Effectiveness of multiple-dose activated charcoal in lamotrigine poisoning: a case series

Abstract

Introduction

Lamotrigine toxicity can cause coma, seizures, and intraventricular conduction disturbances, and treatment options include good supportive care. We report two cases of lamotrigine poisoning in which multiple-dose activated charcoal may have shortened the elimination half-life of lamotrigine.

Case 1

A 21-year-old woman ingested 15.6 g lamotrigine, 14 g levetiracetam, and 15 mg clonazepam. She became comatose and developed generalized tonic seizure. One hour post-ingestion, 50 g activated charcoal was administered. Starting 11 h post-ingestion, 25 g activated charcoal was administered every 4 h for 4 doses. The peak concentration of serum lamotrigine was 49.5 µg/mL, and the elimination half-life after commencement of multiple-dose activated charcoal was 6.5 h.

Case 2

A 46-year-old woman ingested 0.3 g lamotrigine and 0.1 g topiramate twice, 2 h apart. She became drowsy, complained of blurred vision, vertigo, nausea, and vomited. An initial dose of 50 g activated charcoal was administered at 4.5 h post-second ingestion, and subsequent doses of 25 g (total of 3 doses) were administered every 4 h, commencing at 8.5 h post-second ingestion. The peak concentration of serum lamotrigine was 19.9 µg/mL, and the elimination half-life after commencement of multiple-dose activated charcoal was 9.3 h.

Discussion

The mean elimination half-life of lamotrigine in healthy volunteers and epileptic patients receiving lamotrigine monotherapy is 22.8–37.4 h. In our two cases, multiple-dose activated charcoal may have shortened the elimination half-life of lamotrigine, possibly by inhibiting enterohepatic circulation. Multiple-dose activated charcoal should be considered an option for treating lamotrigine poisoning.

Keywords:

• Lamotrigine
• poisoning
• elimination half-life
• multiple-dose activated charcoal
• enterohepatic circulation

Disclosure statement

No potential conflict of interest was reported by the author(s).