Lamotrigine

Lamotrigine is an anticonvulsant medication in the phenyltriazine class used to treat epilepsy and bipolar disorder. It is approved for maintenance treatment of bipolar I depression and as adjunctive therapy for partial-onset seizures in adults and children, and as monotherapy for partial seizures in certain settings. It may also be used as adjunctive therapy for generalized tonic-clonic seizures. The exact mechanism is not fully understood, but lamotrigine is believed to inhibit voltage-gated sodium channels and reduce glutamate release, stabilizing neuronal membranes.

Common adverse effects include dizziness, headache, nausea, sleepiness, and blurred vision. A serious rash, including Stevens–Johnson syndrome, can occur, particularly during the initial weeks of treatment or with rapid titration. If a serious rash develops, lamotrigine should be discontinued promptly. Dosing must be titrated slowly to minimize this risk. Other adverse effects may include rash, diplopia, and coordination problems.

Dosing is individualized and titrated gradually. In adults, a typical starting regimen is 25 mg once daily for two weeks, then 50 mg once daily for two weeks, then 100 mg once daily, with adjustments based on indication and concomitant medications. If used with valproate, starting doses are much lower; if used with enzyme inducers (such as carbamazepine or phenytoin), higher doses may be required. Lamotrigine is primarily metabolized by hepatic glucuronidation, and drug interactions can affect its levels. Valproate increases lamotrigine levels, while enzyme inducers decrease them; estrogen-containing contraceptives can also lower lamotrigine concentrations.

Lamotrigine is available as brand-name Lamictal and Lamictal XR, as well as generic formulations. Pregnancy should be considered carefully, as lamotrigine carries fetal risk, including a possible orofacial cleft, though risk is lower than with some alternatives. Monitoring for rash and mood changes and regular clinical follow-up are advised.