Alain Pineau

Evaluation of a Methotrexate Chemiluminescent Microparticle Immunoassay Comparison to Fluorescence Polarization Immunoassay and Liquid Chromatography–Tandem Mass Spectrometry

OBJECTIVES For most laboratories, methotrexate (MTX) concentrations are routinely monitored by fluorescence polarization immunoassay (FPIA). In anticipation of an announced withdrawal of the FPIA reagent on the Abbott TDxFLx (Abbott Diagnostics, Abbott Park, IL), we have evaluated a new reagent kit developed by Abbott on the Architect i1000, based on chemiluminescent microparticle immunoassay (CMIA). METHODS Precision, inaccuracy, and selectivity were assessed. Interassay variability was established using 75 plasma patient samples treated with MTX and analyzed by two methods: FPIA and liquid chromatography-tandem mass spectrometry (LC-MS/MS). RESULTS FOR MTX,: the intraday inaccuracy was between -6.37% and +3.52%, while interday performance was between -3.70% and 7.90%. Intraday and interday imprecision was less than 2.65% and less than 2.22%, respectively. The correlation coefficient between CMIA and FPIA or LC-MS/MS was 0.9969 and 0.9985, respectively. CONCLUSIONS These results comparing CMIA vs FPIA and LC-MS/MS indicate that CMIA is a suitable alternative to the FPIA method.

Comparison Between an Automated and Manual Extraction for the Determination of Immunosuppressive Drugs Whole Blood Concentrations by Liquid Chromatography Tandem Mass Spectrometry.

The whole blood extraction for liquid chromatography tandem mass spectrometry (LC‐MS/MS) of simultaneous quantification of cyclosporine A (Cys A), tacrolimus (Tacrs), sirolimus (Siros), and everolimus (Evers) is still performed manually in many laboratories. The analytical results obtained with an automated method using a liquid handler versus a classical manual preparation were compared.

Fatal anoxia due to rachacha consumption: Two cases reported.

Deaths due to ingesting rachacha, which is a homemade paste obtained by decocting poppy heads, are very rare. No fatalities have been recorded in scientific publications. This product is not considered to be very dangerous by its users. We are reporting the first deaths (a 30-year-old man and a 28-year-old woman), after ingesting rachacha balls and alcohol consumption during an evening with a friend. Signs compatible with acute anoxia were observed during autopsy. Toxicological analyses highlighted the presence of morphine and codeine in the blood, urine and bile, with an absence of 6-acetylmorphine. Concomitant consumption of alcohol certainly played a role in the occurrence of death. The black paste found at the scene was identified as rachacha. The mean of consumption (orally) was confirmed by the presence of morphine and codeine in the gastric contents of both victims. The analysis of hair samples was performed to reveal the substance consumption history. Therefore, a possibility of contamination by sweat and/or putrefactive liquids in the post-mortem period must be considered for the interpretation of the results. These two cases show that taking rachacha can be dangerous, especially when combined with the consumption of substances which could potentiate respiratory depression induced by morphine.

Difference between plasma and red blood cell acetone distribution during the first 60 h of a massive intoxication

After a first episode of acetone intoxication six months earlier (1 L of acetone with plasma concentration at hospital admission of 3.7 g/L), a 55-year-old patient was hospitalized in intensive care because of coma (Glasgow Coma Scale [GCS] 3). He was currently prescribed quetiapine, levodopa, propranol, oxazepam, and domperidone for a Parkinsons disease associated with vestibular disorders and depressive syndrome. Brain CT-scan was non-contributory and an acute kidney injury (serum creatinine of 153 mmol/L on day 1) was not felt to be related to circulatory failure (heart rate 70/min, blood pressure 100/60mmHg) but could have been an artifact due to interference of acetone with the creatinine dosage method (Jaffe reaction colorimetric kit, Roche, Basel, Switzerland). The blood pH was 7.36 with serum bicarbonate of 24.9mmol/L. The patient was maintained on mechanical ventilation, slowly aroused and extubation was possible on day 4. He was discharged at his baseline neurological status and GCS 15. Plasma, whole blood, urine, and CSF samples were taken during hospitalization. CSF was obtained at admission to assess for possible meningitis and a urine sample was obtained for toxicological screening. Acetone quantification was done in head-space gas chromatography coupled with flame ionization detection Agilent 7890A GC system (Agilent, Palo Alto, CA). Pharmacokinetics parameters were calculated using a non-compartmental analysis [1]. Acetone plasma concentration at hospital admission was of 4.4 g/L (Figure 1). Maximum concentrations of acetone in whole blood, CSF and urine were of 2.49 g/L, 3.44 g/L and 2.36 g/L respectively (Figure 1). Calculated terminal half-life was 17 h. Pharmacokinetics of acetone is presented in Figure 1. Whole blood concentrations were equal to plasma concentrations 60 h after intake.

Stability and Compatibility of Antibiotics in Peritoneal Dialysis Solutions Applied to Automated Peritoneal Dialysis in The Pediatric Population

♦ Objectives: Assess the stability of several antibiotics in peritoneal dialysis (PD) solutions under common conditions of use in pediatrics, particularly in automated PD. ♦ Methods: Amoxicillin, cefazolin, cefepime, ceftazidime, imipenem, cotrimoxazole, tobramycin, vancomycin, and the association of ceftazidime + vancomycin and ceftazidime + tobramycin, were tested in 3 different PD solutions: bicarbonate/lactate solution with 2 glucose concentrations (Physioneal 1.36 and 3.86%; Baxter Healthcare Corporation, Deerfield, IL, USA) and an icodextrin-containing solution (Extraneal; Baxter Healthcare Corporation, Deerfield, IL, USA). Concentrations were those recommended in guidelines for the treatment of peritonitis in pediatrics. Physioneal bags were incubated at 37°C for 24 hours, whereas Extraneal bags were stored 12 hours at room temperature (22 ± 2°C) and then 12 hours at 37°C. Drug concentrations were determined using high performance liquid chromatography (HPLC). Each measure was taken in triplicate. Stability of antibiotics was defined as less than 10% degradation of the drug over time. ♦ Results: Cefazolin, cotrimoxazole, tobramycin, and vancomycin were stable under studied conditions. Ceftazidime was stable 24 hours in icodextrin, 12 hours in Physioneal 1.36% and 6 hours in Physioneal 3.86%. The association of tobramycin or vancomycin did not influence the stability of ceftazidime. Cefepime and amoxicillin were stable 6 h, 4 h, and 8 h in Physioneal 1.36%, 3.86% and Extraneal, respectively. The stability of imipenem was very low: 2 h in Physioneal and 6 h in Extraneal. Moreover, an increasingly yellow coloration was observed with the use of imipenem, whereas no color change or precipitation occurred in other bags. ♦ Conclusion: Cefazolin, tobramycin, cotrimoxazole, and vancomycin are stable in PD solutions up to 24 hours and can be administered in the PD bag for the treatment of peritonitis, even in automated PD under studied conditions. However, amoxicillin, cefepime, ceftazidime, and imipenem must be used with caution due to their lack of stability.