Plasma concentrations of antiretroviral drugs in a successful 4-days-a-week maintenance treatment strategy in HIV-1 patients (ANRS 170-Quatuor trial).

OBJECTIVES: Charaterization of the plasma concentrations of antiretrovirals in a 4-days-a-week maintenance treatment strategy in the ANRS-170-QUATUOR study. METHODS: Patients were randomized in two groups receiving triple therapy taken 4-days-ON and 3-days-OFF (4/7) or continuous therapy (7/7). Plasma antiretroviral concentrations were monitored during the 'ON-treatment period' (Day 3 or 4 of the 4-day treatment block) and the 'OFF-treatment period' (Day 3 of the 3-day drug cessation) for the 4/7 group, or before the daily drug intake for the 7/7 group, until week-48 (W48). After W48, all patients switched to the 4/7 strategy and were followed until W96. RESULTS: W0 measured concentrations were comparable in both groups, except for raltegravir, concentrations of which were higher in the 4/7 group, and were all above the values usually recommended to be effective in therapeutic drug monitoring. Comparison of ON-period median concentrations between the two groups showed a statistical difference for rilpivirine [88 ng/mL (interquartile range (IQR) = 64-112) for 4/7 arm versus 130 ng/mL (82-160) for 7/7 arm, P < 0.001] and tenofovir [tenofovir disoproxil fumarate: 93 ng/mL (73-135) for 4/7 arm versus 117 ng/mL (83-160) for 7/7 arm, P < 0.001; tenofovir alafenamide: 11 ng/mL (7-15) for 4/7 arm versus 14 ng/mL (11-18) for 7/7 arm, P = 0.001]. Median OFF concentrations were significantly lower (P < 0.001) at the 48 week analysis for all medications except for raltegravir (P = 0.493) and atazanavir (P = 0.105), for which the numbers of patients were very small. CONCLUSIONS: The 4/7-day treatment option led to antiretroviral blood levels close to continuous treatment after the four consecutive days of medication, and to low levels at the end of the non-treatment period.

Correlation between Saliva Levels and Serum Levels of Free Uremic Toxins in Healthy Volunteers.

The objective of the present study was to investigate the putative correlation between the saliva concentration and free serum concentration for 10 uremic toxins (UTs; eight protein-bound solutes: 3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid (CMPF), hippuric acid (HA), indole-3-acetic acid (3-IAA), indoxyl sulfate (I3S), kynurenic acid (KA), kynurenine (KYN), p-cresyl glucuronide (pCG), and p-cresyl sulfate (pCS); two free, water-soluble, low-molecular weight solutes: phenylacetylglutamine (PAGN) and trimethylamine N-oxide (TMAO); and three precursors: tyrosine (Tyr), phenylalanine, and tryptophan). Saliva samples and blood samples were collected simultaneously from 18 healthy volunteers. After the addition of internal standards, 50 µL of saliva or serum were precipitated with methanol. UTs and precursors were quantified using a validated LC-MS/MS method. The saliva-serum correlation was statistically significant (according to Spearman's coefficient) for six UTs (TMAO, HA, I3S, pCS, 3-IAA, and CMPF). Tyr presented a weak saliva-serum correlation (p = 0.08), whereas the other two precursors did not show a saliva-serum correlation. For three UTs (KYN, KA and pCG), we were unable to test the correlation since the saliva or serum levels were too low in many of the volunteers. The present study is the first to report on the saliva concentrations of TMAO, KYN, HA, PAGN, pCG, and 3-IAA.

Validation of Liquid Chromatography Coupled with Tandem Mass Spectrometry for the Determination of 12 Tyrosine Kinase Inhibitors (TKIs) and Their Application to Therapeutic Drug Monitoring in Adult and Pediatric Populations.

Tyrosine kinase inhibitors (TKIs) are used as targeted cancer therapies in adults and have an off-label pediatric application for the treatment of Langerhans cell histiocytosis. A multitarget LC-MS/MS method was developed and validated for the determination of alectinib, alectinib-M4, binimetinib, cobimetinib, crizotinib, dabrafenib, encorafenib, imatinib, lorlatinib, osimertinib, AZ5104, and trametinib. A total of 150 µL of internal standard methanolic solution was added to 50 µL of plasma sample to precipitate proteins. After centrifugation, 10 µL of the supernatant was injected into the chromatographic system. The chromatographic separation was conducted on a Kinetex C18 Polar column with a gradient of 2 mM ammonium formate in 0.1% formic acid and acetonitrile over 5 min. Limits of detection and quantification, linearity, accuracy, precision, selectivity, carryover, matrix effect, recovery, and stability were evaluated and satisfied EMA guidelines on bioanalytical methods. This method has been successfully applied to the therapeutic drug monitoring (TDM) of adults with melanoma and lung cancer, as well as children with histiocytosis, to improve the pharmacokinetic data for these drugs, with the aim of enhancing the therapeutic management and follow-up of patients. Blood concentrations of trametinib and binimetinib were different in the two groups, highlighting the age-related inter-individual variability of these molecules and the need for TDM.

Pharmacological data of a successful 4-days-a-week regimen in HIV antiretroviral therapy (ANRS 162-4D trial).

INTRODUCTION: Few data are available on plasma concentrations of antiretroviral therapy (ARV) during intermittent treatment. OBJECTIVE: To compare plasma concentrations in OFF vs ON treatment periods at several time points during treatment. METHODS: During a successful 48-week multicenter study (ANRS 162-4D trial) of 4 days with treatment (ON) followed by 3 days without treatment (OFF) in adults treated by two nucleoside analogues and a third agent belonging to a boosted protease-inhibitor (PI, darunavir [DRV], atazanavir [ATV], lopinavir [LPV]) or a non-nucleoside-reverse-transcriptase inhibitor (NNRTI, efavirenz [EFV], etravirine [ETR], rilpivirine [RPV]) conducted in 100 patients (96% success), we determined the plasma concentrations of ARV. Blood samples were collected for analysis at inclusion (W0, 7/7 strategy for all patients), W16 and W40 (ON) and at W4, W8, W12, W24, W32 and W48 (OFF). RESULTS: A total of 866 samples was analysed. Plasma concentrations were not statistically lower after 4 days (ON) vs 7/7 days of treatment except for RPV (-30 ng/mL at 4/7, P = 0.003). Significant lower plasma concentrations were observed for OFF vs ON except for ETR (n = 5, P = 0.062). Overall, 87.1% of ON concentrations (ATV 92.1%, DRV 51.1%, LPV 62.5%, EFV 94.4%, ETR 100% and RPV 94.9%) and 21.8% of OFF concentrations (ATV 1.4%, DRV 0.0%, LPV 0.0%, EFV 16.0%, ETR 92.6% and RPV 39.0%) were above the theoretical limit of efficacy of the molecule. In the OFF period, 85.8% of PI concentrations were under the limit of quantification, while 98.0% of NNRTI concentrations were quantifiable. CONCLUSION: Despite low/undetectable PI/NNRTI plasma concentrations in the OFF period, patients maintained an undetectable viral load. The mechanistic explanation should be investigated.

[Accreditation of the toxicological screening: recommendations of the SFBC-SFTA group]. / Accréditation du criblage toxicologique : recommandations du groupe SFBC-SFTA.

Toxicological screening is a specific approach to analytical toxicology that uses analytical tools such as GC-MS, LC-UV (diode array) or LC-MS. Toxicological screening allows the detection and simultaneous identification of a large number of compounds. The results may be based on the use of one or more techniques. As part of the accreditation process for medical biology examinations according to standard NF EN ISO 15189, the group from SFTA and SFBC recommends an approach to accredit toxicological screening. Indeed, the complexity of the accreditation of this analysis comes in particular from the high number of compounds that can be detected. Validation parameters are discussed in the specific context of toxicological screening by considering two distinct approaches: the simple identification of compounds, or the identification and estimation of a range of concentration related to clinical outcomes.

Four-days-a-week antiretroviral maintenance therapy in virologically controlled HIV-1-infected adults: the ANRS 162-4D trial.

Background: Intermittent treatment could improve the convenience, tolerability and cost of ART, as well as patients' quality of life. We conducted a 48 week multicentre study of a 4-days-a-week antiretroviral regimen in adults with controlled HIV-1-RNA plasma viral load (VL). Methods: Eligible patients were adults with VL < 50 copies/mL for at least 1 year on triple therapy with a ritonavir-boosted PI (PI/r) or an NNRTI. The study protocol consisted of the same regimen taken on four consecutive days per week followed by a 3 day drug interruption. The primary outcome was the proportion of participants remaining in the strategy with VL < 50 copies/mL up to week 48. The study was designed to show an observed success rate of > 90%, with a power of 87% and a 5% type 1 error. The study was registered with ClinicalTrials.gov (NCT02157311) and EudraCT (2014-000146-29). Results: One hundred patients (82 men), median age 47 years (IQR 40-53), were included. They had been receiving ART for a median of 5.1 (IQR 2.9-9.3) years and had a median CD4 cell count of 665 (IQR 543-829) cells/mm3. The ongoing regimen included PI/r in 29 cases and NNRTI in 71 cases. At 48 weeks, 96% of participants (95% CI 90%-98%) had no failure while remaining on the 4-days-a-week regimen. Virological failure occurred in three participants, who all resumed daily treatment and became resuppressed. One participant stopped the strategy. No severe treatment-related events occurred. Conclusions: Antiretroviral maintenance therapy 4 days a week was effective for 48 weeks in 96% of patients, leading to potential reduction of long-term toxicities, high adherence to the antiretroviral regimen and drug cost saving.

The measured glomerular filtration rate (mGFR) before and 6 months after bariatric surgery: A pilot study.

INTRODUCTION: Over the last few decades, the prevalence of obesity has increased dramatically. This increase has been mirrored by a rise in the risk of a number of health conditions, including hypertension, diabetes and chronic kidney disease. Although the weight loss following bariatric surgery has been shown to relieve the severity of diabetes and reduce hypertension, the effect on renal function has been less extensively evaluated. OBJECTIVE: The aims of the present study were to: (i) compare the estimated glomerular filtration rate (eGFR, using the MDRD and CKD-EPI equations) and the calculated glomerular filtration rate (using the 24-hour urine volume) with the measured glomerular filtration rate (mGFR) assessed with the plasma iohexol clearance method in severely obese patients, and (ii) evaluate the effect of weight loss on the mGFR 6 months after bariatric surgery. METHODS: Before and six months after bariatric surgery (Roux-en-Y gastric bypass or sleeve gastrectomy), eligible patients for bariatric surgery were admitted as day cases to the nephrology unit, where they underwent a plasma iohexol clearance test. The GFR was also estimated using the MDRD and CKDEPI equations and the 24-hour urine method. Changes in eGFR and mGFR were compared using a Wilcoxon test for paired data. RESULTS: Data from 16 patients with severe obesity (mean ± standard deviation of Body Mass Index [BMI]: 43.9 ± 7.3 kg/m2) were analyzed. At baseline, 12 (75%) presented with hypertension and 10 (63%) presented with diabetes. The median [range] iohexol clearance rate was 109 [57-194] mL/min. The plasma iohexol clearance test evidenced hyperfiltration (mGFR>120 mL/min) in 7 patients. In contrast, the eGFR values generated by the MDRD equation, the CKDEPI equation and the GFR MFR calculated with the 24-hour urine method only identified hyperfiltration in 1, 0 and 5 patients, respectively. Six months after surgery, the mean BMI had fallen significantly (P<0.0012), and the severity of diabetes (according to the HbA1c level) had decreased significantly from 6.6 [6.0-9.8] % to 5.7 [5.2-8.6] % (P=0.025). The iohexol clearance rate increased slightly after bariatric surgery. Changes in BMI after surgery do not seem to be correlated with the changes in iohexol clearance. In patients displaying hyperfiltration at baseline, the mGFR fell significantly (n=7; P=0.01) and returned to near normal values. No significant changes in the eGFR were observed. CONCLUSION: Our results suggest that MDRD and CKD-EPI equations do not provide accurate estimates of the true GFR in severely obese patients (particularly in those with hyperfiltration). Iohexol clearance or other methods for determining mGFR should constitute the gold standard for the accurate evaluation of renal function in this context. Renal function (as evaluated by the mGFR) improved 6 months after bariatric surgery in severely obese individuals particularly in patients displaying hyperfiltration at baseline. However, these observations must be confirmed in a larger study with a longer follow-up period.

Identification and quantification of 4-methylethcathinone (4-MEC) and 3,4-methylenedioxypyrovalerone (MDPV) in hair by LC-MS/MS after chronic administration.

4-Methylethcathinone (4-MEC) and 3,4-methylenedioxypyrovalerone (MDPV) are synthetic cathinones. The objective of this study was to develop a method in order to measure these compounds in hair of a patient. After decontamination, 20mg of hair were grinded and incubated in phosphate buffer pH 5.0 in presence of 100ng of MDMA-d5 used as internal standard. Double basic liquid-liquid extraction was performed. Samples were separated on a 1.9µm Hypersil GOLD PFP column (100×2.1mm) using gradient elution. Compounds were detected by a LCQ TSQ Vantage XP triple-quadrupole mass spectrometer. SRM transitions m/z 192.1→146.1 and 174.2, m/z 276.1→175.0 and 205.1 and m/z 199.1→165.1 were used for 4-MEC, MDPV and IS, respectively. The assay was accurate and precise over the range 0.001 (lower limit of quantification) to 1ng/mg in hair. No matrix effect was observed. The method has been applied to a 30-year-old man who usually consumed cathinones for 6 months administered intravenously and was admitted to a general hospital for delirious and tachycardia after absorption of 10g of a powder sold as 4-MEC and 5g of MDPV. Both 4-MEC (30ng/mg) and MDPV (1ng/mg) were identified in the hair at high concentrations showing a regular consumption of these drugs. Many others compounds were also identified (mephedrone, MDMA, MDA, cocaine and metabolites, tramadol, hydroxyzine, aripiprazole, haloperidol). Few data are available on concentration of these new designer drugs in hair however important in order to determine the acute or chronic consumption of these drugs.

An Automated Method for the Determination of Trimebutine and N-Mono-Desmethyl Trimebutine by On-Line Turbulent Flow Coupled with Liquid Chromatography-Tandem Mass Spectrometry in Human Plasma: Application to a Fatal Poisoning Case with Toxicokinetic Study.

A liquid chromatography-MS-MS turbulent flow on-line extraction method was developed for the determination of trimebutine (TMB) and its main active metabolite N-mono-desmethyltrimebutine (nortrimebutine or nor-TMB) in human plasma. After protein precipitation and internal standard (IS, haloperidol-d4) addition, 50 µL of the supernatant were transferred onto a Cyclone-Turbo-Flow extraction column followed by an Hypersil PFP Gold analytical column. Detection was carried out on a triple quadrupole tandem mass spectrometer using positive electrospray ionization. The transitions used were m/z 388.0→343.0, 374.0→195.0 and 380.1→169.0 for TMB, nor-TMB and IS, respectively. The method was validated over the concentration range of 10-1,000 ng/mL for both compounds. The accuracy evaluated at three concentrations was within 90.0-98.5% and the intra- and interday coefficient of variation's for the two molecules were <8.7%. The method was applied to a toxicokinetic study of a self-poisoning case with TMB in a 19-old girl. The concentration of TMB decreased from 747 to 77 ng/mL, while nor-TMB decreased from 9,745 to 205 ng/mL after 5 days and the fatal issue. This case confirms the literature underlining the potential toxicity of TMB, which has long time been considered as a harmless molecule.

Quantification of remifentanil and propofol in human plasma: a LC-MS/MS assay validated according to the EMA guideline.

BACKGROUND: Remifentanil and propofol are often used in combination for general anesthesia. We developed a method using LC-MS for their simultaneous measurement in human plasma. Methodology & results: After addition of remifentanil-(13)C6 and propofol-d18 (IS), 500 µl of plasma were extracted with ethylacetate/hexane. Analysis conditions included gradient elution (water/acetonitrile), electrospray ionization and detection with a triple quadripole mass spectrometer. Remifentanil and propofol were ionized in the positive and negative mode, respectively. The method was validated according to the European Medicines Agency guideline for the validation of bioanalytical methods, then successfully applied to clinical samples from three patients who had undergone liver transplantation. CONCLUSION: This method is suitable for the simultaneous quantification of remifentanil and propofol in clinical studies.

Plasma and Intracellular Antiretroviral Concentrations in HIV-Infected Patients under Short Cycles of Antiretroviral Therapy.

Study of plasma and intracellular concentrations of atazanavir, lopinavir, nevirapine, and efavirenz was conducted on 48 patients under short cycles of antiretroviral therapy. Intracellular concentrations (IC) were still measurable for all drugs after 85 h or 110 h drug intake despite the absence of drug in plasma for atazanavir and lopinavir. A linear relationship between plasma and intracellular efavirenz was observed. Further studies to fully understand the impact of IC in the intermittent antiviral treatment are required.

A LC/MS/MS micro-method for human plasma quantification of vemurafenib. Application to treated melanoma patients.

As previously shown for imatinib, therapeutic drug monitoring (TDM) of vemurafenib should be important to measure efficacy of the treatment in melanoma patient. A micro-method based on liquid chromatography coupled to triple quadrupole spectrometry detection using only 10µL of plasma was validated. A simple protein precipitation with water/acetonitrile was used after addition of vemurafenib-(13)C6 as internal standard. The ion transitions used to monitor analytes were m/z 490.2→m/z 255.2 and m/z 383.3 for vemurafenib and m/z 496.2→m/z 261.2 and m/z 389.3 for vemurafenib-(13)C6. Calibration curves were linear in the 0.1-100µg/mL range, the limits of detection and quantification being 0.01µg/mL and 0.1µg/mL, respectively. The intra- and inter-assay precisions evaluated at 0.1, 0.3, 15, 45 and 80µg/mL were lower than 13.3% and the accuracies were in the 93.7-105.8 range. No matrix effect was observed. At steady state, the results of TDM of vemurafenib in 26 patients treated by 960mg twice daily (n=60 samples), 13 patients with 740mg twice daily (n=13) and one with 1200mg twice daily (n=3) showed a great variability of the pharmacokinetics of this compound.

A practical tranexamic acid dosing scheme based on population pharmacokinetics in children undergoing cardiac surgery.

BACKGROUND: Pediatric cardiac surgery patients are at high risk for bleeding, and the antifibrinolytic drug tranexamic acid (TA) is often used to reduce blood loss. However, dosing schemes remain empirical as a consequence of the absence of pharmacokinetic study in this population. The authors' objectives were thus to investigate the population pharmacokinetics of TA in pediatric cardiac surgery patients during cardiopulmonary bypass (CPB). METHODS: Twenty-one patients were randomized to receive TA either continuously (10 mg/kg followed by an infusion of 1 mg · kg · h(-1) throughout the operation, and 10 mg/kg into the CPB) or discontinuously (10 mg/kg, then 10 mg/kg into the CPB and 10 mg · kg · h(-1) at the end of CPB). Serum concentrations were measured at eight time points with chromatography-mass spectrometry and the data were modeled using Monolix (Lixoft, Orsay, France). RESULTS: Tranexamic acid pharmacokinetics was ascribed to a two-compartment open model. The main covariate effects were body weight and CPB. Representative pharmacokinetic parameters adjusted to a 70-kg body weight were as follows: systemic clearance, 2.45 l/h; volume of distribution in the central compartment, 14.1 l; intercompartmental clearance, 5.74 l/h; and peripheral volume, 32.8 l. In accordance with this model, the authors proposed a weight-adjusted dosing scheme to maintain effective TA concentrations in children during surgery, consisting of one loading dose followed by a continuous infusion. CONCLUSIONS: The authors report for the first time the pharmacokinetics of TA in children undergoing cardiac surgery with CPB, and propose a dosing scheme for optimized TA administration in those children.

An automated method for measurement of methoxetamine in human plasma by use of turbulent flow on-line extraction coupled with liquid chromatography and mass spectrometric detection.

Methoxetamine is a new ketamine derivative designer drug which has recently become available via the Internet marketed as "legal ketamine". It is a new dissociative recreational drug, acting as an NMDA receptor antagonist and dopamine reuptake inhibitor. The objective of this study was to develop on-line automated sample preparation using a TurboFlow device coupled with liquid chromatography with ion-trap mass spectrometric detection for measurement of methoxetamine in human plasma. Samples (100 µL) were vortex mixed with internal standard solution (ketamine-d4 in acetonitrile). After centrifugation, 20 µL of the supernatant was injected on to a 50 mm × 0.5-mm C18XL Turboflow column. The retained analytes were then back-flushed on to a 50 mm × 3-mm (3 µm) Hypersil Gold analytical column for chromatographic separation, then eluted with a formate buffer-acetonitrile gradient. Methoxetamine and the IS were ionized by electrospray in positive mode. Parent [M + H](+) ions were m/z 248.1 for methoxetamine and m/z 242.0 for the IS. The most intense product ions from methoxetamine (m/z 203.0) and the IS (m/z 224.0) were used for quantification. The assay was accurate (96.8-108.8% range) and precise (intra and inter-day coefficients of variation <8.8%) over the range of 2.0 (lower limit of quantification) to 1000.0 ng mL(-1) (upper limit of quantification). No matrix effect was observed. This method has been successfully applied to determination of plasma concentrations of methoxetamine in the first French hospitalization case report after acute intoxication; the plasma concentration was 136 ng mL(-1).

Measurement of atropine and scopolamine in hair by LC-MS/MS after Datura stramonium chronic exposure.

BACKGROUND: Datura stramonium is an herbaceous annual plant. All parts of the plant contain tropane alkaloids such as atropine and scopolamine. We report the case of a 22-year-old man admitted to a general hospital for visual and aural hallucinations. One week after his admission, as the hallucinations remained, the patient was transferred to a psychiatric hospital. Neither blood nor urine was conserved during his hospitalization, so a hair analysis was requested in order to identify a possible consumption of a Datura seed infusion. METHODS: After decontamination and washing, hair strands were segmented into four pieces and grinded into a fine and homogeneous powder. We then incubated 20 mg for 10 min in 1 mL of phosphate buffer at pH 5.0 in the presence of 100 ng of ketamine-d4, used as internal standard (IS). Liquid-liquid extraction was performed with 4 mL of a mixture of hexane/ethyl acetate (1/1, v/v). The residue was reconstituted in 80 µL of mobile phase. A further 10 µL were injected into an 1.9 µm Hypersil GOLD PFP column (100 mm×2.1 mm) eluted with a gradient of acetonitrile and 2 mmol/L 0.1% formate buffer at a flow rate of 300 µL/min. Compounds were detected by a LCQ TSQ Vantage XP triple-quadripole mass spectrometer equipped with an electrospray ionization (ESI) source set in positive mode. SRM transitions m/z 290.2→124.1, m/z 304.2→138.1, and m/z 242.1→129.1 were optimized for atropine, scopolamine and IS, respectively. RESULTS: The assay was accurate and precise over the range of 1.0 (lower limit of quantification) to 1000.0 pg/mg (upper limit of quantification) in hair. Both atropine (from 8.4 to 15.0 pg/mg) and scopolamine (1.0-1.3 pg/mg) were identified in the four segment of the hair showing a regular consumption of Datura admitted by the patient himself. CONCLUSION: We report here the first description of atropine with scopolamine in a Caucasian dark man's hair after D. stramonium chronic exposure, using a validated LC-MS/MS method.

Evaluation of the first immunoassay for the semi-quantitative measurement of meprobamate in human whole blood or plasma using biochip array technology.

BACKGROUND: Meprobamate is a carbamate, and the main metabolite of carisoprodol. It is used as an anxiolytic agent. Overdose of both drugs produces intoxication that is often serious and sometimes life threatening. However there was until now no immunoassay for the diagnosis of this intoxication. METHODS: A chemiluminescent immunoassay for the semi-quantitative measurement of meprobamate in human blood and plasma has recently been developed, using the Evidence Investigator system (Randox®). In this study, the immunoassay was evaluated by testing drug-free (n=10) or spiked whole blood and plasma samples (n=70), and authentic post mortem whole blood samples from deceased patients in which meprobamate was present (n=38) or not (n=10). A previously validated gas chromatography-mass spectrometry (GC-MS) method was used for confirmation and quantification. 97 psychoactive drugs including carisoprodol were analyzed for possible interference. RESULTS: With a cut-off at 0.5 mg/L, specificity, sensitivity and accuracy were 100%, 97.2% and 97.6%, respectively. All the untreated patients presented results under the cut-off. Meprobamate was not detected in three whole blood samples spiked with concentrations under the therapeutic range. In the authentic patients (n=48), there were no false-negative results. A good correlation was found between the immunoassay and GC-MS (r=0.90). Quantitative results of the immunoassay are approximately two-fold lower than GC-MS results. Only carisoprodol presented a cross-reactivity, 38±6.6% at 10 mg/L, and 26±4.8% at 100mg/L. CONCLUSION: The first meprobamate immunoassay has shown very good specificity, selectivity and accuracy, which allow its use in hospital clinical laboratories for rapid diagnosis of meprobamate (or carisoprodol) intoxications.