USE OF LAMOTRIGINE IN PREGNANCY

Lamotrigine is an anticonvulsant used either as sole treatment or as adjunctive treatment of focal and generalized seizures, including tonic-clonic seizures and seizures associated with Lennox-Gastaut syndrome. Lamotrigine is also used in the treatment of bipolar disorder.

The available data on lamotrigine use in pregnancy are derived mainly from studies of women with epilepsy. Overall congenital malformation rates have been studied in over 12,800 infants exposed to lamotrigine in early pregnancy; the majority of the data do not provide evidence that lamotrigine use is associated with an increased risk of overall malformation or a number of specific malformations.

There is currently no credible evidence suggesting an increased risk of miscarriage, stillbirth, premature delivery or small for gestational age infants following exposure to lamotrigine. Data regarding adverse neurodevelopmental outcomes following prenatal exposure to lamotrigine are generally reassuring. There are currently no studies which provide evidence of an increased rate of autism diagnoses following prenatal exposure to lamotrigine; however, some studies have reported an increased rate of autism symptoms. Further research is required to confirm or refute this finding.

Lamotrigine is a weak folate antagonist and a single study has reported a statistically significant increased risk of overall malformation in children born to mothers taking lamotrigine who were prescribed <5mg folic acid per day. UK guidelines state that women who take any antiepileptic medication should be prescribed high dose folic acid (5mg).

Use of any centrally acting drug throughout pregnancy or near delivery may be associated with an increased risk of poor neonatal adaptation syndrome (PNAS). These symptoms are likely to be more severe in infants exposed in utero to more than one CNS acting drug. Where lamotrigine has been used during the latter stages of pregnancy, particularly in combination with other CNS acting medications, delivery should be planned in a unit with adequate neonatal facilities.

Plasma concentrations of lamotrigine have been shown to decline as pregnancy progresses and regular clinical review of women taking lamotrigine is therefore recommended. The lamotrigine dose may need to be increased on the basis of plasma-drug concentration monitoring or according to clinical response to maintain seizure control, particularly in later pregnancy.

Lamotrigine should only be used during pregnancy where the benefits of treatment are considered to outweigh any potential risks. Other risk factors may be also present in individual cases which may independently increase the risk of adverse pregnancy outcome. Clinicians are reminded of the importance of consideration of such factors when performing case-specific risk assessments.