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

Pharmacokinetics of daunorubicin and daunorubicinol in infants with leukemia treated in the interfant 99 protocol

BACKGROUND

There is an extreme paucity of pharmacokinetic data for anticancer agents in infants. Therefore, we aimed at characterizing the pharmacokinetics for daunorubicin in infants and examined their relationship to age, body weight, and body surface area.

PROCEDURE

Leukemia patients treated according to the Interfant 99 protocol received 30 mg/m(2) daunorubicin, with dose reduction to 3/4 for patients 6-12 months old and 2/3 for patients <6 months, respectively. Plasma samples from 21 patients (aged 0.05-1.88 years) were collected and analyzed for daunorubicin and daunorubicinol. Samples from 12 children (age 1.6-18.8 years), who received daunorubicin in an earlier investigation, were used for pharmacokinetic model building using the software NONMEM.

RESULTS

Plasma concentration time profiles could be described using a two compartment model. Daunorubicin clearance was 43.9 L hr(-1) m(-2) +/- 65% and central volume of distribution 16.4 L m(-2) +/- 46%, whereas apparent clearance of daunorubicinol was 19.1 L hr(-1) m(-2) +/- 32% and apparent volume of distribution 228 L m(-2) +/- 80% (mean +/- interindividual variability). No age-dependency in any of the BSA-normalized pharmacokinetic parameters was observed. Consequently, due to the empirical dose reduction in infants the overall exposure to daunorubicinol in infants was smaller than would be expected from older children. Patients aged <6 months experienced more infections in the induction phase than the group aged 6-12 months at diagnosis. Other toxicities were similar in both groups.

CONCLUSION

We observed no indication of an age-dependency in the pharmacokinetics of daunorubicin. Pediatr Blood Cancer 2010;54:355-360.

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.

Chromatographic analysis of anticancer drugs

The present review on the methods for the analysis of anticancer drugs should be seen as an addition to the excellent work of Eksborg and Ehrsson published half a decade ago in this journal (Vol. 340, p.31). The style and format have been followed closely, with the focus again on chromatographic techniques. We felt it important to add a list of compound (group) structures as a service to the reader. Methods have been reviewed for alkylating agents, platinum compounds, antitumour antibiotics, antimetabolites, alkaloids, suramin, 1-hydroxy-3-amino-propylidene-1,1-bisphosphonate and tamoxifen.

High-performance liquid chromatography of anthracycline antibiotics with electrochemical detection. Application to the clinical pharmacokinetics of 4′-deoxydoxorubicin

The high-performance liquid chromatography with electrochemical detection (HPLC-EC) of six anthracycline antibiotics is described. All the compounds of interest may be analysed using a reversed-phase column (ODS Hypersil or Zorbax ODS) and a mobile phase consisting of acetonitrile-isopropanol-0.1 M phosphate buffer (pH 4.5). The use of short columns (7.5 cm) allowed short analysis times and improved sensitivity, such that detection limits of between 1 and 2 ng ml(-1) could be achieved. Sample preparation involved an alkaline extraction into chloroform, followed by a back extraction into acid solution. Final clean-up of the samples is achieved by shaking the final acidic extract with an organic solvent. The precision of the assay for the compounds studied ranges between 1.22 and 6.46% and the accuracy ranges between 94.5 and 106.0%. The analytical methodology developed is applied to the clinical pharmacokinetics of 4'-deoxydoxorubicin. The correlation between plasma levels found by HPLC-EC and those found by HPLC with fluorescence detection is excellent (r(2) = 0.990).

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 uptake, retention and cytotoxicity of daunorubicin by human myeloid cells

We studied the cellular uptake and retention of daunorubicin (D1) in two human leukemic cell lines (ML1 and K562) and myecloblasts from an untreated patient with acute myelogenous leukemia (AML). The rate of uptake and the steady-state level of D1 were not temperature dependent but increased markedly with increases in the pH of the medium. Also, saturation kinetics were not demonstrable using concentrations of D1 up to 111 microM. Together, these observation suggest a transport mechanism for D1 compatible with passive diffusion. Accumulation of D1 was increased only in cells from the AML patient with addition of sodium azide, whereas drug efflux was not increased significantly in the presence of glucose in MLI or K562 cells. Although the rate of uptake and steady-state levels of D1 were the same in these cells, metabolism and cytotoxicity of D1 differed. Our results indicate that ML1 cells can be used as a pharmacologic model for studying the metabolism and resistance of D1 in vivo.

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.