Anthracyclines: recent developments in their separation and quantitation

Real-time SERS monitoring anticancer drug release along with SERS/MR imaging for pH-sensitive chemo-phototherapy

In situ and real-time monitoring of responsive drug release is critical for the assessment of pharmacodynamics in chemotherapy. In this study, a novel pH-responsive nanosystem is proposed for real-time monitoring of drug release and chemo-phototherapy by surface-enhanced Raman spectroscopy (SERS). The Fe3O4@Au@Ag nanoparticles (NPs) deposited graphene oxide (GO) nanocomposites with a high SERS activity and stability are synthesized and labeled with a Raman reporter 4-mercaptophenylboronic acid (4-MPBA) to form SERS probes (GO-Fe3O4@Au@Ag-MPBA). Furthermore, doxorubicin (DOX) is attached to SERS probes through a pH-responsive linker boronic ester (GO-Fe3O4@Au@Ag-MPBA-DOX), accompanying the 4-MPBA signal change in SERS. After the entry into tumor, the breakage of boronic ester in the acidic environment gives rise to the release of DOX and the recovery of 4-MPBA SERS signal. Thus, the DOX dynamic release can be monitored by the real-time changes of 4-MPBA SERS spectra. Additionally, the strong T2 magnetic resonance (MR) signal and NIR photothermal transduction efficiency of the nanocomposites make it available for MR imaging and photothermal therapy (PTT). Altogether, this GO-Fe3O4@Au@Ag-MPBA-DOX can simultaneously fulfill the synergistic combination of cancer cell targeting, pH-sensitive drug release, SERS-traceable detection and MR imaging, endowing it great potential for SERS/MR imaging-guided efficient chemo-phototherapy on cancer treatment.

Immobilization-Free Determination of Dissociation Constants Independent of Ligand Size Using MicroScale Thermophoresis

The quantitative characterization of aptamer-ligand interactions is an important step in the aptamer development process. However, certain pitfalls impede K_D determination, especially when working with small molecule ligands. These include altered binding behavior caused by ligand immobilization. Further, the compulsory requirement for major differences in size between the bound and unbound state makes small molecule ligands ineligible for separation-based methods. MicroScale Thermophoresis circumvents such limitations as binding is accurately quantified with both binding partners free in solution and independent of ligand size. In this chapter, we present a protocol for the characterization of a DNA aptamer binding to its small molecule ligand daunorubicin.

High-Throughput Method for the Simultaneous Determination of Doxorubicin Metabolites in Rat Urine after Treatment with Different Drug Nanoformulations

Doxorubicin (DOX) is one of the most effective cytotoxic agents against malignant diseases. However, the clinical application of DOX is limited, due to dose-related toxicity. The development of DOX nanoformulations that significantly reduce its toxicity and affect the metabolic pathway of the drug requires improved methods for the quantitative determination of DOX metabolites with high specificity and sensitivity. This study aimed to develop a high-throughput method based on high-performance liquid chromatography with fluorescence detection (HPLC-FD) for the quantification of DOX and its metabolites in the urine of laboratory animals after treatment with different DOX nanoformulations. The developed method was validated by examining its specificity and selectivity, linearity, accuracy, precision, limit of detection, and limit of quantification. The DOX and its metabolites, doxorubicinol (DOXol) and doxorubicinone (DOXon), were successfully separated and quantified using idarubicin (IDA) as an internal standard (IS). The linearity was obtained over a concentration range of 0.05–1.6 μg/mL. The lowest limit of detection and limit of quantitation were obtained for DOXon at 5.0 ng/mL and 15.0 ng/mL, respectively. For each level of quality control (QC) samples, the inter- and intra-assay precision was less than 5%. The accuracy was in the range of 95.08–104.69%, indicating acceptable accuracy and precision of the developed method. The method was applied to the quantitative determination of DOX and its metabolites in the urine of rats treated by novel nanoformulated poly(lactic-co-glycolic acid) (DOX-PLGA), and compared with a commercially available DOX solution for injection (DOX-IN) and liposomal-DOX (DOX-MY).

Epirubicin-loaded marine carrageenan oligosaccharide capped gold nanoparticle system for pH-triggered anticancer drug release

Gold nanoparticles (AuNPs) and the pH stimuli-responsive drug delivery system have been extensively applied in cancer treatment. Carrageenan derived from marine red algae shows a promising application prospect for drug delivery as a nanomaterial for its biodegradability, abundance, and non-toxicity. Carrageenan oligosaccharide (CAO) was used as a biocompatible reductant for green synthesis of CAO-AuNPs, and the obtained CAO-AuNPs were further used as a delivery system for pH-triggered delivery of epirubicin (EPI). The EPI-CAO-AuNPs were demonstrated to be spherical and homogeneous with mean diameter of 141 ± 6 nm by means of electron microscopy and Malvern particle size analyzer. Results showed that the release of EPI from EPI-CAO-AuNPs was significant under acidic condition that simulated cancer environment, while it was negligible under physiological pH in vitro. Confocal laser scanning microscope and flow cytometry analysis showed that EPI-CAO-AuNPs were localized in cellular nucleus and induced more apoptosis of HCT-116 and HepG2 cells than free EPI. A new pH-triggered anticancer drug release was achieved by EPI-CAO-AuNPs system for the first time. The developed EPI-CAO-AuNPs nanosystem shows a promising prospect for pH-triggered delivery of antitumor drugs, and our work provides a new idea for targeted drug delivery by using biocompatible marine carbohydrates as nanomaterial.

Immunocytochemistry for Drugs Containing an Aliphatic Primary Amino Group in the Molecule, Anticancer Antibiotic Daunomycin as a Model

An immunocytochemistry (ICC) for the anticancer antibiotic daunomycin (DM) was developed using a combination of anti-DM serum produced against N-(gamma-male-imidobutyryloxy)succinimide (GMBS)-conjugated DM, and DM-uptake human melanoma BD cells. The antiserum was demonstrated to be specific for DM and the structurally related analogs adriamicin and epirubicin by an ICC model system of the enzyme immunoassay (EIA) using glutaraldehyde (GA)-conjugated DM as a solid phase antigen. No cross-reaction occurred with any of the other antibiotics tested such as bleomycin, pepleomycin, and mitomycin C. Successful DM ICC required a series of processes prior to the immunocytochemical reaction: the cells were first fixed with GA, then reduced with NaBH4, treated with hydrochloric acid, and finally digested with protease. The cell specimens were then subjected to immunoreaction with anti-DM serum followed by peroxidase-labeled goat anti-rabbit IgG/Fab', and in both immune reagents the detergent Triton X-100 was contained as well. The present ICC covering all these processes successfully stained for DM in the nucleus and in the perinuclear Golgi region of the cytoplasm of the BD cells, consistent with the results obtained by the DM autofluorescence method. This ICC was found to be three times as sensitive as the cytofluorometric method and applicable to the paraffin sections of the liver of rats 24 hr after an IV injection of DM. The principle used in the present study for developing DM ICC might be applied to other drugs containing the primary amino group(s) in the molecule. Thus, these ICCs for drugs are direct, precise and easy new methods that should have potential for pharmacology and toxicology studies of drugs, revealing the localization of a drug in cells and tissues.

Nanotherapeutics With Anthracyclines: Methods of Determination and Quantification of Anthracyclines in Biological Samples

Anthracyclines, e.g. doxorubicin, pirarubicin, are widely used as cytostatic agents in the polymer nanotherapeutics designed for the highly effective antitumor therapy with reduced side effects. However, their precise dosage scheme needs to be optimized, which requires an accurate method for their quantification on the cellular level in vitro during nanocarrier development and in body fluids and tissues during testing in vivo. Various methods detecting the anthracycline content in biological samples have already been designed. Most of them are highly demanding and they differ in exactness and reproducibility. The cellular uptake and localization is predominantly observed and determined by microscopy techniques, the anthracycline content is usually quantified by chromatographic analysis using fluorescence detection. We reviewed and compared published methods concerning the detection of anthracycline nanocarriers.

Identification of four new degradation products of epirubicin through forced degradation, LC-UV, MSn and LC-MS-TOF studies

Epirubicin (EPI) was subjected to International Conference on Harmonization recommended forced degradation under the conditions of hydrolysis, oxidation, dry heat and photolysis to characterize its possible impurities and/or degradation products. The drug was found highly unstable to alkaline hydrolysis even at room temperature, unstable to acid hydrolysis at 80°C and to oxidation at room temperature. The hydrolytic and oxidative degradation products were resolved on an Agilent RP8 (150 mm × 4.6 mm; 5 µm) column with isocratic elution using mobile phase composed of ammonium formate (10 mM, pH 3.0), acetonitrile and methanol. The drug degraded to four oxidative products (O-I, O-II, O-III and O-IV) and to one acid hydrolyzed product (A-I). Purity of each peak in liquid chromatography-ultraviolet (LC-UV) chromatogram was ascertained through photodiode array (LC-PDA) analysis. The products were characterized through electrospray ionization-mass spectrometry (+ESI-MS(n)) studies on EPI and liquid chromatography-time of flight mass spectrometry (LC-MS-TOF) studies on degraded drug solutions. The products, O-I-O-IV, were characterized as 2-hydroxy-8-desacetylepirubicin-8-hydroperoxide, 4-hydroxy-8-desacetylepirubicin-8-hydroperoxide, 8-desacetylepirubicin-8-hydroperoxide and 8-desacetylepirubicin, respectively, and product A-I was characterized as deglucosaminylepirubicin. While A-I was found to be a pharmacopoeial impurity, all oxidative products were found to be new degradation impurities. The mechanisms and pathways of degradation of EPI were discussed and outlined.

Four new degradation products of doxorubicin: An application of forced degradation study and hyphenated chromatographic techniques

Forced degradation study on doxorubicin (DOX) was carried out under hydrolytic condition in acidic, alkaline and neutral media at varied temperatures, as well as under peroxide, thermal and photolytic conditions in accordance with International Conference on Harmonization (ICH) guidelines Q1(R2). It was found extremely unstable to alkaline hydrolysis even at room temperature, unstable to acid hydrolysis at 80 °C, and to oxidation at room temperature. It degraded to four products (O-I-O-IV) in oxidative condition, and to single product (A-I) in acid hydrolytic condition. These products were resolved on a C₈ (150 mm×4.6 mm, 5 µm) column with isocratic elution using mobile phase consisting of HCOONH₄ (10 mM, pH 2.5), acetonitrile and methanol (65:15:20, v/v/v). Liquid chromatography-photodiode array (LC-PDA) technique was used to ascertain the purity of the products noted in LC-UV chromatogram. For their characterization, a six stage mass fragmentation (MS⁶) pattern of DOX was outlined through mass spectral studies in positive mode of electrospray ionization (+ESI) as well as through accurate mass spectral data of DOX and the products generated through liquid chromatography-time of flight mass spectrometry (LC-MS-TOF) on degraded drug solutions. Based on it, O-I-O-IV were characterized as 3-hydroxy-9-desacetyldoxorubicin-9-hydroperoxide, 1-hydroxy-9-desacetyldoxorubicin-9-hydroperoxide, 9-desacetyldoxorubicin-9-hydroperoxide and 9-desacetyldoxorubicin, respectively, whereas A-I was characterized as deglucosaminyl doxorubicin. While A-I was found to be a pharmacopoeial impurity, all oxidative products were found to be new degradation impurities. The mechanisms and pathways of degradation of doxorubicin were outlined and discussed.

Quantification of doxorubicin in biofluids using white light excitation fluorescence

A fiber optic spectrometer setup was designed for white light excitation fluorescence 'WLEF' based measurements. Using this setup, two different analytical methods, a self referencing ratio-metric and a difference WLEF methods, were developed for the quantification of doxorubicin (DXR) in biofluids. It was seen that Acetonitrile (ACN) acts as an efficient and transparent extracting medium for DXR. The figures of merit and the percent recoveries of DXR in blood serum, even in presence of external fluorophores and in urine samples are comparable with existing analytical methods. The compact spectrometer is expected to be useful for easy quantification of fluorescent pharmaceuticals in biofluids.

Total synchronous fluorescence spectroscopic data modeled with first- and second-order algorithms for the determination of doxorubicin in human plasma

In this work, we present the development of a method for the determination of doxorubicin in plasma samples in the presence of an unexpected component (riboflavin) by using total synchronous fluorescence spectroscopic data matrices. To the best of our knowledge, this is the first time that the second-order advantage is obtained with this kind of data. Two strategies including unfolding the data and: (a) processing with multivariate curve resolution coupled to alternating least-squares as first-order data or (b) processing with unfolded partial least-squares and exploiting the second-order advantage by the residual bilinearization procedure were considered. The calibration set was built with human plasma samples spiked with doxorubicin, while the validation set was prepared with human plasma samples spiked with both doxorubicin and riboflavin, a drug whose spectrum highly overlaps with the one corresponding to doxorubicin. Both methodologies reached good indicators of accuracy: recoveries of ca. 100 ± 8% and REP of ca. 5%; and precision: coefficient of variations between 7 and 9%.

Iron oxide nanoparticle-based magnetic resonance method to monitor release kinetics from polymeric particles with high resolution

A new method to precisely monitor rapid release kinetics from polymeric particles using super paramagnetic iron oxide nanoparticles, specifically by measuring spin-spin relaxation time (T(2)), is reported. Previously, we have published the formulation of logic gate particles from an acid-sensitive poly-β-aminoester ketal-2 polymer. Here, a series of poly-β-aminoester ketal-2 polymers with varying hydrophobicities were synthesized and used to formulate particles. We attempted to measure fluorescence of released Nile red to determine whether the structural adjustments could finely tune the release kinetics in the range of minutes to hours; however, this standard technique did not differentiate each release rate of our series. Thus, a new method based on encapsulation of iron oxide nanoparticles was developed, which enabled us to resolve the release kinetics of our particles. Moreover, the kinetics matched the relative hydrophobicity order determined by octanol-water partition coefficients. To the best of our knowledge, this method provides the highest resolution of release kinetics to date.

Aptamers for pharmaceuticals and their application in environmental analytics

Aptamers are single-stranded DNA or RNA oligonucleotides, which are able to bind with high affinity and specificity to their target. This property is used for a multitude of applications, for instance as molecular recognition elements in biosensors and other assays. Biosensor application of aptamers offers the possibility for fast and easy detection of environmental relevant substances. Pharmaceutical residues, deriving from human or animal medical treatment, are found in surface, ground, and drinking water. At least the whole range of frequently administered drugs can be detected in noticeable concentrations. Biosensors and assays based on aptamers as specific recognition elements are very convenient for this application because aptamer development is possible for toxic targets. Commonly used biological receptors for biosensors like enzymes or antibodies are mostly unavailable for the detection of pharmaceuticals. This review describes the research activities of aptamer and sensor developments for pharmaceutical detection, with focus on environmental applications.

Analysis of anticancer drugs: a review

In the last decades, the number of patients receiving chemotherapy has considerably increased. Given the toxicity of cytotoxic agents to humans (not only for patients but also for healthcare professionals), the development of reliable analytical methods to analyse these compounds became necessary. From the discovery of new substances to patient administration, all pharmaceutical fields are concerned with the analysis of cytotoxic drugs. In this review, the use of methods to analyse cytotoxic agents in various matrices, such as pharmaceutical formulations and biological and environmental samples, is discussed. Thus, an overview of reported analytical methods for the determination of the most commonly used anticancer drugs is given.

Quantitative liquid chromatographic analysis of anthracyclines in biological fluids

Anthracyclines are amongst the most widely used drugs in oncology, being part of the treatment regimen in most patients receiving systemic chemotherapy. This review provides a comprehensive summary of the sample preparation techniques and chromatographic methods that have been developed during the last two decades for the analysis of the 4 most administered anthracyclines, doxorubicin, epirubicin, daunorubicin and idarubicin in plasma, serum, saliva or urine, within the context of clinical and pharmacokinetic studies or for assessing occupational exposure. Following deproteinization, liquid-liquid extraction, solid phase extraction or a combination of these techniques, the vast majority of methods utilizes reversed-phase C18 stationary phases for liquid chromatographic separation, followed by fluorescence detection, or, more recently, tandem mass spectrometric detection. Some pros and cons of the different techniques are addressed, in addition to potential pitfalls that may be encountered in the analysis of this class of compounds.

CE-LIF method for the separation of anthracyclines: application to protein binding analysis in plasma using ultrafiltration

Anthracyclines are chemotherapeutic drugs that are widely used in the treatment of cancers such as lung and ovarian cancers. The simultaneous determination of the anthracyclines, daunorubicin, doxorubicin and epirubicin, was achieved using CE coupled to LIF, with an excitation and emission wavelength of 488 and 560 nm, respectively. Using a borate buffer (105 mM, pH 9.0) and 30% MeOH, a stable and reproducible separation of the three anthracyclines was obtained. The method developed was shown to be capable of monitoring the therapeutic concentrations (50-50 000 ng/mL) of anthracyclines. LODs of 10 ng/mL, calculated at an S/N = 3, were achieved. Using the CE method developed, the in vitro protein binding to plasma was measured by ultrafiltration, and from this investigation the estimated protein binding was determined to be in the range of 77-94%.

Simultaneous determination of cyclophosphamide, ifosfamide, doxorubicin, epirubicin and daunorubicin in human urine using high-performance liquid chromatography/electrospray ionization tandem mass spectrometry: bioanalytical method validation

A reversed-phase high-performance liquid chromatography (rp-HPLC) system interfaced with an electrospray ionization (ESI) source coupled to tandem mass spectrometry (MS/MS) was developed and validated for the determination of cyclophosphamide (CP), ifosfamide (IF), daunorubicin (DNR), doxorubicin (DXR), and epirubicin (EPI) in human urine. The analysis of samples containing multiple analytes with a dissimilar range of polarities was carried out using a conventional reversed-phase chromatographic BDS Hypersil C8 column. The analytical run was 15 min. The triple quadrupole mass spectrometer was operated in positive ion mode and multiple reaction monitoring (MRM) was used for drug quantification. The method was validated over a concentration range of 0.2 to 4.0 microg.L(-1) for CP, IF, DXR, EPI and 0.15-2.0 microg.L(-1) for DNR in human urine. The lower limit of quantification (LLOQ) was 0.2 microg.L(-1) for CP, IF, EPI and was set at 0.3 and 0.15 microg.L(-1) for DXR and DNR, respectively. The relative standard deviations (RSD%) were <11.2% for inter- and intra-day precisions. The overall accuracy was also within 114.7% for all analytes at the concentrations of the quality control samples. The potential of ionization suppression resulting from the endogenous biological material on the rp-HPLC/MS/MS method was evaluated and measured. The feasibility of the proposed HPLC/ESI-MS/MS procedure was demonstrated by analyzing urine samples from pharmacy technicians and nurses working in hospitals or personnel employed in drug-manufacturing plants.

A DNA aptamer with high affinity and specificity for therapeutic anthracyclines

We describe the characterization of a DNA aptamer that displays high affinity and specificity for the anthracyclines daunomycin and doxorubicin, both of which are frequently used in chemotherapy. Aptamers were isolated from a pool of random sequences using a semiautomated procedure for magnetic beads. All selected aptamers displayed high affinity for the target molecule daunomycin. One aptamer was further characterized and exhibited a dissociation constant (KD) of 20 nM. To examine the aptamer's binding properties and clarify its applicability for diagnostic assays, its performance under various buffer conditions was evaluated. The aptamer proved to be very robust and not dependent on the presence of specific ions. It also tolerated a wide pH range and immobilization via 5'-biotinylation. Furthermore, a competition assay for sensitive daunomycin detection was established. This not only allows the determination of the aptamer's specificity but also allows the quantification of as little as 8.4 microg/L daunomycin and doxorubicin.

Immunocytochemical studies on the distribution pattern of daunomycin in rat gastrointestinal tract

The cancer drug daunomycin is used in treatment of leukemia but possesses severe side effects that involve the gastrointestinal tract. We therefore used a newly developed immunocytochemical procedure to determine the distribution of DM in the gastrointestinal tracts of rats after i.v. injection. Two hours after injection, DM was diffusely distributed in nuclei and most parts of the cytoplasm of intestinal epithelial cells. The cytoplasmic immunoreactivity for DM was most pronounced in small granules of the apical cytoplasm. Sixteen hours after injection, DM immunostaining was by and large absent in the villous epithelium but persisted in the intestinal crypts. In addition, staining was also detected in endothelial cells, scattered cells of the lamina propria and in smooth muscle cells. After 5 days, only little staining for DM remained. Similar findings were made in the colon. In the gastric mucosa, DM accumulation persisted at 16 h in some glandular cells but was lost from the surface epithelium. No staining was detected in saline-injected control rats. The distribution of DM accumulation correlated partially with the distribution of apoptotic cells as detected by the TUNEL procedure. Our results pinpoint that DM may exert prolonged effects on glandular and regenerative cells of the gastrointestinal tract-an observation that may explain the gastrointestinal toxicity of the drug. It seems possible that DM accumulation in surface epithelial cells is rapidly cleared through drug transporters.

Evaluation of relative DNA binding affinities of anthrapyrazoles by electrospray ionization mass spectrometry

Binding interactions of a new series of anthrapyrazoles (APs) with DNA were evaluated by electrospray ionization mass spectrometry (ESI-MS). Relative binding affinities were estimated from the ESI-MS data based on the fraction of bound DNA for DNA/anthrapyrazole mixtures, and they show a correlation to the shift in melting point of the DNA measured from a previous study. Minimal sequence specificity was observed for the series of anthrapyrazoles. Upon collisionally activated dissociation of the duplex/anthrapyrazole complexes, typically ejection of the ligand was the dominant pathway for most of the complexes. However, for complexes containing AP2 or mitoxantrone, strand separation with the ligand remaining on one of the single strands was observed, indicative of a different binding mode or stronger binding.

Improved immunocytochemical detection of daunomycin

Improved immunocytochemical (ICC) detection of the anthracycline anticancer antibiotic daunomycin (DM) has been achieved by use of hydrogen peroxide oxidation prior to ICC staining for DM. The new method greatly enhanced the localization of DM accumulation in cardiac, smooth and skeletal muscle of rats after a single i.v. dose of the drug. DM accumulated in the nuclei as well as in the sarcoplasm, where it occurred in the form of small granules, which were particularly evident in cardiac muscle cells. The distribution of the granules coincided with that of mitochondria. Uptake of DM in nuclei and mitochondria of heart muscle cells may help to improve our understanding of the cardiac toxicity of DM and related anthracycline antibiotics. A number of ELISA tests were carried out in order to elucidate the mechanisms of H2O2-assisted antigen retrieval. A possible mechanism is that DM is reduced and converted to its semiquinone and/or hydroquinone derivative in vivo. Oxidation by hydrogen peroxide acts to convert these derivatives back to the native antigen. The improved ICC methodology using oxidation to recreate native antigens from reduced metabolites may be helpful also with respect to the localization of other drugs.

Adriamycin-induced oxidative mitochondrial cardiotoxicity

The anticancer agent Adriamycin (ADR) has long been recognized to induce a dose-limiting cardiotoxicity. Numerous studies have attempted to characterize and elucidate the mechanism(s) behind its cardiotoxic effect. Despite a wealth of data covering a wide-range of effects mediated by the drug, the definitive mechanism remains a matter of debate. However, there is consensus that this toxicity is related to the induction of reactive oxygen species (ROS). Induction of ROS in the heart by ADR occurs via redox cycling of the drug at complex I of the electron transport chain. Many studies support the theory that mitochondria are a primary target of ADR-induced oxidative stress, both acutely and long-term. This review focuses on the effects of ADR redox cycling on the mitochondrion, which support the hypothesis that these organelles are indeed a major factor in ADR cardiotoxicity. This review has been constructed with particular emphasis on studies utilizing cardiac models with clinically relevant doses or concentrations of ADR in the hope of advancing our understanding of the mechanisms of ADR toxicity. This compilation of current data may reveal valuable insights for the development of therapeutic strategies better tailored to minimizing the dose-limiting effect of ADR.

Distribution of anticancer antibiotic daunomycin in the rat heart and kidney revealed by immunocytochemistry using monoclonal antibodies

Two monoclonal antibodies (ADM-1-11 and 79-31 mAbs) were raised against daunomycin (DM) conjugated to bovine serum albumin via the cross-linker N-(gamma-maleimidobutyryloxy)succinimide. The monoclonal antibodies (mAbs) specifically detected DM as well as its analogs doxorubicin and epirubicin, but did not react with other anticancer antibiotics, including pepleomycin, mitomycin C, and actinomycin D. The mAbs reacted strongly with glutaraldehyde-conjugated DM in an enzyme linked immunosorbent assay (ELISA) used as a model system for immunocytochemistry as well as in appropriately pretreated sections of tissues from animals injected with DM. No staining occurred in tissues from uninjected animals. In order to perform DM ICC a number of tissue treatment conditions critical to the detection of low molecular weight substances were employed. Uptake of DM was studied in rats after a single i.v. or i.p. administration of the drug. In the heart, accumulation of DM occurred in nuclei and in the cytoplasm. In the kidney, DM immunoreactivity accumulated in all segments of the nephron except for the proximal tubules. Since the proximal tubules are known to be where a variety of transport systems including P-glycoprotein (Pgp) and organic anion-transporting polypeptides (OATPs) in drug interactions occur, the absence of DM accumulation in these segments may reflect a transport phenomenon depending upon such transporters. The availability of methods to study sites of accumulation of DM offers possibilities for understanding toxic side effects of this drug on the heart and kidney. Moreover, the immunocytochemical methodology developed may prove useful for the localization of other low molecular weight drugs that can be fixed in situ by glutaraldehyde.

Doxorubicin encapsulation and diffusional release from stable, polymeric, hydrogel nanoparticles

We have recently described the preparation of stable, polymeric nanoparticles, composed of poly(ethylene glycol) and poloxamer 407 (Pluronic F127), prepared via inverse emulsion photopolymerization. In the present study we report on the performance of this novel colloidal system as a controlled delivery system for small hydrophobic drugs. Successful encapsulation of doxorubicin occurred through hydrophobic interactions, taking advantage of particle nanoarchitecture. Loadings of up to 8.7wt.% were achieved with a reproducible, fast, solvent evaporation procedure. In vitro drug release, monitored by fluorescence spectrometry and HPLC, revealed a minor burst (approximately 10% at 37 degrees C) and sustained, diffusional release for over 1 week; furthermore, drug encapsulation significantly delayed doxorubicin degradation kinetics.

A HPLC method for the simultaneous determination of seven anthracyclines

A HPLC method has been developed for the determination of epirubicin hydrochloride, doxorubicin hydrochloride and idarubicin hydrochloride in the presence of four other anthracyclines. This method ensures the rapid determination of seven anthracyclines. It is simple and rapid and does not require any preliminary treatment of the sample. The method was fully validated.

Coformulated N-Octanoyl-glucosylceramide Improves Cellular Delivery and Cytotoxicity of Liposomal Doxorubicin

The anticancer agent doxorubicin is in certain cases administered as a long-circulating liposomal formulation. Due to angiogenesis-related structural abnormalities in the endothelial lining of many neoplasms, these complexes tend to extravasate and accumulate in the tumor stroma. However, delivery of doxorubicin is still not optimal since liposomes are not taken up directly by tumor cells. Instead, doxorubicin is gradually released into the interstitial space, and the subsequent uptake by surrounding cells is a limiting step in the delivery process. We recently demonstrated that plasma membrane-inserted short-chain sphingomyelin facilitates the cellular uptake of free doxorubicin. Here, we report that N-octanoyl-glucosylceramide acts equally potent but is itself less toxic. When coformulated with liposomal doxorubicin, this short-chain glycosphingolipid administered to cultured A431 epidermoid carcinoma cells led to superior (up to 4-fold) cellular doxorubicin accumulation and cytotoxicity, compared with control doxorubicin liposomes. These results were fully reproducible when N-octanoyl-glucosylceramide was postinserted into Caelyx, a commercial liposomal doxorubicin preparation. The doxorubicin-potentiating effect of N-octanoyl-glucosylceramide-enriched liposomes proved relatively insensitive to high serum concentrations, indicating that in vivo application is a feasible option. N-Octanoyl-glucosylceramide enrichment might thus represent a major improvement of conventional liposomal doxorubicin formulations.

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.

Chromatographic behavior of epirubicin and its analogues on high-purity silica in hydrophilic interaction chromatography

Hydrophilic interaction chromatography has been applied for the separation of epirubicin and its analogues using high-purity silica column with aqueous-organic mobile phase. Parameters affecting the chromatographic behavior of the solutes such as organic modifier, buffer pH, ionic strength and sample size, have been investigated. Of utmost importance for successful separation of these analogues is the choice of organic modifier, since it impacts both the solvent selectivity and the ionization of silica silanols as well as buffer solution, and consequently the retention behavior of solutes. Acetonitrile was shown to offer superior separation of these analogues to methanol, isopropanol or tetrahydrofuran. Results of the effects of organic modifier, buffer pH and ion strength indicate that the retention mechanism is a mixed-mode of adsorption and ion exchange. In addition, an irreversible adsorption of these compounds was found on silica in the weakly acidic or neutral mobile phases, and the effect of various factors on irreversible adsorption was also preliminarily discussed. More significantly, these basic compounds have exhibited peaks with a slanted front and a sharp tail, a typical overloading peak profile belonging to the behavior of competitive anti-Langmuir isotherm by increasing the sample size at the experimental conditions.

High performance liquid chromatographic determination of some co-administered anticancer drugs in pharmaceutical preparations and in spiked human plasma

Two HPLC methods are introduced in this paper for the simultaneous determination of doxorubicin hydrochloride (DOX) and 5-fluorouracil (5-FU), combination I, and of cytarabine (CYT) and etoposide (ETO), combination II, as co-administered drugs. In both combinations, a [250 mm x 4.6 mm C-18 column is used. The mobile phase for combination I consists of a mixture of acetonitrile and 0.05 M disodium hydrogenphosphate (50:50, v/v) containing 0.1% sodium laurylsulfate (SLS) adjusted to pH 3.7 at a flow rate 1 ml/min, with UV detection at 260 nm and ambient temperature. For combination II, the mobile phase consists of a mixture of 0.02 M sodium dihydrogenphosphate aqueous solution adjusted to pH 6.0 (with 0.2 M orthophosphoric acid or sodium hydroxide) and acetonitrile in a ratio of (7:3) at a flow rate 1 ml/min, with UV detection at 254 nm and ambient temperature. The methods also permitted the determination of methyl hydroxybenzoate (MHB) which is used as a preservative in DOX vials, combination I, and of benzyl alcohol (BZA) preservative in ETO vials, combination II. The proposed HPLC methods were successfully applied to the determination of the investigated drugs, of the two combinations, both in injection solutions and spiked human plasma samples with high precision and accuracy. Linearity, validation, accuracy, precision, limits of detection, limits of quantitation, and other aspects of analytical validation are presented in the text.

Electrochemical behavior and square wave voltammetric determination of doxorubicin hydrochloride

The electrochemical behavior of doxorubicin hydrochloride was investigated by cyclic voltammetry (CV) and square wave voltammetry (SWV). From CV and SWV studies of doxorubicin hydrochloride in the acetate buffers of various pH values, it was found that protons were involved in the reduction of the antibiotic at the H+/e- ratio at one (deltaEp/pH = -53 approximately -61 mV at 23 degrees C), proposing the electrochemical reduction of the quinone moiety in its anthraquinone aglycone. Its electrochemical behavior was pseudo-reversible in the acetate buffer of pH 3.5 by exhibiting the well-defined single cathodic and anodic waves and the ratio of Ip(a)/Ip(c) at approximately one over the scan rates of 10 approximately 100 mV/s. Fast and sensitive SWV showing a single peak of doxorubicin has been applied for its quantitative analysis using an acetate buffer of pH 3.5. A linearity was obtained when the peak currents (Ip) were plotted against concentrations of doxorubicin in the range of 5.0 x 10(-7) M approximately 1.0 x 10(-5) M with a detection limit of 1.0 x 10(-7) M.

Structure and function of "metalloantibiotics"

Although most antibiotics do not need metal ions for their biological activities, there are a number of antibiotics that require metal ions to function properly, such as bleomycin (BLM), streptonigrin (SN), and bacitracin. The coordinated metal ions in these antibiotics play an important role in maintaining proper structure and/or function of these antibiotics. Removal of the metal ions from these antibiotics can cause changes in structure and/or function of these antibiotics. Similar to the case of "metalloproteins," these antibiotics are dubbed "metalloantibiotics" which are the title subjects of this review. Metalloantibiotics can interact with several different kinds of biomolecules, including DNA, RNA, proteins, receptors, and lipids, rendering their unique and specific bioactivities. In addition to the microbial-originated metalloantibiotics, many metalloantibiotic derivatives and metal complexes of synthetic ligands also show antibacterial, antiviral, and anti-neoplastic activities which are also briefly discussed to provide a broad sense of the term "metalloantibiotics."

A validated assay for measuring doxorubicin in biological fluids and tissues in an isolated lung perfusion model: matrix effect and heparin interference strongly influence doxorubicin measurements

Doxorubicin is an antineoplasic agent active against sarcoma pulmonary metastasis, but its clinical use is hampered by its myelotoxicity and its cumulative cardiotoxicity, when administered systemically. This limitation may be circumvented using the isolated lung perfusion (ILP) approach, wherein a therapeutic agent is infused locoregionally after vascular isolation of the lung. The influence of the mode of infusion (anterograde (AG): through the pulmonary artery (PA); retrograde (RG): through the pulmonary vein (PV)) on doxorubicin pharmacokinetics and lung distribution was unknown. Therefore, a simple, rapid and sensitive high-performance liquid chromatography method has been developed to quantify doxorubicin in four different biological matrices (infusion effluent, serum, tissues with low or high levels of doxorubicin). The related compound daunorubicin was used as internal standard (I.S.). Following a single-step protein precipitation of 500 microl samples with 250 microl acetone and 50 microl zinc sulfate 70% aqueous solution, the obtained supernatant was evaporated to dryness at 60 degrees C for exactly 45 min under a stream of nitrogen and the solid residue was solubilized in 200 microl of purified water. A 100 microl-volume was subjected to HPLC analysis onto a Nucleosil 100-5 microm C18 AB column equipped with a guard column (Nucleosil 100-5 microm C(6)H(5) (phenyl) end-capped) using a gradient elution of acetonitrile and 1-heptanesulfonic acid 0.2% pH 4: 15/85 at 0 min-->50/50 at 20 min-->100/0 at 22 min-->15/85 at 24 min-->15/85 at 26 min, delivered at 1 ml/min. The analytes were detected by fluorescence detection with excitation and emission wavelength set at 480 and 550 nm, respectively. The calibration curves were linear over the range of 2-1000 ng/ml for effluent and plasma matrices, and 0.1 microg/g-750 microg/g for tissues matrices. The method is precise with inter-day and intra-day relative standard deviation within 0.5 and 6.7% and accurate with inter-day and intra-day deviations between -5.4 and +7.7%. The in vitro stability in all matrices and in processed samples has been studied at -80 degrees C for 1 month, and at 4 degrees C for 48 h, respectively. During initial studies, heparin used as anticoagulant was found to profoundly influence the measurements of doxorubicin in effluents collected from animals under ILP. Moreover, the strong matrix effect observed with tissues samples indicate that it is mandatory to prepare doxorubicin calibration standard samples in biological matrices which would reflect at best the composition of samples to be analyzed. This method was successfully applied in animal studies for the analysis of effluent, serum and tissue samples collected from pigs and rats undergoing ILP.