Pharmacotherapy
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The likelihood of a drug reaction with lamotrigine is increased by dose escalation that is too rapid or drug interactions that increase the concentration of lamotrigine. There is a well-documented interaction between valproic acid and lamotrigine in which lamotrigine levels are increased, subsequently increasing the risk of a drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome. This syndrome is characterized by fever, lymphadenopathy, diffuse maculopapular rash, multivisceral involvement, eosinophilia, and atypical lymphocytes and has a mortality rate of 10-40%. ⋯ Use of the Drug Interaction Probability Scale indicated that a drug interaction between lamotrigine and ginseng was the probable cause (score of 5). The proposed mechanism of the interaction is ginseng inhibition of the uridine diphosphate glucuronosyltransferase 2B7 enzyme, similar to the mechanism of the interaction with valproic acid. Clinicians should be aware of this probable drug interaction and avoid coadministration of ginseng and lamotrigine or use a more conservative dose titration of lamotrigine for patients who are also taking ginseng.