Lamotrigine Pregnancy and Breastfeeding Warnings
Lamotrigine Pregnancy Warnings
Researchers working with the North American Antiepileptic Drug (NAAED) Pregnancy Registry reported an unexpectedly high prevalence of isolated, non-syndromic, cleft palate and/or cleft lip in infants exposed to lamotrigine monotherapy during the first trimester of pregnancy. In the NAAED registry, 564 pregnant women were treated with lamotrigine monotherapy, and 5 oral cleft cases (2 isolated cleft lip, 3 isolated cleft palate) occurred (total prevalence of 8.9 per 1000). Prevalence of non-syndromic oral clefts among infants of nonepileptic mothers not taking lamotrigine in other studies from the U.S., Australia and Europe range from 0.50 to 2.16 per 1000. Animal studies have revealed maternal toxicity and secondary fetal toxicity producing reduced fetal weight, delayed ossification, and fetal death. Animal studies have also reported that lamotrigine has decreased fetal folate concentrations, an effect known to be associated with teratogenesis in humans. There are no controlled data in human pregnancy. Lamotrigine serum concentrations in a newborn child comparable to those usually achieved in active treatment have been reported. Pregnancy increases lamotrigine clearance by over 50%. This effect occurs early in pregnancy and reverts quickly after delivery. Lamotrigine levels should be monitored before, during, and after pregnancy. Women should be advised to notify their physician if they plan to start or stop use of oral contraceptives or other female hormonal preparations. Physiological changes during pregnancy may affect lamotrigine concentrations and/or therapeutic effect. Decreased lamotrigine concentrations during pregnancy and restoration of prepartum concentrations after delivery have been reported. Dosage adjustments may be necessary to maintain clinical response.
FDA pregnancy category: C Lamotrigine should only be given during pregnancy when there are no alternatives and benefit outweighs risk. Physicians are advised to recommend that pregnant patients taking lamotrigine enroll in the North American Antiepileptic Drug (NAAED) Pregnancy Registry. This can be done by calling the toll free number 1-888-233-2334, and must be done by patients themselves. Information on the registry can also be found at the website http://www.aedpregnancyregistry.org/.
Lamotrigine Breastfeeding Warnings
Nursing should be discontinued in infants with lamotrigine toxicity. Caution is recommended when administered to a nursing woman. Excreted into human milk: Yes Excreted into animal milk: Unknown Breast fed infants are at risk for high serum lamotrigine levels because maternal serum and milk levels can rise to high levels postpartum if lamotrigine dosage has been increased during pregnancy but not later reduced to the prepregnancy dosage. Lamotrigine exposure is further increased due to the immaturity of the infant glucuronidation capacity needed for drug clearance. Adverse effects including apnea, drowsiness, and poor sucking have been reported in infants who have been nursed by mothers using lamotrigine. Whether or not these effects were caused by lamotrigine is unknown. Nursing infants should be closely monitored for adverse effects. Measurement of infant serum levels should be performed to rule out toxicity if concerns arise. Nursing should be discontinued in infants with lamotrigine toxicity.
Thirty women and their nursing infants participated in the study, providing a total of 210 breast milk samples. The mean milk/plasma ratio was 41.3%. There was trend of higher lamotrigine concentrations in breast milk 4 hours after the maternal dose. Infant plasma concentrations were 18.3% of maternal plasma concentrations. The theoretical infant lamotrigine dose was 0.51 mg/kg per day, and the relative infant lamotrigine dose was 9.2%. Mild thrombocytosis was present in 7 of 8 infants at the time of serum sampling. No other adverse events were observed or reported in the breastfed infants. Consistent with previous investigations of medications in breast milk, the lamotrigine milk/plasma ratio is highly variable.
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