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Aim/Background: In this study, a stability-indicating method of the anticancer agent cabazitaxel was developed and validated. This method will be used to determine the chemical stability of commercially available concentrate-solvent mixture cabazitaxel (Jevtana®) to examine the possibility of multi-dosing from the same product vial after storage. The impossibility to re-use leftovers today is contributing to an unnecessary and significant financial waste. Methods: A forced degradation study of cabazitaxel was performed under different conditions to produce degradation products. Acidic, basic, oxidation, heat, and ultraviolet (UV) light conditions were tested. The method to determine the stability was developed so that potential degradation products would be shown in the UV spectra after separation from cabazitaxel with a C18 column in a high-performance liquid chromatography (HPLC) system. The only degradation product occurring during storage in room temperature and ambient light was identified by accurate mass Orbitrap Mass Spectrometry. Results: A stability-indicating method for cabazitaxel (Jevtana®) concentrate-solvent mixture has been developed. We demonstrated that this method can be applied to stability studies with the purpose of multi-dosing cabazitaxel from a chemical/physical stability perspective within the tested period of time and conditions. Conclusion: As an addition, the only naturally occurring degradation product found has been identified and a degradation reaction has been suggested.

Therapeutic monoclonal antibodies (mAbs) are rapidly taking over the treatment of many malignancies, and an astonishing number of mAbs is in development. This causes a high demand for quantification of mAbs in biomatrices both for measuring therapeutic mAb concentrations and to support pharmacokinetics and pharmacodynamics studies. Conventionally, ligand-binding assays are used for these purposes, but LC–MS is gaining popularity. Although intact (top-down) and subunit (middle-down) mAb quantification is reported, signature peptide (bottom-up) quantification is currently most advantageous. This review provides an overview of the reported bottom-up mAb quantification methods in biomatrices as well as general recommendations regarding signature peptide and internal standard selection, reagent use and optimization of digestion in bottom-up quantification methods.

Protein kinases inhibitors or, more generally, signal transduction inhibitors (STIs) can be used to treat diseases in which deregulation of the protein kinase activity plays a role, such as in cancer. A wide variety of drugs has been developed and/or is under investigation to act as protein kinase inhibitors, especially in tyrosine kinase inhibition. The bioanalysis of STIs has received considerable attention in the past 20 years. Liquid chromatography-tandem mass spectrometry (LC-MS-MS) in selected-reaction monitoring (SRM) mode is the method-of-choice in such studies. In several of these studies from us and others, structures are proposed for the product ions applied in SRM. A critical review of these proposed structures is presented using accurate-m/z data, which we have now generated with a linear-ion-trap-Orbitrap hybrid mass spectrometer. This led to adaptation and new structural proposals of 18 product ions for 13 STIs. Our investigation endorses the power of accurate-m/z analysis in structure elucidation of product ions in bioanalytical LC-MS-MS studies and for which the SRM mode in tandem-quadrupole instruments is apparently less suitable.

Azacitidine is a cytidine analog used in the treatment of myelodysplastic syndromes, chronic myelomonocytic leukemia and acute myeloid leukemia. The pharmacological effect of azacitidine arises after incorporation into the DNA and RNA. To this end, the drug first has to be converted into its triphosphate forms. This paper describes the development of an assay for quantitative determination of azacitidine triphosphate (aza-CTP) in peripheral blood mononuclear cells (PBMCs). To quantify aza-CTP, separation from the endogenous nucleotides cytidine triphosphate (CTP) and uridine triphosphate (UTP) is required. This was a challenge as the structures of these nucleotides are highly similar and the monoisotopic molecular masses of aza-CTP, UTP and the naturally occurring [(13)C]- and [(15)N]-isotopes of CTP differ less than 0.02 Da. Efforts to select a specific MS(2)-fragment for aza-CTP using a triple quadrupole mass spectrometer remained without success. Therefore, we investigated the feasibility to separate these highly resembling nucleotides based on accurate mass spectrometry using a linear trap quadrupole (LTQ) coupled with an Orbitrap. The LTQ-Orbitrap was able to differentiate between aza-CTP and the endogenous nucleotides UTP and [(13)C]-CTP. There was no baseline resolution between aza-CTP and [(15)N]-CTP, but the [(15)N]-CTP interference was low. For quantification, extracted ion chromatograms were obtained for the accurate m/z window of the aza-CTP product ion. The assay was able to determine aza-CTP concentrations in PBMC lysate from 40.7 to 281 nM. Assuming that an average cell suspension extracted from 16 mL blood contains 10 to 42 million PBMCs per mL, this range corresponds with 2.58/10.9-17.8/74.9 pmol aza-CTP per million PBMCs. Intra-assay accuracies were between -1.1 and 9.5% deviation and coefficient of variation values were ≤13.2%. The assay was successfully applied to quantify aza-CTP in samples from two patients treated with azacitidine. Aza-CTP concentrations up to 19.0 pmol per million PBMCs were measured. This is the first time that aza-CTP concentrations were quantified in PBMCs from patients treated with azacitidine.

A combined assay for the determination of paclitaxel, docetaxel and ritonavir in human plasma is described. The drugs were extracted from 200 μL human plasma using liquid-liquid extraction with tertiar-butylmethylether, followed by high performance liquid chromatography analysis using 10 mM ammonium hydroxide pH 10:methanol (3:7, v/v) as mobile phase. Chromatographic separation was obtained using a Zorbax Extend C(18) column. Labelled analogues of the analytes are used as internal standards. For detection, positive ionization electrospray tandem mass spectrometry was used. Method development including optimisation of the mass transitions and response, mobile phase optimisation and column selection are discussed. The method was validated according to FDA guidelines and the principles of Good Laboratory Practice (GLP). The validated range was 0.5-500 ng/mL for paclitaxel and docetaxel and 2-2000 ng/mL for ritonavir. For quantification, quadratic calibration curves were used (r(2)>0.99). The total runtime of the method is 9 min and the assay combines analytes with differences in ionisation and desired concentration range. Inter-assay accuracy and precision were tested at four concentration levels and were within 10% and less than 10%, respectively, for all analytes. Carry-over was less than 6% and endogenous interferences or interferences between analytes and internal standards were less than 20% of the response at the lower limit of quantification level. The matrix factor and recovery were determined at low, mid and high concentration levels. The matrix factor was around 1 for all analytes and total recovery between 77.5 and 104%. Stability was investigated in stock solutions, human plasma, dry extracts, final extracts and during 3 freeze/thaw cycles. The described method was successfully applied in clinical studies with oral administration of docetaxel or paclitaxel in combination with ritonavir.

Sunitinib is an orally active, multitargeted tyrosine kinase inhibitor which has been used for the treatment of metastatic renal cell carcinoma and imatinib-resistant gastrointestinal stromal tumors. We aimed to investigate the in vivo roles of the ATP-binding cassette drug efflux transporters ABCB1 and ABCG2 in plasma pharmacokinetics and brain accumulation of oral sunitinib, and the feasibility of improving sunitinib kinetics using oral coadministration of the dual ABCB1/ABCG2 inhibitor elacridar. We used in vitro transport assays and Abcb1a/1b(-/-) , Abcg2(-/-) and Abcb1a/1b/Abcg2(-/-) mice to study the roles of ABCB1 and ABCG2 in sunitinib disposition. In vitro, sunitinib was a good substrate of murine (mu)ABCG2 and a moderate substrate of human (hu)ABCB1 and huABCG2. In vivo, the systemic exposure of sunitinib after oral dosing (10 mg kg(-1) ) was unchanged when muABCB1 and/or muABCG2 were absent. Brain accumulation of sunitinib was markedly (23-fold) increased in Abcb1a/b/Abcg2(-/-) mice, but only slightly (2.3-fold) in Abcb1a/b(-/-) mice, and not in Abcg2(-/-) mice. Importantly, a clinically realistic coadministration of oral elacridar and oral sunitinib to wild-type mice resulted in markedly increased sunitinib brain accumulation, equaling levels in Abcb1a/1b/Abcg2(-/-) mice. This indicates complete inhibition of the blood-brain barrier (BBB) transporters. High-dose intravenous sunitinib could saturate BBB muABCG2, but not muABCB1A, illustrating a dose-dependent relative impact of the BBB transporters. Brain accumulation of sunitinib is effectively restricted by both muABCB1 and muABCG2 activity. Complete inhibition of both transporters, leading to markedly increased brain accumulation of sunitinib, is feasible and safe with a clinically realistic oral elacridar/sunitinib coadministration.

PURPOSE: Plitidepsin absorption, distribution, metabolism and excretion characteristics were investigated in a mass balance study, in which six patients received a 3-h intravenous infusion containing 7 mg 14C-plitidepsin with a maximum radioactivity of 100 µCi. METHODS: Blood samples were drawn and excreta were collected until less than 1% of the administered radioactivity was excreted per matrix for two consecutive days. Samples were pooled within-patients and between-patients and samples were screened for metabolites. Afterwards, metabolites were identified and quantified. Analysis was done using Liquid Chromatography linked to an Ion Trap Mass Spectrometer and offline Liquid Scintillation Counting (LC-Ion Trap MS-LSC). RESULTS: On average 4.5 and 62.4% of the administered dose was excreted via urine over the first 24 h and in faeces over 240 h, respectively. Most metabolites were found in faeces. CONCLUSION: Plitidepsin is extensively metabolised and it undergoes dealkylation (demethylation), oxidation, carbonyl reduction, and (internal) hydrolysis. The chemical formula of several metabolites was confirmed using high resolution mass data.

A sensitive and accurate method for the determination of vatalanib in human EDTA plasma was developed using high-performance liquid chromatography and detection with tandem mass spectrometry. Stable isotopically labeled imatinib was used as internal standard. Plasma proteins were precipitated and an aliquot of the supernatant was directly injected onto a Phenomenex Gemini C18 analytical column (50 mm x 2.0 mm ID, 5.0 microm particle size) and then compounds were eluted with a linear gradient. The outlet of the column was connected to a Sciex API 365 triple quadrupole mass spectrometer and ions were detected in positive multiple reaction monitoring mode. The lower limit of quantification was 10 ng/mL (S/N approximately 10, CV < or = 8.4%). This method was validated over a linear range from 10 to 2500 ng/mL, and results from the validation study demonstrated a good intra- and inter-assay accuracy (inaccuracy < or = 9.57%) and precision (CV < or = 8.81%). This method has been used to determine plasma vatalanib concentrations in patients with advanced solid tumor, enrolled in a phase I pharmacokinetic trial with the drug.

A sensitive and specific liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay for the quantification of miltefosine is presented. A 250 mu L human EDTA plasma aliquot was spiked with miltefosine and extracted by a solid-phase extraction method. Separation was performed on a Gemini C 18 column (150 mm x 2.0 mm I.D., 5 mu m) using an alkaline eluent. Detection was performed by positive ion electrospray ionization followed by triple-quadrupole mass spectrometry. The assay has been validated for miltefosine from 4 to 2000 ng/mL using 250 mu L human EDTA plasma samples. Results from the validation demonstrate that miltefosine can be accurately and precisely quantified in human plasma. At the lowest level, the intra-assay precision was lower than 10.7%, the inter-assay precision was 10.6% and accuracies were between 95.1 and 109%. This assay is successfully used in a clinical pharmacokinetic study with miltefosine. (c) 2008 Elsevier B.V. All rights reserved

Purpose Perifosine is an orally applicable, membrane-targeted alkylphosphocholine analogue with antitumour activity and radiosensitising properties in preclinical models. The purpose of this phase I study was to determine the feasibility and tolerability of concurrent daily perifosine and radiation in patients with advanced cancer. Patients and methods Starting dose of perifosine was 50mg/day; dose escalation was in steps of 50mg. Daily administration commenced 2 days before radiotherapy and was continued throughout the radiation treatment. At least three patients were entered at each dose level; at the 150mg/day level 10 patients were included. Pharmacokinetic sampling was performed weekly pre-dosing. Twenty-one patients were entered. Tumour types included NSCLC ( n =17), prostate, oesophageal, colon and bladder cancer. Most patients (16/21) had received prior chemotherapy; none radiotherapy. Median number of daily perifosine administrations was 31 (range 24–53). Mean radiation dose (BED 10 ) was 59.8Gy (range 50.7–87.5Gy in 13–28 fractions). Results Major drug-related toxicities according to CTC criteria were nausea in 57%, fatigue in 48%, vomiting in 38%, diarrhoea in 38% and anorexia in 19%. No bone marrow toxicity was observed. DLT (nausea/vomiting) was encountered in two of five patients at the 200mg/day dose level. Dose-dependent steady-state plasma levels were reached after 1 week. Major radiotherapy-related acute toxicity consisted of dysphagia in 38% and pneumonitis in 29%. Conclusion Perifosine can be safely combined with fractionated radiotherapy. A dosage of 150mg/day, to be started at least 1 week prior to radiotherapy, is recommended for phase II evaluation.

A pharmacokinetic-pharmacodynamic study was performed in opioid-dependent patients in the Netherlands, who were currently treated with high doses of pharmaceutically prepared heroin on medical prescription. Besides intravenous heroin, heroin was prescribed for inhalation by "chasing the dragon" method. In this technique, heroin base is heated on aluminium foil, and heroin vapours are inhaled into the lungs. Not much is known about the pharmacokinetics profile and bioavailability of this specific administration method. Therefore, a study was performed on pharmacokinetics and pharmacodynamics of heroin inhalation and intravenous use. Eleven patients who injected heroin and 9 patients who inhaled heroin entered the study. They were on steady-state heroin treatment for at least 12 months. For safety reasons, there was no crossing-over between heroin injection or inhalation. In a double-blind randomised study, 67-100-150% of the regular heroin maintenance dose was administered to each patient. Maximal single heroin dose was 450 mg. Plasma concentrations of heroin and its metabolites 6-monoacetylmorphine, morphine and morphine-glucuronides were analysed using LC-MS-MS. Blood pressure, heart rate, skin temperature and reaction time were assessed. Furthermore, visual analogue scales regarding craving and appreciation of heroin effect were scored by the subjects. Both in inhaling and injecting patients, the areas under curve of heroin and all measured metabolites were linearly related to heroin dose. Mean C(max) of heroin and its metabolites were 2-6 times lower after inhalation, than after intravenous injection. Bioavailability (F) of heroin inhalation was estimated as 52% (95% CI 44-61%). Heroin was rapidly cleared from plasma. Cl/F was 930 l/hr (95% CI 799-1061 l/hr) after intravenous administration, and 1939 l/hr (95% CI 1661-2217 l/hr) after inhalation. Heroin Cl and Vd were correlated to body weight (R(2) 15-19%). Morphine-glucuronides levels were inversely related to creatinine clearance. After heroin administration, the reaction time was significantly prolonged with 28+/-5.3 msec. in injecting and 13+/-4.9 msec. in inhaling patients. Cardiovascular changes were only mild after heroin administration. Craving-scores declined immediately after heroin administration in both administration groups. Subjective heroin effect was rated more positively in heroin inhaling than in injecting patients, despite the lower C(max) levels following heroin inhalation. In both groups, in this blinded study heroin dose increments were more appreciated than dose reductions. Increments of 50% of the regular heroin dose did not cause any serious side effect.

For a pharmacokinetic-pharmacodynamic study in opioid tolerant patients, who were treated with heroin in combination with methadone, a liquid chromatographic assay with tandem mass spectrometry detection (LC-MS/MS) was developed for the simultaneous determination of heroin, methadone, heroin metabolites 6-monoacetylmorphine, morphine, and morphine-6 and 3-glucuronide and methadone metabolite EMDP. To detect any abuse of substances besides the prescribed opioids the assay was extended with the detection of cocaine, its metabolites benzoylecgonine and norcocaine and illicit heroin adulterants acetylcodeine and codeine. Heroin-d6, morphine-d3, morphine-3-glucuronide-d3 and methadone-d9 were used as internal standards. The sample pre-treatment consisted of solid phase extraction using mixed mode sorbent columns (MCX Oasis). Chromatographic separation was performed at 25 degrees C on a reversed phase Zorbax column with a gradient mobile phase consisting of ammonium formate (pH 4.0) and acetonitrile. The run time was 15 min. MS with relatively mild electrospray ionisation under atmospheric pressure was applied. The triple quadrupole MS was operating in the positive ion mode and multiple reaction monitoring (MRM) was used for drug quantification. The method was validated over a concentration range of 5-500 ng/mL for all analytes. The total recovery of heroin varied between 86 and 96% and of the heroin metabolites between 76 and 101%. Intra-assay and inter-assay accuracy and precision of all analytes were always within the designated limits (< or =20% at lower limit of quantification (LLQ) and < or =15% for other samples). This specific and sensitive assay was successfully applied in pharmacokinetic studies with medically prescribed heroin and toxicological cases.

Indisulam is a new anticancer drug with a unique mechanism of action, arresting the cell cycle at the G1/S transition. The major excretory pathway of indisulam is via the urine, accounting for 63% of the radioactive dose ([(14)C]indisulam) administered in a human mass balance study. Radiochromatographic profiling of urine samples resulted in the detection of several radioactive peaks. The purpose of the present investigation was to elucidate the chemical structures of these observed indisulam metabolites. We collected fractions after chromatographic separation of the urine samples. These fractions were analysed using tandem mass spectrometry. We propose the chemical structure of 15 indisulam metabolites in urine. The metabolism of indisulam is very complex, consisting of oxidative dechlorination, hydroxylation, hydrolysis, acetylation, sulphation and glucuronidation. The clinical relevance of the observed indisulam metabolites needs further investigation.

Imexon (4-imino-1,3-diazabicyclo[3,1,0]-hexan-2-one) is a member of the class of 2-cyanoaziridine derivatives, which have been of interest as immunomodulators and anticancer agents since the late 1970s. The pharmaceutical development of imexon necessitated the availability of an assay for the quantification and purity determination of imexon active pharmaceutical ingredient (API) and the drug in its pharmaceutical dosage form. A liquid chromatographic (LC) method with ultraviolet (UV) detection was developed, using a reverse phase column with phosphate buffer (pH 6; 50 mM) as mobile phase and UV detection at 230 nm. Although retention capacity for imexon was small (capacity factor of 0.5), the method was found to be linear over the concentration range of interest of 1.0-25 microg/mL, precise, accurate, and stability-indicating. Moreover, the use of LC-mass spectrometry (MS) and on-line photodiode array (PDA) detection enabled us to propose structures for four degradation products. Two of these products were also found as impurities in the API. The degradation products, including chloro- and hydroxy-derivatised products were shown to arise from nucleophilic reactions with the activated aziridine moiety of imexon. The developed LC-UV method was found suitable for the pharmaceutical quality control of imexon API and the drug in its pharmaceutical dosage form.

In preparation for a treatment program concerning the medical coprescription of heroin and methadone to treatment-resistant addicts in the Netherlands, we studied a novel strategy for monitoring co-use of illicit (nonprescribed) heroin. A deuterated analogue of heroin was added (1:20) to pharmaceutical, smokable heroin (a powder mixture of 75% w/w diacetylmorphine base and 25% w/w caffeine anhydrate), to be used by inhalation after volatilization ("chasing the dragon"). Plasma and urine samples were collected from nine male patients who had used pharmaceutical, smokable heroin during a four-day stay in a closed clinical research unit, and these samples were analyzed by liquid chromatography coupled with tandem mass spectrometry. Ratios of deuterated and undeuterated diacetylmorphine and 6-acetylmorphine (MAM/MAM-d3) in plasma and urine were calculated from peak areas of these substances in the respective chromatograms. The MAM/MAM-d3 ratios in plasma and urine were normally distributed (with small standard deviations) and independent from concentrations of 6-acetylmorphine and from time after use of pharmaceutical heroin. A MAM/MAM-d3 ratio in urine above 32.8 was considered indicative of co-use of illicit heroin, and this value was associated with a false-positive rate of only 1% (95% confidence interval: -1 to 3%). The MAM/MAM-d3 ratio was detectable in urine for 4-9.5 h after use of pharmaceutical, smokable heroin. Addition of stable, isotopically labelled heroin to pharmaceutical, smokable heroin is considered to be a feasible strategy for the detection of co-use of illicit heroin by patients in heroin-assisted treatment.

Fludarabine and cyclophosphamide are anticancer agents mainly used in the treatment of hematologic malignancies. We have developed and validated an assay using high-performance liquid chromatography (HPLC) coupled with electrospray ionization tandem mass spectrometry for the quantification of fludarabine in combination with cyclophosphamide in human heparin and human EDTA plasma. Sample pre-treatment consisted of a protein precipitation with cold acetonitrile (−20°C) using 250 µL of plasma. Separation was performed on an Extend C18 column (150 × 2.1 mm i.d.; 5 µm) with a stepwise gradient using 1 mM ammonia solution and acetonitrile at a flow rate of 400 µL/min. The analytical run time was 12 min. The triple quadrupole mass spectrometer was operated in the positive ion mode and multiple reaction monitoring was used for drug quantification. The method was validated over a concentration range of 1 to 100 ng/mL for fludarabine and cyclophosphamide in human heparin and human EDTA plasma. The coefficients of variation were

Cyclodextrins are capable to solubilise lipophilic drugs via (partial) inclusion in their lipophilic cavity. This, however, also provides the potential for the extraction of small molecules from production materials. In the present study, the potency of the commercially available and used cyclodextrin, 2-hydroxypropyl-beta-cyclodextrin (HPbetaCD) to extract the preservative 2-phenylphenol (2-PP) from platinum cured silicone tubing was tested. The presence of 2-PP was structurally confirmed with HPLC-UV and LC/MS/MS in HPbetaCD solutions after incubation with platinum cured silicone tubing. HPbetaCD concentration and prior tubing sterilisation were found not to influence the levels of 2-PP extracted. Interestingly, extraction to ethanol was 15-fold higher than observed for HPbetaCD solutions. 2-PP was extracted from silicone tubing during routine manufacture of a blank dosage form formulated with only HPbetaCD, resulting in detectable levels of 2-PP in the final product. In a freeze-dried dosage form containing HPbetaCD and an active pharmaceutical ingredient (exhibiting a stability constant for HPbetaCD/drug of 1045 L/mol), on the other hand, 2-PP was undetectable.

E7070 (indisulam) is a novel anticancer drug currently undergoing clinical investigation. We present a sensitive and specific method for the quantitative determination of E7070 and its metabolite M1 (1,4-benzenedisulphonamide) in human plasma, urine and faeces. The analytes and their tetra-deuterated analogues, which were used as internal standards, were isolated from the biological matrix by solid-phase extraction with OASIS cartridges (0.5 mL plasma or 1 mL urine) and by liquid-liquid extraction with ethyl acetate at pH 5 (1 mL faecal homogenate). The analytes were separated on a C8 reversed-phase chromatographic column and analyzed using electrospray ionization and tandem mass spectrometric detection in the negative ion mode. The validated concentration ranges in plasma were 0.1–20 μg/mL for E7070 and 0.01–2 μg/mL for M1. In urine and faecal homogenate, a concentration range from 0.05–10 μg/mL or μg/g, respectively, was validated for both analytes. Validation of the plasma assay was performed according to the most recent FDA guidelines. The assay fulfilled all generally accepted requirements for linearity (r > 0.99, residuals between −8 and 10%), accuracy (−13.5 to 1.4%) and precision (all less than 11%) in the tested matrices. We investigated recovery, stability (working solutions at −20°C and at room temperature, biological matrices at −20°C, room temperature and after 3 freeze/thaw cycles; final extracts at room temperature) and robustness. All these parameters were found acceptable. This method is suited for mass balance studies or therapeutic drug monitoring, as demonstrated by a case example showing plasma concentrations and cumulative excretion of E7070 and M1 in urine and faeces. Furthermore, we show the presence of E7070 metabolites in patient urine. Copyright © 2004 John Wiley & Sons, Ltd.

A method was developed for the bio-analysis of Ecteinascidin 743 (ET-743) using miniaturized liquid chromatography (LC) coupled to an electrospray ionization sample inlet (TurbolonSpray) and two quadrupole mass analyzers (LC/ESI-MS/MS). Solid-phase extraction was used as a sample pretreatment procedure. Ecteinascidin 743 is a very potent anticancer compound and is administered in microgram m-2 dosages, which demands special requirements in terms of sensitivity for the analytical method supporting clinical pharmacokinetic studies. Using conventional LC/UV, a lower limit of quantitation (LLQ) of 1 ng ml-1 plasma was reached using a 500 microliters sample volume, but LC/ESI-MS/MS permitted an LLQ of 10 pg ml-1. The latter method was found to be accurate and precise, and provided a broad linear concentration range of 0.010-2.50 ng ml-1.

Item does not contain fulltext To support pharmacokinetic-guided dosing in individual patients, a fast and accurate method for simultaneous determination of anticancer tyrosine kinase inhibitors (TKIs) dasatinib, erlotinib, gefitinib, imatinib, lapatinib, nilotinib, sorafenib and sunitinib in human plasma was developed using high-performance liquid chromatography and detection with tandem mass spectrometry (HPLC-MS/MS). Stable isotopically labeled compounds of the eight different TKIs were used as internal standards. Plasma proteins were precipitated and an aliquot of supernatant was directly injected onto a reversed phase chromatography system consisting of a Gemini C18 column (50 x 2.0 mm i.d., 5.0 microm particle size) and then compounds were eluted with a gradient. The outlet of the column was connected to a triple quadrupole mass spectrometer with electrospray interface. Ions were detected in the positive multiple reaction monitoring mode. This method was validated over a linear range from 20.0 to 10,000 ng/mL for erlotinib, gefitinib, imatinib, lapatinib, nilotinib and sorafenib, and from 5.00 to 2500 ng/mL for dasatinib and sunitinib. Results from the validation study demonstrated good intra- and inter-assay accuracy (

We present a sensitive validated LC–MS/MS assay for the simultaneous determination of cabazitaxel and docetaxel in human plasma, with calibration ranges of 1.0–150 ng/mL for cabazitaxel and 0.1–15 ng/mL for docetaxel. Sample pretreatment consisted of liquid–liquid extraction with tert -butyl methyl ether. Chromatographic separation was achieved on a Zorbax Extend C 18 column using a gradient mixture of 10 mM ammonium hydroxide and methanol. Mass detection was carried out by turbo ion spray ionization in positive ion multiple reaction monitoring mode. All inter-day accuracies and precisions were within ±15% of the nominal value and within ±20% at the lower limit of quantitation. Demethylations of cabazitaxel yielding the metabolites RPR112698 and RPR123142 were monitored semi-quantitatively and quantified as ng docetaxel equivalents. Plasma samples of a prostate cancer patient treated with cabazitaxel were analyzed to demonstrate the usefulness of the presented assay for clinical drug monitoring. In conclusion, this method can be applied to support clinical pharmacokinetic studies with the novel anticancer drug cabazitaxel.

Capecitabine is the oral prodrug of the anticancer drug 5-fluorouracil (5-FU). The purpose of this study was to quantify capecitabine and its metabolites including 5'-deoxy-5-fluorocytidine (5'-dFCR), 5'-deoxy-5-fluorouridine (5'-dFUR), 5-FU, dihydro-5-fluorouracil (FUH(2)), α-fluoro-ureidopropionic acid (FUPA) and fluoro-β-alanine (FBAL) in human plasma using liquid chromatography coupled to electrospray tandem mass spectrometry. To this end two individual assays were developed: one for the simultaneous quantification of capecitabine, 5'-dFCR and 5'-dFUR using reversed phase chromatography and gradient elution, and one assay for 5-FU, FUH(2), FUPA and FBAL using hydrophilic interaction chromatography and isocratic elution. Both assays were fully validated according to current FDA guidelines. Total run time for the capecitabine assay was 9.0min, and of the 5-FU assay 5.0min. Analyte extraction was performed by protein precipitation. Stable labeled isotopes for each of the analytes were used as internal standards. The linear ranges of the analytes were 50-6000ng/mL for the capecitabine assay and 50-5000ng/mL for the 5-FU assay. Validation results demonstrate that capecitabine and its metabolites can be rapidly, accurately, precisely and robustly quantified in human plasma with the presented methods. Both assays are currently in extensive use in support of pharmacokinetic studies in patients treated with capecitabine or 5-FU.

Morphine-6-glucuronide, the active metabolite of morphine, and to a lesser extent morphine itself are known to accumulate in patients with renal failure. A number of cases on non-lethal morphine toxicity in patients with renal impairment report high plasma concentrations of morphine-6-glucuronide, suggesting that this metabolite achieves sufficiently high brain concentrations to cause long-lasting respiratory depression, despite its poor central nervous system penetration. We report a lethal morphine intoxication in a 61-year-old man with sickle cell disease and renal impairment, and we measured concentrations of morphine and morphine-6-glucuronide in blood, brain and cerebrospinal fluid. There were no measurable concentrations of morphine-6-glucuronide in cerebrospinal fluid or brain tissue, despite high blood concentrations. In contrast, the relatively high morphine concentration in the brain suggests that morphine itself was responsible for the cardiorespiratory arrest in this patient. Given the fatal outcome, we recommend to avoid repeated or continuous morphine administration in renal failure.

Atazanavir is a commonly prescribed protease inhibitor for treatment of HIV-1 infection. Thus far, only limited data are available on the in vivo metabolism of the drug. Three systemic circulating metabolites have been reported, but their chemical structures have not been released publicly. Atazanavir metabolites may contribute to its effectiveness but also to its toxicity and interactions. Thus, there is a need for extensive metabolic profiling of atazanavir. Our goals were to screen and identify previously unknown atazanavir metabolites and to develop a sensitive metabolite profiling method in plasma. Five atazanavir metabolites were detected and identified in patient samples using liquid chromatography coupled to linear ion trap mass spectrometry: one N-dealkylation product (M1), two metabolites resulting from carbamate hydrolysis (M2 and M3), a hydroxylated product (M4), and a keto-metabolite (M5). For sensitive semiquantitative analysis of the metabolites in plasma, the method was transferred to liquid chromatography coupled to triple quadrupole mass spectrometry. In 12 patient samples, all the metabolites could be detected, and possible other potential atazanavir keto-metabolites were found. Atazanavir metabolite levels were positively correlated with atazanavir levels, but interindividual variability was high. The developed atazanavir metabolic screening method can now be used for further clinical pharmacological research with this antiretroviral agent.

Purpose: Imatinib, a BCR-ABL tyrosine kinase inhibitor, is a substrate of the efflux transporters P-glycoprotein (P-gp; ABCB1) and ABCG2 (breast cancer resistance protein), and its brain accumulation is restricted by both transporters. For dasatinib, an inhibitor of SCR/BCR-ABL kinases, in vivo interactions with P-gp and ABCG2 are not fully established yet. Experimental Design: We used Abcb1a/1b−/−, Abcg2−/−, and Abcb1a/1b;Abcg2−/− mice to establish the roles of P-gp and ABCG2 in the pharmacokinetics and brain accumulation of dasatinib. Results: We found that oral uptake of dasatinib is limited by P-gp. Furthermore, relative brain accumulation, 6 hours after administration, was not affected by Abcg2 deficiency, but absence of P-gp resulted in a 3.6-fold increase after oral and 4.8-fold higher accumulation after i.p. administration. Abcb1a/1b;Abcg2−/− mice had the most pronounced increase in relative brain accumulation, which was 13.2-fold higher after oral and 22.7-fold increased after i.p. administration. Moreover, coadministration to wild-type mice of dasatinib with the dual P-gp and ABCG2 inhibitor elacridar resulted in a similar dasatinib brain accumulation as observed for Abcb1a/1b;Abcg2−/− mice. Conclusions: Brain accumulation of dasatinib is primarily restricted by P-gp, but Abcg2 can partly take over this protective function at the blood-brain barrier. Consequently, when both transporters are absent or inhibited, brain uptake of dasatinib is highly increased. These findings might be clinically relevant for patients with central nervous system Philadelphia chromosome–positive leukemia, as coadministration of an inhibitor of P-gp and ABCG2 with dasatinib might result in better therapeutic responses in these patients.

The formation and stability of benzo[a]pyrene DNA adducts were studied in tissues of BALB/c mice exposed to benzo[a]pyrene (B[a]P). The DNA adducts were visualized with an immunocytochemical peroxidase staining technique using an antiserum specific for the major B[a]P-derived adduct in DNA [(+/-)trans-7,8-dihydroxy-anti-9,10-epoxy-7,8,9,10- tetrahydrobenzo[a]pyrene (BPDE-N2-dG)]. The nuclear staining density was measured by microdensitometry. When mice were treated with an increasing dose of B[a]P the nuclear staining increased in the tissues studied (lung, heart and kidney). A linear relationship was found between the immunocytochemical nuclear staining signal and the actual DNA adduct level in the lung as measured by 32P-postlabeling. Maximum adduct formation was found 5 days after a single i.p. injection of B[a]P. Adduct levels decreased gradually after 7 days, but even after 61 days a slight specific staining was still present, suggesting that not all adducts had disappeared at that time. As judged from the disappearance of [3H]thymidine from prelabeled DNA the loss of adducts from the lung was not a result of DNA repair but one of cell turnover. In human white blood cells B[a]P-derived adducts could be detected after in vitro incubation with the reactive metabolite of B[a]P (BPDE). Dose-response studies demonstrated a positive relationship between BPDE-DNA adduct formation, the immunocytochemical staining signal and the BPDE concentration in the culture medium.

For the quantification of the HIV-integrase inhibitor raltegravir in human plasma, dried blood spots and peripheral blood mononuclear cell (PBMC) lysate, an assay was developed and validated, using liquid chromatography coupled with tandem mass spectrometry. The assay also allowed detection, but no quantification due to absence of reference substance, of the main metabolite, raltegravir-glucuronide. Raltegravir was extracted from plasma by means of protein precipitation with a mixture of methanol and acetonitrile using only 50microL plasma. Extraction from dried blood spots was performed with a simple one-step extraction with a mixture of methanol, acetonitrile and 0.2M zincsulphate in water (1:1:2, v/v/v) and extraction from cell lysate was performed in 50% methanol in water. Chromatographic separation was performed on a reversed phase C18 column (150mmx2.0mm, particle size 5microm) with a quick stepwise gradient using an acetate buffer (pH 5) and methanol, at a flow rate of 0.25mL/min. The analytical run time was 10min. The triple quadrupole mass spectrometer was operated in the positive ion-mode and multiple reaction monitoring was used for drug quantification. The method was validated over a range of 50-10,000ng/mL in plasma and dried blood spots and a range of 1-500ng/mL in PBMC lysate. Dibenzepine was used as the internal standard. The method was proven to be specific, accurate, precise and robust. Accuracies ranged from 104% to 105% in plasma, from 93% to 105% in dried blood spots and from 82% to 113% in PBMC lysate. Precision over the complete concentration range was less than 6%, 11% and 13% in plasma, dried blood spots and PBMC lysate, respectively. The method is now applied for therapeutic drug monitoring and pharmacological research in HIV-infected patients treated with raltegravir.

We have undertaken a study among coke-oven workers to test the feasibility of an enzyme-linked immunosorbent assay with anti-trans-7,8-dihydroxy-9,10-epoxy-7,8,9,10-tetrahydro-benzo[a]pyrene- DNA antibodies for monitoring occupational exposure to polycyclic aromatic hydrocarbons (PAH). Coke-oven workers are occupationally exposed to relatively high levels of PAH and are at increased risk for lung cancer. Three blood samples were collected from each of the 56 coke-oven workers exposed to PAH and 44 unexposed workers employed in a steel-rolling factory of the same plant. In addition, PAH levels were measured in ambient air by personal sampling, and the excretion of 1-hydroxypyrene in urine was also measured on 3 consecutive working days. All participants were interviewed regarding working conditions, personal hygiene, and smoking habits. The results showed that the coke-oven workers were exposed to substantial concentrations of atmospheric PAH (1-186 micrograms/m3), including benzo[a]pyrene (0.1-7.8 micrograms/m3) and pyrene (0.6-23.6 micrograms/m3). Both benzo[a]pyrene and pyrene were shown to be representative for the whole group of PAH. Forty-seven percent of the coke-oven workers had detectable levels of PAH-DNA adducts in their white blood cells, compared with 30% of the controls. In both groups, smokers had significantly higher levels of PAH-DNA adducts than did nonsmokers. At one site, we found the correlation positive between DNA adducts and the duration of exposure (r = .47, P = .005). Generally, the correlation was not significant between PAH-DNA adducts in blood and the concentration of PAH in the air and 1-hydroxypyrene in urine.

In an attempt to probe for polycyclic aromatic hydrocarbon (PAH)-DNA adducts in human subjects resulting from smoking (or other chronic environmental exposure), lung tissue and lung tumours were obtained from patients hospitalized for lung cancer. DNA was isolated from the tissue samples and examined both in an ELISA using a polyclonal antibody against (+/-)trans-7,8-dihydroxy-anti-9,10-epoxy-7,8,9,10- tetrahydrobenzo[a]pyrene (BPDE)-DNA as well as by the nuclease P1-mediated modification of the 32P-post-labelling technique. The ELISA results showed BPDE-DNA antigenicity in lung DNA from 6 out of 21 patients, and adduct levels ranged from 2 to 134 adducts per 10(8) nucleotides. For all 21 patients, the autoradiographs of chromatograms of 32P-postlabelled digests of DNA from non-tumorous lung tissue showed a strong diagonal radioactive zone (DRZ). This DRZ was generally absent in tumorous tissue. DNA samples that were positive in the ELISA contained a dominant spot within the DRZ that co-chromatographed with the major BPDE-DNA adduct (BPDE-dG). The quantities of the BPDE-dG spots ranged from 2.1 to 42 adducts in 10(9) nucleotides. These values were lower than the levels found in the ELISA but correlated well with the ELISA results (Kendall W = 0.97; P = 0.00). The levels of the DRZ adducts ranged from 1.9 to 34 adducts in 10(8) nucleotides. Correlations between smoking and DNA adduct levels were poor because of the small number of current smokers (n = 13). However, smokers of filter cigarettes had significantly lower DNA adduct levels compared with smokers of cigarettes without a filter (P = 0.02 by Fischer's exact test).

Proper regulation of intracellular levels of protoporphyrin IX (PPIX), the direct precursor of heme, is important for cell survival. A deficiency in ferrochelatase, which mediates the final step in heme biosynthesis, leads to erythropoietic protoporphyria (EPP), a photosensitivity syndrome caused by the accumulation of PPIX in the skin. We have previously shown that mice with a deficiency in the ABC transporter Bcrp1/Abcg2 display a novel type of protoporphyria. This protoporphyria is mild compared with ferrochelatase-dependent EPP, and in itself not sufficient to cause phototoxicity, but it might exacerbate the consequences of other porphyrias. In this study, we identified the mouse harderian gland as a novel expression site of Bcrp1. Because of its pronounced role in porphyrin secretion, the harderian gland presents a useful tool to study the mechanism of Bcrp1-related protoporphyria and transport of porphyrins. Bcrp1−/− harderian gland displayed a highly increased accumulation of PPIX glycoconjugates, and a similar shift was seen in Bcrp1−/− liver. Tear- and hepatobiliary excretion data suggest that Bcrp1 controls intracellular levels of PPIX by mediating high affinity transport of its glycoconjugates and possibly low-affinity transport of unconjugated PPIX. This mechanism may allow cells to prevent or reduce cytotoxicity of PPIX under excess conditions, without spillage under physiological conditions where PPIX is needed.

Glucuronidation is a major hepatic detoxification pathway for endogenous and exogenous compounds, resulting in the intracellular formation of polar metabolites that require specialized transporters for elimination. Multidrug resistance proteins (MRPs) are expressed in the liver and can transport glucuronosyl-conjugates. Using morphine as a model aglycone, we demonstrate that morphine-3-glucuronide (M3G), the predominant metabolite, is transported in vitro by human MRP2 (ABCC2), a protein present in the apical membrane of hepatocytes. Loss of biliary M3G secretion in Mrp2(-/-) mice results in its increased sinusoidal transport that can be attributed to Mrp3. Combined loss of Mrp2 and Mrp3 leads to a substantial accumulation of M3G in the liver, from which it is transported across the sinusoidal membrane at a low rate, resulting in the prolonged presence of M3G in plasma. Our results show that murine Mrp2 and Mrp3 provide alternative routes for the excretion of a glucuronidated substrate from the liver in vivo.

A sensitive and specific LC-MS/MS assay for the quantitative determination of EO9 and its metabolite EO5a is presented. A 200-µl human plasma aliquot was spiked with a mixture of deuterated internal standards EO9-d3 and EO5a-d4 and extracted with 1.25 ml ethyl acetate. Dried extracts were reconstituted in 0.1 M ammonium acetate—methanol (7 : 3, v/v) and 25 µl-volumes were injected into the HPLC system. Separation was achieved on a 150 × 2.1 mm C18 column using an alkaline eluent (1 mM ammonium hydroxide—methanol (gradient system)). Detection was performed by positive ion electrospray followed by tandem mass spectrometry. The assay quantifies a range from 5 to 2500 ng/ml for EO9 and from 10 to 2500 ng/ml EO5a using 200 µl of human plasma samples. Validation results demonstrate that EO9 and EO5a concentrations can be accurately and precisely quantified in human plasma. This assay will be used to support clinical pharmacologic studies with EO9. Copyright © 2006 John Wiley & Sons, Ltd.

We present a highly sensitive, rapid method for the determination of platinum originating from the anticancer agents cisplatin, carboplatin, and oxaliplatin in human plasma ultrafiltrate. The method is based on the quantification of platinum by inductively coupled plasma mass spectrometry and allows quantification of 7.50 ng l-1 platinum in only 150 microl of matrix. Sample pretreatment involves dilution of samples with 1% HNO3. Validation fulfilled the most recent FDA guidelines for bioanalytical method validation. Validated ranges of quantification were 7.50 ng l-1 to 1.00x10(5) ng l-1 in plasma ultrafiltrate for all three platinum compounds. The assay is now successfully used to support pharmacokinetic studies in cancer patients treated with cisplatin, carboplatin, or oxaliplatin.

The aim of this study was to investigate the use of illicit heroin among patients in a heroin-assisted treatment program. In this program, pharmaceutical-grade heroin was administered to heroin-addicted patients. Monitoring of illicit heroin use was considered important for the evaluation of this treatment program. Acetylcodeine and codeine, common adulterants of "street" heroin, were used as markers for illicit heroin. A liquid chromatography method with tandem mass spectrometric detection (LC-MS-MS) was developed, for quantitative analysis of heroin and methadone, their metabolites, and the simultaneous detection of acetylcodeine. One-hundred patients in a heroin-assisted treatment program were screened for acetylcodeine in plasma. Furthermore, patients were interviewed about illicit heroin use, and they were tested for alcohol and cocaine use. In plasma samples of 16% of the patients, acetylcodeine was detected. Overall agreement between self-report and plasma samples was 95% (kappa: 0.81). Patients who tested positive for acetylcodeine had visited the outpatients' clinics significantly less frequently than the patients who tested negative. Alcohol and cocaine use was more common in patients who tested positive for acetylcodeine. Illicit heroin use was observed in a limited percentage of patients. Overall agreement between self-report and markers of illicit heroin use was good.

Trabectedin (ET-743, Yondelis™) is a novel anti-cancer drug currently undergoing phase II–III evaluation, that has shown remarkable activity in pre-treated patients with soft tissue sarcoma. Despite extensive pharmacokinetic studies, the human disposition and metabolism of trabectedin remain largely unknown. We aimed to determine the metabolic profile of trabectedin and to identify its metabolites in humans. We analysed urine and faeces (the major excretory route) from eight cancer patients after a 3 or 24 h intravenous administration of [14C]trabectedin. Using liquid chromatography with tandem quadrupole mass spectrometric detection (LC-MS/MS) and radiochromatography with off-line radioactivity detection by liquid scintillation counting (LC-LSC), we characterised the metabolic profile in 0–24 h urine and 0–120 h faeces. By radiochromatography, a large number of trabectedin metabolites were detected. Incubation with β-glucuronidase indicated the presence of a glucuronide metabolite in urine. Trabectedin, ET-745, ET-759A, ETM-259, ETM-217 (all available as reference compounds) and a proposed new metabolite coined ET-731 were detected using LC-MS/MS. The inter-individual differences in radiochromatographic profiles were small and did not correlate with polymorphisms in drug-metabolising enzymes (CYP2C9, 2C19, 2D6, 2E1, 3A4, GST-M1, P1, T1 and UGT1A1 2B15) as determined by genotyping. Trabectedin is metabolically converted to a large number of compounds that are excreted in both urine and faeces. In urine and faeces we have confirmed the presence of trabectedin, ET-745, ET-759A, ETM-259, ETM-217 and ETM-204. In addition we have identified a putative new metabolite designated ET-731. Future studies should be aimed at further identification of possible metabolites and assessment of their activity.

Pharmaceutical smokable heroin was developed for a clinical trial on medical co-prescription of heroin and methadone. This product, consisting of 75% w/w diacetylmorphine base and 25% w/w caffeine anhydrate, was intended for use via "chasing the dragon", that is, inhalation after volatilization. This procedure involves heating the powder mixture, which may lead to formation of degradation products that could subsequently be inhaled. We developed a method that used a high-performance liquid chromatography system that was compatible with photodiode-array detection and mass spectrometric detection to separate diacetylmorphine- and caffeine-related compounds in a wide polarity range for analysis of the vapor. This method was used to analyze the contents of the plastic drinking straws that were used by patients to inhale the vapors from pharmaceutical heroin used via chasing the dragon, which were considered to be representative of the vapors the patients inhaled. They contained primarily unchanged diacetylmorphine, its main metabolite 6-acetylmorphine, caffeine, and some morphine. Several unidentified peaks were observed in the straw chromatograms. Chemical structures were proposed for nine degradation products: morphine derivatives with different substitution patterns of the C(3), C(6), and/or N(17) positions, which comprised 0.4-9.7% of the straw sample residue weight. Activity and toxicity of most of these compounds are unknown and require further investigation.

Glucuronidation is a major detoxification pathway for endogenous and exogenous compounds in mammals that results in the intracellular formation of polar metabolites, requiring specialized transporters to cross biological membranes. By using morphine as a model aglycone, we demonstrate that multidrug resistance protein 3 (MRP3/ABCC3), a protein present in the basolateral membrane of polarized cells, transports morphine-3-glucuronide (M3G) and morphine-6-glucuronide in vitro . Mrp3 (-/-) mice are unable to excrete M3G from the liver into the bloodstream, the major hepatic elimination route for this drug. This results in increased levels of M3G in liver and bile, a 50-fold reduction in the plasma levels of M3G, and in a major shift in the main disposition route for morphine and M3G, predominantly via the urine in WT mice but via the feces in Mrp3 (-/-) mice. The pharamacokinetics of injected morphine-glucuronides are altered as well in the absence of Mrp3, and this results in a decreased antinociceptive potency of injected morphine-6-glucuronide.

In preparation for a trial on co-prescription of inhalable heroin and methadone, two methods for inhalation of heroin/caffeine tablets were compared: the commonly used method of 'chasing the dragon' and a standardised procedure for inhalation of volatilised heroin, using a heating device. Five male addicts inhaled a tablet of smokable heroin daily for 5 days, alternating the inhalation method. Plasma concentrations of heroin, 6-acetylmorphine, morphine and morphine-3- and -6-glucuronide were determined using a liquid chromatography method with tandem mass spectrometric detection. The exposure to heroin and its metabolites (expressed as areas under the concentrationtime curve) was significantly lower after smoking via the heating device than after 'chasing the dragon': heroin 80% and 6-acetylmorphine 73% lower (p

C1311 (5-[[2-(diethylamino)ethyl]amino]-8-hydroxyimidazo [4,5,1-de]-acridin-6-one-dihydrochloride trihydrate) is the lead compound from the group of imidazoacridinones, a novel group of rationally designed anticancer agents. The pharmaceutical development of C1311 necessitated the availability of an assay for the quantification and purity determination of C1311 active pharmaceutical ingredient (API) and its pharmaceutical dosage form. A reversed-phase liquid chromatographic method (RP-LC) with ultraviolet (UV) detection was developed, consisting of separation on a C18 column with phosphate buffer (60 mM; pH 3 with 1 M citric acid)–acetonitrile–triethylamine (83:17:0.05, v/v/v) as the mobile phase and UV-detection at 280 nm. The method was found to be linear over a concentration range of 2.50–100 μg/mL, precise and accurate. Accelerated stress testing showed degradation products, which were well separated from the parent compound, confirming its stability-indicating capacity. Moreover, the use of LC–MS and on-line photo diode array detection enabled us to propose structures for four degradation products. Two of these products were also found as impurities in the API and more abundantly in an impure lot of API.

The alkylating agents cyclophosphamide (CP) and N, N', N"-triethylenethiophosphoramide (thiotepa) are often co-administered in high-dose chemotherapy regimens. Since these regimens can be complicated by the occurrence of severe and sometimes life-threatening toxicities, pharmacokinetically guided administration of these compounds, to reduce variability in exposure, may lead to improved tolerability. For rapid dose adaptations during a chemotherapy course, we have developed and validated an assay, using liquid chromatography coupled with electrospray tandem mass spectrometry (LC/MS/MS), for the routine quantification of CP, thiotepa and their respective active metabolites 4-hydroxycyclophosphamide (4OHCP) and N, N', N"-triethylenephosphoramide (tepa) in plasma. Because of the instability of 4OHCP in plasma, the compound is derivatized with semicarbazide (SCZ) immediately after sample collection and quantified as 4OHCP-SCZ. Sample pretreatment consisted of protein precipitation with a mixture of methanol and acetronitrile using 100 microl of plasma. Chromatographic separation was performed on an Zorbax Extend C18 column (150 x 2.1 mm i.d., particle size 5 microm), with a quick gradient using 1 mM ammonia solution and acetonitrile, at a flow-rate of 0.4 ml min(-1). The analytical run time was 10 min. The triple quadrupole mass spectrometer was operating in the positive ion mode and multiple reaction monitoring was used for drug quantification. The method was validated over the concentration ranges 200-40,000 ng ml(-1) for CP, 50-5000 ng ml(-1) for 4OHCP-SCZ and 5-2500 ng ml(-1) for thiotepa and tepa, using 100 microl of human plasma. These dynamic concentration ranges proved to be relevant in daily practice. Hexamethylphosphoramide was used as an internal standard. The coefficients of variation were

Previous studies have shown by quantification of the parent drug and the known metabolites M-1, M-2, M-3 and M-4 that the mass balance of docetaxel in mice and humans is not complete. We therefore used reversed-phase high-performance liquid chromatography (HPLC) with photodiode array (PDA) detection and tandem mass spectrometry to trace and identify putative metabolites in the feces and bile of mice injected intravenously with docetaxel. HPLC-PDA revealed two metabolic products in the feces and more than ten potential new metabolites in the bile. Mass spectrometry was performed on docetaxel reference compound, on the known metabolites M-1, M-2, M-3 and M-4, and on HPLC eluate fractions containing metabolic products, six fractions originating from the bile and two from the feces. The mass spectra of the most abundant unknown metabolite in the bile and the feces were identical, and indicated that this structure contained a carboxyl moiety at the tert-butyl group. Under the conditions of storage this product degraded to metabolite M-4. All other unknown metabolites found in the bile samples were oxidized products, with the oxidations in both the C-13 side chain and the baccatin structure, the latter being a new finding.

We have developed and validated an assay, using liquid chromatography coupled with electrospray tandem mass spectrometry (LC-MS/MS), for the quantification of the novel protease inhibitors (PIs) atazanavir and tipranavir. The sample pre-treatment consisted of protein precipitation with a mixture of methanol and acetronitrile using 100 microl plasma for atazanavir and 50 microl for tipranavir. Chromatographic separation was achieved on an Inertsil ODS3 column (50 mm x 2.0 mm i.d., particle size 5 microm), with a quick stepwise gradient using an acetate buffer (pH 5) and methanol, at a flow rate of 0.5 ml/min. The analytical run time was 5.5 min. The triple quadrupole mass spectrometer operated in the positive ion-mode and multiple reaction monitoring (MRM) was used for drug quantification. The assay was linear over a concentration range of 0.05-10 microg/ml for atazanavir and 0.1-75 microg/ml for tipranavir. Saquinavir-d5 was used as internal standard. The intra- and inter-day coefficients of variation were less than 3.8% for atazanavir and less than 10.4% for tipranavir. Accuracies were within +/-7.3 and +/-7.2% for atazanavir and tipranavir, respectively. Both drugs were stable under various relevant storage conditions. The validated concentration ranges proved to be adequate to measure concentrations of human immunodeficiency virus type-1 (HIV-1)-infected individuals. The developed method could easily be combined with a previously developed LC-MS/MS assay for the quantification of protease inhibitors.

Previous mass balance studies in humans and mice have shown that the fecal and urinary recovery of paclitaxel and known metabolites (3' -hydroxypaclitaxel, 6alpha-hydroxypaclitaxel and 3',6alpha-dihydroxypaclitaxel) was not complete. Obviously this discrepancy is caused by the existence of other yet unknown metabolites. Mdr1a/1b(-/-) mice excrete very low quantities of unchanged paclitaxel. We have therefore used these mice receiving i.v. [3H]paclitaxel to further study the metabolic fate of paclitaxel. The major part of the radiolabel, being 70%, was excreted in the feces. A lipophilic sample, containing about 70% of the radioactivity present in the feces sample, was obtained by diethyl ether extraction. The aqueous residue containing about 30% of the radioactivity was further extracted using methanol. The high-performance liquid chromatography (HPLC) chromatograms of the lipophilic and aqueous sample revealed two and five putative new metabolites of paclitaxel, respectively. The HPLC fractions containing substantial amounts of radioactivity were subjected to tandem mass spectrometry. Two novel monohydroxylated paclitaxel structures were identified, which are probably 2m-hydroxypaclitaxel and 19-hydroxypaclitaxel, structures previously identified in rats. Including these metabolites, about 60% of the mass balance of paclitaxel could be quantified.

HIV protease inhibitors are important antiretroviral drugs which have substantially reduced the morbidity and mortality associated with HIV-1 infection. Recent data have shown relationships between plasma concentrations of the protease inhibitors and clinical response, which makes therapeutic drug monitoring valuable. We have developed and validated an assay, using liquid chromatography coupled with electrospray tandem mass spectrometry (LC/MS/MS), for the routine quantification of the six licensed protease inhibitors (amprenavir, indinavir, lopinavir, nelfinavir, ritonavir and saquinavir) and the pharmacologically active nelfinavir metabolite M8 in plasma. The sample pretreatment consisted of protein precipitation with a mixture of methanol and acetronitrile using only 100 µl of plasma. Chromatographic separation was performed on an Inertsil ODS3 column (50 × 2.0 mm i.d., particle size 5 µm), with a quick stepwise gradient using an acetate buffer (pH 5) and methanol, at a flow rate of 0.5 ml min−1. The analytical run time was 5.5 min. The use of a 96-well plate autosampler allowed batch sizes up to 150 patient samples. The triple-quadrupole mass spectrometer was operated in the positive ion mode and multiple reaction monitoring was used for drug quantification. The method was validated over the concentration ranges 0.01–10 µg ml−1 for indinavir and saquinavir, 0.1–10 µg ml−1 for amprenavir, 0.05–10 µg ml−1 for nelfinavir and ritonavir, 0.1–20 µg ml−1 for lopinavir and 0.01–5 µg ml−1 for M8. Saquinavir-d5 and indinavir-d6 were used as internal standards. The coefficients of variation were always

Purpose: Ecteinascidin 743 (ET-743) is a novel, marine-derived anticancer agent currently under clinical development for the treatment of solid tumors. The aim of this study was to develop and validate limited sampling strategies for the prediction of ET-743 clearance in phase II studies, using two techniques: the stepwise linear regression approach and the Bayesian estimation approach. Methods: Data from a phase I dose-finding study were used with ET-743 administered as a 24-h infusion. Plasma concentration time data from 34 patients treated with 1200, 1500 or 1800 µg/m2 ET-743 were randomly divided into an index data set, used for the development of the strategies, and a validation data set. With the linear regression approach, clearance (obtained by non-compartmental analysis) was correlated with the ratios of dose to the observed concentrations. For the Bayesian approach a three-compartment population pharmacokinetic model was developed; optimal time-points were selected using the D-optimality algorithm. The strategies were compared by assessment of their predictive performance of CL in the validation data set. Results: The linear regression method yielded a single-point sampling schedule with no significant bias and acceptable precision (–0.03% and 21%, respectively). With the Bayesian approach, a three-sample strategy was selected which resulted in less-accurate, but unbiased, predictions (bias 13%, precision 34%). Conclusions: Optimal sampling strategies were developed and validated for estimation of ET-743 clearance. Although the linear regression approach showed slightly better predictive performance, the Bayesian approach is preferred for the current phase II studies as it is more robust and flexible and allows the description of the full pharmacokinetic profile.

Ecteinascidin 743 (ET-743) is an anticancer agent derived from the Caribbean tunicate Ecteinascidia turbinata. In the present article, the pharmacokinetics and pharmacodynamics of ET-743 are described within a phase I study. Forty patients with solid tumors initially received ET-743 as a 1-h i.v. infusion every 21 days at nine dose levels (50-1100 microg/m(2)). The maximal tolerated dose (MTD) was 1100 microg/m(2), with thrombocytopenia and fatigue as dose-limiting toxicities (DLTs). As this MTD was substantially lower than in parallel phase I studies, dose escalation continued using a prolonged, 3-h infusion. Thirty-two patients were entered at five dose levels (1000-1800 microg/m(2)). The MTD was 1800 microg/m(2) with pancytopenia and fatigue as DLTs. The recommended phase II dose was 1650 microg/m(2) given over 3 h at which 12 patients were treated. Pharmacokinetic monitoring was performed for both treatment schedules. Non-compartmental pharmacokinetic parameters at the recommended dose with the 3-h infusion were (mean value+/-SD): clearance 87+/-30 l/h and mean elimination half-life 26+/-7 h. Pharmacokinetics were linear at the dose range tested with this schedule. The percentage decrease in platelets, white blood cells and neutrophils correlated with the area under the plasma concentration versus time curve (AUC), dose and maximal plasma concentration (C(max)). Hepatic toxicity increased with dose, AUC and C(max). Administration of 1650 microg/m(2) ET-743 over 3 h seemed clinically feasible; pharmacokinetics were linear with this schedule. Hepatic and hematological toxicities correlated with exposure to ET-743.

Ecteinascidin 743 (ET-743) is a potent anti-tumoral agent of a marine origin. It is currently being tested in phase II clinical trials using a 3-weekly 24-h i.v. infusion of 1500 microg/m(2) and 3-h infusions of 1650 microg/m(2). Knowledge of the metabolism of ET-743 is, however, still scarce. In the present study, a qualitative chromatographic discovery of metabolites of ET-743 in man is reported. ET-743 and its demethylated analog ET-729 were incubated at 37 degrees C in the presence of enzyme systems, pooled human microsomes, pooled human plasma and uridine 5'-diphosphoglucuronyltransferase, respectively, in appropriate media. Reaction products were investigated chromatographically using photodiode array and ion spray-mass spectrometric detection (LC-MS). The main reaction products in microsomal incubations of ET-743 resulted from a remarkable breakdown of the molecule. In plasma the drugs were deacetylated, and the transferase did actually yield a glucuronide of both ET-743 and ET-729. In contrast, screening of urine, plasma and bile, collected from patients treated with ET-743 at the highest dose levels, using a sensitive LC-MS assay, did not result in detection of ET-729 and metabolites which were generated in vitro. The urinary excretion of ET-743 in man was lower than 0.7% of the administered dose for a 24-h infusion.

Doxorubicin and paclitaxel both display strong antitumor activity in the treatment of breast cancer. The optimal schedule of this combination, however, remains undefined. In this phase I and pharmacologic study, we administered weekly 12 mg/m2 doxorubicin as a bolus infusion immediately followed by a 1 h 80 mg/m2 paclitaxel infusion to patients with metastatic breast cancer. A total of 119 weekly courses were delivered to seven patients. Grade IV neutropenia was observed in two patients at the first dose level, thus already defining the maximum tolerated dose. Pronounced non-hematologic toxicities were mild neuropathy (grade I: 39%) and stomatitis (grade I: 19%, grade II: 8%). No signs of cardiac toxicity were observed with this dose schedule. Three partial responses were achieved in this group of heavily pretreated patients. The pharmacokinetics of paclitaxel, doxorubicin and Cremophor EL with this schedule were analyzed. Overall, the schedule was well tolerated and combined with its preliminary response rate justifies further evaluation in phase II studies.

A high performance liquid chromatographic (HPLC) assay is described for the determination of the investigational anticancer drug 9 aminocamptothecin (9-AC) as the lactone form (9AC(lac)) and as the total of the lactone and hydroxycarboxylate forms (9AC-(tot)), in micro volumes of plasma. The analytical methodology reported here involves a protein precipitation step with cold methanol (-30 degrees C) as sample pretreatment procedure. The methanolic extract is used for the determination of 9AC-(tot). The intact (active) lactone form of 9-AC is separated from the hydroxycarboxylate form in the methanolic plasma extract by solid phase extraction within 48 h after sampling and deproteination. After evaporation to dryness (nitrogen, 40 degrees C) the extract can be stored at -70 degrees C for at least 3 weeks. The drug is analysed by reversed-phase liquid chromatography on a Zorbax SB RP-18 column, using methanol-water eluent (pH 2.2) and fluorescence detection. The presented assay is linear over a concentration range 0.2-100 ng.ml-1 with a detection limit and a limit of quantitation of 0.05 and 0.2 ng.ml-1, respectively, for both 9-AC(tot) and 9-AC(lac) using a 100 ml plasma sample. The proposed method has been implemented in a phase I clinical trial for pharmacokinetic evaluation of this potential new drug.

A reversed-phase high-performance liquid chromatographic method has been developed and validated for the quantification of the novel anticancer drug Ecteinascidin 743 in human plasma. The sample pretreatment of the plasma samples involved a solid-phase extraction (SPE) on cyano columns. Propyl-p-hydroxybenzoate was added after the sample pretreatment to correct for variability in injection volumes. The separation was performed on a Zorbax SB-C18 column (75x4.6 mm I.D., particle size 3.5 microm) with acetonitrile-25 mM phosphate buffer, pH 5.0 (70:30, v/v) as the mobile phase. The flow-rate was 1.0 ml/min and the eluent was monitored at 210 nm. The accuracies and precisions of the assay fall within +/-15% for all quality control samples and within +/-20% for the lower limit of quantitation, which was 1.0 ng/ml using 500 microl of plasma. The overall recovery of the sample pretreatment procedure for Ecteinascidin 743 was 87.0+/-5.9%. The drug was found to be stable in human plasma at -30 degrees C for at least 2 months. At room temperature Ecteinascidin 743 was stable in human plasma for 5 h at most.