Lamotrigine as a possible cause of QRS prolongation in a patient with known seizure disorder

Abstract

Lamotrigine and felbamate are 2 newer anticonvulsant medications used to control refractory partial and generalized seizures. Although several cases of lamotrigine toxicity secondary to acute intentional or unintentional overdose have been described, there is little published information related to potential side-effects associated with the therapeutic use of these agents. Described is a case of a 22-year-old woman who presented to the emergency department after experiencing 2 seizure-like episodes. Findings on evaluation included nystagmus, ataxia, widening of the QRS complex and right-axis deviation on ECG. The patient reported only therapeutic use of her medications. The lamotrigine level was 14.8 mg/L. The mechanism of action for lamotrigine is blockade of the sodium channels; therefore, the patient was treated with intravenous sodium bicarbonate with resultant QRS narrowing following administration. RÉSUMÉLa lamotrigine et le felbamate sont deux antiépileptiques plus récents utilisés pour maîtriser les crises d'épilepsie partielles et généralisées réfractaires. Bien que plusieurs cas de toxicité de la lamotrigine secondaire à une intoxication aiguë intentionnelle ou non intentionnelle aient été décrits, il existe peu d'information publiée relative aux effets indésirables possibles associés à l'usage thérapeutique de ces agents. Nous décrivons le cas d'une jeune femme de 22 ans qui s'est présentée à l'urgence après avoir été victime de deux épisodes ressemblant à des crises d'épilep-sie. Les constatations lors de l'évaluation incluaient un nystagmus, de l'ataxie, un élargissement du complexe QRS et une déviation axiale droite à l'ECG. La patiente dit n'avoir utilisé ses médica-ments qu'à des doses thérapeutiques. Le niveau de lamotrigine était de 14,8 mg/L. Le mécanisme d'action de la lamotrigine est le blocage des canaux sodiques; par conséquent, la patiente fut traitée à l'aide de bicarbonate de sodium intraveineux, qui eut pour effet de provoquer le rétré-cissement du complexe QRS.

Complete heart block and death following lamotrigine overdose

“…2 In rare instances, lamotrigine overdose has produced more severe symptoms such as seizures, lengthening of the QRS interval, and ventricular dysrhythmias. [3][4][5][6] We report a unique case of lamotrigine overdose associated with complete heart block and death with confirmatory concentrations. In addition, we describe the toxicokinetics of lamotrigine and the effect of hemodialysis (HD) on lamotrigine concentrations.…”

Lipid Emulsion as Rescue Therapy in Lamotrigine Overdose

“…The efficacy of activated charcoal in the treatment of lamotrigine overdose is unclear given the drug's rapid absorption after oral administration. As lamotrigine exerts anticonvulsant effects via the sodium channel blockade similar to tricyclic antidepressant agents, blood alkalinization is recommended as it decreases the ionized proportion of the drug and attenuates its toxicity (3,4).…”

Significant lamotrigine overdose associated with acute pancreatitis

“…Other signs include tachycardia and respiratory depression. 4,6 Furthermore, lamotrigine toxicity has been reported to occasionally lead to multi{organ system abnormalities similar to an anticonvulsant hypersensitivity syndrome. 4 Until recently treatment had been mainly supportive, however Sirianni and colleagues used the knowledge that lamotrigine is highly lipophilic to treat a case of refractory cardiovascular collapse due to lamotrigine and buproprion overdose with a lipid infusion.…”