Phenyltriazines

Phenyltriazines

The phenyltriazine lamotrigine is chemically unrelated to other anticonvulsants. This drug is FDA-approved as adjunctive therapy for adults who have partial seizures and for children older than age 2 who have generalized seizures or Lennox-Gastaut syndrome. It may also be used as monotherapy for partial seizures in adults after a hepatic enzyme–inducing anticonvulsant has been discon-tinued.

Pharmacokinetics

Lamotrigine is rapidly and well absorbed. It’s metabolized by the liver and excreted by the kidneys. Clearance is increased in the presence of other enzyme-inducing an-ticonvulsants. Lamotrigine isn’t significant-ly bound to plasma proteins.

Pharmacodynamics

Lamotrigine’s precise mechanism of action is unknown, but the drug is thought to block voltage-sensitive sodium channels, thus inhibiting the release of the excitatory neurotransmitters gluta-mate and aspartate.

Pharmacotherapeutics

Lamotrigine prevents partial seizure activity. In addition, lamotri-gine appears to be effective for many types of generalized seizures. However it can worsen myoclonic seizures.

The drug may also lead to improvement in the patient’s mood.

Drug interactions

Lamotrigine’s effects may be decreased if the drug is given with carbamazepine, phenytoin, phenobarbital, primidone, or aceta-minophen.

Lamotrigine may produce additive effects when combined with folate inhibitors.

Valproic acid may decrease lamotrigine clearance and increase the steady-state level and effects of lamotrigine. (See Adverse re-actions to lamotrigine.)