Olivier Roussel

Respiratory effects of buprenorphine/naloxone alone and in combination with diazepam in naive and tolerant rats

Respiratory depression has been attributed to buprenorphine (BUP) misuse or combination with benzodiazepines. BUP/naloxone (NLX) has been marketed as maintenance treatment, aiming at preventing opiate addicts from self-injecting crushed pills. However, to date, BUP/NLX benefits in comparison to BUP alone remain debated. We investigated the plethysmography effects of BUP/NLX in comparison to BUP/solvent administered by intravenous route in naive and BUP-tolerant Sprague-Dawley rats, and in combination with diazepam (DZP) or its solvent. In naive rats, BUP/NLX in comparison to BUP significantly increased respiratory frequency (f, P<0.05) without altering minute volume (VE). In combination to DZP, BUP/NLX significantly increased expiratory time (P<0.01) and decreased f (P<0.01), tidal volume (VT, P<0.001), and VE (P<0.001) while BUP only decreased VT (P<0.5). In BUP-tolerant rats, no significant differences in respiratory effects were observed between BUP/NLX and BUP. In contrast, in combination to DZP, BUP/NLX did not significantly alter the plethysmography parameters, while BUP increased inspiratory time (P<0.001) and decreased f (P<0.01) and VE (P<0.001). In conclusion, differences in respiratory effects between BUP/NLX and BUP are only significant in combination with DZP, with increased depression in naive rats but reduced depression in BUP-tolerant rats. However, BUP/NLX benefits in humans remain to be determined.

Illicit Drugs in Oral Fluid: Evaluation of Two Collection Devices

Driving after illicit drug use is a worldwide growing concern requiring rapid and sensitive screening at the roadside. It is noteworthy that the sampling method used to collect oral fluid (OF) may significantly influence drug concentrations in the collected sample and thus alter the accuracy of the measurement. We evaluated two OF collection devices, Quantisal® and Certus® collectors, for their suitability for collecting samples to allow laboratory confirmation of driving after illicit drug use. Four parameters were studied including (i) the collected OF volume; (ii) the recovery efficiency using OFs spiked with opiates, cannabinoids, amphetamines, cocaine and its metabolites; (iii) drug stability after storage for 1, 7 and 14 days at -20°C, +4°C and room temperature; and (iv) the impact of mouth cells present in the collected OF on drug stability. Drug concentrations were measured using gas and liquid chromatography-mass spectrometry. Certus® collector allowed the collection of significantly larger (0.94xa0±xa00.18 mL vs. 0.84xa0±xa00.06 mL, P =xa00.08) but less reproducible OF volumes (19 vs. 6.7%) compared with Quantisal® collector. Drug recovery was significantly better with Quantisal® than with Certus® collector, especially when used to detect cannabinoids (0.94 vs. 0.54, P <xa00.001 for ∆9-tetrahydrocannabinol (THC)). For both OF collectors, storage at 4°C was preferable except for methadone, the stability of which was altered by adherence to the collector device. In the presence of mouth cells in the OF sample, THC concentrations were significantly decreased at Day 7 in comparison with Day 1 with both collection devices (P =xa00.001 with Quantisal® collector and P =xa00.01 with Certus® collector). In conclusion, Quantisal® collector is more reliable than Certus® collector although the practicability of both devices remains to be determined at the roadside.

Impact of lowering confirmatory test cutoff value in pre-enlistment urine cannabinoids screening: about five years' experience in the French Gendarmerie.

The guidelines for screening of urinary cannabinoids require that all specimens testing positive should be confirmed by gas chromatography-mass spectrometry at a confirmatory test cutoff value of 15 ng/mL of 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THCCOOH). To assess the impact of lowering the confirmatory test cutoff value on the diagnostic sensitivity and efficiency of a cannabinoid testing program, the results of 986 confirmation analyses of positive screening tests, conducted in the framework of medical fitness examinations prior to enlistment in the French Gendarmerie between January 1, 2005, and December 31, 2009, were retrospectively studied. If the confirmatory test cutoff value of THCCOOH is set at 5 ng/mL instead of 15 ng/mL as recommended by guidelines, the number of confirmed results increases by 25.2%. The positive predictive value of the initial screening test rises from 63.9 to 80.0%. Only one true-positive applicant has appealed. His THCCOOH urinary concentration, which was incompatible with passive cannabis smoke exposure, was confirmed by another laboratory. The use of a confirmatory test cutoff value lower than that recommended significantly increases the diagnostic sensitivity of the screening program for urinary cannabinoids without altering its specificity.

Is the 3,4-methylendioxypyrovalerone/mephedrone combination responsible for enhanced stimulant effects? A rat study with investigation of the effect/concentration relationships

RationaleThe use of synthetic cathinones as recreational drugs frequently sold in combination has been increasing exponentially. However, the consequences of combining cathinones on the resulting stimulant effects and the pharmacokinetics have been poorly investigated.Objective and methodsTo study 3,4-methylenedioxypyrovalerone (MDPV; 3xa0mg/kg) and mephedrone (4-MMC; 30xa0mg/kg)-induced effects on rat locomotor activity and pharmacokinetics, administered alone or in combination by the intragastric route. The pharmacokinetic parameters were determined using non-compartmental analysis and the relationships between the locomotor activity and drug concentrations using sigmoidal Emax modeling.ResultsLocomotor activity significantly increased during the first hour post-administration with the MDPV/4-MMC combination in comparison to MDPV (pu2009<u20090.001) and 4-MMC (pu2009<u20090.01) alone. The pharmacokinetic profile of MDPV, but not 4-MMC, was significantly modified with the combination resulting in decreases in Cmax (16.4u2009±u20095.5 versus 62.2u2009±u200914.2xa0μg/L, pu2009<u20090.05) and AUC0u2009→u2009∞ (708u2009±u200991 versus 3316u2009±u2009682xa0μg/L/min, pu2009<u20090.01) and increases in V/F (582.6u2009±u2009136.8 versus 115.9u2009±u200942.7xa0L/kg, pu2009<u20090.05) and Cl/F (4.6u2009±u20090.7 versus 1.2u2009±u20090.4xa0L/kg/min, pu2009<u20090.01) in comparison to MDPV alone. The sigmoidal Emax model fitted the observed data well; MDPV being markedly more potent than 4-MMC (EC50, 0.043 versus 0.7xa0μmol/L). The enhancing factor representing the MDPV contribution to the alteration in the relationships between locomotor activity and 4-MMC concentrations was 0.3.ConclusionAn MDPV/4-MMC combination results in enhanced stimulant effects in the rat, despite significant reduction in MDPV bioavailability. Enhanced effects could be explained by increased MDPV distribution and/or possible complementation at the brain dopaminergic targets. However, the exact consequences of the MDPV/4-MMC combination in humans remain to be clarified.

Neurorespiratory Effects of Buprenorphine and Ethanol in Combination: a Mechanistic Study of Drug-Drug Interactions in the Rat

Respiratory depression and fatalities have been attributed to ethanol/buprenorphine (BUP) combination in drug addicts maintained with BUP/naloxone or BUP alone. The exact mechanisms of the ethanol/BUP interaction and the contribution to the toxicity of norbuprenorphine (NBUP), the main BUP metabolite with respiratory depressant properties are unknown. We investigated the sedative and plethsymographic effects resulting from the co-administration of intragastric ethanol (3u2009g/kg) and intravenous BUP (30u2009mg/kg) in Sprague–Dawley rats. We determined the whole blood pharmacokinetics of ethanol (using gas chromatography coupled to mass spectrometry), BUP and its metabolites (using liquid chromatography coupled to tandem mass spectrometry) and investigated the mechanisms of drug–drug interactions in the presence or absence of naloxone (7.5u2009mg/kg). Ethanol/BUP and ethanol/BUP/naloxone combinations significantly deepened sedation in comparison to BUP alone (P < .01) and BUP/naloxone (P < .05), respectively. Ethanol/BUP combination significantly increased the inspiratory time and decreased the minute volume in comparison to BUP alone (P < .01 and P < .01, respectively) and ethanol/BUP/naloxone (P < .05 and P < .01, respectively). Neither naloxone nor flumazenil reversed ethanol/BUP-induced sedation and respiratory depression. In the presence of ethanol, the area under the BUP concentration–time curve was significantly decreased (P < .05), BUP volume of distribution increased (P < .05) and the metabolic ratios of NBUP and norbuprenorphine-3-glucuronide increased (P < .01). In conclusion, the ethanol/BUP combination results in marked sedation and respiratory depression in the rat, prevented but not reversed by naloxone. Ethanol/BUP interactions are mainly pharmacokinetic resulting in increased NBUP production. Despite the non-reversal by naloxone and flumazenil of the effects attributed to the ethanol/BUP combination, protection provided by naloxone suggests an additional pharmacodynamic interaction.

W3: The French experience of establishing an oral fluid roadside drug test

Introduction In 2005, following on from the findings of the ROSITA and DrUID projects, the French government made the decision to investigate possible alternative matrices to urine for drug screening at the roadside. A special committee, which included French ministerial representatives, was established in 2006 and they decided to use a special procurement contract in the form of a “competitive dialogue”: this allowed manufacturers of screening devices to improve their product in accordance with the committee’s recommendations. From initial investigations carried out, oral fluid (OF) was found to be the best alternative matrix (non invasive sample taking, difficult to adulterate, existing prototypes), and so this was chosen for this work. The devices included in the work were screening tests based on immunochromatographic methods. Method In France the four major categories of drugs tested for are cannabis, cocaine, opiates and amphetamines therefore the devices selected had to detect these compounds. The French gendarmerie and police played an important role in this previously unfamiliar testing and 3 OF devices remained for evaluation in the final step of the selection process. For this step, 2 field evaluation studies were carried out in 3 of the most active territorial road units by the Centre of Research and Expertise on Logistic (CREL). In the first study, approximately 500 individuals were involved. A urine sample was collected for screening, if positive a blood sample for confirmation and one of the OF devices was tested. In the second study, 100 participants were involved and standard urine and blood confirmation was carried out but also OF was tested against all three of the devices for a comparative study. The toxicology unit of our laboratory performed more than 400 of the confirmatory analyses by a validated GC-MS method. For both of the field studies, CREL processed the findings from the roadside units carrying out the screening and determined sensitivity, specificity and efficacy of the 3 devices. As a result, the Rapid Stat ® (Mavand) screening device was introduced for roadside drug testing. French law was subsequently modified in July 2008 to allow the use of an OF screening test operated by a police officer (as opposed to medical personnel). Results & discussion This change in legislation has resulted in a dramatic increase in the number of roadside drug tests performed and consequently the number of confirmatory analyses in blood (an increase from 15,000 in 2004 to 76,000 in 2010). Although OF has a number of factors requiring consideration when collecting, analysing and interpreting findings, it has become an accepted matrix for this type of testing and one which we are investigating. In March 2011, a new public contract was announced. A new device (Drugwipe5S ® , Securetec) was appointed, for 2011 to 2015. Last year, the Directorate General of the French Gendarmerie tasked our laboratory to carry out a feasibility study on the use of OF in confirmatory analyses. This includes evaluating financial, organisational and philosophical implications and establishing risk assessment criteria. With help from laboratories in Belgium and Switzerland, the analytical component of this study is now underway and several steps are planned, including the selection of the OF collection device, the choice of biological markers and the validation of both field testing devices and analytical methods. At this time, the collection device has already been chosen, the biological markers are being established and analytical method development is in progress. Since the work is in the early stages, no conclusion can be drawn as yet however, OF analysis offers us an interesting alternative matrix for future screening and confirmation.

Recherche des causes toxiques de la mort

Resume Le toxicologue judiciaire n’est pas le seul acteur dans la recherche des causes de la mort. Celle-ci debute, des l’autopsie, dans les mains du medecin legiste qui constitue les prelevements et consigne les elements d’orientation pour son collegue du laboratoire. Des prelevements decoulent les analyses toxicologiques realisables. Ainsi, dans le contexte contemporain d’exigence, il convient d’harmoniser ces prelevements et examens afin d’assurer une egalite de traitement. Nous decrivons les protocoles de prelevements et les exigences analytiques actuelles, de la table d’autopsie a la paillasse du laboratoire. Enfin, les besoins evoluant au gre de l’apparition de nouvelles substances et les possibilites analytiques au gre des innovations techniques, un etat des mesures techniques prises en anticipation des futures demandes clot cet article.