Serum levels of lamotrigine during delivery in mothers and their infants

Monitoring of lamotrigine concentrations in mothers, colostrum, and breastfed newborns during the early postpartum period

OBJECTIVE

To analyse the concentrations of lamotrigine in maternal serum, colostrum, and serum of breastfed newborns, and to evaluate the effect of comedication with enzyme-inducing antiseizure medication and valproic acid.

METHODS

This cohort study collected data from 158 women and 143 breastfed newborns. Maternal serum, milk (i.e., colostrum), and newborn serum samples were collected between the 2nd and 5th postnatal days, and lamotrigine concentrations were measured by high-performance liquid chromatography.

RESULTS

The median lamotrigine concentrations were 2.7 mg/L in maternal serum, 1.4 mg/L in milk, and 1.7 mg/L in newborn serum. The median milk/maternal serum concentration ratio was 0.60, the median newborn/maternal serum concentration ratio was also 0.60, and the median newborn serum/milk concentration ratio was 1.00. A significant correlation was observed between milk and maternal serum concentrations and between newborn serum and milk concentrations, maternal serum concentrations, maternal daily dose, and dose related to maternal body weight.

CONCLUSIONS

Exposure to lamotrigine in breastfed newborns is lower than exposure during pregnancy. However, by the same dose by the same mother, lamotrigine concentrations in both maternal serum and milk increase significantly after delivery. This finding, together with the immature function of eliminating enzymes in newborns, may be the reason for reaching concentrations in the reference range used for the general epileptic population in breastfed newborns. Therapeutic monitoring of breastfed newborns serum concentrations of lamotrigine is not mandatory; however, if signs of possible adverse events are noted, newborn serum concentrations should be analysed.

Chicken embryo as animal model to study drug distribution to the developing brain

INTRODUCTION

Rodent models are routinely used to assess the safety and developmental toxicity of pharmaceuticals, along with analysis of their distribution. These models require sacrifice of parent females, have challenges in the estimation of the number of embryos and stage of development, and are expensive and time-consuming. In this study, we used fertilized chicken eggs as an alternative model to address drug distribution to the developing brain of two antiepileptic drugs, valproic acid (VPA) and lamotrigine (LTG) at two developmental stages.

METHODS

VPA or LTG was injected into the allantois of the egg on embryonic day 13 (E13) or E16. Whole chicken brains were harvested at time-points of 5 min to 24 h and the concentrations of the drugs determined using GC/MS and LC-MS/MS, for VPA and LTG, respectively.

RESULTS

VPA and LTG had distinct absorption and elimination phases and were found in the brain as early as 5-15 min after injection. Both drugs reached the brain in clinically relevant concentrations, with C_max 10-30% of the calculated concentration assuming uniform distribution throughout the egg. LTG concentrations were higher when injected at E13 compared to E16.

CONCLUSION

The chicken embryo model may be a suitable alternative animal model for preclinical drug distribution studies. It enables to easily approach antenatal development on an individual level, with a precise number of experimental animals, high reproducibility and low time and cost. Knowledge of the concentrations reaching the brain at different developmental stages with different drugs is important for the planning and interpretation of neurodevelopmental toxicity studies.

Therapeutic Drug Monitoring of Antiepileptic Drugs in Women with Epilepsy Before, During, and After Pregnancy

During pregnancy, the pharmacokinetics of an antiepileptic drug is altered because of changes in the clearance capacity and volume of distribution. These changes may have consequences for the frequency of seizures during pregnancy and fetal exposure to antiepileptic drugs. In 2009, a review was published providing guidance for the dosing and therapeutic drug monitoring of antiepileptic drugs during pregnancy. Since that review, new drugs have been licensed and new information about existing drugs has been published. With this review, we aim to provide an updated narrative overview of changes in the pharmacokinetics of antiepileptic drugs in women during pregnancy. In addition, we aim to formulate advice for dose modification and therapeutic drug monitoring of antiepileptic drugs. We searched PubMed and the available literature on the pharmacokinetic changes of antiepileptic drugs and seizure frequency during pregnancy published between January 2007 and September 2018. During pregnancy, an increase in clearance and a decrease in the concentrations of lamotrigine, levetiracetam, oxcarbazepine's active metabolite licarbazepine, topiramate, and zonisamide were observed. Carbamazepine clearance remains unchanged during pregnancy. There is inadequate or no evidence for changes in the clearance or concentrations of clobazam and its active metabolite N-desmethylclobazam, gabapentin, lacosamide, perampanel, and valproate. Postpartum elimination rates of lamotrigine, levetiracetam, and licarbazepine resumed to pre-pregnancy values within the first few weeks after pregnancy. We advise monitoring of antiepileptic drug trough concentrations twice before pregnancy. This is the reference concentration. We also advise to consider dose adjustments guided by therapeutic drug monitoring during pregnancy if the antiepileptic drug concentration decreases 15-25% from the pre-pregnancy reference concentration, in the presence of risk factors for convulsions. If the antiepileptic drug concentration changes more than 25% compared with the reference concentration, dose adjustment is advised. Monitoring of levetiracetam, licarbazepine, lamotrigine, and topiramate is recommended during and after pregnancy. Monitoring of clobazam, N-desmethylclobazam, gabapentin, lacosamide, perampanel, and zonisamide during and after pregnancy should be considered. Because of the risk of teratogenic effects, valproate should be avoided during pregnancy. If that is impossible, monitoring of both total and unbound valproate is recommended. More research is needed on the large number of unclear pregnancy-related effects on the pharmacokinetics of antiepileptic drugs.

Therapeutic Drug Monitoring in Pregnant Patients

During pregnancy, there are several physiological changes during each trimester that can affect the absorption, distribution, metabolism, and elimination of drugs. Although there is a potential need to understand the pharmacokinetics and pharmacodynamics of drugs in pregnant patients, therapeutic drug monitoring is not well established for various drug classes due to ethical and safety concerns regarding the neonate. Potential risks from in utero drug exposure to the fetus may impact growth and development and may cause malformations or teratogenesis. The clinician must consider the benefits of drug treatment for the pregnant mother versus the risk to the fetus, before prescribing medications during pregnancy. The objective of this review is to aid clinicians, pharmacists, and laboratorians in understanding the pharmacokinetic and pharmacodynamic changes during pregnancy, to provide drug class recommendations for monitoring therapy throughout pregnancy via therapeutic drug monitoring, and to highlight the recent directives of governing agencies on maternal and fetal health.

[Transfer Mechanisms of Compounds between Mother and Fetus/Infant Aimed for Optimized Medication during Pregnancy and Breastfeeding]

Potential risks to the fetus or infant should be considered prior to medication during pregnancy and lactation. It is essential to evaluate the exposure levels of drugs and their related factors in addition to toxicological effects. Epilepsy is one of the most common neurological complications in pregnancy; some women continue to use antiepileptic drugs (AEDs) to control seizures. Benzodiazepines (BZDs) are widely prescribed for several women who experience symptoms such as anxiety and insomnia during the postpartum period. In this review, we describe the 1) transport mechanisms of AEDs across the placenta and the effects of these drugs on placental transporters, and 2) the transfer of BZDs into breast milk. Our findings indicated that carrier systems were involved in the uptake of gabapentin (GBP) and lamotrigine (LTG) in placental trophoblast cell lines. SLC7A5 was the main contributor to GBP transport in placental cells. LTG was transported by a carrier that was sensitive to chloroquine, imipramine, quinidine, and verapamil. Short-term exposure to 16 AEDs had no effect on folic acid uptake in placental cells. However, long-term exposure to valproic acid (VPA) affected the expression of folate carriers (FOLR1, SLC46A1). Furthermore, VPA administration changed the expression levels of various transporters in rat placenta, suggesting that sensitivity to VPA differed across gestational stages. Lastly, we developed a method for quantifying eight BZDs in human breast milk and plasma using LC/MS/MS, and successfully applied it to quantify alprazolam in breast milk and plasma donated by a lactating woman.

Comprehensive Measurements of Intrauterine and Postnatal Exposure to Lamotrigine

OBJECTIVE

The aim of this study was to measure and investigate correlations of lamotrigine concentrations in maternal as well as umbilical cord blood, amniotic fluid, and breast milk to account for the distribution of the drug.

METHODS

Concentrations of lamotrigine were measured in 19 mother-infant pairs at the time of delivery. To account for the penetration ratio into amniotic fluid, cord blood and breast milk, the concentration of lamotrigine in the particular environment was divided by the concentration in maternal serum. A no-intercept model was applied for associations between maternal serum concentrations, amniotic fluid, umbilical cord blood, and breast milk concentrations.

RESULTS

The mean daily dosage of lamotrigine was 351.32 mg (range 50-650 mg). We detected associations between maternal serum and amniotic fluid (β = 0.088, p < 0.001), as well as umbilical cord (β = 0.939, p < 0.001) and breast milk (β = 0.964, p < 0.001). The median penetration ratio into amniotic fluid, cord blood, and breast milk was 0.68, 0.92, and 0.77, respectively.

CONCLUSIONS

Lamotrigine concentrations in amniotic fluid, cord blood, and breast milk give evidence that the fetus/newborn is constantly exposed to lamotrigine. Maternal serum concentrations predicted exposure via amniotic fluid, umbilical cord, and breast milk. Data suggest that therapeutic drug monitoring can be recommended as part of the clinical routine in psychopharmacotherapy for pregnant or breastfeeding women.

Cellular uptake properties of lamotrigine in human placental cell lines: Investigation of involvement of organic cation transporters (SLC22A1-5)

Lamotrigine (LTG) is an important antiepileptic drug for the treatment of seizures in pregnant women with epilepsy. However, it is not known if the transport of LTG into placental cells occurs via a carrier-mediated pathway. The aim of this study was to investigate the uptake properties of LTG into placental cell lines (BeWo and JEG-3), and to determine the involvement of organic cation transporters (OCTs, SLC22A1-3) and organic cation/carnitine transporter (OCTNs, SLC22A4-5) in the uptake process. The uptake of LTG at 37 °C was higher than that at 4 °C. OCT1 and OCTNs were detected in both cell lines. The uptake of LTG was not greatly affected by the extracellular pH, Na⁺-free conditions, or the presence of l-carnitine, suggesting that OCTNs were not involved. Although several potent inhibitors of OCTs (chloroquine, imipramine, quinidine, and verapamil) inhibited LTG uptake, other typical inhibitors had no effect. In addition, siRNA targeted to OCT1 had no significant effect on LTG uptake. The mRNA expression in human term placenta followed the order OCTN2 > OCT3 > OCTN1 > OCT1 ≈ OCT2. These observations suggested that LTG uptake into placental cells was carrier-mediated, but that OCTs and OCTNs were not responsible for the placental transport process.

A Short Communication: Lamotrigine Levels in Milk, Mothers, and Breastfed Infants During the First Postnatal Month

BACKGROUND

Lamotrigine has become the most frequently prescribed drug in the treatment of pregnant women with epilepsy. Although some relevant studies have found a wide milk/maternal serum as well as infant/maternal serum concentration ratio, different infant ages at the time of sampling and small number of patients preclude comparison. The aim of this study was to provide a consistent evaluation.

METHODS

Data of 43 nursing women treated by lamotrigine were evaluated retrospectively. The authors followed the transport of lamotrigine during the first postnatal month from mothers to breastfed infants through maternal milk between the years 2002 and 2017.

RESULTS

Lamotrigine concentrations varied from 1.1 to 14.9 mg/L in the maternal serum, from <0.66 to 9.1 mg/L in the milk and between <0.66 and 6.9 mg/L in the infant serum. The milk/maternal serum concentration ratio ranged from <0.18 to 0.74 and the infant/maternal serum concentration ratio measured between <0.15 and 0.74. Highly significant correlations were found between milk and maternal serum levels and between infant serum levels and milk, maternal serum levels, lamotrigine daily dose, and also maternal dose related to the body weight.

CONCLUSIONS

The authors confirmed the wide range of the milk/maternal serum concentration ratio and the infant/maternal serum concentration ratio. Although the degree of lamotrigine exposure to the breastfed infants was smaller than during gestation, 16% of the infant serum levels measured were within the therapeutic range used for the general epileptic population. Lamotrigine concentration monitoring in breastfed infant, in our opinion, is the most relevant aspect for the analysis of actual lamotrigine exposure in infants, especially in those with clinical symptoms.

Pregnancy Outcomes Following In Utero Exposure to Lamotrigine: A Systematic Review and Meta-Analysis

INTRODUCTION

Lamotrigine is used in pregnancy to control epilepsy and mood disorders. The reproductive safety of this widely used drug remains undefined and may represent a significant public health concern.

OBJECTIVE

We aimed to perform a systematic review and meta-analysis of existing knowledge related to malformation rates and maternal-neonatal outcomes after in utero exposure to monotherapy with lamotrigine.

METHODS

Relevant studies were identified through systematic searches conducted in MEDLINE (Ovid), Embase (Ovid), CENTRAL (Ovid), and Web of Science (Thomson Reuters) from database inception to July 2016; no language or date restrictions were applied. All publications of clinically relevant outcomes of pregnancies following in utero exposure to lamotrigine were included in this systematic review and meta-analysis.

RESULTS

A total of 21 studies describing immediate pregnancy outcomes and rates of congenital malformations fulfilled the inclusion criteria. Compared with disease-matched controls (n = 1412, total number of patients) and healthy controls (n = 774,571, total number of patients), in utero exposure to lamotrigine monotherapy was found to be associated with significantly decreased rates of inborn defects (odds ratio [OR] 1.15; 95% confidence interval [CI] 0.62-2.16 and OR 1.25; 95% CI 0.89-1.74, respectively). Rates of miscarriages, stillbirths, preterm deliveries, and small for gestational age (SGA) neonates were not found to have been increased after in-utero exposure to LTG compared to the general population. Similarly, in utero exposure to lamotrigine monotherapy was not found to be associated with increased rates of inborn defects compared with in utero exposure to carbamazepine, and lamotrigine was found to be statistically significantly less teratogenic than valproic acid (n = 12,958 and 10,748; OR 0.84; 95% CI 0.68-1.03 and OR 0.32; 95% CI 0.26-0.39, respectively).

CONCLUSION

No association was found between prenatal lamotrigine monotherapy and increased rates of birth defects and other explored variables related to adverse pregnancy outcomes.

Placental passage of antiepileptic drugs at delivery and neonatal outcomes

Children of women treated with antiepileptic drugs (AEDs) are at increased risk of adverse outcomes detectable in the neonatal period, which may be associated with the amount of AEDs in the fetal circulation. Placental passage of AEDs can be measured by calculating the ratio of umbilical cord to maternal AED concentrations collected at delivery. The aims of this study were to determine the umbilical cord concentrations and umbilical-to-maternal ratios for AEDs, and whether higher cord concentrations are associated with increased risk of neonatal complications. AED cord and maternal blood concentrations from 70 mother-newborn dyads and neonatal complications were recorded. Logistic regressions were performed to determine the association between AED concentrations and complications. Mean umbilical-to-maternal ratios for total concentrations ranged from 0.79 for carbamazepine to 1.20 for valproic acid, and mean umbilical-to-maternal ratios for free concentrations ranged from 0.86 for valproic acid to 1.42 for carbamazepine, indicating complete placental passage. Neither umbilical cord concentrations nor umbilical-to-maternal ratios were associated with adverse neonatal outcomes. Additional investigations are warranted to delineate the relationship between quantified fetal AED exposure and neonatal complications.

Bipolar Disorder in Pregnancy and Postpartum: Principles of Management

Pregnancy and postpartum represent times of increased vulnerability for women with bipolar disorder, yet this condition remains under-diagnosed and under-treated. As 50 % of pregnancies are unplanned, the risks associated with the illness and the potential risks associated with treatment should be considered when a woman of reproductive age first presents for evaluation. This article reviews the epidemiology of perinatal bipolar disorder, screening recommendations, and treatment with pharmacotherapy and electroconvulsive therapy (ECT). An overview of the data in pregnancy and lactation is presented for lithium, lamotrigine, valproic acid, newer antipsychotics, and ECT. General principles of management include close monitoring in pregnancy and postpartum, careful adjustment of the treatment regimen to attenuate the risk of relapse, and avoidance of valproic acid when possible. Thoughtful consideration of these issues will minimize the risks to the mother and baby.

Lamotrigine dosing for pregnant patients with bipolar disorder

OBJECTIVE

Little information is available on the need for dosage changes for lamotrigine in pregnant women with bipolar disorder. The authors present new data on serial serum levels of lamotrigine in pregnant patients on lamotrigine monotherapy. They also review the epilepsy literature on use of lamotrigine during pregnancy.

METHOD

Lamotrigine serum samples were obtained from eight mother-infant pairs at different time points during pregnancy and the postpartum period.

RESULTS

All of the women were taking lamotrigine throughout pregnancy. Serum-level-to-dose ratios were lower during pregnancy than the postpartum period. Lamotrigine was taken once daily in doses ranging from 100 mg to 300 mg. Three patients had an increase of 50 mg to their daily dose across pregnancy. The change in serum lamotrigine levels in the postpartum period ranged from a 30% decrease to a 640% increase compared with the first level obtained during pregnancy. Level-to-dose ratios obtained within 4 weeks after delivery reflected a mean level 402% greater than the baseline level during gestation. Compared with the third trimester, lamotrigine serum concentration increased an average of 154% within 5 weeks after delivery. The most dramatic increase in lamotrigine serum level early after delivery occurred at 1.5 weeks. The mean infant cord level was 66% of the maternal serum level at delivery. The mean breast-fed infant serum level was 32.5% of the maternal serum levels.

CONCLUSIONS

The pattern of lamotrigine changes during pregnancy in these women with bipolar disorder was consistent with that described in the epilepsy literature.

Pharmacotherapy in pregnancy; effect of ABC and SLC transporters on drug transport across the placenta and fetal drug exposure

Pharmacotherapy during pregnancy is often inevitable for medical treatment of the mother, the fetus or both. The knowledge of drug transport across placenta is, therefore, an important topic to bear in mind when deciding treatment in pregnant women. Several drug transporters of the ABC and SLC families have been discovered in the placenta, such as P-glycoprotein, breast cancer resistance protein, or organic anion/cation transporters. It is thus evident that the passage of drugs across the placenta can no longer be predicted simply on the basis of their physical-chemical properties. Functional expression of placental drug transporters in the trophoblast and the possibility of drug-drug interactions must be considered to optimize pharmacotherapy during pregnancy. In this review we summarize current knowledge on the expression and function of ABC and SLC transporters in the trophoblast. Furthermore, we put this data into context with medical conditions that require maternal and/or fetal treatment during pregnancy, such as gestational diabetes, HIV infection, fetal arrhythmias and epilepsy. Proper understanding of the role of placental transporters should be of great interest not only to clinicians but also to pharmaceutical industry for future drug design and development to control the degree of fetal exposure.