Measurement of 4-hydroxycyclophosphamide in serum by reversed-phase high-performance liquid chromatography

A review of bioanalytical methods for chronic lymphocytic leukemia drugs and metabolites in biological matrices

Quantitation of drugs used for the treatment of chronic lymphocytic leukemia in various biological matrices during both pre-clinical and clinical developments is very important, often in routine therapeutic drug monitoring. The first developed methods for quantitation were traditionally done on LC in combination with either UV or fluorescence detection. However, the emergence of LC with mass spectrometry in tandem in early 1990s has revolutionized the quantitation as it has provided better sensitivity and selectivity within a shorter run time; therefore it has become the choice of method for the analysis of various drugs. In this article, an overview of various bioanalytical methods (HPLC or LC-MS/MS) for the quantification of drugs for the treatment of chronic lymphocytic leukemia, along with applicability of these methods, is given.

Simultaneous analysis of cyclophosphamide, doxorubicin and doxorubicinol by liquid chromatography coupled to tandem mass spectrometry

A method for the simultaneous determination of cyclophosphamide (CP), doxorubicin (dox), and doxorubicinol (dol) was developed and validated to analyze 400 microL of plasma from patients receiving chemotherapeutic treatment with CP and dox. Final calibration ranges for the analytes were 0.440-60.0 microg/mL for cyclophosphamide, 7.20-984 ng/mL for dox and 3.04-104 ng/mL for dol. The samples were prepared using solid phase extraction and analyzed using a gradient separation over a Waters Symmetry C18, 2.1 by 30 mm (Milford, MA) column. Detection was achieved in positive mixed reaction monitoring mode on a triple quadrupole mass spectrometer.

Simple method based on fluorescent detection for the determination of 4-hydroxycyclophosphamide in plasma

Cyclophosphamide is a prodrug used both as a single drug and in combination chemotherapy. Cyclophosphamide is converted to its active metabolite (4-hydroxycyclophosphamide) by the cytochrome P450 enzymes. A liquid chromatography method including liquid-liquid extraction and protein precipitation in one step was developed to measure 4-hydroxycyclophosphamide in plasma. The 4-hydroxycyclophosphamide was stabilized and converted to a fluorescent dansylhydrazone derivative, which was chromatographed on a reverse-phase column and detected using a spectrofluorometric detector at excitation of 350 nm and emission of 550 nm. The limit of quantitation was 60 ng/mL and the between-day accuracy and precision were less than 9%. The method was applied to the analysis of plasma from patients who had received an intravenous infusion of 1 g/m(2) cyclophosphamide.

Separation methods for alkylating antineoplastic compounds

The separating method for alkylating neoplastic compounds were reviewed based on the classification of the Merck Index (12th Edition). Each section, whenever available or relevant, was subdivided according to the following approach: stability studies, extraction methods, gas chromatography, high-performance liquid chromatography and capillary electrophoresis. At the end of each chapter a separate table summarizing the main characteristics of the separating method were established. In particular LODs and/or LOQs were expressed as quantity to facilitate comparison between methods. This review highlights the problems to measure trace levels of these compounds into biological fluids with respect to their instability, adsorption to glass and plastic or derivatization requirements. Over the last decades, HPLC seems to be more popular than GC for separating the alkylating agents. The development of narrow- or microbore LC coupled to MS is certainly the way to further improve both separation and sensitivity obtained in the different papers surveyed for this review.

Cyclophosphamide and related anticancer drugs

This article presents an overview of the methods of bioanalysis of oxazaphosphorines, in particular, cyclophosphamide, ifosfamide, and trofosfamide as well as their metabolites. The metabolism of oxazaphosphorines is complex and leads to a large variety of metabolites and therefore the spectrum of methods used is relatively broad. The various methods used are shown in a table and the particularly important assays are described.

Simple and selective determination of the cyclophosphamide metabolite phosphoramide mustard in human plasma using high-performance liquid chromatography

A simple and selective assay for the determination of the alkylating cyclophosphamide metabolite phosphoramide mustard (PM) in plasma was developed and validated. PM was determined after derivatisation by high-performance liquid chromatography (HPLC) with ultraviolet detection at 276 nm. Sample pre-treatment consisted of derivatisation of PM with diethyldithiocarbamate (DDTC) at 70 degrees C for 10 min, followed by extraction with acetonitrile in the presence of 0.7 M sodium chloride. Phase separation occurred due to the high salt content of the aqueous phase. The HPLC system consisted of a C8 column with acetonitrile-0.025 M potassium phosphate buffer, pH 8.0, (32:68, v/v) as the mobile phase. The entire sample handling procedure, from collection at the clinical ward until analysis in the laboratory, was optimised and validated. Calibration curves were linear from 50 to 10,000 ng/ml. The lower limit of quantification and the limit of detection (using a signal-to-noise ratio of 3) were 50 and 40 ng/ml, respectively, using 500 microl of plasma. Within-day and between-day precisions were below 11% over the entire concentration range and the accuracies were between 100 and 106%. PM was found to be stable at -30 degrees C for at least 10 weeks both in plasma and as a DDTC-derivative in a dry sample. A pharmacokinetic pilot study in two patients receiving 1,000 mg/m2 CP in a 1-h infusion demonstrated the applicability of the assay.

Pharmacokinetics of cyclophosphamide (CP) and 4-OH-CP/aldophosphamide in systemic vasculitis

Cyclophosphamide given in association with corticosteroids has markedly improved the prognosis of systemic vasculitis. Little information has been reported on cyclophosphamide pharmacokinetics in these diseases and data evaluating its metabolite, 4-hydroxycyclophosphamide/aldophosphamide, pharmacokinetics and concentrations are lacking. Cyclophosphamide was administered as a 1-h intravenous infusion every 3 weeks for six cycles to ten vasculitis patients. Serum cyclophosphamide and 4-hydroxycyclophosphamide/aldophosphamide concentrations were assayed on the first cycle of the treatment by reversed-phase high-pressure liquid chromatography with ultraviolet detection. The mean (+/- SD) 4-hydroxycyclophosphamide/aldophosphamide and cyclophosphamide areas under the serum concentration-time curves were, respectively, 1.86 +/- 1.12 and 154.1 +/- 62.7 mg/L x h with a ratio of 1.30 +/- 0.76%. The mean maximum serum 4-hydroxycyclophosphamide/aldophosphamide was reached 2.3 h after cyclophosphamide administration. The mean (+/- SD) cyclophosphamide and 4-hydroxycyclophosphamide/aldophosphamide half-lives were, respectively, 5.5 +/- 3.1 and 7.6 +/- 2.3 h. The results are consistent with those obtained for cancer patients, in spite of a wide interpatient variability of concentrations and pharmacokinetic parameters.

Determination of cyclophosphamide and its metabolites in human plasma by high-performance liquid chromatography-mass spectrometry

A sensitive HPLC-MS method was developed for the simultaneous determination of cyclophosphamide and its metabolites 4-hydroxycyclophosphamide (aldocyclophosphamide), 4-ketocyclophosphamide, caboxyphosphamide and 3-dechloroethylifosfamide in human plasma. 4-Hydroxycyclophosphamide was converted with methylhydroxylamine to the stable methyloxime form. We used a solid-phase extraction with C18 cartridges followed by HPLC-MS with the single mass spectrometer SSQ 7000 of Finnigan. The limits of detection were 15 ng/ml for cyclophosphamide, 3-dechloroethylifosfamide and ketocyclophosphamide in each case and 30 ng/ml for carboxyphosphamide and 4-hydroxycyclophosphamide, respectively. First results of pharmacokinetics are shown.

High-performance liquid chromatographic determination of stabilized 4-hydroxyifosfamide in human plasma and erythrocytes

A method using reversed-phase high-performance liquid chromatography (RP-HPLC) is described for the measurement of the stabilized activated metabolite of ifosfamide, 4-hydroxyifosfamide (4-OHIF), in human plasma and erythrocytes. Immediately after sample collection and plasma-erythrocyte separation at 4 degrees C, 4-OHIF was stabilized by derivatization with semicarbazide (SCZ). The sample pretreatment involved liquid-liquid extraction with ethyl acetate. RP-HPLC was executed with a C8 column and acetonitrile-0.025 M potassium dihydrogenphosphate buffer (pH 7.40)-triethylamine (13.5:86:0.5, v/v) as mobile phase. The analyte was determined with UV detection at 230 nm. Complete validation, optimisation and stability studies were performed and the method proved to be specific, sensitive and with a stable analyte in the range of clinically relevant concentrations (0.1-10 microg/ml) after conventional dosing. The lower limit of quantitation was 100 ng/ml using 1.00 ml of sample. Accuracy was between 94.1 and 107.0%. Within-day and between-day precisions were less than 6.2% and 7.2%, respectively. 4-OHIF-SCZ was found to be stable in the biological matrix at -20 degrees C for at least 1 month. A pharmacokinetic study conducted in a patient receiving 9 g/m2 over 3 days by means of a continuous infusion, demonstrated the applicability of this method.

Quantitation of taurolidine decomposition in polymer solutions by chromotropic acid formaldehyde assay method

A sensitive, selective, and specific assay was needed to study the degradation kinetics of taurolidine and its stabilization by polyvinylpyrrolidone (PVP). The purpose of the present study was to evaluate the usefulness of the chromotropic acid method and other formaldehyde or amine derivatization methods. The methods evaluated included formaldehyde derivatization with chromotropic acid, acetylacetone, 4-amino-5-hydrazino-3-mercapto-1,2,4-triazole, semicarbazide hydrochloride, or 2,4-dinitrophenylhydrazine and taurolidine decomposition product derivatization with dansylchloride or 7-chloro-4-nitrobenz-2-oxa-1,3-diazole chloride. Results indicated that the chromotropic acid method provided sufficient selectivity, reproducibility and sensitivity. It was able to quench taurultam decomposition and avoided PVP interference. The method was optimized by performance based selection of reagent lots, appropriate reagent storage and preparation, and controlled derivatization conditions. In conclusion, the optimized chromotropic method was the most appropriate method for quantitating taurolidine decomposition.