Quantification of mitoxantrone in bone marrow by high-performance liquid chromatography with electrochemical detection

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.

Determination of mitoxantrone in mouse whole blood and different tissues by high-performance liquid chromatography

A high-performance liquid chromatographic (HPLC) method was developed for the specific determination of mitoxantrone (MTO) in whole blood and different tissues of mice (liver, heart, spleen, kidneys). MTO was extracted into dichloromethane with ametantrone (AMT) as internal standard. The different tissues were homogenised in citrate buffer (pH 3.0) containing 20% ascorbic acid. Separation of MTO and AMT was carried out using a Nucleosil C18 column. The mobile phase consisted of acetonitrile (33%) and 0.16 M ammonium formate buffer, pH 2.7. UV detection was used at 658 nm. Baseline separation of AMT and MTO was achieved in all matrices. The calibration curves were linear in all matrices (r > 0.999) in the concentration range of 2-200 micrograms/l for whole blood and 2-700 micrograms/l for tissue homogenates, respectively. The within-day and between-day precision studies showed good reproducibility with coefficients of variation below 4.5% for whole blood and below 10% for tissue homogenates, respectively. The extraction efficiencies of MTO are 60% in whole blood and 38% in tissue homogenates. The method described is suitable for pharmacokinetic studies on the distribution of MTO in different tissues of mice.

Local hyperthermic treatment does not enhance mitoxantrone effectiveness for responses of a rat solid tumour regrowing after irradiation

Tumours regrowing after irradiation may respond differently to chemo-hyperthermia as compared to non- irradiated tumours. In this study, the efficacy of combined treatment of previously irradiated tumors with mitoxantrone and local hyperthermia (HT) was investigated. Rat R-1 tumours were irradiated with dose fractions of 5Gy X-rays applied on 4 consecutive days. Animals were retreated with mitoxantrone (5mg/kg i.p.), HT (1 h at 43 degrees C) or mitoxantrone + HT (3-h interval) on day 9 after the start of irradiation when tumour volumes were decreasing, or on day 16 when tumour volumes were increasing again. Pharmacokinetics were studied in relation to tumor cell survival and tumour growth delay. No Ht=induced changes in the pharmacokinetics of mitoxantrone were observed. The data on clonogenic survival correlated well with these findings and combined treatment were not more effective than mitoxantrone alone. In the treatment schedule applied, HT did not induce pharmacokinetic changes in irradiated tumours leading to an enhanced cytotoxicity of mitoxantrone. The HT- enhanced effectiveness of the drug observed in non- irradiated tumours is much less in pre-irradiated tumours. Responses of regrowing tumours to combined chemo- hyperthermia depend in a complex way on the stage of regrowth and on the treatment schedule.

Direct determination of mitoxantrone in plasma by high performance liquid chromatography using an automatic precolumn-switching system as sample clean-up procedure

A high-performance liquid chromatography method which uses direct injection and a column-switching valve for determination of mitoxantrone in plasma is described. After addition of internal standard, plasma was deproteinized by adding 5-sulphosalicylic acid reagent. The supernatant was injected onto an enrichment precolumn flushed with washing solvent (methanol and water 5:95). Absorbed mitoxantrone was backflushed from the precolumn into an analytical column C18 Nucleosil 250 x 4 mm with a gradient elution (solvent A, ammonium formate buffer 1.6 M, pH 4.3; solvent B, acetonitrile and water 40:60; linear gradient from 45 to 55% of B for 30 min was programmed) at a flow rate of 1.3 mL/min. Detection was carried out at 665 nm. This method showed obvious advantages over conventional extraction procedures in terms of speed and facility of sample handling.