Abstract

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.

Links

Publisher Full Text

Authors

Alvarez JC, Duverneuil C, Zouaoui K, Abe E, Charlier P, de la Grandmaison GL, Grassin-Delyle S

Institution

Laboratoire de Pharmacologie, Toxicologie, Centre Hospitalier Universitaire Raymond Poincaré, AP-HP, et Université Versailles Saint Quentin, Garches, France. jean-claude.alvarez@rpc.aphp.fr

Source

Clinica chimica acta; international journal of clinical chemistry 413:1-2 2012 Jan 18 pg 273-7

MeSH

Anti-Anxiety Agents
Gas Chromatography-Mass Spectrometry
Humans
Immunoassay
Lab-On-A-Chip Devices
Limit of Detection
Luminescence
Meprobamate
Reproducibility of Results

Pub Type(s)

Journal Article

Language

eng

PubMed ID

22057036