Lamotrigine-induced carbamazepine toxicity: an interaction with carbamazepine-10,11-epoxide.
We report an interaction between lamotrigine (LTG), a new antiepileptic drug (AED), and carbamazepine (CBZ) and its primary metabolite CBZ-10,11-epoxide (CBZ-E) in 9 consecutive patients (5 male, 4 female, aged 19-31 years). After introduction of LTG (median daily dose 200 mg, range 100-300 mg) the mean serum CBZ-E concentration increased by 45% (P less than 0.01) and the CBZ-E/CBZ ratio increased by 19% (P less than 0.02). In 4 patients these changes were associated with clinical toxicity (dizziness, nausea, diplopia). The possibility of an increase in serum CBZ-E concentrations needs to be considered if toxicity symptoms develop when LTG is added to CBZ therapy.
Warner
T
T
Epilepsy Research Group, Chalfont Centre for Epilepsy, Queen Square, London, UK.
Patsalos
P N
PN
Prevett
M
M
Elyas
A A
AA
Duncan
J S
JS
D000328:Adult; D000927:Anticonvulsants / Q000009:adverse effects*; D002220:Carbamazepine / Q000009:adverse effects* / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D002851:Chromatography, High Pressure Liquid; D004347:Drug Interactions; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D000077213:Lamotrigine; D008297:Male; D011863:Radioimmunoassay; D014227:Triazines / Q000009:adverse effects*
D000927:Anticonvulsants; D014227:Triazines; D002220:Carbamazepine; C012227:carbamazepine epoxide; D000077213:Lamotrigine