Hair Analysis of Methoxphenidine in a Forensic Chemsex Case

Methoxphenidine (MXP, 2-MeO-diphenidine) is a dissociative anaesthetic drug of the diarylethylamine type, recently introduced for recreational purposes through the online-based sale of new psychoactive substances (NPS). The concentration of MXP in hair has never been reported, either in cases of chemsex use or in fatal cases. A 55-year-old man was found dead at home the morning after a chemsex party. Toxicological analyses indicated high concentrations of MXP in femoral blood (606 µg/L), cardiac blood (254 µg/L), and hair (13 ng/mg). We also identified 3-MMC in femoral blood (traces) and urine (238 µg/L). The concentrations of all other drugs were consistent with living subjects. This case highlights the risk of methoxphenidine poisoning in the context of chemsex and emphasises the importance of including NPS in post-mortem toxicology examinations.

Suitability of infrared spectroscopy for drug checking in harm reduction centres

Drug checking is a service for people who use drugs that includes product analysis and an individual interview including results feedback and harm reduction counselling. It uses different analytical methods but few studies demonstrate their value in current practice. The main objective of this work is to compare the analytical performance of IR spectroscopy to laboratory reference method in the context of drug checking in a harm reduction centre. The secondary objectives are to carry out a description of the people who use drugs requesting a product analysis, and to compare the assumed compositions of products purchased with their real compositions. During 2018, all requests for drug testing analysis were included for on-site analysis by IR spectrometry in a harm reduction center and verified by the reference method (UPLC-HRMS) at Bordeaux University Hospital Center. Socioeconomic and product data were also collected. One hundred and thirty-six samples were collected. The results obtained with IR and UPLC-HRMS were compared. IR spectrometry results did not match with reference method in 8 % (n=11) of cases, corresponding to blotters, cannabis and some psychoactive substances present in mixture or in small quantities. Among the products collected, only 5.1 % (n=7) did not correspond to the declared product, either alone or with adulterants. The IR spectrometer allows a simple and rapid detection of at least one molecule, most often the one of interest. However, it is limited to powder and tablet type matrices and is not suitable for blotters, cannabis, mixed or low content substances for which high resolution mass spectrometry remains the reference method.

Efficiency and safety of oxcarbazepine in mood disorders: A naturalistic study exploring the interest of plasma dosages

Objective

To investigate whether measurement of plasma levels can predict tolerance to oxcarbazepine (OXC).

Methods

We reviewed medical records to identify all inpatients consecutively treated by OXC at the University Department of Psychiatry in Bordeaux. Adverse effects were rated before treatment onset, at day 3, then every week and at discharge or at discontinuation. Residual hydroxy-OXC concentrations were measured on blood samples at the same periods.

Results

OXC was prescribed to 20 patients with bipolar (n = 18) or schizoaffective bipolar-type disorder (n = 2). Reported side effects were transient and occurred mostly at the beginning of the treatment. Three patients stopped OXC because of severe cutaneous side effects. Residual hydroxy-OXC plasma levels were similar in patients with or without occurrence of side effects at all times of assessment.

Conclusion

Our data suggest that the occurrence of severe side-effects is relatively high with OXC. Measurement of plasma OXC levels does not appear to be of interest in clinical practice since plasma concentrations are not predictive of the occurrence of side effects.

Biomonitoring of occupational exposure to 5-FU by assaying α-fluoro-β-alanine in urine with a highly sensitive UHPLC-MS/MS method

5-Fluorouracil (5-FU) is one of the most widely antineoplastic drugs handled by healthcare professionals.

High throughput routine determination of 17 tyrosine kinase inhibitors by LC-MS/MS

Several studies have shown that therapeutic drug monitoring of tyrosine kinase inhibitors (TKI) can improve their benefit in cancer. An analytical tool has been developed in order to quantify 17 tyrosine kinase inhibitors and 2 metabolites in human plasma (afatinib, axitinib, bosutinib, crizotinib, dabrafenib, dasatinib, erlotinib, gefitinib, imatinib, lapatinib, nilotinib, ponatinib, regorafenib, regorafenib M2, regorafenib M5, ruxolitinib, sorafenib, sunitinib, vandetanib). Drugs were arranged in four groups, according to their plasma concentration range: 0.1-200ng/ml, 1-200ng/ml, 4-800ng/ml and 25-5000ng/ml. Solid phase extraction was used and separation was performed with HPLC using a gradient system on a solid core particle C18 column (5×2.1mm, 1.6μm). Ions were detected with a triple quadrupole mass spectrometry system. This assay allows rapid determination of 19 TKI in less than 5min per run. This high throughput routine method will be useful to adjust doses of oral anticancer drugs in order to improve treatments efficacy.

An UPLC-MS/MS method for the quantification of BRAF inhibitors (vemurafenib, dabrafenib) and MEK inhibitors (cobimetinib, trametinib, binimetinib) in human plasma. Application to treated melanoma patients

Targeted therapies for cancers are fast-growing therapies. For instance kinase inhibitors such as BRAF inhibitors (BRAFi) and MEK inhibitors (MEKi) are increasingly used to treat malignant melanoma. The metabolic profile of these drugs can result in great interindividual variability, justifying therapeutic drug monitoring (TDM). We describe a rapid and specific method for quantification of 2 BRAFi (vemurafenib, dabrafenib) and 3 MEKi (cobimetinib, trametinib and binimetinib). Chromatography was performed on a Waters Acquity-UPLC system with CORTECS C18+ column, under a gradient of 10% acetic acid in water/acetonitrile. An Acquity-TQD® with electrospray ionization was used for detection. Samples were prepared by solid phase extraction (Oasis® MCX microElution) before injection in the system. Calibration curves ranges from 0.4 to 100μg/ml for vemurafenib, from 1 to 1000ng/ml for dabrafenib, from 0.5 to 500ng/ml for cobimetinib and binimetinib, and from 0.75 to 250ng/ml for trametinib. At all concentrations the bias was within ±15% of the nominal concentrations and precision was ≤15%. All results were within the acceptance criteria of the EMA guidelines on method validation. This rapid, sensitive and specific UPLC-MS/MS method can perform simultaneous quantification of targeted therapies used in malignant melanoma and is usable for routine TDM.

Highly sensitive LC-MS/MS methods for urinary biological monitoring of occupational exposure to cyclophosphamide, ifosfamide, and methotrexate antineoplastic drugs and routine application

Highly sensitive ESI-LC-MS/MS methods were developed for urinary biological monitoring of occupational exposure to cyclophosphamide (CP), ifosfamide (IF), and methotrexate (MTX), which are hazardous antineoplastic drugs frequently handled by healthcare professionals. Extraction methods consisted of liquid/liquid extraction for simultaneous urinary CP and IF assays, and of solid phase extraction for the urinary MTX assay. A good linearity (r2>0.997), precision (CV<14.6%), and accuracy (bias<9.9%) were achieved for all compounds. The limit of detection (LOD) was 10pg/ml and the lower limit of quantification (LOQ) was 20pg/ml for all three drugs. Applying these methods in routine, more than 116 healthcare professionals occupationally exposed to antineoplastic drugs were monitored and 635 urines were analysed. Eleven healthcare professionals (9.5%) were found to be contaminated to at least one of the three antineoplastic drugs. Among analysed urines, 22 samples were found positives. The measured concentrations ranged from 20.1 to 1850pg/ml and, for six samples, concentrations were at CP trace level, between the LOD and LOQ values (10-20pg/ml). Such efficient analytical tools combining high specificity with high sensitivity are essential for reliable detection and routine biological monitoring of healthcare professionals occupationally exposed to these widely used antineoplastic drugs. These methods allow to monitor the healthcare professionals exposure to antineoplastic drugs in the aim to assess the effectiveness of collective and individual protective measures.

Acute Methiopropamine Intoxication After "Synthacaine" Consumption

Use of methiopropamine (MPA), a synthetic metamfetamine analog, has been detected since 2011 in Europe, but there is limited information on its acute toxicity. A 30-year-old man was admitted to the emergency department in a confused state, with paranoid delusion, auditory and visual hallucinatory experiences, and incoherent speech following the use of "synthacaine" (a slang term derived from "synthetic" and "cocaine"). Toxicological screening for pharmaceuticals and drugs of abuse by liquid chromatography-diode-array detector, gas chromatography-mass spectrometry and liquid chromatography-tandem mass spectrometry (LC-MS-MS) detected MPA, which was subsequently quantified by a specific LC-MS-MS method. Of note, 13 h after presentation to the emergency department, the plasma concentration of MPA was 14 ng/mL. This case report confirms the toxicity of MPA and the need for toxicological analysis to confirm the substance actually ingested by users of new psychoactive substances.

Relationship between imatinib trough concentration and outcomes in the treatment of advanced gastrointestinal stromal tumours in a real-life setting

BACKGROUND

Imatinib has dramatically improved the prognosis of advanced gastrointestinal stromal tumours (GISTs). Clinical trial data showed that patients with trough imatinib plasma concentrations (Cmin) below 1100 ng/ml (quartile 1) had shorter time to progression, but no threshold has been defined. The main objective of this study was to investigate in advanced GIST whether a Cmin threshold value associated with a longer progression-free survival (PFS) could be specified. This would be the first step leading to therapeutic drug monitoring of imatinib in GIST.

PATIENTS AND METHODS

Advanced GIST patients (n=96) treated with imatinib 400 mg/d (41 stomach, 34 small bowel, and 21 other primary site localisations) were prospectively included in this real-life setting study. Routine plasma level testing imatinib (Cmin) and clinical data of were recorded prospectively.

RESULTS

Small bowel localisation was associated with an increased relative risk of progression of 3.09 versus stomach localisation (p=0.0255). Mean Cmin (±standard deviation) was 868 (±536) ng/ml with 75% inter-individual and 26% intra-patient variability. A Cmin threshold of 760 ng/ml defined by log-rank test was associated with longer PFS for the whole population (p=0.0256) and for both stomach (p=0.043) and small bowel (p=0.049) localisations when analysed separately. Multivariate Cox regression analysis found that Cmin above 760 ng/ml was associated with 65% reduction risk of progression (p=0.0271) in the whole population independently of the anatomical localisation.

CONCLUSION

Concentration of imatinib significantly influences duration of tumour control treatment in GIST patients with a Cmin threshold of 760 ng/ml associated with prolonged PFS in real-life setting.

Therapeutic drug monitoring of imatinib in chronic myeloid leukemia: experience from 1216 patients at a centralized laboratory

This study set out to examine in a large real-life cohort of patients with chronic myeloid leukemia (CML) the impact of imatinib threshold of 1000 ng/mL on molecular response, as suggested in a small subset of patients. Patient plasma samples were submitted from around France to a central facility, free of charge under the auspices of the European Treatment and Outcome Study (EUTOS) for CML. Submitting physicians were required to complete an 'imatinib monitoring request form', including details of why therapeutic drug monitoring (TDM) was requested, dose and duration of imatinib treatment, cytogenetic and molecular response, adverse events, and concurrent medications. Imatinib trough plasma concentration (C(min)) was measured at the central facility. Among 1985 eligible plasma samples analyzed, from 1216 CML patients, imatinib C(min) correlated positively with reported imatinib dose, but interpatient variability in C(min) was high (60%). A logistic regression analysis revealed that treatment duration and imatinib C(min) > 1000 ng/mL were significantly associated with major and complete molecular responses with odds ratios of 1.69 and 2.08, respectively. These data support in real-life setting that imatinib C(min) threshold of 1000 ng/mL is associated with major and complete molecular response and that TDM could play an important role in dose optimization.

Suicide with cisatracurium and thiopental: forensic and analytical aspects

The suicide of a 43-year-old male by intravenous injection of cisatracurium, a non-depolarizing neuromuscular blocking agent, and thiopental, an ultra-short-acting barbiturate, is presented. Systematic toxicological screening by gas chromatography-mass spectrometry (GC-MS), liquid chromatography (LC)-diode-array detection, and LC-MS-MS confirmed the presence of thiopental. A large peak in the GC-MS chromatogram was matched by the Pfleger-Maurer library as corlumine, but neither atracurium neither its metabolite, laudanosine, were detected. To confirm the absence or the presence of laudanosine in the blood sample, an ultra-performance liquid chromatography-MS-MS method for cisatracurium and laudanosine quantification was developed. The calibration range was 2.5-500 ng/mL for laudanosine and 10-500 ng/mL for cisatracurium. The biases were lower than 12.3%. Intraday and interday precisions, expressed as coefficient of variation, were lower than 13.3%. This method allowed to confirm the presence of laudanosine and measurement of laudanosine in all samples. The femoral blood concentration was therapeutic (0.46 μg/mL). This case report documents a possible analytical pitfall and describes a simple and fast method for cisatracurium determination. Moreover, the purpose of this case report was to document the postmortem redistribution of cisatracurium and laudanosine, which could help make it possible to interpret tissue or cardiac blood concentrations in forensic cases where femoral blood is not available.

Postmortem redistribution of two antipsychotic drugs, haloperidol and thioridazine, in the rat

Antipsychotic drugs may be associated with arrhythmia, ventricular fibrillation, or torsades de pointes, which can result in sudden death. These drugs could therefore be found in postmortem toxicological analyses of autopsy specimens following unexplained sudden death. The drug concentrations in tissues and body fluids change between the death and postmortem specimens collection because of postmortem redistribution. For this reason, it is often difficult to interpret the postmortem analysis. The aim of this study was to investigate postmortem redistribution of the two cardiotoxic antipsychotic drugs, haloperidol and thioridazine, in order to interpret the postmortem analysis. We have chosen the rat as an animal model. The rats received 1 mg/kg of haloperidol and 5 mg/kg of thioridazine by intraperitoneal injection. They were sacrificed and left at room temperature for 2, 6, 12, 24, or 48 h, at which times blood and tissue samples were taken. The drug analyses in tissues and blood were done using a liquid chromatography- tandem mass spectrometry method. Our results show that there is a redistribution of the two drugs from the lung to the cardiac blood. The concentration of the antipsychotic drugs in the lung decreased rapidly, whereas in the cardiac blood, this concentration increased within the first 2 h postmortem. By 48 h after death, the concentrations of the antipsychotic drugs were about twice as high as the initial concentrations in the cardiac blood. For the lungs, a decrease of 50% was observed between 0 and 48 h. Only myocardium and muscle concentrations did not change with the postmortem delay.

Accuracy of information on substance use recorded in medical charts of patients with intentional drug overdose

Psychoactive substance use is a risk factor for suicidal behavior and current intoxication increases the likelihood of serious intentional drug overdose (IDO). The objective was to assess the accuracy of information on substance use recorded in medical charts using toxicological assays as a reference in subjects admitted for IDO to an emergency department. Patients (n=1190) consecutively admitted for IDO were included. Information on substance use was recorded in routine practice by the emergency staff and toxicological assays (cannabis, opiate, buprenorphine, amphetamine/ecstasy, cocaine, LSD) were carried out in urine samples collected as part of routine management. The information on substance use was recorded in medical charts for 24.4% of subjects. A third of subjects (27.5%) were positive for toxicological assays. Recorded substance use allowed correct classification of nearly 80% of subjects. However, specificity (88.6%) was better than sensitivity (54.2%). Compared with toxicological assays, medical records allowed identification of only half of the subjects with current substance use. The usefulness of systematic toxicological assays during hospitalization for IDO should be assessed in further studies exploring whether such information allows medical management to be modified and contributes to improving prognosis.

Quantification of Eight New Antidepressants and Five of their Active Metabolites in Whole Blood by High-Performance Liquid Chromatography-Tandem Mass Spectrometry

A liquid chromatography-tandem mass spectrometry method is described for the blood determination of selective serotonin reuptake inhibitors (fluoxetine, paroxetine, sertraline, fluvoxamine, and citalopram), serotonin noradrenaline reuptake inhibitors (milnacipram and venlafaxine), a noradrenergic and specific serotoninergic antidepressant (mirtazapine) and five of their active metabolites (norfluoxetine, desmethylcitalopram, didesmethylcitalopram, desmethylvenlafaxine, and desmethylmirtazapine). After a liquid-liquid extraction from blood, the compounds and the internal standard (methylrisperidone) were eluted on a XTerra RP18 column with a gradient of acetonitrile/ammonium formate buffer 4 mmol/L pH 3.2. They were then detected by electrospray ionization mass spectrometry with multiple reaction monitoring mode. The calibration curves were linear over the range 5-500 ng/mL (20-2000 ng/mL for venlafaxine and desmethylvenlafaxine). The limit of quantification was set at 5 ng/mL for each compound (except for venlafaxine and desmethylvenlafaxine: 20 ng/mL). The bias were lower than 12%. Intraday and interday precisions, expressed as variation coefficient, were lower than 11%. The extraction recoveries were between 70 and 90% except for desmethylmirtazapine, desmethylvenlafaxine, milnacipram, and didesmethylcitalopram. This specific and sensitive method allows management of intoxication and is suitable for the routine determination of antidepressants in forensic investigations.

Trough plasma imatinib concentrations are associated with responses to standard-dose imatinib in chronic myeloid leukemia and could improve its clinical management

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Background: Variable responses to imatinib in the treatment of myelogenous leukemia (CML) are incompletely understood. Previous studies focused on cellular mechanisms of resistance to imatinib. Another hypothesis for variable response lies in pharmacokinetic variability that may reduce drug exposure in patients receiving imatinib. Methods: Using high- performance liquid chromatography-tandem mass spectrometry, we assessed trough plasma imatinib concentrations at steady state (Cmin) in more than 150 CML patients. Major molecular response (MMR) was defined as a 3 logarithm reduction of BCR-ABL transcripts, quantified from peripheral blood using Q-RTPCR. In addition, suboptimal response criteria defined by the European Leukemianet were used to increase doses of imatinib. Results: i) we assessed Cmin in 85 CML patients and demonstated a correlation with imatinib doses (median values 813, 1,135, 1,709 ng/ml for respectively 300,400, 600 mg/day). ii) for 68 patients after at least one year's treatment mean Cmin were significantly higher in the group with MMR (34 patients) than in the group without (1,452.1±649.1 ng per milliliter vs. 869.3±427.5 ng per milliliter, P<0.001) whereas there was no difference in the imatinib daily dose. For Cmin and their discrimination potential for MMR, the area under receiver-operating characteristic curve was 0.775, with best sensitivity (76.5 percent) and specificity (70.6 percent) at a plasma threshold of 1,002 ng per milliliter. iii) dose escalation of imatinid, 400mg up to 600mg was proposed in 8 patients in suboptimal response (3 according to cytogenetic criteria and 5 according to molecular criteria). The median Cmin increase from 573 ng/ml [181–1,376] to 1,139 ng/ml [733–2,262] and 5 patients had a cytogenetic (n=3) or a molecular (n=2) response. Conclusions: Monitoring of imatinib plasma levels could be very useful for the management of CML patients, or should at least be checked in the case of treatment failure or suboptimal response or in patients nonadherent with imatinib or with a drug-drug interaction suspicion.

No significant financial relationships to disclose.

Quantification of Tricyclic Antidepressants and Monoamine Oxidase Inhibitors by High-Performance Liquid Chromatography-Tandem Mass Spectrometry in Whole Blood

Here we describe a liquid chromatography-tandem mass spectrometry method for the blood determination of tricyclic antidepressant drugs (amitriptyline, clomipramine, trimipramine, and imipramine, doxepin, mianserin, maprotyline, dosulepine, amoxapine), their active metabolites (desipramine, nortriptyline, demethylclomipramine, and nordoxepin), and monoamine oxidase inhibitors (toloxatone and moclobemide). A nontricyclic antidepressant (viloxazine) and two other anxiolytic drugs (buspirone and hydroxyzine) that could be encountered in toxicology have been included to this method. After a liquid-liquid extraction from blood, the compounds and their internal standard (methylrisperidone) were eluted on a XTerra RP18 column with a gradient of acetonitrile/ammonium formate buffer 4 mmol/L (pH 3.2). They were then detected by electrospray ionization mass spectrometry with multiple reaction monitoring mode. The calibration curves were linear over the range 5-100 ng/mL. The limit of quantification was 2 ng/mL for each compound. The bias were lower than 10%. Intraday and interday precisions, expressed as variation coefficient, were lower than 13%. The extraction recoveries were between 60 and 80% except for moclobemide, viloxazine, and toloxatone (10-60%). This specific and sensitive method allows management of intoxication and is suitable for the routine determination of antidepressants in forensic investigation.

Trough imatinib plasma levels are associated with both cytogenetic and molecular responses to standard-dose imatinib in chronic myeloid leukemia

Using high-performance liquid chromatography-tandem mass spectrometry, we assessed trough imatinib plasma levels in 68 patients with chronic myeloid leukemia (CML) who responded or not to standard-dose imatinib, after at least 12 months' treatment. Mean trough imatinib plasma levels were significantly higher in the group with complete cytogenetic response (56 patients) than in the group without (12 patients; P = .03) and higher in the group with major molecular response (MMR) than in the group without (34 patients [1452 +/- 649 ng/mL] versus 34 patients [869 +/- 427 ng/mL]; P < .001). Regarding trough imatinib plasma levels and their discrimination potential for MMR, the area under receiver operating characteristic curve was 0.775, with best sensitivity (77%) and specificity (71%) at a plasma threshold of 1002 ng/mL. Therefore, monitoring of imatinib plasma levels could be very useful for the management of patients with CML or should at least be checked in the case of treatment failure or suboptimal response.

Bioavailability and urinary excretion of isoflavones in humans: effects of soy-based supplements formulation and equol production

Soy isoflavones (IF) are of particular interest for their possible estrogenic effects on the symptoms of menopause. The bioavailability of IF is clearly a factor influencing their biological activity. The first aim of this study was to elucidate the impact of the matrix process and especially the formulation of soy-based capsules on IF bioavailability. Twelve healthy volunteers were recruited for a randomized, double-blind, two-way crossover trial and received a single dose of the two soy-based formulations, one containing a pure soy standardized extract of IF, and the other containing soy flour in addition to the standardized extract of IF. Using a new and validated ELISA method, we measured the plasma and urinary concentrations of genistein, daidzein and its metabolite equol. Based on European Medicine Evaluation Agency recommendations, the main pharmacokinetic parameters allowed us to demonstrate the bioequivalence of the two formulations, indicating that the presence or absence of soy flour did not alter either the absorption or the elimination of daidzein and genistein. As bioequivalence was demonstrated, we pooled data collected during the two study-periods to address another original issue: Did the ability to produce equol affect the bioavailability of daidzein? We demonstrated that daidzein excretion was significantly lower in equol producers compared with equol non producers over the entire elimination period of the soy IF. This difference disappeared when equol excretion was added to daidzein excretion in equol producers. Our results indicated that the production of equol could partly explain the difference in daidzein bioavailability after IF ingestion.

Fully Automated Analytical Method for Mycophenolic Acid Quantification in Human Plasma Using On-line Solid Phase Extraction and High Performance Liquid Chromatography With Diode Array Detection

We have developed a new fully automated method for mycophenolic (MPA) acid quantification in plasma to optimize therapeutic drug monitoring of tranplant patients. This method involved solid-phase extraction on disposable extraction cartridges and reversed-phase high-performance liquid chromatography with diode array detection. Solid-phase extraction was performed automatically by an automated sample with extraction catridges system. After washing, MPA was eluted from the cartridge onto a Chromolith RP-18e column. MPA and the internal standard were detected at 306 nm. The retention time of MPA was 6.3 minutes. The developed method was linear from 0.2 to 20 microg/mL. The limit of quantification was 0.2 microg/mL. The method showed a good precision with intraday and interday variation coefficient less than 6%. The intraday accuracy ranged from 97.6% to 100.4% and the interday accuracy varied from 97.1% to 100.8%. The extraction efficiency was greater than 90%. This method is simple and shows a good specificity with respect to commonly co-prescripted drugs.

Myocardium distribution of sertindole and its metabolite dehydrosertindole in guinea-pigs

Sertindole, like other atypical antipsychotics, has been shown to increase the action potential duration and QT interval in a concentration dependent manner, in in vitro electrophysiological studies. However, this does not always translate into increased duration of the QT interval, increased risk of torsade de pointes or sudden death in clinical practice. The reasons for these apparent discrepancies are unclear and many studies have underscored the importance of the interpretation of in vitro electrophysiological data in the context of other pharmacodynamic (e.g. cardiac ion channels target, receptor affinity) and pharmacokinetic parameters (total plasma drug concentration and drug distribution). To address the possible relevance of the concentrations used in experimental studies, the myocardium distribution of sertindole and its metabolite was determined after single and repeated intraperitoneal administration to guinea-pigs. The data suggest that the plasma concentration appears to predict the concentration in the myocardium and that the myocardium concentrations of sertindole are 3.1 times higher than plasma concentrations. Using these data, the relevance of in vitro electrophysiological studies to clinical plasma concentrations has been appraised.

Clonal analysis of HIV-1 variants in proviral DNA during treatment interruption in patients with multiple therapy failures

BACKGROUND

Treatment interruption (TI) in antiretroviral-treated patients on virological failure (VF) often results in a shift from resistant to wild-type HIV-1 in plasma. A clonal analysis was set out to determine the importance of archiving of resistant HIV-1 variants during TI and its relationship with the occurrence of a VF after treatment resumption.

METHODS

A fragment of the pol gene was cloned and sequenced from peripheral blood mononuclear cells DNA sampled at the end of TI. Clonal sequences were compared to bulk plasma sequences determined before TI, after TI and at VF.

RESULTS

Four patients were enrolled; all had a complete reversion to wild-type HIV-1 at the end of TI. In two patients with subsequent VF, archiving of minority resistant variants was detected in proviral DNA. Archived resistant variants were found to be phylogenetically linked to sequences detected before TI and at VF, suggesting the re-expansion of resistant HIV-1 from archived quasi-species.

CONCLUSION

In patients having a TI in the context of VF, archiving of resistant HIV-1 variants in proviral DNA can be involved into the mechanisms of further VF after treatment resumption.

Quantification of Imatinib in Human Plasma by High-Performance Liquid Chromatography-Tandem Mass Spectrometry

Imatinib, also known as Gleevec or Glivec, is a selective tyrosine kinase inhibitor currently used for the treatment of Philadelphia chromosome-positive chronic myeloid leukemia (CML) and for other malignant pathologies. We have developed a LC-MS-MS [corrected] method that could be used for imatinib therapeutic drug monitoring in plasma. After a liquid-liquid extraction, the imatinib and its deuterated internal standard were eluted on an XTerra RP18 column with a gradient of acetonitrile-ammonium formiate buffer 4 mmol/L, pH 3.2. Imatinib was detected by electrospray ionization mass spectrometry with multiple reaction-monitoring mode. The calibration curves were linear over the range 10-5000 ng/mL. The limit of quantification was set at 10 ng/mL. The bias was lower than 8%. Intra-day and inter-day precisions were lower than 8%. The extraction recovery was higher than 90%. This method is simple, adapted to routine application, and allows accurate therapeutic monitoring of imatinib. It can be used to evaluate patient adherence to daily oral therapy, drug-drug interactions, or pharmacokinetic/pharmacodynamic relationships.

Atypical antipsychotics: from potassium channels to torsade de pointes and sudden death

Syncope and sudden death are features of schizophrenia that can be attributed to ischaemic heart disease, the use of antipsychotics (because of proarrhythmia or other reasons such as pharyngeal dyskinesia) or the psychiatric disease itself. Cases have been described with most antipsychotics and have led to the withdrawal, temporary suspension from the market or restricted use of antipsychotics, such as sultopride, droperidol, sertindole or thioridazine. Reviewing the available data shows that all antipsychotics tested affect the cardiac potassium channel, with the concentration that produces 50% inhibition (IC50) ranging from 1 nmol/L (haloperidol) to 6 micromol/L (olanzapine). Experimental in vitro or in vivo electrophysiological studies have shown a dose-dependent increase in the duration of the action potential with various degrees of indicators of serious arrhythmogenicity. However, this does not always translate clinically into an increased duration of the QT interval or increased risk of torsade de pointes or sudden death in clinical trials or pharmacoepidemiological studies. In turn, QT prolongation in clinical trials does not always translate to an increased risk of torsade de pointes or sudden death. The reasons for these apparent discrepancies are unclear and could be related to insufficiently powered field studies, low plasma and tissue drug concentrations with reference to in vitro data or drug effects on other receptors or ion channels that have a protective effect. Alternatively, risks that were not apparent from preclinical or clinical data could be related to the use of the drug in high-risk patients, metabolic interactions or other factors that would only be encountered in large postmarketing populations. The assessment of cardiovascular safety, both preclinical and during premarketing clinical trials, needs to be supported by appropriately powered pharmacoepidemiology studies.

Simplified ultraviolet liquid chromatographic method for determination of sertindole, dehydrosertindole and norsertindole, in human plasma

An ultra-violet high-performance liquid chromatographic method was developed for the determination of sertindole, an atypical antipsychotic drug and its main metabolites dehydrosertindole and norsertindole, in human plasma. With a small sample volume, after a single-step liquid-liquid extraction, the compounds were separated on a reversed-phase XTerra RP(18) column, eluted with 45% of acetonitrile and 55% of ammonium acetate buffer (0.05 M, adjusted pH 8) and detected at 256 nm within 11 min. This method shows a good linearity for plasma concentration between 5-100 ng/ml and 100-1000 ng/ml, a good precision (inter and intra day CV < 11%) and a good inter-assay accuracy (bias < 11%). The limit of quantification concentration was 5 ng/ml. The absolute recovery of sertindole was higher than 99%. This rapid and sensitive method could be used for therapeutic drug monitoring as well as for overdose management.

Determination of myocardium to plasma concentration ratios of five antipsychotic drugs: comparison with their ability to induce arrhythmia and sudden death in clinical practice

Reviewing available data shows that most of antipsychotic drugs are associated with arrhythmia and sudden death. Experimental studies have shown a HERG channel blockade, a dose-dependent increase in duration of action potential or of QT interval, with various degrees of indicators of serious arrhythmogenicity. However, it seems difficult to relate these in vitro and in vivo preclinical models to clinical findings, in part, because the relationship between concentrations used and in vivo tissue concentrations during treatment in man is not known. Consequently, we established the myocardium to plasma concentration ratios for a series of antipsychotic drugs by intraperitoneal administration of different level doses to the guinea pig. Then, we compared these values to their ability to induce arrhythmia or torsade de pointes in clinical practice. The myocardium to plasma concentration ratios were 2.2 for clozapine, 2.7 for olanzapine, 3.1 for sertindole, 4.5 for risperidone, and 6.4 for haloperidol. These data suggest that when the ratio is higher than 4, arrhythmia and sudden death may be expected. On the contrary, when the ratio is less than 3, little effect may be predicted. These results underscore the importance of interpreting HERG channel data and electrophysiological data in the context of other pharmacokinetic parameters such as myocardium to plasma distribution.