Lamotrigine overdose presenting as anticonvulsant hypersensitivity syndrome

OBJECTIVE: TO describe the laboratory and physical manifestations of lamotr igine toxicity presenting as anticonvulsant hypersensitivity syndrome. CASE SUMMARY.: A 49-year-old white man presented to our institution with a two-d ay history of low-grade fever, erythema, and edema involving the periorbita l area. Five days earlier, he had been placed on lamotrigine treatment for bipolar disorder. He inadvertently received four daily doses of lamotrigine 2700 mg each. Physical examination was significant for periorbital edema a nd discrete and confluent blanching red macules and papules involving the f ace, trunk, and extremities. Laboratory tests revealed leukocytosis, hepati tis, and acute renal failure. With normalization of the laboratory results, the eruptions and edema gradually resolved. DISCUSSION: Lamotrigine toxicity can lead to periorbital edema, rash, and m ultiorgan system abnormalities. This presentation has clinical and laborato ry similarities with anticonvulsant hypersensitivity syndrome, which sugges ts that at some threshold concentration the amount of lamotrigine may overw helm the body's ability to metabolize the drug, leading to a similar hypers ensitivity reaction. Lamotrigine is a relatively new agent, and this report may provide useful insights on evaluating the clinical toxicology of this agent. CONCLUSIONS: Healthcare providers should be aware that lamotrigine overdose may present with multiorgan involvement similar to anticonvulsant hypersen sitivity syndrome.