High-performance liquid chromatographic determination of doxorubicin and its metabolites in plasma and tissue

Advances in targeted therapy for malignant lymphoma

The incidence of lymphoma has gradually increased over previous decades, and it ranks among the ten most prevalent cancers worldwide. With the development of targeted therapeutic strategies, though a subset of lymphoma patients has become curable, the treatment of refractory and relapsed diseases remains challenging. Many efforts have been made to explore new targets and to develop corresponding therapies. In addition to novel antibodies targeting surface antigens and small molecular inhibitors targeting oncogenic signaling pathways and tumor suppressors, immune checkpoint inhibitors and chimeric antigen receptor T-cells have been rapidly developed to target the tumor microenvironment. Although these targeted agents have shown great success in treating lymphoma patients, adverse events should be noted. The selection of the most suitable candidates, optimal dosage, and effective combinations warrant further investigation. In this review, we systematically outlined the advances in targeted therapy for malignant lymphoma, providing a clinical rationale for mechanism-based lymphoma treatment in the era of precision medicine.

Quantification of Doxorubicin and metabolites in rat plasma and small volume tissue samples by liquid chromatography/electrospray tandem mass spectroscopy

The anthracycline Doxorubicin (DXR) is used widely for the treatment of human malignancies, and drug delivery technologies are under investigation to enhance antitumor selectivity and effectiveness. A liquid chromatography-tandem mass spectroscopy (LC-MS/MS) method was developed to identify and quantify DXR and key metabolites in small-volume biological samples. The assay was linear over the therapeutically relevant concentration range (0.125-10,000 nM); in brain tissue, the lower limit of quantification was 0.247 nM and the sensitivity was 1.4 pg. The ability to quantify DXR and detect metabolite formation may provide insight into the toxicity and bioavailability of drug incorporated into carriers such as liposomes.

A Pegylated Liposomal Platform: Pharmacokinetics, Pharmacodynamics, and Toxicity in Mice Using Doxorubicin as a Model Drug

Aims were to observe pharmacokinetics, pharmacodynamics, and toxicity for constructing a Sino-pegylated liposomal platform. Human hepatocarcinoma cells (Bel7402) and murine hepatocarcinoma cells (H(22)) were used for the cytotoxicity assay and the in vivo solid xenograft tumor model in mice, respectively. Pharmacokinetic results in mice showed that the pegylated liposomal doxorubicin markedly prolonged the blood circulation of doxorubicin. Elimination half-time (T(1/2,gamma)) of pegylated, regular liposomal doxorubicin and free doxorubicin were 46.09 +/- 14.44, 26.04 +/- 3.34, and 23.72 +/- 5.13 h, respectively. The area under the concentration-time curves (AUC(0- infinity )) (h. microg/g) of the pegylated and regular liposomal doxorubicin were 6.8- and 2.6-fold higher than that of free doxorubicin, respectively. Cytotoxicity and antitumor activity in vivo indicated that activity of the pegylated liposomal doxorubicin was higher than that of the regular or the free one, respectively. After two weeks of tail intravenous injection of the pegylated liposomal doxorubicin at a single dose of 10 mg/kg, no significant damage was observed in gastric, intestinal mucosa, and heart muscle, but pronounced damages were found in the control group after dosing free doxorubicin. The results demonstrate that the pegylated liposomes improve the efficacy of toxics and reduce the toxicity, therefore providing favorable evidence for building a pegylated liposomal platform.

Pharmacokinetics and tissue distribution of idarubicin-loaded solid lipid nanoparticles after duodenal administration to rats

Idarubicin-loaded solid lipid nanoparticles (IDA-SLN) and idarubicin in solution were prepared and the two formulations were administered to rats, either by the duodenal route or intravenously (iv). The aim of this research was to study whether the bioavailability of idarubicin can be improved by administering IDA-SLN duodenally to rats. Idarubicin and its main metabolite idarubicinol were determined in plasma and tissues by reversed-phase high-performance liquid chromatography. The pharmacokinetic parameters of idarubicin found after duodenal administration of the two formulations were different: area under the curve of concentration versus time (AUC) and elimination half-life were approximately 21 times and 30 times, respectively, higher after IDA-SLN administration than after the solution administration. Tissue distribution also differed: idarubicin and idarubicinol concentrations were lower in heart, lung, spleen, and kidneys after IDA-SLN administration than after solution administration. The drug and its metabolite were detected in the brain only after IDA-SLN administration, indicating that SLN were able to pass the blood-brain barrier. After iv IDA-SLN administration, the AUC of idarubicin was lower than after duodenal administration of the same formulation. Duodenal administration of IDA-SLN modifies the pharmacokinetics and tissue distribution of idarubicin. The IDA-SLN act as a prolonged release system for the drug.

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.

Cellular uptake and cytotoxicity of solid lipid nanospheres (SLN) incorporating doxorubicin or paclitaxel

Solid Lipid Nanospheres (SLN) are colloidal therapeutic systems proposed for several administration routes and obtained by dispersing warm microemulsions in cold water. SLN as carriers of doxorubicin and paclitaxel have been previously studied. In this study, the cellular uptake of SLN and the cytotoxicity of doxorubicin and paclitaxel incorporated into SLN were investigated on two cell-lines, human promyelocytic leukemia (HL60) and human breast carcinoma (MCF-7). Cellular uptake of SLN was determined by incorporating 6-coumarin as fluorescent marker. The cellular uptake of fluorescent SLN was clearly evidenced by fluorescence microscopy. The cytotoxicity of doxorubicin incorporated in SLN was higher compared to the conventional doxorubicin solution, even at the lower concentrations. Paclitaxel in SLN was about 100-fold more effective than free paclitaxel on MCF-7 cells, while on HL60 cells a lower sensitivity was achieved with paclitaxel in SLN. Unloaded SLN had no cytotoxic effect on HL60 and MCF-7 cells.

Non-stealth and stealth solid lipid nanoparticles (SLN) carrying doxorubicin: pharmacokinetics and tissue distribution after i.v. administration to rats

Non-stealth and stealth solid lipid nanoparticles (SLN) carrying doxorubicin were prepared as drug delivery systems. The pharmacokinetics and tissue distribution of doxorubicin in these SLN were studied after i.v. administration to conscious rats and were compared to the commercial solution of doxorubicin. The same dose of each formulation (6 mg kg(-1)of body weight) of doxorubicin was injected in the rat jugular vein. Blood samples were collected after 1, 15, 30, 45, 60 min and 2, 3, 6, 12, and 24 h after the injection. Rats were sacrificed after intervals of 30 min, 4 h, and 24 h and samples of liver, spleen, heart, lung, kidney, and brain were collected. In all samples, the concentration of doxorubicin and of the metabolite, doxorubicinol, were determined. Doxorubicin and doxorubicinol were still present in the blood 24 h after injection of stealth and non-stealth SLN, while they were not detectable after the injection of the commercial solution. The results confirmed the prolonged circulation time of the SLN compared to the doxorubicin solution. In all rat tissues, except the brain, the amount of doxorubicin was always lower after the injection of the two types of SLN than after the injection of the commercial solution. In particular, SLN significantly decreased the heart concentration of doxorubicin.

Doxorubicin does not spread systemically following a local injection into the eyelids of rabbits

PURPOSE

An experimental treatment for benign essential blepharospasm and hemifacial spasm involves the direct injection of doxorubicin into the eyelids to permanently kill muscle. This study examined the extent of local and systemic spread of doxorubicin after localized injections of low doses into the eyelid and determined the length of time doxorubicin was retained in the eyelid after injection.

METHODS

Two mg doxorubicin was injected subcutaneously into the lower eyelids of rabbits. After various time periods, the eyelids were removed and dissected into three separate specimens consisting of skin, subcutaneous connective tissue including orbicularis oculi muscle, or palpebral conjunctiva. Nearby tissues were also collected, including facial muscles and extraocular muscles. Urine, blood, kidney, spleen, heart and liver samples were collected. All tissues were prepared for HPLC determination of doxorubicin concentration.

RESULTS

Doxorubicin was detected in all three eyelid specimens for the first 4 days after injection, although by the fourth day the level of doxorubicin was greatly reduced. On and after the seventh day, there was no detectable doxorubicin in the treated eyelid tissues. There were no detectable levels of doxorubicin in the urine or any other body tissue at any of the post-injection intervals examined. There was no long term retention in any of the eyelid tissues examined.

CONCLUSIONS

The well described array of serious systemic side effects caused by the use of high systemic doses of doxorubicin as a chemotherapeutic agent made it critical to ascertain how long doxorubicin remained within the injected eyelids, and to determine to what extent and with what time course local injections of chemically intact doxorubicin might spread systemically. The short retention of the active or unmetabolized drug at the injection site is important, since more than one set of injections has been required for satisfactory amelioration of muscle spasms in blepharospasm and hemifacial spasm patients. The lack of detectable systemic spread of the drug distant from the local site of injection as well as the lack of long term retention of the locally injected doxorubicin lends support for the safety of doxorubicin administered in this manner to blepharospasm and hemifacial spasm patients.

Therapeutic drug monitoring of doxorubicin in paediatric oncology using capillary electrophoresis

A method for the determination of doxorubicin and its main metabolite doxorubicinol in human plasma is described. Two different sample preparation procedures are applied depending on the expected concentration: To monitor the peak plasma levels, 10 microL of plasma are deproteinated with acetonitrile. After centrifugation, the supernatant is directly applied to the capillary by hydrodynamic injection. For the determination of lower amounts of doxorubicin and its main metabolite doxorubicinol 100 microL of plasma is extracted by liquid-/liquid extraction with chloroform. After evaporation of the organic phase, the sample is reconstituted in acetonitrile/water (95/5 v/v) and injected into the capillary by electrokinetic injection. Idarubicin serves as the internal standard. Laser-induced fluorescence detection with an Ar-ion laser emitting at 488 nm and a 520 nm cut-off filter is used for detection. The accuracy of the method was calculated to be 3.0% at higher concentrations and 15.0% at the limit of quantification. Reproducibility data are in accordance to the generally accepted criteria for bioanalytical methods. The limit of quantification is 2 microg/L, enabling us to monitor doxorubicin plasma levels for several days after application. Noninvasive blood sampling (from the fingertip) using heparinized capillaries was found to be a simple and convenient procedure and provides reproducible data. Initial results show high interindividual variability in doxorubicin peak plasma levels.

Simultaneous high-performance liquid chromatographic determination of a glucuronyl prodrug of doxorubicin, doxorubicin and its metabolites in human lung tissue

A rapid and sensitive method was developed for the simultaneous determination of the new doxorubicin glucuronide prodrug HMR 1826, the parent drug doxorubicin and its metabolites in human lung tissue samples. Homogenization of frozen tissue samples with the micro-dismembrator was followed by a silver nitrate precipitation step. By removing the exceeding silver ions with sodium chloride further purification steps could be omitted. Compounds were separated by isocratic high-performance liquid chromatography on a LiChrospher 100 RP18 column and a mobile phase consisting of citric acid buffer-acetonitrile-methanol-tetrahydrofuran within 30 min and quantified with fluorescence detection. The method showed good recoveries for all compounds (86-99%) and a linear calibration range of 20 ng/g-80 microg/g for doxorubicin and 1-600 microg/g for HMR 1826.

Quantitation of cell-associated doxorubicin by high-performance liquid chromatography after enzymatic desequestration

A method for measuring cellular concentrations of the anthracycline doxorubicin was developed. The assay involves cell lysis and protein degradation by detergent and proteinase K treatment followed by DNA hydrolysis using DNase I. Prior to high-performance liquid chromatography, samples are deproteinized by the addition of ZnSO4 and methanol. The assay is linear with respect to both the cellular drug content and the number of cells assayed over the ranges tested, and drug recovery is close to 100%. The method has a limit of detection of 50 fmol injected doxorubicin. Within run and between-day coefficients of variation have consistently been found to be in the 5% and 10% range, respectively, in different cell lines exposed to doxorubicin in vitro. The method has been evaluated in analyses of doxorubicin levels in mononuclear blood cells of patients. The assay offers several advantages over commonly used organic extraction techniques and may improve cellular drug monitoring during anthracycline therapy in patients.

Chromatographic analysis and pharmacokinetics of liposome-encapsulated doxorubicin in non-small-cell lung cancer patients

A sensitive and specific quantitative assay for total doxorubicin concentrations in plasma containing liposome-encapsulated doxorubicin hydrochloride (TLC D-99) was developed, with solvent extraction and reversed-phase high-performance liquid chromatography (HPLC). Separation of doxorubicin from its metabolites was accomplished with a 15 cm x 3.9 mm i.d., microBondapak phenyl analytical HPLC column. Optimum chromatographic conditions, obtained with a mobile phase gradient from 85 to 50% (v/v) 16 mM ammonium formate buffer in tetrahydrofuran at a flow rate of 2 mL/min, gave a detection limit of 0.3 pmol/injection. Eleven-point standard curves with from 0.00595 to 29.8 microM TLC D-99 and 0.1 microM internal standard in plasma were analyzed on three separate occasions to formally validate this assay. An overall correlation coefficient of 0.9985 was found for the logarithmic transformed data. The pharmacokinetic characteristics of doxorubicin were investigated after administration of TLC D-99 to 12 non-small-cell lung cancer patients as an intravenous infusion at doses of 60 and 75 mg/m2. The data are best described by a three-compartment model with alpha, beta, and gamma elimination half-lives of 0.0721, 2.84, and 25.2 h for the 60-mg/m2 group and 0.103, 2.56, and 14.9 h for the 75-mg/m2 patients. A mean plasma clearance of 9.89 L/h (range: 1.95 to 23.4 L/h) was found for the 60-mg/m2 patients, with that from the 75-mg/m2 group being within these values. Mean area under the plasma concentration versus time curve estimates of 37.1 and 47.9 microM/h were observed for the patients receiving 60 and 75 mg/m2, respectively. The plasma concentration-time course for total doxorubicin following administration of TLC D-99 suggests that the disposition of the liposomal formulation is determined more by the pharmacokinetics of the liposome than the encapsulated drug.

Stability studies with a high-performance liquid chromatographic method for the determination of a new anthracycline analogue, 3'-deamino-3'-[2-(S)-methoxy-4-morpholino)doxorubicin (FCE 23762), in the final drug formulation

A high-performance liquid chromatographic method was studied to optimize the separation of FCE 23762, a new antitumour agent, from both synthetic impurities and degradation products having very similar molecular structures. The main problems faced in the analytical method development using the most common reversed-phase columns available arose from the presence of analytical peaks with poor symmetry, a long analysis time and the separation between FCE 23762 and its R-isomer, which was often unsuitable for the correct determination of the drug substance. The use of a new stationary phase, Zorbax Rx-C8, together with a suitable mobile phase resulted in a good separation between the diastereomers, with satisfactory peak symmetry and run time. The method permitted the study of the stability of the drug substance in formulations for clinical trials.

The influence of partial hepatectomy on the pharmacokinetics of preoperatively injected 4'-epidoxorubicin in rats

Preoperative administration of 4'-epidoxorubicin (Epi-A) has been suggested as adjuvant therapy in patients undergoing liver resection for hepatocarcinoma. To assess the influence of partial hepatectomy on the pharmacokinetics of Epi-A, an experimental study in rats was undertaken in which 5 mg/kg Epi-A was given i.v. 10 min prior to a 2/3 hepatic resection or sham operation. Epi-A levels in liver tissue and plasma were determined using a sensitive and specific HPLC method. A marked uptake of Epi-A in liver tissue was found at 10 min after injection. The partially hepatectomized rats showed a 2-fold increase in AUC between 4 and 72 h as compared with the sham-operated controls. The terminal half-life from 24 to 72 h was not significantly changed by the partial hepatectomy. The plasma binding of Epi-A was measured at 4 h post-surgery. The fraction of unbound Epi-A was 0.16 in partially hepatectomized animals and 0.20 in sham-operated rats. The results indicate that when Epi-A is given prior to liver resection, a dose reduction might be necessary to avoid increased side effects due to the rise in AUC.