Lamotrigine clearance increases by 5 weeks gestational age: Relationship to estradiol concentrations and gestational age

The impact of pregnancy-related hormonal and physiological changes on antiseizure medications: expert perspective

INTRODUCTION

Epilepsy is a disorder of recurrent, unprovoked seizures affecting approximately 15 million individuals of childbearing potential worldwide. Patients with epilepsy rely on regular daily therapy with antiseizure medications (ASMs). Furthermore, ASMs are also prescribed for other neuropsychiatric indications (e.g. bipolar disorder, pain, migraines) with over 2% of the pregnancies in the United States involving prenatal exposure to ASMs.

AREAS COVERED

ASM concentrations are affected by hormonal and physiological changes in pregnancy, including increases in renal and hepatic blood flow, decreased protein binding, and changes in enzyme activity. Clearance changes typically reverse within a few weeks after delivery. During pregnancy, many ASMs, such as lamotrigine, levetiracetam, and oxcarbazepine, should have serum concentrations monitored and doses increased to maintain the individualized target range for seizure control. ASMs metabolized via glucuronidation, primarily lamotrigine, undergo marked increases in clearance throughout pregnancy, requiring about 3-fold the pre-pregnancy daily dose by delivery. Postpartum, ASM doses are usually decreased over several weeks to prevent drug toxicity.

EXPERT OPINION

In the future, the development of a physiologically-based pharmacokinetic model for various ASMs may enable empiric dose adjustments in pregnancy without the difficulties of frequent therapeutic drug monitoring.

Step Climb Dosing Guidance From Simulation Studies on Lamotrigine Concentration Changes During Pregnancy

Empiric Dosing Strategies to Predict Lamotrigine Concentrations During Pregnancy Barry JM, French JA, Pennell PB, Karanam A, Harden CL, Birnbaum AK. Pharmacotherapy . 2023;43(10):998-1006. doi:10.1002/phar.2856 . PMID: 37475496 Introduction: Maintaining seizure control with lamotrigine is complicated by altered pharmacokinetics and existence of subpopulations in whom clearance increases or remains constant during pregnancy. Objective: Our objective was to characterize the potential for particular dosing scenarios to lead to increased seizure risk or toxicity. Methods: Lamotrigine pharmacokinetic parameters obtained from our previous study were applied to a one-compartment model structure with subpopulations (75:25%) exhibiting different clearance changes. A single-patient simulation was conducted with typical pharmacokinetic parameter values from each subpopulation. Population-level simulations (N = 48,000) included six dosing scenarios and considered four preconception doses using the R package mrgsolve (Metrum Research Group). Thresholds for efficacy and toxicity were selected as drug concentration that are 65% lower than preconception concentrations and doubling of preconception concentrations, respectively. Results: Individual simulation results demonstrated that without dose increases, concentrations fell below 0.65 at 6-8 weeks in the high clearance change (HC) subpopulation, depending on preconception clearance. While no simulated dosing regimen allowed all women in both subpopulations to maintain preconception concentrations, some regimens provided a more balanced risk profile than others. Predicted concentrations suggested potential increased seizure risk for 7%-100% of women in the HC group depending on preconception dose and subpopulation. Additionally, in 63% of dosing scenarios for women with low clearance change (LC), there was an increased risk of toxicity (34%-100% of women). Significance: A substantial percentage of simulated individuals had concentrations low enough to potentially increase seizure risk or high enough to create toxicity. Early clearance changes indicate possible subpopulation categorization if therapeutic drug monitoring is conducted in the first trimester. An arbitrary “one-size-fits-all” philosophy may not work well for lamotrigine dosing adjustments during pregnancy and reinforces the need for therapeutic drug monitoring until a patient is determined to be in the LC or HC group.

Empiric dosing strategies to predict lamotrigine concentrations during pregnancy

INTRODUCTION

Maintaining seizure control with lamotrigine is complicated by altered pharmacokinetics and existence of subpopulations in whom clearance increases or remains constant during pregnancy.

OBJECTIVE

Our objective was to characterize the potential for particular dosing scenarios to lead to increased seizure risk or toxicity.

METHODS

Lamotrigine pharmacokinetic parameters obtained from our previous study were applied to a one-compartment model structure with subpopulations (75:25%) exhibiting different clearance changes. A single-patient simulation was conducted with typical pharmacokinetic parameter values from each subpopulation. Population-level simulations (N = 48,000) included six dosing scenarios and considered four preconception doses using the R package mrgsolve (Metrum Research Group). Thresholds for efficacy and toxicity were selected as drug concentration that are 65% lower than preconception concentrations and doubling of preconception concentrations, respectively.

RESULTS

Individual simulation results demonstrated that without dose increases, concentrations fell below 0.65 at 6-8 weeks in the high clearance change (HC) subpopulation, depending on preconception clearance. While no simulated dosing regimen allowed all women in both subpopulations to maintain preconception concentrations, some regimens provided a more balanced risk profile than others. Predicted concentrations suggested potential increased seizure risk for 7%-100% of women in the HC group depending on preconception dose and subpopulation. Additionally, in 63% of dosing scenarios for women with low clearance change (LC), there was an increased risk of toxicity (34%-100% of women).

SIGNIFICANCE

A substantial percentage of simulated individuals had concentrations low enough to potentially increase seizure risk or high enough to create toxicity. Early clearance changes indicate possible subpopulation categorization if therapeutic drug monitoring is conducted in the first trimester. An arbitrary "one-size-fits-all" philosophy may not work well for lamotrigine dosing adjustments during pregnancy and reinforces the need for therapeutic drug monitoring until a patient is determined to be in the LC or HC group.

Managing Antiseizure Medications in Pregnancy: Is Earlier and More Frequent Monitoring Better?

Background and Objective

Medication management in pregnant women with epilepsy (PWWE) poses challenges, and understanding the effects of metabolic changes on antiseizure medications (ASMs) is important in planning care for PWWE. The possible teratogenic effects and risks of poorly controlled seizures have to be weighed. There are data in the literature on clinical management of ASMs including the effects of drug levels on seizures and factors that predict seizure frequency, but timing and frequency of monitoring and dose adjustment paradigms have not been well studied.

Methods

This retrospective study was approved by the Institutional Review Board at Johns Hopkins University. We retrospectively identified adult PWWE evaluated during pregnancy at the Johns Hopkins Bayview Medical Center epilepsy clinic, between January 1, 2007, and January 1, 2021. We reviewed charts for information regarding demographics, medical and epilepsy history, medications, serum drug levels, and dosing paradigms. We assessed risk factors for breakthrough seizures with a focus on frequency and timing of laboratory testing. We calculated the dose-normalized concentration (DNC) for analysis with levetiracetam and lamotrigine, assessing changes in DNC over time by half trimesters, and analyzed DNC and effects on seizures in pregnancy. We also compared preemptive vs clinically based lamotrigine dose adjustments in managing epilepsy in pregnancy.

Results

A total of 45 pregnancies in 39 patients were included in this study, 8 generalized, 28 focal epilepsy, and 3 unclassified. 31 PWWE (36 pregnancies) were on lamotrigine and/or levetiracetam, and 14 of these pregnancies experienced breakthrough seizures, 77% in the first trimester. Seizures led to the diagnosis of pregnancy in 5 patients. The DNC for levetiracetam decreased significantly compared with prepregnancy levels by the second half of the first trimester and demonstrated variable but frequently significant or near significant reduction throughout pregnancy. DNC for lamotrigine decreased significantly in the first half of the first trimester and remained significant throughout pregnancy. Age of mother at conception, week of first ASM serum level and number of levels obtained during pregnancy, and epilepsy type were not associated with breakthrough/increase in seizures. The history of drug resistance (p = 0.038) was associated with a higher odds of seizures. In those on lamotrigine, preemptive dose adjustments demonstrated similar results regarding seizure control when compared with clinical-based or laboratory-based dose management (p = 0.531).

Discussion

This study demonstrates that frequency and timing of ASM level monitoring may not affect overall seizure outcomes during pregnancy in those on lamotrigine or levetiracetam. Furthermore, one can consider preemptive dose adjustments or a laboratory-based/clinical-based approach in managing lamotrigine as both seem safe and feasible. However, in those with drug-resistant epilepsy before pregnancy, earlier and closer monitoring is warranted given the risk of seizures early during pregnancy. Larger prospective studies are needed to confirm these results.

Design Considerations for Pharmacokinetic Studies During Pregnancy

Most of the interventions performed by obstetric providers involve the administration of drugs. Pregnant patients are pharmacologically and physiologically different from nonpregnant young adults. Therefore, dosages that are effective and safe for the general public may be inadequate or unsafe for the pregnant patient and her fetus. Establishing dosing regimens appropriate for pregnancy requires evidence generated from pharmacokinetic studies performed in pregnant people. However, performing these studies during pregnancy often requires special design considerations, evaluations of both maternal and fetal exposures, and recognition that pregnancy is a dynamic process that changes as gestational age advances. In this article, we address design challenges unique to pregnancy and discuss options for investigators, including timing of drug sampling during pregnancy, appropriate selection of control groups, pros and cons of dedicated and nested pharmacokinetic studies, single-dose and multiple-dose analyses, dose selection strategies, and the importance of integrating pharmacodynamic changes into these protocols. Examples of completed pharmacokinetic studies in pregnancy are provided for illustration.

Treatment and Management of Mental Health Conditions During Pregnancy and Postpartum: ACOG Clinical Practice Guideline No. 5

PURPOSE

To assess the evidence regarding safety and efficacy of psychiatric medications to treat mental health conditions during pregnancy and lactation. The conditions reviewed include depression, anxiety and anxiety-related disorders, bipolar disorder, and acute psychosis. For information on screening and diagnosis, refer to American College of Obstetricians and Gynecologists (ACOG) Clinical Practice Guideline Number 4, "Screening and Diagnosis of Mental Health Conditions During Pregnancy and Postpartum" (1).

TARGET POPULATION

Pregnant or postpartum individuals with mental health conditions with onset that may have predated the perinatal period or may have occurred for the first time in pregnancy or the first year postpartum or may have been exacerbated in that time.

METHODS

This guideline was developed using an a priori protocol in conjunction with a writing team consisting of one specialist in obstetrics and gynecology and one maternal-fetal medicine subspecialist appointed by the ACOG Committee on Clinical Practice Guidelines-Obstetrics and two external subject matter experts. ACOG medical librarians completed a comprehensive literature search for primary literature within Cochrane Library, Cochrane Collaboration Registry of Controlled Trials, EMBASE, PubMed, and MEDLINE. Studies that moved forward to the full-text screening stage were assessed by two authors from the writing team based on standardized inclusion and exclusion criteria. Included studies underwent quality assessment, and a modified GRADE (Grading of Recommendations Assessment, Development and Evaluation) evidence-to-decision framework was applied to interpret and translate the evidence into recommendation statements.

RECOMMENDATIONS

This Clinical Practice Guideline includes recommendations on treatment and management of perinatal mental health conditions including depression, anxiety, bipolar disorders, and acute postpartum psychosis, with a focus on psychopharmacotherapy. Recommendations are classified by strength and evidence quality. Ungraded Good Practice Points are included to provide guidance when a formal recommendation could not be made because of inadequate or nonexistent evidence.

Pharmacokinetic Evaluation in Pregnancy-Current Status and Future Considerations: Workshop Summary

As pregnant individuals have traditionally been excluded from clinical trials, there is a gap in knowledge at the time of drug approval regarding safety, efficacy, and appropriate dosing for most prescription medications used during pregnancy. Physiologic changes in pregnancy can result in changes in pharmacokinetics that can impact safety or efficacy. This highlights the need to foster further research and collection of pharmacokinetic data in pregnancy to ensure appropriate drug dosing in pregnant individuals. Therefore, the US Food and Drug Administration and the University of Maryland Center of Excellence in Regulatory Science and Innovation hosted a workshop on May 16 and 17, 2022, titled "Pharmacokinetic Evaluation in Pregnancy." This is a summary of the workshop proceedings.

Principles of Obstetric Pharmacology: Maternal Physiologic and Hepatic Metabolism Changes

Since the recognition of pregnancy as a special pharmacokinetic population in the late 1990s, investigations have expanded our understanding of obstetric pharmacology. Many of the basic physiologic changes that occur during pregnancy impact on drug absorption, distribution, or clearance. Activities of hepatic metabolizing enzymes are variably altered by pregnancy, resulting in concentrations sufficiently different for some drugs that efficacy or toxicity may be affected. Understanding these unique pharmacologic changes will better inform our use of medications for our pregnant patients.

Management of Anti-Seizure Medications during Pregnancy: Advancements in The Past Decade

Management of seizures often involves continuous medication use throughout a patient's life, including when a patient is pregnant. The physiological changes during pregnancy can lead to altered drug exposure to anti-seizure medications, increasing patient response variability. In addition, subtherapeutic anti-seizure medication concentrations in the mother may increase seizure frequency, raising the risk of miscarriage and preterm labor. On the other hand, drug exposure increases can lead to differences in neurodevelopmental outcomes in the developing fetus. Established pregnancy registries provide insight into the teratogenicity potential of anti-seizure medication use. In addition, some anti-seizure medications are associated with an increased risk of major congenital malformations, and their use has declined over the last decade. Although newer anti-seizure medications are thought to have more favorable pharmacokinetics in general, they are not without risk, as they may undergo significant pharmacokinetic changes when an individual becomes pregnant. With known changes in metabolism and kidney function during pregnancy, therapeutic monitoring of drug concentrations helps to determine if and when doses should be changed to maintain similar seizure control as observed pre-pregnancy. This review concentrates on the results from research in the past decade (2010-2022) regarding risks of major congenital malformations, changes in prescribing patterns, and pharmacokinetics of the anti-seizure medications that are prescribed to pregnant patients with epilepsy.

Pharmacokinetic data in pregnancy: A review of available literature data and important considerations in collecting clinical data

Pregnancy-related physiological changes can alter the absorption, distribution, metabolism and excretion of medicines which may affect the safety and efficacy of the medicines administered in pregnancy. Pharmacokinetic data can thus be instrumental in supporting dose adjustments required in this population. This review considers the availability of published pharmacokinetic data for over 200 medicines of interest for use in pregnancy in the UK, to identify whether sufficient data currently exists, in principle, for any medicine or group of medicines to support dose adjustments to maintain maternal health through pregnancy. Very limited data was found for many of the medicines of interest. Nevertheless, well documented, large changes of exposure for some drugs, where data is available, highlights the urgent need to collect more data of good quality to inform appropriate doses, when needed, in this population. In addition, clinical study methodology can have an impact on the usefulness of the data and key clinical design aspects are highlighted for consideration in future clinical study design.

Sex and gender differences in epilepsy

Sex and gender differences in epilepsy are important influencing factors in epilepsy care. In epilepsy, the hormonal differences between the sexes are important as they impact specific treatment considerations for patients at various life stages particularly during early adulthood with establishment of the menstrual cycle, pregnancy, perimenopause and menopause. Choice of antiseizure medication may have direct consequences on hormonal cycles, hormonal contraception, pregnancy and fetal risk of major congenital malformation. Conversely hormones whether intrinsic or extrinsically administered may have direct impact on antiseizure medications and seizure control. This chapter explores these important influences on the management of persons with epilepsy.

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.

Dosage Optimization of Lamotrigine in Pregnancy: A Pharmacometric Approach using Modeling and Simulation

Lamotrigine is the most widely used anti-epileptic drug in pregnancy due to its low teratogenicity. However, there is an increased metabolism & clearance of Lamotrigine in pregnancy contributing to suboptimal drug therapy and poor disease control, prompting the need for pro-active dosage adjustments. The present study aimed to develop a pharmacometric model-based framework for recommending optimal dosage regimen for Lamotrigine in pregnancy. A systematic review was performed to obtain the literature aggregate data on clearance of Lamotrigine in pregnancy. The data was incorporated into simulations using PUMAS software for estimating the plasma concentrations at preconception stage and three trimesters. Simulated drug-exposures for different doses were investigated to ascertain plasma concentrations similar to the pre-conception and above minimum effective concentration. The simulated mean steady state trough plasma concentrations (mg/L) of Lamotrigine in non-pregnant and pregnant women at 3 trimesters decreased significantly (p<0.001) viz. 4.31±1.14, 3.17± 0.93, 2.14±0.86, 1.51±0.65 respectively. The simulation studies revealed that 150mg, 175mg, 225mg and 250mg twice daily doses, in pre-conception stage and three trimesters respectively achieve the target concentrations. Thus, the model-informed dosage regimen of Lamotrigine proposed in this study shall be considered to initiate the dosing in pregnant women, however the safety and efficacy of the drug have to be assured through therapeutic drug monitoring, in order to avoid therapeutic failure of Lamotrigine in pregnancy. This article is protected by copyright. All rights reserved.

Antiseizure Medication Concentrations During Pregnancy: Results From the Maternal Outcomes and Neurodevelopmental Effects of Antiepileptic Drugs (MONEAD) Study

IMPORTANCE

During pregnancy in women with epilepsy, lower blood concentrations of antiseizure medications can have adverse clinical consequences.

OBJECTIVE

To characterize pregnancy-associated concentration changes for several antiseizure medications among women with epilepsy.

DESIGN, SETTING, AND PARTICIPANTS

Enrollment in this prospective, observational cohort study, Maternal Outcomes and Neurodevelopmental Effects of Antiepileptic Drugs (MONEAD), occurred from December 19, 2012, to February 11, 2016, at 20 US sites. Enrolled cohorts included pregnant women with epilepsy and nonpregnant control participants with epilepsy. Inclusion criteria were women aged 14 to 45 years, an intelligence quotient greater than 70 points, and, for the cohort of pregnant women, a fetal gestational age younger than 20 weeks. A total of 1087 women were assessed for eligibility; 397 were excluded and 230 declined. Data were analyzed from May 1, 2014, to June 30, 2021.

EXPOSURE

Medication plasma concentrations in women taking monotherapy or in combination with noninteracting medications. The cohort of pregnant women was monitored through 9 months post partum, with similar time points for control participants.

MAIN OUTCOMES AND MEASURES

Dose-normalized concentrations were calculated as total or unbound plasma medication concentrations divided by total daily dose. Phlebotomy was performed during 4 pregnancy study visits and 3 postpartum visits for the pregnant women and 7 visits over 18 months for control participants. The primary hypothesis was to test pregnancy changes of dose-normalized concentrations from nonpregnant postpartum samples compared with those of control participants.

RESULTS

Of the 351 pregnant women and 109 control participants enrolled in MONEAD, 326 pregnant women (median [range] age, 29 [19-43] years) and 104 control participants (median [range] age, 29 [16-43] years) met eligibility criteria for this analysis. Compared with postpartum values, dose-normalized concentrations during pregnancy were decreased by up to 56.1% for lamotrigine (15.60 μg/L/mg to 6.85 μg/L/mg; P < .001), 36.8% for levetiracetam (11.33 μg/L/mg to 7.16 μg/L/mg; P < .001), 17.3% for carbamazepine (11.56 μg/L/mg to 7.97 μg/L/mg; P = .03), 32.6% for oxcarbazepine (11.55 μg/L/mg to 7.79 μg/L/mg; P < .001), 30.6% for unbound oxcarbazepine (6.15 μg/L/mg to 4.27 μg/L/mg; P < .001), 39.9% for lacosamide (26.14 μg/L/mg to 15.71 μg/L/mg; P < .001), and 29.8% for zonisamide (40.12 μg/L/mg to 28.15 μg/L/mg; P < .001). No significant changes occurred for unbound carbamazepine, carbamazepine-10,11-epoxide, and topiramate, although a decrease was observed for topiramate (29.83 μg/L/mg to 13.77 μg/L/mg; P = .18). Additionally, compared with dose-normalized concentrations from control participants, pregnancy dose-normalized median (SE) concentrations decreased significantly by week of gestational age: carbamazepine, -0.14 (0.06) μg/L/mg (P = .02); carbamazepine unbound, -0.04 (0.01) μg/L/mg (P = .01); lacosamide, -0.23 (0.07) μg/L/mg (P < .001); lamotrigine, -0.20 (0.02) μg/L/mg (P < .001); levetiracetam, -0.06 (0.03) μg/L/mg (P = .01); oxcarbazepine, -0.14 (0.04) μg/L/mg (P < .001); oxcarbazepine unbound, -0.11 (0.03) μg/L/mg (P < .001); and zonisamide, -0.53 (0.14) μg/L/mg (P < .001) except for topiramate (-0.35 [0.20] μg/L/mg per week) and carbamazepine-10,11-epoxide (0.02 [0.01] μg/L/mg).

CONCLUSIONS AND RELEVANCE

Study results suggest that therapeutic drug monitoring should begin early in pregnancy and that increasing doses of these anticonvulsants may be needed throughout the course of pregnancy.

Estrogen profile- and pharmacogenetics-based lamotrigine dosing regimen optimization: Recommendations for pregnant women with epilepsy

During pregnancy, various physiological changes occur that can alter the pharmacokinetics of antiepileptic drugs, such as lamotrigine (LTG). Anticipating the change in LTG dose required to achieve a pre-pregnancy target concentration is challenging. This study aimed to develop a refined population pharmacokinetic (PopPK) model of LTG in pregnant women with epilepsy (WWE) to identify factors explaining the variability in pharmacokinetics and to establish a model-informed individualized dosing regimen. On that basis, a coarsened model containing only clinical variables was also developed to examine its predictive performance compared to the refined model. In total, 322 concentration-time points from 51 pregnant WWE treated with LTG were employed to establish a refined PopPK model that included endogenous estrogen profiles, variants of candidate genes encoding LTG-metabolizing enzymes and -transporter proteins, and other clinical variables and a coarsened model that included only clinical variables, respectively. Data from an additional 11 patients were used for external validation of these two models. A nonlinear mixed-effect modeling approach was used for PopPK analysis of LTG. The standard goodness-of-fit method, bootstrap, normalized prediction distribution errors and external evaluation were adopted to estimate the stability and predictive performance of the candidate models. Akaike information criterion (AIC) was used to compare the goodness of fit between these two models. A lower AIC indicates a better fit of the data and the preferred model. Recommended dosing regimens for pregnant WWE were selected using Monte Carlo simulation based on the established optimal model. In the refined PopPK model, the population mean of apparent LTG clearance (CL/F) in pregnant WWE was estimated to be 2.82 L/h, with an inter-individual variability of 23.6%. PopPK analysis indicated that changes in estrogen profile during pregnancy were the predominant reason for the significant variations in LTG-CL/F. Up to the 3rd trimester, the concentration accumulation effect of E2 increased LTG-CL/F by 5.109 L/h from baseline levels. Contrary to effect of E2, E3 as the main circulating estrogen in pregnancy with a peak value of 34.41 ng/mL is 1000-fold higher than that in non-pregnancy reduced LTG-CL/F by 1.413 L/h. In addition, the UGT2B7 rs4356975 C > T and ABCB1 rs1128503 A > G variants may contribute to a better understanding of the inter-individual variability in LTG-CL/F. LTG-CL/F was 1.66-fold higher in UGT2B7 rs4356975 CT or TT genotype carriers than in CC genotype carriers. In contrast, ABCB1 rs1128503 GG genotype carriers had only 71.9% of the LTG-CL/F of AA or AG genotype carriers. In the coarsened PopPK model, the gestational age was a promising predictor of changes in LTG-CL/F. When comparing these two models, the refined PopPK model was favored over the coarsened PopPK model (AIC = -30.899 vs. -20.017). Monte Carlo simulation based on optimal PopPK model revealed that the LTG dosage administered to carriers of the UGT2B7 rs4356975 CT or TT genotype required a 33-50% increase to reach the pre-pregnancy target concentration, and carriers of the ABCB1 rs1128503 GG genotype required a 33-66% lower dose of LTG than carriers of the ABCB1 rs1128503 AA or AG genotype. Changes in estrogen profile during pregnancy was a better predictor of variations in LTG-CL/F than gestational age. The developed model based on estrogen profile and pharmacogenetics can serve as a foundation for further optimization of dosing regimens of LTG in pregnant WWE.

Response to levetiracetam or lamotrigine in subjects with Juvenile Myoclonic Epilepsy previously treated with valproic acid: A single center retrospective study

BACKGROUND

Valproic acid (VPA) is the most effective medication in juvenile myoclonic epilepsy (JME) but, due to its teratogenic potential, levetiracetam (LEV) and lamotrigine (LTG) are preferred in women of childbearing age. The aim of this study was to compare the effectiveness and tolerability of LEV and LTG monotherapy in patients with a previous good seizure control in VPA monotherapy, in which VPA was withdrawn because of teratogenic potential or adverse drug effects.

METHODS

We retrospectively analyzed 65 patients with JME which had been followedup at the Epilepsy Center of Pisa University Hospital, identifying 28 subjects who had been successfully treated with VPA monotherapy and who were shifted to another monotherapy. The second monotherapy was LEV for 14 subjects and LTG for the remaining 14 ones. Drug efficacy was measured in terms of seizure freedom for more than twelve months after reaching the minimum effective or the highest tolerated dose.

RESULTS

In terms of seizure control, our analysis showed a significantly better outcome for LEV compared to LTG (14.3% and 71.4% of seizure relapse, respectively, p = 0.006) monotherapy. Such a higher efficacy was confirmed in those subjects with seizure relapse on LTG, who achieved good seizure control after switching to LEV monotherapy (89% of cases). Concerning tolerability, none of the patients reported severe side effects.

CONCLUSION

Although obtained in a small case series, our analysis showed a significant better efficacy of LEV compared to LTG in monotherapy, in patients with JME with a good response to VPA, concerning both myoclonic and generalized tonic-clonic seizures.

Antiepileptic Drug Exposure in Infants of Breastfeeding Mothers With Epilepsy

Importance

There is limited information on infant drug exposure via breastfeeding by mothers who are receiving antiepileptic drug therapy.

Objective

To provide direct, objective information on antiepileptic drug exposure through breast milk.

Design, Setting, and Participants

This prospective cohort study was conducted between December 2012 to October 2016, with follow-up in children until 6 years of age at 20 sites across the United States. Data were collected via an observational multicenter investigation (Maternal Outcomes and Neurodevelopmental Effects of Antiepileptic Drugs [MONEAD]) of outcomes in pregnant mothers with epilepsy and their children. Pregnant women with epilepsy who were aged 14 to 45 years, had pregnancies that had progressed to less than 20 weeks' gestational age, and had measured IQ scores of more than 70 points were enrolled and followed up through pregnancy and 9 postpartum months. Their infants were enrolled at birth. Data were analyzed from May 2014 to August 2019.

Exposures

Antiepileptic drug exposure in infants who were breastfed.

Main Outcomes and Measures

The percentage of infant-to-mother concentration of antiepileptic drugs. Antiepileptic drug concentrations were quantified from blood samples collected from infants and mothers at the same visit, 5 to 20 weeks after birth. Concentrations of antiepileptic drugs in infants at less than the lower limit of quantification were assessed as half of the lower limit. Additional measures collected were the total duration of all daily breastfeeding sessions and/or the volume of pumped breast milk ingested from a bottle.

Results

A total of 351 women (of 865 screened and 503 eligible individuals) were enrolled, along with their 345 infants (179 female children [51.9%]; median [range] age, 13 [5-20] weeks). Of the 345 infants, 222 (64.3%) were breastfed; the data collection yielded 164 matching infant-mother concentration pairs from 138 infants. Approximately 49% of all antiepileptic drug concentrations in nursing infants were less than the lower limit of quantification. The median percentage of infant-to-mother concentration for all 7 antiepileptic drugs and 1 metabolite (carbamazepine, carbamazepine-10,11-epoxide, levetiracetam, lamotrigine, oxcarbazepine, topiramate, valproate, and zonisamide) ranged from 0.3% (range, 0.2%-0.9%) to 44.2% (range, 35.2%-125.3%). In multiple linear regression models, maternal concentration was a significant factor associated with lamotrigine concentration in infants (Pearson correlation coefficient, 0.58; P < .001) but not levetiracetam concentration in infants.

Conclusions and Relevance

Overall, antiepileptic drug concentrations in blood samples of infants who were breastfed were substantially lower than maternal blood concentrations. Given the well-known benefits of breastfeeding and the prior studies demonstrating no ill effects when the mother was receiving antiepileptic drugs, these findings support the breastfeeding of infants by mothers with epilepsy who are taking antiepileptic drug therapy.

Drugs in pregnancy: Pharmacologic and physiologic changes that affect clinical care

Pharmacologic interventions play a major role in obstetrical care throughout pregnancy, labor and delivery and the postpartum. Traditionally, obstetrical providers have utilized standard dosing regimens developed for non-obstetrical indications based on pharmacokinetic knowledge from studies in men or non-pregnant women. With the recognition of pregnancy as a special pharmacokinetic population in the late 1990s, investigators have begun to study drug disposition in this unique patient dyad. Many of the basic physiologic changes that occur during pregnancy have significant impact on drug absorption, distribution and clearance. Activity of Phase I and Phase II drug metabolizing enzymes are differentially altered by pregnancy, resulting in drug concentrations sufficiently different for some medications that efficacy or toxicity is affected. Placental transporters play a major dynamic role in determining fetal drug exposure. In the past two decades, we have begun to expand our understanding of obstetrical pharmacology; however, to truly optimize pharmacologic care of our pregnant patients and their developing fetus, additional research is critically needed.

Psychotropic drug use in perinatal women with bipolar disorder

Optimal dose management of psychotropic drugs during the perinatal period reduces the risk for recurrence of mood episodes in women with Bipolar Disorder. Physiological changes during pregnancy are associated with decreases in the plasma concentrations of the majority of mood stabilizing medications. Regular symptom and drug concentration monitoring for lithium and anticonvulsants with reflexive dose adjustment improves the probability of sustained symptom remission across pregnancy. The elimination clearance trajectory across pregnancy for psychotropics dictates the frequency of laboratory monitoring and dose adjustment. The literature on the pharmacokinetics of lithium, lamotrigine, carbamazepine and atypical antipsychotics during pregnancy and postpartum are reviewed, recommendations for symptom and laboratory monitoring are proposed and recommendations for dose adjustments are presented.

Pharmacokinetic studies in pregnancy

The effects of the many biochemical and physiologic changes of pregnancy on the dose-response relationship of drugs administered to pregnant women are poorly understood. The dose-response relationship is affected by pharmacokinetics, or what the body does to a drug, and pharmacodynamics, or what a drug does to the body. Insights into the potential effects of the changes of pregnancy on one aspect of the dose-response relationship of a drug can be obtained by studying the pharmacokinetics of the drug in the various stages of pregnancy and the postpartum period. There are several available approaches to studying pharmacokinetic changes in pregnancy. Single trough screening studies can provide qualitative estimates of elimination clearance, which with the dosing rate determines the steady-state drug concentration, throughout pregnancy and into the postpartum period. Population pharmacokinetic studies such as two stage pharmacokinetic studies and studies using a nonlinear mixed effects pharmacokinetic modeling approach can characterize pharmacokinetic changes more rigorously.

Epilepsy

The management of epilepsy during pregnancy involves optimizing seizure control for the mother, while ensuring the best outcome for the developing fetus. Preconception counseling regarding contraception, folic acid, and antiseizure medications (ASMs) will maximize positive outcomes. Folic acid supplementation is recommended to decrease risk of neural tube defects, similar to the general population, and has been associated with improved cognitive outcomes and decreased risk of autistic traits in offspring. Efforts should be made to optimize the ASM regimen before pregnancy to the fewest number of ASMs, lowest effective doses, with avoidance of more teratogenic agents such as valproic acid. Valproic acid is associated with the highest increased risk of major congenital malformations, as well as reduced cognitive outcomes and neurodevelopmental disorders. Decreasing or changing ASMs during pregnancy should be done with caution, as convulsive seizures have been associated with adverse fetal outcomes including cognitive impairment. Physiologic changes during pregnancy affect ASM levels and in turn, risk for seizures, necessitating frequent monitoring of ASM serum concentrations. Mothers should also be counseled postpartum about how the benefits of breastfeeding outweigh the transmission of medication into breast milk. Communication between providers (obstetrics and neurology) and pregnant women with epilepsy is essential.

Change in antiepileptic drug prescription patterns for pregnant women with epilepsy over the years: Impact on pregnancy and fetal outcomes

AIMS AND OBJECTIVES:

The objectives of the study were: (1) to determine if there is a change in pattern of antiepileptic drug (AED) prescription during pregnancy in women with epilepsy (WWE) attending a tertiary care institute in North India and (2) to determine if change in AED prescription pattern has resulted in improved fetal and maternal outcomes in WWE.

PATIENTS AND METHODS:

The current study was a retrospective analysis of records of WWE attending a medical and surgical disorder clinic of obstetrics and gynecology department of a tertiary care teaching hospital in North India. We retrospectively collected data of all the patients during the 5-year period from 2011 to 2015 (Group A) (n = 177) and compared it with our previously published data during the years 1987–1994 (Group B) (n = 219).

RESULTS:

There was significantly higher use of (i) levetiracetam (LEV) in Group A compared to Group B when women on monotherapy were compared (P<0.0001) and (ii) LEV (P<0.0001), clobazam (P<0.0001) and lamotrigine (P=0.0004) in Group A compared to Group B when women on polytherapy were compared. A significantly higher (P=0.02) number of women were using more than two antiepileptic drugs simultaneously in Group A compared to Group B. There was a significantly higher incidence (P = 0.001) of small for gestational age babies in Group A.

CONCLUSION:

Although there is an increase in the use of newer AEDs in WWE during pregnancy in North Indian population, it has not resulted in improved maternal and fetal outcomes. (2) to determine if change in AED prescription pattern has resulted in improved fetal and maternal outcomes in WWE.

Pharmacokinetic changes and therapeutic drug monitoring of lamotrigine during pregnancy

OBJECTIVES

To evaluate the pharmacokinetic changes in lamotrigine (LTG) from prepregnancy to postpartum and to assess the impact of therapeutic drug monitoring (TDM) on seizure management during pregnancy in a Chinese population.

METHODS

A series of women who were on LTG monotherapy before conception or during pregnancy were included in this retrospective study. The clinical characteristics of the mothers and fetuses were collected. The apparent clearance (AC) and the ratio to target concentration (RTC) were calculated for each trimester or for each month. RTCs were compared between patients with and without an increase in the frequency of seizures. A receiver operating characteristic curve to determine the RTC threshold, which predicts increased seizure frequency best, was drawn.

RESULTS

A total of 12 patients and their 12 pregnancies were reviewed retrospectively. AC increased by 82.5% during the first trimester (p = 0.0343), 203.2% during the second trimester (p = 0.0010), and 197.0% during the third trimester (p = 0.0061) compared with the prepregnancy level. The value returned to the prepregnancy level after delivery. Seven patients who had adequate baseline information were included to examine the association between serum LTG concentration and seizure frequency. The RTC values of patients with and without an increased frequency of seizures were significantly different (p = 0.0164), and increased seizure frequency was associated with a lower RTC. An RTC < 0.64 was a predictor of deteriorating seizures.

CONCLUSIONS

The pharmacokinetic changes in LTG during pregnancy displayed marked interpatient variation. TDM can support a rational treatment plan for LTG use during pregnancy. We recommend regular monitoring of LTG serum concentrations from prepregnancy to postpartum.