title: A case series of patients with lamotrigine toxicity at one center from 2003 to 2012.
abstract: BACKGROUND
  Lamotrigine is a phenyltriazine compound that inhibits voltage-gated sodium channels, decreasing release of glutamate and aspartate, and inhibits serotonin, norepinephrine and dopamine reuptake. Reports of toxicity in the literature are limited to case reports and primarily involve coingestants. This case series is intended to report the clinical manifestations of lamotrigine toxicity.
  
  
  METHODS
  This retrospective case series from 2003 to 2012 studies the effects of lamotrigine toxicity when not confounded by coingestants. Admission records at an inpatient toxicology center were reviewed for lamotrigine-only exposure based on history with supporting laboratory data when available. After identification, these charts were reviewed again to characterize vital signs, neurological examination findings, specific laboratory and electrocardiography parameters, and complications.
  
  
  RESULTS
  Fifty-seven patients were identified with possible lamotrigine toxicity. Nine patients, including three toddlers, had lamotrigine-only ingestions. Three of these patients had seizures, four were hypertensive, five were tachycardic, and four experienced tachypnea. Mental status was altered in all nine (depressed (n = 4), agitated (n = 5) or both (n = 3)). Five patients were hyperreflexic and experienced intermittent myoclonus, and two had inducible clonus. On electrocardiogram, two patients experienced QRS prolongation (114-116 ms), and four had QTc prolongation (463-586 ms). No patient had life-threatening symptoms or signs. Serum levels of lamotrigine were available in seven patients, and averaged 35.4 mg/L (17-90 mg/L). The therapeutic range for sLTG is 3-14 mg/L.
  
  
  CONCLUSIONS
  Lamotrigine toxicity manifested with minor-moderate neurologic and/or electrocardiographic effects. Toxicity reflects the known pharmacologic actions of lamotrigine: serotonin, norepinephrine and dopamine reuptake inhibition, and sodium channel blockade.
authors.affiliation: PinnacleHealth Toxicology Center, Department of Internal Medicine, Harrisburg, PA 17101, USA. pwmoore@pinnaclehealth.org
authors.forename: P W
authors.initials: PW
authors.lastname: Moore
authors.forename: J W
authors.initials: JW
authors.lastname: Donovan
authors.forename: K K
authors.initials: KK
authors.lastname: Burkhart
authors.forename: D
authors.initials: D
authors.lastname: Haggerty
mesh_terms: D018759:Adrenergic Uptake Inhibitors / Q000506:poisoning; D000328:Adult; D001145:Arrhythmias, Cardiac / Q000139:chemically induced* / Q000175:diagnosis / Q000628:therapy; D002675:Child, Preschool; D018765:Dopamine Uptake Inhibitors / Q000506:poisoning; D062787:Drug Overdose; D004562:Electrocardiography; D018691:Excitatory Amino Acid Antagonists / Q000097:blood / Q000493:pharmacokinetics / Q000506:poisoning*; D005260:Female; D006801:Humans; D007223:Infant; D000077213:Lamotrigine; D008297:Male; D008875:Middle Aged; D020258:Neurotoxicity Syndromes / Q000175:diagnosis / Q000209:etiology* / Q000628:therapy; D014179:Neurotransmitter Uptake Inhibitors / Q000097:blood / Q000493:pharmacokinetics / Q000506:poisoning*; D010414:Pennsylvania; D012189:Retrospective Studies; D012640:Seizures / Q000139:chemically induced / Q000175:diagnosis; D017367:Selective Serotonin Reuptake Inhibitors / Q000506:poisoning; D013406:Suicide, Attempted; D013997:Time Factors; D014227:Triazines / Q000097:blood / Q000493:pharmacokinetics / Q000506:poisoning*; D061567:Voltage-Gated Sodium Channel Blockers / Q000097:blood / Q000493:pharmacokinetics / Q000506:poisoning*; D055815:Young Adult
chemical_list: D018759:Adrenergic Uptake Inhibitors; D018765:Dopamine Uptake Inhibitors; D018691:Excitatory Amino Acid Antagonists; D000077213:Lamotrigine; D014179:Neurotransmitter Uptake Inhibitors; D017367:Selective Serotonin Reuptake Inhibitors; D014227:Triazines; D061567:Voltage-Gated Sodium Channel Blockers