Normocytic Normochromic Anaemia and Asymptomatic Neutropenia in a 40-Day-Old Infant Breastfed by an Epileptic Mother Treated With Lamotrigine: Infant's Adverse Drug Reaction

Medicines postpartum in Sweden and coverage in Janusmed Breastfeeding

PURPOSE

The purpose of this article is (1) to investigate which medicines are prescribed and dispensed to women the first 6 months postpartum, (2) to identify medicines dispensed postpartum but not recommended during breastfeeding, and (3) to find medicines commonly dispensed postpartum, but not currently included in Janusmed Breastfeeding.

METHODS

In this register-based cohort study covering births between January 2017 and August 2019, the Swedish Medical Birth Register (MBR), the Prescribed Drug Register, and Janusmed Breastfeeding were linked to identify medicines dispensed to women during the first 6 months postpartum, and how they are covered and classified in Janusmed Breastfeeding.

RESULTS

During the first 6 months postpartum, 66% of women purchased at least one prescription medicine from the pharmacy. The most common medicines were contraceptive agents, analgesics, antibiotics, and glucocorticoids. A third of the 30 most commonly dispensed medicines have no information available about the safety of use in breastfeeding. The most dispensed medicines, where the database advises against use in breastfeeding, included several antitussive agents, a local anaesthetic, and several gestagens. The most commonly dispensed medicines not covered by the Janusmed Breastfeeding were medicines for dry eyes, for assisted reproduction, and HIV.

CONCLUSION

Prescribed medicines compatible with breastfeeding are more common during the first 6 months postpartum than medicines not compatible with breastfeeding, but medicines which lack evidence for safety in breastfeeding are still commonly used.

Management of anti-seizure medications in lactating women with epilepsy

Epilepsy is a common neurological disease. At present, there are about 70 million epilepsy patients in the world, half of them are women, and 30–40% of women with epilepsy are of childbearing potential. Patients with epilepsy who are of childbearing potential face more challenges, such as seizures caused by hormonal fluctuations and the risk of adverse effects on the mother and baby from taking anti-seizure medications (ASMs). Breast milk is one of the best gifts that a mother can give her baby, and breastfeeding can bring more benefits to the baby. Compared with healthy people, people with epilepsy have more concerns about breastfeeding because they are worried that ASMs in their milk will affect the growth and development of the baby, and they are always faced with the dilemma of whether to breastfeed after childbirth. Regarding, whether women with epilepsy can breastfeed while taking ASMs, and whether breastfeeding will adversely affect the baby is still an important topic of concern for patients and doctors. This article reviews the existing research on breastfeeding-related issues in women with epilepsy to guide clinical practice, and improve the breastfeeding compliance of women 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.

Magnitude of Lamotrigine Exposure Through Breastfeeding

Importance: Lamotrigine use during breastfeeding has significantly increased in the recent years, whereas breast milk lamotrigine pharmacokinetics data are still sparse. Objectives: To assess lamotrigine exposure in breastfed infants by monitoring maternal serum and breast milk concentrations. Methods: Breastfeeding women treated with lamotrigine were recruited to this study. Maternal trough breast milk and serum samples were collected, and additional breast milk samples were collected 1, 3, 6, 9, 12 hours after lamotrigine consumption. Trough breast milk/serum ratios (M/S ratio) and breast milk area under the curve (AUC) values were calculated. Results: Twenty-one breastfeeding women were recruited to this study, and the final dataset was based on the samples collected from 17 women. Lamotrigine trough serum and mother's milk concentrations were 5.1 ± 3.3 mg/L and 3.1 ± 1.9 mg/L, respectively (mean ± standard deviation). The trough M/S ratio of lamotrigine was 0.66 ± 0.22. The lamotrigine breast milk average AUC was 41.7 ± 24.6 mg·h/L. The estimated infant dose of lamotrigine was 0.52 ± 0.31 mg/kg/day and 0.26 ± 0.15 mg/kg/day for fully and partially breastfed infants, respectively. Significant correlation was found between the maternal lamotrigine serum trough concentrations and the breast milk parameters: trough breast milk concentrations (Spearman's rho = 0.986, p < 0.0001) and breast milk AUC values (Spearman's rho = 0.941, p < 0.0001). No significant correlation was found between the maternal lamotrigine daily dose and serum trough concentrations, breast milk trough concentrations, and breast milk AUC values (Spearman's rho = 0.294, 0.285, and 0.438, p = 0.252, 0.396, and 0.078, respectively). Conclusion and Relevance: High correlation between the maternal lamotrigine trough serum concentrations and the breast milk AUC values was found, implying that monitoring the maternal lamotrigine serum concentrations can be useful for prediction of exposure of infants to lamotrigine through the breast milk. The trial was registered in the Israeli trials registry MOH_2021-09-05_010243 at September 5, 2021 Retrospectively registered https://my.health.gov.il/CliniTrials.

Incorporating Breastfeeding-Related Variability with Physiologically Based Pharmacokinetic Modeling to Predict Infant Exposure to Maternal Medication Through Breast Milk: a Workflow Applied to Lamotrigine

Current methods to assess risk in infants exposed to maternal medication through breast milk do not specifically account for infants most vulnerable to high drug exposure. A workflow applied to lamotrigine incorporated variability in infant anatomy and physiology, milk intake volume, and milk concentration to predict infant exposure. An adult physiologically based pharmacokinetic model of lamotrigine was developed and evaluated. The model was scaled to account for growth and maturation of a virtual infant population (n=100). Daily infant doses were simulated using milk intake volume and concentration models described by a nonlinear equation of weight-normalized intake across infant age and a linear function on the relationship of observed milk concentrations and maternal doses, respectively. Average infant plasma concentration at steady state was obtained through simulation. Models were evaluated by comparing observed to simulated infant plasma concentrations from breastfeeding infants based on a 90% prediction interval (PI). Upper AUC ratio (UAR) was defined as a novel risk metric. Twenty-five paired (milk concentrations measured) and 18 unpaired (milk concentrations unknown) infant plasma samples were retrieved from the literature. Forty-four percent and 11% of the paired and unpaired infant plasma concentrations were outside of the 90% PI, respectively. Over all ages (0-7 months), unpaired predictions captured more observed infant plasma concentrations within 90% PI than paired. UAR was 0.18-0.44 when mothers received 200 mg lamotrigine, suggesting that infants can receive 18-44% of the exposure per dose as compared to adults. UARs determined for further medications could reveal trends to better classify at-risk mother-infant pairs.

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.