Algorithm for lamotrigine dose adjustment before, during, and after pregnancy

Abstract

Treatment with lamotrigine (LTG) during pregnancy is associated with a pronounced risk of seizure deterioration, because pregnancy accelerates LTG elimination. The extent to which pregnancy affects LTG pharmacokinetics is unpredictable and varies considerably among patients. We propose an algorithm for systematic LTG plasma concentration monitoring and dose adjustment to guide the clinician between the risk of seizure deterioration and LTG toxicity by maintaining a stable LTG concentration, using the optimal prepregnancy target concentration as a reference. The reference LTG plasma concentration (RC) should be determined before pregnancy or as early in pregnancy as possible. After conception, plasma concentration of LTG should be measured every 4 weeks throughout pregnancy. When the LTG plasma concentration falls below the RC, the dose of LTG should be increased by 20-25%. Post-partum, the plasma concentration of LTG should be measured within the first or second week, and if the LTG plasma concentration is higher than the RC, the LTG dose should be reduced by 20-25% and the procedure repeated until RC is re-established. Seizure deterioration during pregnancy may be prevented or reduced by closely and systematically following our proposed algorithm.