Rapid high-performance liquid chromatographic assay for the anthracyclines daunorubicin and 7-con-O-methylnogarol in plasma

Analysis of daunorubicin and its metabolite daunorubicinol in plasma and urine with application in the evaluation of total, renal and metabolic formation clearances in patients with acute myeloid leukemia

This report presents improved analysis methods of daunorubicin (DAUN) and its metabolite daunorubicinol (DAUNOL) in small volumes of plasma, as total and unbound concentrations, as well as in urine. This study also presents the pharmacokinetics of DAUN and DAUNOL in patients (n = 12) diagnosed with acute myeloid leukemia treated with intravenous DAUN (60 mg/m²/day, for three days). Serial blood and urine samples were collected up to 144 h after the beginning of the first infusion. The analytical methods presented no significant matrix effect. The linear ranges were 0.1-1000 ng/mL in plasma, 0.05-40 ng/mL in ultrafiltrate and 0.5-3000 ng/ml in urine. The precision and accuracy presented coefficients of variation and standard errors lower than 15 % in the three matrices. The methods allowed for the quantification of samples up to 144 h after the beginning of the first infusion. Unbound fractions for DAUN and DAUNOL were 23.91 % (17.33-32.99) and 29.23 % (25.84-33.07), respectively. The fraction recovered in urine was 4.40 % (3.87-5.03) for DAUN and 7.91 % (6.86-9.19) for DAUNOL. Total 292.96 L/h (261.74-327.90), renal 13.01 L/h (11.44-14.88), and hepatic 280.26 L/h (248.40-317.91) clearances of DAUN, as well as the DAUNOL formation clearance 23.41 L/h (19.09-28.97), were evaluated.

Method for Analysis, and Distribution Profile, of Covalently-linked Ferritin-daunorubicin Conjugate in the Blood of Trypanosome-infected Mice

Daunorubicin is a highly potent trypanocide in-vitro but is inactive in-vivo. When daunorubicin is conjugated to bovine serum albumin or horse spleen ferritin using Schiffs base linkages, the complex is trypanocidal in-vitro and in-vivo. We have developed novel analytical methods, using HPLC with fluorimetric detection, for the quantitation of daunorubicin and doxorubicin in biological samples, either as unconjugated drug, or when covalently linked to macromolecules or particles. Ferritin-daunorubicin conjugate (25 mg kg−1) was administered intraperitoneally to mice infected with monomorphic Trypanosoma brucei rhodesiense; peak plasma levels occurred after 1·5 h, and were 5 times higher than those resulting from administration of an equivalent amount of unconjugated daunorubicin. Plasma levels then declined rapidly (t½ for 1–6 h period was 0·58 and 0·86 h respectively for conjugated and unconjugated daunorubicin). However, higher plasma levels were seen 24 h after treatment, suggesting the distribution profile of daunorubicin when conjugated to ferritin is multiphasic with resultant high levels of daunorubicin obtained for a prolonged time period.

High-performance liquid chromatographic methods for the determination of topoisomerase II inhibitors

Various methods for separating eleven different types of topoisomerase II (TOPO-2) inhibitors, including epipodophyllotoxins, anthracyclines, anthracenediones, anthrapyrazoles, anthracenebishydrazones, indole derivatives, aminoacridines, benzisoquinolinediones, isoflavones, bisdioxopiperazines and thiobarbituric acids, are summarized. Proper sample preparation and storage is critical to the successful analysis of some TOPO-2 inhibitors due to difficulties associated with adsorption, instability and complex biological components. Solid-phase and liquid-liquid extractions are widely used to separate TOPO-2 inhibitors from biological samples, although simple deproteinization followed by direct analysis of the supernatant is preferable to extraction based on its speed and simplicity. High-performance liquid chromatography (HPLC) is the favored method for the bioanalysis of TOPO-2 inhibitors. UV or diode array detection is generally employed for early pharmacokinetic studies, while fluorescence or electrochemical detection is used more frequently for analytes with fluorescent or oxidative-reductive properties. For analyses requiring highly sensitive and/or specific detection, electrospray mass spectrometry (ESI-MS or ESI-MS-MS) provides a suitable alternative. A comprehensive compilation of the HPLC techniques currently used to separate TOPO-2 inhibitors will aid the future development of analytical methods for new TOPO-2 inhibitors.

Simultaneous determination of epirubicin, doxorubicin and their principal metabolites in human plasma by high-performance liquid chromatography and electrochemical detection

A high-performance liquid chromatographic method with electrochemical detection has been developed for the simultaneous determination of epirubicin, 13-S-dihydroepirubicin, doxorubicin and 13-S-dihydrodoxorubicin in human plasma. An aliquot of 200 microl plasma, spiked with internal standard, was extracted by solid-phase extraction using polymeric adsorbent columns. Chromatography was performed using a C18 reversed-phase column with a mobile phase consisting of water-acetonitrile (71:29, v/v) containing 0.05 M Na2HPO4 and 0.05% v/v triethylamine adjusted to pH 4.6 with citric acid. Linearity of the method was obtained in the concentration range of 1-500 ng/ml for all the analytes. Analytical recoveries of the analytes ranged from 89 to 93%. The assay can be used for the simultaneous determination of the four analytes, or for epirubicin and its metabolite or doxorubicin and its metabolite, using the other parent drug as an internal standard. The method was applied to analyze human plasma samples from patients treated with epirubicin using doxorubicin as an internal standard.

Optimised separation of E- and Z- isomers of tamoxifen, and its principal metabolites using reversed-phase high performance liquid chromatography

A reversed phase isocratic high-performance liquid chromatographic method is reported in which a formal structured procedure, the solvent selectivity triangle, was applied to predict the mobile phase composition giving baseline resolution of the clinically important triphenylethylene antioestrogenic agent (Z)-tamoxifen, its principal (Z)-metabolites, and also the clinically relevant (E)-geometric isomers of tamoxifen and 4-hydroxytamoxifen. The technique of solvent selectivity triangle was used to select the optimal organic modifier parameter for use with a Hichrom ODS 1 column, to achieve baseline separation of six triphenylethylene solutes. The detection system utilised post-column ultraviolet irradiation to convert solutes into their respective photocyclisation products, followed by fluorescence detection (lambda[ex] = 254 nm, lambda[em] = 360 nm), and the low detection limit for tamoxifen in serum of 0.1 microM. The optimal mobile phase composition was determined to be methanol-acetonitrile-water-trichloroacetic acid (50:31:18.9:0.1, v/v, pH 2.9). A single stage liquid-liquid extraction method for determination of triphenylethylene drugs in serum was developed. Reproducible recoveries for the (Z)-geometric isomers of tamoxifen (84 +/- 3%) and its principal metabolites including Metabolite Y (94 +/- 3%), N-desmethyltamoxifen (94 +/- 3%) and 4-hydroxytamoxifen (92 +/- 3%) were achieved, though more variable results were obtained for their corresponding (E)-geometric isomers (71 +/- 7% and 70 +/- 10%, respectively).

Determination of plasma concentrations of epirubicin and its metabolites by high-performance liquid chromatography during a 96-h infusion in cancer chemotherapy

In order to determine epirubicin and its metabolites at low concentrations (< 38 ng/ml) in small plasma samples, a fast reliable method based on a precipitation pre-treatment and sensitive reversed-phase isocratic HPLC has been developed and validated for epirubicin in the range 5-100 ng/ml. The R.S.D. was 5-9% over this concentration range. For human serum containing 25 ng/ml of epirubicin, the inter- and intra-day variation was < 10%. Recoveries of the metabolites epirubicinol, 7-deoxydoxorubicinone and 7-deoxydoxorubicinolone at 20 ng/ml ranged from 94-104%. The assay has been used to study human plasma samples taken during a 96-h infusion of epirubicin in a patient with multiple myeloma. The combined levels of the unseparated metabolites, epirubicin glucuronide and epirubicinol glucuronide, were semiquantitatively determined after treatment with beta-glucuronidase. The metabolites epirubicinol and 7-deoxydoxorubicinolone, but not 7-deoxydoxorubicinone, were also detected and measured.

Solid-phase extraction and optimized separation of doxorubicin, epirubicin and their metabolites using reversed-phase high-performance liquid chromatography

A reversed-phase isocratic high-performance liquid chromatographic method is described in which a formal structured procedure was applied to predict the mobile phase composition giving optimal baseline resolution of the clinically important anticancer agents doxorubicin and 4'-epidoxorubicin (epirubicin), their principal metabolites, and daunorubicin (internal standard). These formal statistical procedures included the simultaneous techniques of solvent selectivity triangle and factorial design for range-finding preliminary studies, followed by use of the modified simplex, a sequential procedure. These were used to select the parameters of organic modifier, buffer strength and pH necessary for use with a Spherisorb ODS 1 column, to achieve optimal separation of eight anthracycline solutes. Ultraviolet and fluorescence detection was used (lambda ex = 254 nm, lambda em = 560 nm), and the latter gave a low detection limit for doxorubicin in serum of 1 ng ml-1. The optimal mobile phase composition was determined to be acetonitrile-0.06 M Na2 HPO4 containing 0.05% (v/v) triethylamine adjusted to pH 4.6 with 0.03 M citric acid (35:65, v/v). A solid-phase extraction method was developed to enable the selective isolation of anthracyclines by adsorption onto C8 Bond-Elut cartridges, and is based on extraction of serum spiked with a mixture of the anthracycline solutes. The anthracyclines were eluted using acetonitrile-0.2 M Na2 HPO4 containing 0.05% (v/v) triethylamine adjusted to pH 3.6 with 0.1 M citric acid (67.5:32.5, v/v). Reproducible recoveries for doxorubicin (94 +/- 8%) and for epirubicin (96 +/- 8%) were obtained (n = 5). In particular, recoveries for the 7-deoxyaglycone metabolite (99%) were higher than other extraction methods cited.(ABSTRACT TRUNCATED AT 250 WORDS)

A sensitive and reproducible HPLC assay for doxorubicin and pirarubicin

A high-performance liquid chromatographic method with spectrofluorometric detection has been developed for the analysis of doxorubicin (DOX), pirarubicin (PIRA) and their metabolite, doxorubicinol, in plasma. The detection was performed at 480 nm for excitation, and 590 nm for emission. The proposed technique is selective, reliable, and sensitive. The limit of quantification was 2 ng ml-1 for DOX and 5 ng ml-1 for PIRA. The reproducibility of the analytical method through statistical coefficients is approximately 5%. The accuracy of the method is good; the relative error is less than 5%.

High performance liquid chromatography determination of doxorubicin and daunorubicin in plasma using UV detection and column switching

A method for the determination of doxorubicin and daunorubicin in plasma is described. The plasma is injected directly into a loop column and then washed with water. After switching the injection valve, the sample is separated on a phenyl column using detection at 254 nm. The detection limit is 10 ng/mL, the coefficient of variation is 7% for 100 ng/mL of doxorubicin and 4% for 200 ng/mL of daunorubicin.

Anthracycline antitumour agents. A review of physicochemical, analytical and stability properties

A review of physicochemical and analytical properties of anthracycline antitumour agents is presented. The following subjects are discussed: protolytic equilibria, partition and partition coefficients, self-association, adsorptive properties, metal complexation, spectroscopy and chromatography. Furthermore, the stability of anthracyclines in solutions, in pharmaceutical preparations and in biological media is discussed.

Comparative pharmacokinetics and metabolism of doxorubicin and 4-demethoxy-4'-O-methyldoxorubicin in tumor-bearing mice

It has been reported that 4-demethoxy-4'-O-methyldoxorubicin (4-dm-4'-O-methylDX) is more potent than doxorubicin (DX), equally active in some murine leukemias and solid tumors, and almost devoid of cardiotoxicity. We used HPLC to investigate the metabolism and the disposition of this drug in comparison with DX in mice bearing colon 38 adenocarcinoma SC and treated with IV doses of the two drugs that were equiactive and equitoxic (4-dm-4'-O-methylDX 1 mg/kg; DX 10 mg/kg). 4-Dm-4'-O-methylDX was metabolized to a polar metabolite, presumably 4-demethoxyDX, which was eliminated more slowly than the parent drug from all the organs and accounted for 25%-50% of total fluorescence; traces of two metabolites less polar than the parent drug (2% of total fluorescence) were found only at early times in the liver. In DX-treated mice traces of doxorubicinol (1%-3% of total fluorescence) were found in tumor and organs, and two aglycones were detected only at early times in the liver. In plasma both drugs declined biexponentially and 4-dm-4'-O-methylDX was eliminated slightly faster than DX. The rate of elimination of the new analogue from lung, kidney, spleen, and small intestine was faster than that of DX; in heart and liver 4-dm-4'-O-methylDX was detectable for only up to 24 h, while DX was detectable for up to 7 days. In the tumor the kinetics and the elimination patterns of the two drugs were similar. The distribution of 4-dm-4'-O-methylDX, as a percentage of the administered dose, was 1.3-2 times higher than that of DX in the organs and 3 times higher in the tumor, which suggests an improved selectivity of the new analogue for the tumor compared with DX.

Drug level monitoring: cytostatics

The present review on the quantification of cytostatic drugs has mainly been focussed on chromatographic techniques. Special attention has been paid to the precautions that have to be taken into account to ensure the selectivity and accuracy of the various methods. The various cytostatics that have been dealt with are: alkylating agents, antimetabolites, vinca alkaloids, antibiotics, cis-diamminedichloroplatinum, podophyllotoxine derivatives, and nitrosoureas.

Quantitation of daunorubicin and its metabolites by high-performance liquid chromatography with electrochemical detection

A selective and sensitive high-performance liquid chromatographic method was developed for the separation and quantitation of daunorubicin and its metabolites in serum, plasma, and other biological fluids. Daunorubicin and metabolites in human plasma were injected directly into the high-performance liquid chromatography system via a loop-column to pre-extract the drugs from the plasma, and quantitated against a multilevel calibration curve with adriamycin as the internal standard. The column effluent was monitored with an electrochemical detector at an applied oxidative potential of 0.65 V and by fluorescence. Daunorubicin and four metabolites were separated and characterized by this method. In a blinded evaluation of accuracy and precision, the mean coefficients of variation were 3.8, 3.6 and 9.8% at concentrations of 150, 75 and 15 ng/ml, respectively, and blank samples gave negligible readings. The amperometric sensitivity was greater than achieved by fluorescence detection, and offers an alternative method for quantitation of these compounds. The new method has a limit of detection of less than 2 ng on column, allowing quantitation of less than 10 ng/ml in plasma samples without organic extraction prior to chromatographic analysis.

Distribution of daunorubicin, a potent in vitro trypanocide which lacks in vivo activity, in the blood of trypanosome-infected mice

Daunorubicin is a highly potent trypanocide in vitro but lacks significant in vivo activity. Distribution in the drug in the blood components and in trypanosomes from mice infected with Trypanosoma rhodesiense was therefore examined. Drug is accumulated in the trypanosomes in a similar manner to, but to a greater extent than, its accumulation in platelets; it is, however, taken up by erythrocytes to a much smaller extent, Drug concentrations in trypanosomes, platelets and erythrocytes declined with its decline in plasma whereas in white blood cells the drug was retained at a constant level. Daunorubicin concentrations in plasma were several orders of magnitude higher than in vitro trypanocidal concentration. Fluorescence microscopy showed that although daunorubicin reaches the trypanosome nucleus, its concentration decreases rapidly so that adequate levels of drug may not be sustained in the bloodstream form of the organism for a sufficient length of time to give a trypanocidal effect in vivo.