Impact of renal impairment on dihydropyrimidine dehydrogenase (DPD) phenotyping.

BACKGROUND: The chemotherapeutic agent 5-fluorouracil (5-FU) is catabolized by dihydropyrimidine dehydrogenase (DPD), the deficiency of which may lead to severe toxicity or death. Since 2019, DPD deficiency testing, based on uracilemia, is mandatory in France and recommended in Europe before initiating fluoropyrimidine-based regimens. However, it has been recently shown that renal impairment may impact uracil concentration and thus DPD phenotyping. PATIENTS AND METHODS: The impact of renal function on uracilemia and DPD phenotype was studied on 3039 samples obtained from three French centers. We also explored the influence of dialysis and measured glomerular filtration rate (mGFR) on both parameters. Finally, using patients as their own controls, we assessed as to what extent modifications in renal function impacted uracilemia and DPD phenotyping. RESULTS: We observed that uracilemia and DPD-deficient phenotypes increased concomitantly to the severity of renal impairment based on the estimated GFR, independently and more critically than hepatic function. This observation was confirmed with the mGFR. The risk of being classified 'DPD deficient' based on uracilemia was statistically higher in patients with renal impairment or dialyzed if uracilemia was measured before dialysis but not after. Indeed, the rate of DPD deficiency decreased from 86.4% before dialysis to 13.7% after. Moreover, for patients with transient renal impairment, the rate of DPD deficiency dropped dramatically from 83.3% to 16.7% when patients restored their renal function, especially in patients with an uracilemia close to 16 ng/ml. CONCLUSIONS: DPD deficiency testing using uracilemia could be misleading in patients with renal impairment. When possible, uracilemia should be reassessed in case of transient renal impairment. For patients under dialysis, testing of DPD deficiency should be carried out on samples taken after dialysis. Hence, 5-FU therapeutic drug monitoring would be particularly helpful to guide dose adjustments in patients with elevated uracil and renal impairment.

Antibiotic therapy for infectious hemodialysed patients in Bamako: Pharmacokinetic analyses and first improvement suggestions.

Infection which occurs in renal kidney failure patient have to be therapeutically managed immediately and the treatment must be aggressive to be quickly efficient. In Bamako (Mali). Posology adaptation cause a problem in nephrology, especially for the most common used antibiotics to care these infections. Drug dosage is not routinely performed in Bamako. The main objective of this work is to compare anthropometric, clinical and pharmacokinetic profiles and the clinical future between infected hemodialysis patients following an antibiotic therapy in Bamako and Lyon (hospital used as a reference). To reach these objectives, a preliminary punctual study of clinical pharmacokinetic of vancomycin were set up at Bamako, following the personalization therapeutics model from Lyon. Bamako patients' samples were imported to France and dosage analysis were performed at Lyon. BestDose software was used to view and compare complete pharmacokinetic profile. It includes for the first time, in routine, the 50 ml/mn of the renal function during dialyses for 58 patients: 31 for Bamako and 21 for Lyon. The residual concentration at the beginning of the dialysis session was compared. In Bamako, patients are younger, the renal failure is more severe and arteriovenous fistula are never set up, treatments are limited in dose and in duration; the residual concentration before the dialyses are too low; as a consequence, infections are rarely quickly reduced and more especially the death linked to these infections are more important (9 in Bamako versus 1 in Lyon). Urgent corrective measures have to be proposed: propose a conciliation between therapeutic requirements formulated within Lyon protocols and the financial ability of the patient, to promote arteriovenous fistula creation as soon as possible, and develop first dose strategy (unfortunately there is often only one dose): a more aggressive dose estimated from simulation profile performed in this study.

[Multidisciplinary management of voluntary pink oleander poisoning: How to estimate the quantities ingested?] / Prise en charge multidisciplinaire d'une intoxication volontaire au laurier rose : comment estimer les quantités ingérées ?

This is a case of voluntary ingestion of Nerium oleander leaves in an adolescent requiring the use of atropine and emergency chartering of antidigoxin antibodies (Digifab®) due to the difficulty of assessing oleandrin level and associated toxicity. Upon hospital admission, a digoxinemia was performed (0.44µg/mL) and the presence of oleandrine was detected. Oleandrin levels at toxic levels may be suspected by a measure of blood digoxin and explain the patient's clinical signs, which could adapt the therapeutic management.

Issues and limitations of available biomarkers for fluoropyrimidine-based chemotherapy toxicity, a narrative review of the literature.

Fluoropyrimidine-based chemotherapies are widely used to treat gastrointestinal tract, head and neck, and breast carcinomas. Severe toxicities mostly impact rapidly dividing cell lines and can occur due to the partial or complete deficiency in dihydropyrimidine dehydrogenase (DPD) catabolism. Since April 2020, the European Medicines Agency (EMA) recommends DPD testing before any fluoropyrimidine-based treatment. Currently, different assays are used to predict DPD deficiency; the two main approaches consist of either phenotyping the enzyme activity (directly or indirectly) or genotyping the four main deficiency-related polymorphisms associated with 5-fluorouracil (5-FU) toxicity. In this review, we focused on the advantages and limitations of these diagnostic methods: direct phenotyping by evaluation of peripheral mononuclear cell DPD activity (PBMC-DPD activity), indirect phenotyping assessed by uracil levels or UH2/U ratio, and genotyping DPD of four variants directly associated with 5-FU toxicity. The risk of 5-FU toxicity increases with uracil concentration. Having a pyrimidine-related structure, 5-FU is catabolised by the same physiological pathway. By assessing uracil concentration in plasma, indirect phenotyping of DPD is then measured. With this approach, in France, a decreased 5-FU dose is systematically recommended at a uracil concentration of 16 ng/ml, which may lead to chemotherapy under-exposure as uracil concentration is a continuous variable and the association between uracil levels and DPD activity is not clear. We aim herein to describe the different available strategies developed to improve fluoropyrimidine-based chemotherapy safety, how they are implemented in routine clinical practice, and the possible relationship with inefficacy mechanisms.

Development and validation of a method for quantification of human insulin and its synthetic analogues in plasma and post-mortem sera by LC-MS/HRMS.

Analysis of human insulin and its synthetic analogues is increasingly requested for clinical monitoring, for anti-doping purposes, but also for forensic cases. Indeed, insulin analogues may be abused for suicide or homicide - whence their forensic interest. Collection and storage conditions, as well as the phenomenon of degradation make post-mortem serum samples analytically challenging and consequently, the rate of exogenous insulin administration as cause of death is undoubtedly underestimated. However, with recent technological advances and the development of new extraction techniques particularly for anti-doping analyses, detection of insulins in post-mortem samples seems to be achievable. This study describes the first validated quantitative method for analysis human insulin and its six analogues (lispro, aspart, glulisine, glargine, detemir and degludec) in plasma and post-mortem sera. Various extraction processes, namely precipitation + solid phase extraction (SPE), filtration + SPE, precipitation + SPE + immunopurification, and filtration + immunopurification, were assessed to evaluate the lowest limit of detection for all target analogues. The selected sample preparation consists of filtration step followed by immunopurification extraction with an anti-body precoated ELISA plate for plasma. For post-mortem sera, the first step of precipitation was added to remove matrix interferences. The extracts were analyzed by ultra-high-performance liquid chromatography-high resolution mass spectrometry (LC-HRMS), interfaced by electrospray (ESI). The method was validated with respect linearity, precision, accuracy, recovery, matrix effect, dilution and carryover. The limit of quantification (LOQ) in plasma was 0.5 ng/mL for human insulin and rapid-acting insulins, 1.0 ng/mL for glargine, 2.5 ng/mL for degludec and 10 ng/mL for detemir. Two types of post-mortem sera were studied based on the post-mortem interval (PMI): inferior or superior to 48 h. The obtained LOQ were the same for each analogue, independent from the PMI: 1.0 ng/mL for human insulin and rapid-acting insulins, 1.0 ng/mL for glargine, 2.5 ng/mL for degludec and 10 ng/mL for detemir. At the LOQ level, for all insulins and all samples, accuracy was between 70 and 130% and precision inferior to 30%. The validated method was applied to five subjects participating in therapeutic monitoring of insulin and to seven post-mortem cases.

Vectorized gene therapy of liver tumors: proof-of-concept of TG4023 (MVA-FCU1) in combination with flucytosine.

Background: TG4023 is a modified vaccinia virus Ankara (MVA) containing the yeast-originated transgene FCU1, expressing cytosine deaminase and uracil phosphoribosyltransferase enzymes that transform the prodrug flucytosine (5-FC) into cytotoxic 5-fluorouracil (5-FU) and 5-fluorouridine-5'-monophosphate, respectively. This first-in-human study aimed to assess the maximum tolerated dose (MTD) of intratumoral (IT) TG4023 and the safety, feasibility, and proof-of-concept (PoC) of TG4023/5-FC combination to deliver high 5-FU concentrations in tumors. Patients and Methods: Cancer patients without further therapeutic option and with at least one injectable primary or metastatic liver tumor underwent on day 1 a percutaneous IT injection of TG4023 at doses of 107, 108, or 4.108 plaque forming units (p.f.u.) using ultrasound imaging guidance, after a dose-limiting toxicities (DLTs)-driven 3 + 3 dose-escalating design. On day 2, patients were given intravenous and/or oral 5-FC at a dose of 200 mg/kg/day for 14 days and were followed for safety through day 43. Tumor response was assessed at week 6, according to RECIST. Plasma and tumor 5-FU concentrations were measured to establish the PoC. Results: In total, 16 patients completed treatment with TG4023 and 5-FC. One DLT/7 patients (ALT/aspartate aminotransferase transient increase) was observed at 4 × 108 p.f.u.; MTD was therefore not reached. The most frequent adverse events were pyrexia, asthenia, vomiting, and decreased appetite. Eight of 16 patients had stable disease. Mean 5-FU concentrations in plasma were 1.9 ± 2.6 ng/ml and 56 ± 30 ng/g in tumors. Seroconversion for anti-FCU1 antibodies was found for one patient from each cohort (16%, overall). Conclusions: This phase I study demonstrated that IT injections of TG4023 were feasible and well tolerated; MTD was defined as 4 × 108 p.f.u. Therapeutic 5-FU concentrations in tumors established the virus-directed enzyme-prodrug therapy PoC. Clinicaltrials.gov Number: NCT00978107.

State of the art in bile analysis in forensic toxicology.

In forensic toxicology, alternative matrices to blood are useful in case of limited, unavailable or unusable blood sample, suspected postmortem redistribution or long drug intake-to-sampling interval. The present article provides an update on the state of knowledge for the use of bile in forensic toxicology, through a review of the Medline literature from 1970 to May 2015. Bile physiology and technical aspects of analysis (sampling, storage, sample preparation and analytical methods) are reported, to highlight specificities and consequences from an analytical and interpretative point of view. A table summarizes cause of death and quantification in bile and blood of 133 compounds from more than 200 case reports, providing a useful tool for forensic physicians and toxicologists involved in interpreting bile analysis. Qualitative and quantitative interpretation is discussed. As bile/blood concentration ratios are high for numerous molecules or metabolites, bile is a matrix of choice for screening when blood concentrations are low or non-detectable: e.g., cases of weak exposure or long intake-to-death interval. Quantitative applications have been little investigated, but small molecules with low bile/blood concentration ratios seem to be good candidates for quantitative bile-based interpretation. Further experimental data on the mechanism and properties of biliary extraction of xenobiotics of forensic interest are required to improve quantitative interpretation.

Should busulfan therapeutic range be narrowed in pediatrics? Experience from a large cohort of hematopoietic stem cell transplant children.

Busulfan, the corner stone of hematopoietic stem cell transplantation regimens, has a narrow therapeutic window. Therapeutic drug monitoring (TDM)-guided dosing to reach the conventional area under the concentration-time curve (AUC) target range of 900-1500 µmol min/L is associated with better outcomes. We report our experience with busulfan TDM in a large cohort of children. The aims were to investigate the relevance of using a more restricted therapeutic range and investigate the association between busulfan therapeutic range and clinical outcome. This study includes 138 children receiving 16 doses of intravenous busulfan, with the first dose assigned based on weight and doses adjusted to a local AUC target range of 980-1250 µmol min/L. Busulfan TDM combined with model-based dose adjustment was associated with an increased probability of AUC target attainment, for both target range: 90.8% versus 74.8% for the conventional target range and 66.2% versus 43.9% for the local target range (P<0.001). The median follow-up was 56.2 months. Event-free survival was 88.5%, overall survival was 91.5% and veno-occlusive disease occurred in 18.3% of patients. No difference was observed for clinical outcomes depending on the selected target range. Pharmacokinetic monitoring and individualization of busulfan dosage regimen are useful in improving target attainment, but using a restricted target range has no impact on clinical outcomes.

Using bone marrow matrix to analyze meprobamate for forensic toxicological purposes.

Bone marrow (BM) analysis is of forensic interest for postmortem toxicological investigations where blood samples are unavailable or unusable. Due to the lack of studies, it remains difficult to interpret concentrations of xenobiotics measured in this matrix. Based on a statistical approach published previously to interpret meprobamate concentrations in bile and vitreous humor, we propose here a diagnostic test for interpretation of BM meprobamate concentrations from analysis of 99 sets of autopsy data. The mean age was 48 years (range 18-80 years, one unknown) for males and 50 years (range 19-80 years, one unknown) for females, with a male/female ratio at 0.768. A BM concentration threshold of 11.3 µg/g was found to be statistically equivalent to that of a blood meprobamate concentration threshold of 50 µg/ml in distinguishing overdose from therapeutic use. The intrinsic qualities of this diagnostic test were good with sensitivity of 0.82 and specificity of 0.92. Compared to previous tests published with the same objective on vitreous humor and bile, this study shows that BM is a useful alternative matrix to reveal meprobamate overdose when blood, vitreous humor, and bile are not available or unusable.

Gas chromatography-tandem mass spectrometry assay for the quantification of four benzodiazepines and citalopram in eleven postmortem rabbit fluids and tissues, with application to animal and human samples.

Pharmacokinetic studies and postmortem toxicological investigations require a validated analytical technique to quantify drugs on a large number of matrices. Three-step liquid/liquid extraction with online derivatization (silylation) ahead of analysis by gas chromatography-tandem mass spectrometry was developed and validated on rabbit specimens in order to quantify citalopram and 4 benzodiazepines (diazepam, nordazepam, oxazepam and temazepam) in 11 biological matrices (blood, urine, bile, vitreous humor, liver, kidney, skeletal muscle, brain, adipose tissue, bone marrow (BM) and lung). Since the 11 biological matrices came from the same animal species, full validation was performed on 1 matrix, bone marrow (considered the most complex), while the other 10 underwent partial validation. Due to non-negligible matrix effects, calibration curves were performed on each matrix. Within-day and between-day precision (less than 12.0% and 12.6%, respectively) and accuracy (from 88.9% to 106.4%) were acceptable on BM at both low and high concentrations. Assessment on the other matrices confirmed accuracy and within-day precision (less than 12%, and generally between 85.1% and 114.5%, respectively). The lower limit of quantification of the method was 1ng/g for nordazepam, 5ng/g for citalopram and 10ng/g for oxazepam, diazepam and temazepam. The combination of 3-step extraction and MS/MS detection provided good selectivity in all matrices, including the most lipid-rich. Application to real-case samples showed that the method was sensitive enough to describe distribution patterns in an animal experiment, and specific enough to detect molecules in highly putrefied samples from human postmortem cases.

Postmortem measurement of caffeine in bone marrow: influence of sample location and correlation with blood concentration.

Bone marrow (BM) analysis is of forensic interest in postmortem toxicological investigation in case of limited, unavailable or unusable blood samples. However, it remains difficult to determine whether a drug BM concentration is therapeutic or represents overdose, due to the lack of studies on this alternative matrix. Given the variations in BM composition in the body, sample location was suggested to be a relevant factor in assessing BM concentration. The aim of the present study was to compare postmortem caffeine concentrations in various BM sample locations and secondly to consider the correlation between BM and blood concentrations. Six BM samples (right and left side: proximal and medial femur and 5th rib) and a blood sample were collected from 21 forensic autopsies. Gas chromatography coupled to tandem mass spectrometry was performed. Blood caffeine concentrations ranged from 60 to 7591ng/mL. Femoral and rib BM concentrations ranged from 51 to 6171ng/g and 66 to 7280ng/g, respectively. Blood concentrations were always higher than BM concentrations. As a good correlation was demonstrated between blood and rib BM and between blood and the average of the four femoral BM concentrations, blood caffeine concentrations could be correctly extrapolated from BM concentrations. BM caffeine concentration was found to depend on sample location. Rib BM caffeine concentrations appeared to be systematically greater than averaged femur values and concentrations were much more variable between the 4 femur BM samples than between the 2 ribs. From a practical point of view, for caffeine analysis, rib BM appeared more relevant than femoral BM, which requires multisampling to overcome the concentration variability problem.

The acridone derivative MBLI-87 sensitizes breast cancer resistance protein-expressing xenografts to irinotecan.

The breast cancer resistance protein ABCG2 confers cellular resistance to irinotecan (CPT-11) and its active metabolite SN-38. We utilised ABCG2-expressing xenografts as a model to evaluate the ability of a non-toxic ABCG2 inhibitor to increase intracellular drug accumulation. We assessed the activity of irinotecan in vivo in SCID mice: irinotecan completely inhibited the development of control pcDNA3.1 xenografts, whilst only delaying the growth of ABCG2-expressing xenografts. Addition of MBLI-87, an acridone derivative inhibitor, significantly increased the irinotecan effect against the growth of ABCG2-expressing xenografts. In vitro, MBLI-87 was as potent as GF120918 against ABCG2-mediated irinotecan efflux, and additionally was specific for ABCG2. A significant sensitisation to irinotecan was achieved despite the fact that doses remained well below the maximum tolerated dose (due to the rather limited solubility of MBLI-87). This suggested that MBLI-87 is an excellent candidate to prevent drug efflux by ABCG2, without altering plasma concentrations of irinotecan and SN-38 after IP (intra-peritoneal) injections. This could constitute a useful strategy to improve drug pharmacology, to facilitate drug penetration into normal tissue compartments protected by ABCG2, and potentially to reverse drug resistance in cancer cells.

[Evaluation of left ventricular diastolic function in children by doppler tissue imaging]. / Evaluation de la fonction diastolique par Doppler tissulaire chez l'enfant.

Left ventricular diastolic function may change at an early stage in cardiac disease. It is often difficult to assess in daily practice. The use of Doppler tissue imaging at the annulus has been validated in adults. This method is little used in paediatrics and the physiological norms have not been established in children. Forty three children aged 7 days to 241 months were referred for a cardiological opinion with normal echocardiogrammes were included. Myocardial velocities were measured by Doppler tissue imaging of the left and right ventricular walls at different moments of the cardiac cycle in the apical 4-chamber view. A complete study was possible in 39 cases (91%). Doppler tissue imaging was not performed in one case and was incomplete on the right ventricle in 3 children. The median of the lateral mitral tissue E wave (Ea) was 16.3 cm/s and that of the right ventricle was 15.8 cm/s with a tissue Ea/Aa ratio of 2.6 and 1.6 respectively. The median of the tissue S waves was 8.8 cm/s for the left ventricular lateral wall and 13.3 cm/s for the right ventricular lateral wall. The E/Ea ratio of the left ventricular lateral wall was 5.9. Although the velocities of the left ventricular lateral wall were not related to the children's' age or size, the correlations between the E/Ea ratio and age and size were statistically significant. The myocardial velocities of the neonate were characteristic and different to those of the older paediatric population (slower Ea and S waves, faster Aa with a higher E/Ea ratio). The authors conclude that Doppler tissue imaging is feasible in clinical paediatric cardiology. Comparative studies with populations with cardiac disease are necessary to determine pathological values.

Quantitative measurement of propofol and in main glucuroconjugate metabolites in human plasma using solid phase extraction-liquid chromatography-tandem mass spectrometry.

A high-performance liquid chromatographic method coupled with tandem mass spectrometry detection has been developed for the determination of propofol and its main glucuroconjugate metabolites (propofol-glucuronide (PG), 1-quinol-glucuronide (1-QG) and 4-quinol-glucuronide (4-QG) in human plasma. All compounds were extracted with a single solid phase extraction procedure using Max Oasis cartridges. Propofol and thymol (internal standard) were analyzed using a C8 reversed-phase column with a mobile phase consisting of methanol-water (75:25, v/v) containing 0.025% NH(4)OH. Chromatography of glucuroconjugate metabolites and phenyl-beta-d-glucuronide (internal standard) was performed using a hydrophilic interaction liquid chromatography (HILIC) and a mixture of acetonitrile/water/ammonium acetate buffer (100 mM, pH 5, 87/1/12, v/v/v). Both chromatographic separations were achieved in isocratic mode allowing a rapid analysis without re-equilibration of the phase. The method is specific and sensitive with a range of 10-1500 ng mL(-1) for propofol and 1-QG, 20-3000 ng mL(-1) for PG and 25-3750 ng mL(-1) for 4-QG. The regression curves were linear for all compounds. The method is accurate and precise with intra-assay and inter-assay precision <8% and bias < or =6% for all compounds. This assay has allowed the successful measurement of propofol and its main glucuroconjugate metabolites in human plasma from 24 patients undergoing anaesthesia for elective partial hepatectomy surgery.

Hand preference in unimanual and bimanual tasks and postural effect on manual laterality in captive red-capped mangabeys (Cercocebus torquatus torquatus).

Hand preference in 11 captive red-capped mangabeys (Cercocebus torquatus torquatus) was examined under different conditions: a free situation during spontaneous food processing, three different postural conditions (brachiating, and bipedal and tripedal standing), and a situation involving bimanual processing. Generally, individual laterality was found regardless of the task and behavior involved. However, the number of monkeys with hand preferences and the strength of the preference increased with the complexity of the tasks. The monkeys exhibited a significantly higher and positive mean manual preference index (HI) when they were hanging than when they were quadrupedal or sitting. The strength of manual preference (ABS-HI) was in turn higher when the monkeys were hanging or bipedal than when they were quadrupedal. The strength of manual preference was higher for both the bimanual and experimental tasks than for unimanual tasks and spontaneous activities. Although our sample was too small to allow us to make any generalizations concerning lateral preferences in red-capped mangabeys, we propose some hypotheses about the influence of posture stability and task complexity.

Quantification of docetaxel and its main metabolites in human plasma by liquid chromatography/tandem mass spectrometry.

Docetaxel is an antineoplastic agent widely used in therapeutics. The objective of this study was to develop and validate a routine assay, using liquid chromatography coupled to tandem mass spectrometry (LC/MS/MS), for the simultaneous quantification of docetaxel and its main hydroxylated metabolites in human plasma. A structural analogue, paclitaxel, was used as the internal standard. Determination of docetaxel and four metabolites (M1, M2, M3 and M4) was achieved using only 100 microL of plasma. Liquid-liquid extraction was used for sample preparation, with extraction efficiency of at least 90% for all analytes. Detection used positive-mode electrospray ionization in selected reaction monitoring mode. The lower limit of quantification (LLOQ) was 0.5 ng/mL for all analytes. The assay was linear in the calibration curve range 0.5-1000 ng/mL and acceptable precision and accuracy (<15%) were obtained with concentrations above the LLOQ. This method was sufficiently selective and sensitive for quantification of metabolites in plasma from cancer patients receiving docetaxel chemotherapy, and is suitable for routine analyses during pharmacokinetic studies.

Hexose monophosphate shunt activities in human erythrocytes during oxidative damage induced by hydrogen peroxide.

Human red blood cells (HRBCs) were exposed to H(2)O(2) either as bolus or as a flux generated by a glucose-glucose oxidase system. H(2)O(2) concentrations were in the range 10(-5)-10(-3) M and exposure times to the oxidative stress were 10 min and 60 min. The production of NADPH by the hexose monophosphate shunt (HMPS) was accurately measured by gas chromatography-isotope ratio mass spectrometry as the production of (13)CO(2) from [1-(13)C]glucose. Depending on the duration of exposure and H(2)O(2) concentration, the production of (13)CO(2) by HRBCs under a flux of H(2)O(2) was increased two- to eight-fold in comparison with that obtained under a bolus of H(2)O(2). Under flux stimulation, spectral data show the formation of compound I, and a red shift caused by the presence of compounds II and III, whereas under a bolus stress no obvious spectra changes were observed. Inhibition of catalase by 3-amino-1,2,4-triazole (3-AT) or by sodium azide, followed by a bolus of H(2)O(2) led to a two- to five-fold increases in (13)CO(2) production compared with controls, depending on H(2)O(2) concentration. In contrast, 3-AT-inhibited HRBCs exposed to a flux of H(2)O(2) did not present an increase in (13)CO(2) production. The present paper emphasizes the importance and role of NADPH production following a bolus or a flux stimulation of H(2)O(2). The difference between responses in HMPS activities under the two types of stress could be related to a different balance of activity between 'catalatic' and 'peroxidatic' modes of catalase following H(2)O(2) exposure.

Propofol metabolites in man following propofol induction and maintenance.

BACKGROUND: The pharmacokinetics of propofol in man is characterized by a rapid metabolic clearance linked to glucuronidation of the parent drug to form the propofol-glucuronide (PG) and sulfo- and glucuro-conjugation of hydroxylated metabolite via cytochrome P450 to produce three other conjugates. The purpose of this study was to assess the urine metabolite profile of propofol following i.v. propofol anaesthesia in a Caucasian population. METHODS: The extent of phase I and phase II metabolism of propofol was studied in 18 female and 17 male patients after an anaesthesia induced and maintained for at least 4 h with propofol. The infusion rates (mg kg(-1) h(-1)) of propofol were (mean (SD)) 4.1 (1.0) and 4.5 (1.3) for males and females, respectively. Urine was collected from each patient for the periods 0-4, 4-8, 8-12, and 12-24 h after the start of propofol administration. In a preliminary study, the three main glucuro-conjugated metabolites were isolated from urine and characterized by magnetic resonance spectroscopy. The quantification of these metabolites for the different collection periods was then performed by a HPLC-UV assay. RESULTS: Total recovery of propofol in the metabolites studied amounts to 38%, of which 62% was via the PG metabolite and 38% via cytochrome P-450. This percentage is significantly higher than that previously reported from patients after a bolus dose of propofol. Extreme values for PG (0-24 h period) were included from 73 to 49%. There was no significant difference between female and male patients in the metabolite ratio. CONCLUSIONS: We conclude that the extent of hydroxylation in propofol metabolism was higher than in previous findings after administration of anaesthetic doses of propofol. Moreover, the ratio between hydroxylation and glucuronidation of propofol is subject to an inter-patient variability but this does not correlate with the dose of propofol. However, the variation of the metabolite profile observed in the present report does not seem to indicate an extended role of metabolism in pharmacokinetic variability.