol.