Evaluation of Lamotrigine Toxicity Reported to Poison Centers

Abstract

BACKGROUND Lamotrigine is an antiepileptic drug for the treatment of partial and generalized seizures as well as bipolar disorder. Limited published information exists describing the clinical effects of lamotrigine overdose. OBJECTIVE To examine the toxicity of exposures to lamotrigine utilizing national poison center data. METHODS Data on single-substance exposures to lamotrigine reported to the American Association of Poison Control Centers Toxic Exposure Surveillance System in 2000 and 2001 were retrospectively analyzed. RESULTS There were 493 cases that met the inclusion criteria. The majority of exposures occurred within the age groups 20–59 years old (n = 198, 40.2%), followed by 4 years old (n = 173, 35.1%). Overall, the majority of patients (52.1%) exposed to lamotrigine in overdose experienced no toxic clinical effects. The most common clinical effects reported in overdose were drowsiness/lethargy (20.9%), vomiting (11%), nausea (5.1%), ataxia (4.9%), dizziness/vertigo (4.5%), and tachycardia (4.3%). Major clinical effects included coma (n = 6), seizures (n = 8), and respiratory depression (n = 3). Medical outcome was reported as minor in 150 (30.4%), moderate in 73 (14.8%), and major in 13 (2.6%) cases. There were no deaths. CONCLUSIONS These data demonstrate that the majority of patients exposed to lamotrigine in overdose experienced minor or no clinical effects. Although rare, serious effects can also occur.