Doxylamine toxicity: seizure, rhabdomyolysis and false positive urine drug screen for methadone.

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Syed H, Som S, Khan N, Faltas W

Doxylamine toxicity: seizure, rhabdomyolysis and false positive urine drug screen for methadone.

BMJ Case Rep. 2009;2009. pii: bcr09.2008.0879. doi: 10.1136/bcr.09.2008.0879. Epub 2009 Mar 17.

PubMed ID

21686586 [ View in PubMed

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Abstract

The present report highlights the possible adverse effects of doxylamine, a common over the counter sleep aid. Doxylamine is an antihistamine that at toxic doses can cause anticholinergic effects, including seizures, rhabdomyolysis and death. The following case describes a patient with doxylamine toxicity who presented with seizure and confusion. Our patient was managed symptomatically, and remained otherwise stable throughout his hospitalisation. This case is atypical in terms of a delayed rhabdomyolysis and a false positive urine drug screen test for methadone. There is evidence that doxylamine at toxic levels can lead to false positives for methadone and phencyclidine testing using immunoassay-based urine drug screen kits. Urine drug screen testing on patients who are hospitalised is typically performed using immunoassays. However, in certain cases confirmatory secondary testing may be required. Doxylamine is prone to abuse and knowledge of the clinical presentation of its toxicity and the management of acute overdose can be life-saving.

DrugBank Data that Cites this Article

Drug Targets

Drug	Target	Kind	Organism	Pharmacological Action	Actions
Doxylamine	Muscarinic acetylcholine receptor (Protein Group)	Protein group	Humans	Unknown	Antagonist	Details