Lamotrigine Approved in Canada for Lennox-Gastaut Syndrome
Health Canada recently approved lamotrigine (Lamictal®, [Glaxo Wellcome Inc.]) for use in combination with other medications for the treatment of Lennox-Gastaut syndrome (LGS). Lamotrigine has been available in Canada since 1994 as add-on therapy for the management of seizures in adults. It is now approved for monotherapy following polytherapy in adults, and as an add-on therapy in children and adults with LGS.
Because of the possibility of severe side effects, lamotrigine is not recommended for children under 16 years of age except in the treatment of LGS.
Lennox-Gastaut syndrome, which usually develops in children 2-8 years of age, is characterized by frequent (9-70/day), multiple types of seizures with seizure patterns differing widely from person to person; delayed or impaired mental functioning and intellectual disability; and behavioural disturbances.
Because of the multiplicity of seizures, LGS is usually treated with a combination of anti-epileptic medications (AEDs). LGS is often notoriously resistant to treatment: up to 2/3 of patients' seizures are not controlled satisfactorily by conventional AEDs. Lamotrigine may offer hope in this situation as it has been shown to significantly reduce a broader range of LGS-related seizures than do earlier AEDs and it works well in combination with other AEDs. Its broad spectrum of action may permit physicians to reduce the number of AEDs administered to some children with LGS.
To facilitate the initiation of therapy in children, Lamictal® is now available in 5 mg chewable, dispersible [soluble in liquid] tablets.
Lamotrigine is chemically unrelated to other AEDs. Although its mechanism of action is unknown, pharmacological studies suggest that it stabilizes the membranes of neurons thereby preventing the release of the excitatory amino acids, aspartate and glutamate, which are known to contribute to the excessive electrical activity which causes seizures.
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