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Meprobamate poisoning

Authors
Michael Bodmer, MD, MSc
Alessandro Ceschi, MD
Section Editor
Stephen J Traub, MD
Deputy Editor
Jonathan Grayzel, MD, FAAEM

INTRODUCTION

Meprobamate is a sedative and anxiolytic medication that was marketed for decades in the United States and continues to be used in Europe. The first case of meprobamate poisoning was described in 1956 [1]. Due to its substantial abuse potential, meprobamate is no longer recommended for treatment of insomnia and has been replaced by benzodiazepines and other agents. Although use of the drug is declining, significant meprobamate overdose remains a life-threatening emergency.

This topic will review the basic pharmacology, clinical presentation, and management of meprobamate poisoning. Discussions of the general approach to the management of poisoned patients and detailed management of other toxins are found elsewhere. (See "General approach to drug poisoning in adults" and "Initial management of the critically ill adult with an unknown overdose".)

EPIDEMIOLOGY

Meprobamate poisoning is rare and most cases involve suicide attempts [2]. In France, meprobamate has been used more widely and the drug was involved in approximately 7 percent of psychotropic poisonings in 2005 [3]. Mortality in cases of overdose has ranged between 1.7 and 5 percent [4-6]. Meprobamate ingestion is associated with an increased risk of intensive care unit (ICU) admission (adjusted odds ratio [OR] = 2.71; 95% CI: 1.27-5.81) [7].

PHARMACOLOGY

Meprobamate is a carbamate which acts primarily as a sedative by increasing GABAA-mediated neurotransmission in a manner similar to barbiturates [8,9]. Carisoprodol, prescribed as a centrally acting muscle relaxant, is mainly metabolized to meprobamate by cytochrome P450 2C19, shares properties with meprobamate, and also has significant potential for abuse [10-12].

PHARMACOKINETICS AND TOXICOKINETICS

After oral ingestion of a therapeutic dose, meprobamate is rapidly absorbed from the gastrointestinal tract and peak plasma concentrations are reached within one to three hours [13,14]. Protein binding is negligible (14 to 24 percent). The drug’s volume of distribution is reported to be 0.70 L/kg, and is not significantly altered in overdose. A standard single therapeutic dose for an adult ranges from 200 to 800 mg. Significant toxicity is likely with ingestions of 4 to 5 g or more [3,4].

                      

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Literature review current through: Nov 2016. | This topic last updated: Mon Aug 22 00:00:00 GMT+00:00 2016.
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References
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