* Topiramate induces CYP3A4 and is an inhibiter inhibitor of CYP2C19.
* Lamotrigine is principally metabolised by UDP-glucuronosyltransferases.
* This combination of drugs may have possible synergistic effects. However, this combination will also have additive side effects. Dose adaptation will be recommended for this combination.{{PossibleSynergisticEffects}}
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* Topiramate does not cause a significant change in lamotrigine levels. <ref> {{Pubmed|12180999|Berry at al, Lack of an effect of topiramate on lamotrigine serum concentrations. Epilepsia 2002;43(8):818-23}}</ref> Start topiramate according to the general dosing advice.