Studying drugs in human milk: time to unify the approach

Attaining Equity of Access to Research: Perspective on Research in Pregnancy and Breastfeeding Following Dolores Shockley Lecture at ASCPT2024

Everybody deserves access to evidence-based information to make decisions about their health. However, in many situations, clinical trial eligibility criteria mean that specific data do not exist for certain groups of individuals. These include pregnant and breastfeeding women, children, older people, those with hepatic and renal dysfunction, those with acute severe illness, and those with multiple co-morbidities and interacting medications. Resultantly, there may not be specific drug-dosing information for many patients who are treated in a clinical setting. The ASCPT2024 Dolores Shockley Lecture focused on the equitable access to research with a specific focus on clinical pharmacology studies in pregnancy and breastfeeding. To ensure the safe, effective use of medication in pregnancy and breastfeeding, women should be included in clinical trials and pharmacokinetic studies when a medication is anticipated to be used in women of childbearing potential. Community groups should be involved at all stages of research to maintain transparency and trust. This ensures that local priorities are investigated, that communities understand the findings and are empowered to make evidence-based decisions about their own medication use. Principles informing the design of such studies in pregnancy and lactation are in existence. Mathematical techniques such as physiologically-based pharmacokinetic modeling and stochastic simulation and estimation can enhance study design, and population pharmacokinetic modeling be used to understand variability within and between individuals. Data should be made findable, accessible, interoperable, and reusable (FAIR). Information (and where necessary, training) regarding the use of these approaches should be provided to decision-making stakeholders such as ethics committees and regulatory bodies.

Sertraline, citalopram and paroxetine in lactation: passage into breastmilk and infant exposure

Objectives

This study aimed to investigate the plasma and breastmilk concentrations for sertraline, citalopram and paroxetine for assessment of the Milk/Plasma (M/P) ratio and Absolute Infant Dose (AID), and to determine actual infant drug exposure through breastfeeding. Subsequently, informed recommendations will be formulated regarding the advisability of breastfeeding in women undergoing treatment with the three most widely used antidepressants.

Methods

A pharmacokinetic study in lactating women and their infants using sertraline, citalopram or paroxetine was performed. Paired breastmilk and plasma samples and single point infant plasma samples were collected to determine antidepressant concentrations. An Area Under the Curve (AUC) based approach with the trapezoidal rule was used to calculate M/P ratios and AID for all three antidepressants by combining all measured concentrations for the same dose.

Results

Thirty-seven lactating women and their infants participated in this study. 111 paired breastmilk and plasma samples and 37 single point infant plasma samples were collected. Detectable concentrations of sertraline, citalopram and paroxetine were present in all breastmilk samples. For sertraline and citalopram M/P ratio is above one, indicating higher breastmilk than plasma concentrations, however, drug exposure by breastmilk did not lead to detectable plasma drug levels in any of the 15 infants for sertraline, for nine (out of 13) infants for citalopram and for eight (out of nine) infants for paroxetine.

Conclusion

Given the well-known benefits of breastfeeding, our findings support breastfeeding of infants by mothers who are taking sertraline, citalopram or paroxetine is safe. Sertraline and paroxetine are the preferred antidepressants during breastfeeding, reaching mostly undetectable infant drug levels.

Drugs in Human Milk Part 1: Practical and Analytical Considerations in Measuring Drugs and Metabolites in Human Milk

Human milk is a remarkable biofluid that provides essential nutrients and immune protection to newborns. Breastfeeding women consuming medications could pass the drug through their milk to neonates. Drugs can be transferred to human milk by passive diffusion or active transport. The physicochemical properties of the drug largely impact the extent of drug transfer into human milk. A comprehensive understanding of the physiology of human milk formation, composition of milk, mechanisms of drug transfer, and factors influencing drug transfer into human milk is critical for appropriate selection and use of medications in lactating women. Quantification of drugs in the milk is essential for assessing the safety of pharmacotherapy during lactation. This can be achieved by developing specific, sensitive, and reproducible analytical methods using techniques such as liquid chromatography coupled with mass spectrometry. The present review briefly discusses the physiology of human milk formation, composition of human milk, mechanisms of drug transfer into human milk, and factors influencing transfer of drugs from blood to milk. We further expand upon and critically evaluate the existing analytical approaches/assays used for the quantification of drugs in human milk.

Consensus Panel Recommendations for the Pharmacological Management of Breastfeeding Women with Postpartum Depression

INTRODUCTION

Our consensus statement aims to clarify the use of antidepressants and anxiolytics during breastfeeding amidst clinical uncertainty. Despite recent studies, potential harm to breastfed newborns from these medications remains a concern, leading to abrupt discontinuation of necessary treatments or exclusive formula feeding, depriving newborns of benefits from mother's milk.

METHODS

A panel of 16 experts, representing eight scientific societies with a keen interest in postpartum depression, was convened. Utilizing the Nominal Group Technique and following a comprehensive literature review, a consensus statement on the pharmacological treatment of breastfeeding women with depressive disorders was achieved.

RESULTS

Four key research areas were delineated: (1) The imperative to address depressive and anxiety disorders during lactation, pinpointing the risks linked to untreated maternal depression during this period. (2) The evaluation of the cumulative risk of unfavorable infant outcomes associated with exposure to antidepressants or anxiolytics. (3) The long-term impact on infants' cognitive development or behavior due to exposure to these medications during breastfeeding. (4) The assessment of pharmacological interventions for opioid abuse in lactating women diagnosed with depressive disorders.

CONCLUSIONS

The ensuing recommendations were as follows: Recommendation 1: Depressive and anxiety disorders, as well as their pharmacological treatment, are not contraindications for breastfeeding. Recommendation 2: The Panel advocates for the continuation of medication that has demonstrated efficacy during pregnancy. If initiating an antidepressant during breastfeeding is necessary, drugs with a superior safety profile and substantial epidemiological data, such as SSRIs, should be favored and prescribed at the lowest effective dose. Recommendation 3: For the short-term alleviation of anxiety symptoms and sleep disturbances, the Panel determined that benzodiazepines can be administered during breastfeeding. Recommendation 4: The Panel advises against discontinuing opioid abuse treatment during breastfeeding. Recommendation 5: The Panel endorses collaboration among specialists (e.g., psychiatrists, pediatricians, toxicologists), promoting multidisciplinary care whenever feasible. Coordination with the general practitioner is also recommended.

Anidulafungin Levels in Breast Milk After Cessation of Treatment: A Case Report

Background: Anidulafungin has poor oral bioavailability, with hardly any available information on how it affects breast milk, oral absorption, or gastrointestinal side effects in the infant. Case Presentation: A 40-year-old woman who recently gave birth to a healthy infant was treated for a period of 14 days for a Candida glabrata with 100 mg anidulafungin once a day. The department of clinical pharmacy was consulted to provide advice on how long the patient had to wait after ceasing anidulafungin before it was safe to start breastfeeding, with regard to preventing possible side effects of the drug to the infant, such as diarrhea or cholestasis and increase in liver enzyme values. The advice of the hospital pharmacist was pragmatic: to start breastfeeding within 2 days after the medication was discontinued based on half-time. Results: Owing to this lack of information, we measured anidulafungin concentrations in breast milk and found low levels. Conclusion: We concluded that anidulafungin is detectable in breast milk until 32 hours after anidulafungin treatment was stopped, and that no side effects were observed by the infant.

A systematic review on maternal-to-infant transfer of drugs through breast milk during the treatment of malaria, tuberculosis, and neglected tropical diseases

BACKGROUND

Exclusive breastfeeding of infants under 6 months of age is recommended by the World Health Organization. In 2021, over 300 million combined incident cases of malaria, tuberculosis, and neglected tropical diseases (NTDs) were reported, predominantly in low-income countries. For many of the drugs used as first-line treatments for these conditions, there is limited knowledge on infant exposure through breastfeeding with poorly understood consequences. This review summarized available knowledge on mother-to-infant transfer of these drugs to inform future lactation pharmacokinetic studies.

METHODOLOGY

A list of first-line drugs was generated from the latest WHO treatment guidelines. Using standard online databases, 2 independent reviewers searched for eligible articles reporting lactation pharmacokinetics studies and extracted information on study design, participant characteristics, and the mathematical approach used for parameter estimation. A third reviewer settled any disagreements between the 2 reviewers. All studies were scored against the standardized "ClinPK" checklist for conformity to best practices for reporting clinical pharmacokinetic studies. Simple proportions were used to summarize different study characteristics.

FINDINGS

The most remarkable finding was the scarcity of lactation pharmacokinetic data. Only 15 of the 69 drugs we listed had lactation pharmacokinetics fully characterized. Most studies enrolled few mothers, and only one evaluated infant drug concentrations. Up to 66% of the studies used non-compartmental analysis to estimate pharmacokinetic parameters rather than model-based compartmental analysis. Unlike non-compartmental approaches, model-based compartmental analysis provides for dynamic characterization of individual plasma and breast milk concentration-time profiles and adequately characterizes variability within and between individuals, using sparsely sampled data. The "ClinPK" checklist inadequately appraised the studies with variability in the number of relevant criteria across different studies.

CONCLUSIONS/SIGNIFICANCE

A consensus is required on best practices for conducting and reporting lactation pharmacokinetic studies, especially in neglected diseases such as malaria, tuberculosis, and NTDs, to optimize treatment of mother-infant pairs.

Safety of medicines during breastfeeding - from case report to modeling : A contribution from the ConcePTION project

INTRODUCTION

Despite many research efforts, current data on the safety of medicines during breastfeeding are either fragmented or lacking, resulting in restrictive labeling of most medicines. In the absence of pharmacoepidemiologic safety studies, risk estimation for breastfed infants is mainly derived from pharmacokinetic (PK) information on the medicine. This manuscript provides a description and a comparison of the different methodological approaches that can yield reliable information on medicine transfer into human milk and the resulting infant exposure.

AREA COVERED

Currently, most information on medicine transfer in human milk relies on case reports or traditional PK studies, which generate data that can hardly be generalized to the population. Some methodological approaches, such as population PK (popPK) and physiologically-based PK (PBPK) modeling, can be used to provide a more complete characterization of infant medicine exposure through human milk and simulate the most extreme situations, while decreasing the burden of sampling in breastfeeding women.

EXPERT OPINION

PBPK and popPK modeling are promising approaches to fill the gap of knowledge in medicine safety in breastfeeding, as illustrated with our escitalopram example.

Breastfeeding and the patient's perspective

PURPOSE

The purpose of this article is to summarize available data on breastfeeding in patients with a cancer diagnosis.

MATERIALS AND METHODS

A review of available literature in the MEDLINE database was performed and the data summarized. In addition, two patient interviews were conducted to gain insight into the patient perspective.

RESULTS

Breastmilk is the nutritional standard for human infants and understanding the implications of a cancer diagnosis on lactation is important in optimizing maternal and infant outcomes. Though limited, available data suggest that breastfeeding may be a safe and appropriate option for some patients undergoing treatment of a malignancy.

CONCLUSIONS

Patient experiences with breastfeeding in the setting of a cancer diagnosis vary widely, and depend on the type of malignancy, the timing of the diagnosis, and the indicated treatment. Breastfeeding may be an appropriate option for certain patients after multidisciplinary counseling. Alternatives to breastfeeding exist for patients who are unable to or do not desire to breastfeed.

Validation and application of a quantitative LC-MS/MS assay for the analysis of first-line anti-tuberculosis drugs, rifabutin and their metabolites in human breast milk

Breast milk is the preferred method of infant nutrition. Breastfeeding infants born to mothers treated for TB may be at risk of drug toxicity through breast milk exposure, or potentially be vulnerable to select for drug resistance with low level drug exposure. Except for isoniazid, the quantification of first-line TB drugs including rifabutin in breast milk has not been previously described and will provide much-needed insight to TB drug exposure in breastfeeding infants. We developed and validated a novel method to quantify several first-line TB drugs and their major metabolites in breast milk. Accuracy and precision were assessed during three consecutive, independent validation batches over a calibration range of 0.300-30.0 µg/mL for isoniazid and ethambutol, 0.150-15.0 µg/mL for acetyl isoniazid, desacetyl rifampicin, rifampicin, and pyrazinamide, 0.0150-1.50 µg/mL for rifabutin, and 0.00751-0.751 µg/mL for deacetyl rifabutin in breast milk. The method was reproducible for all analytes when using breast milk from six different sources and was not influenced by matrix effects with a mean regression precision (CV(%)) ranging between 1.0 and 2.8. The average recovery of analytes from the matrix was 76.7-99.1%, with a CV(%) between 0.4 and 4.4, while the average process efficiency was between 74.4 and 93.1% with a CV(%) between 1.9 and 8.3. Although only acetyl isoniazid, isoniazid, ethambutol, and pyrazinamide were successfully assayed in breast milk, samples taken from mothers treated for rifampicin-resistant TB and the inclusion of all first-line TB drugs, including rifabutin in the assay development and validation process will allow future quantification of these analytes in breast milk.

Postpartum depression: A role for psychedelics?

BACKGROUND

Postpartum depression (PPD) is a major public health concern and has, at its core, a sense of maternal 'disconnection' - from the self, the infant, and the support system. While PPD bears similarities with MDD, there is increasing evidence for its distinct nature, especially with the unique aspect of the mother-infant relationship. Current treatment modalities for PPD, largely based on those used in major depressive disorder (MDD), have low remission rates with emerging evidence for treatment resistance. It is, therefore, necessary to explore alternative avenues of treatment for PPD.

OBJECTIVE

In this narrative review, we outline the potential therapeutic rationale for serotonergic psychedelics in the treatment of PPD, and highlight safety and pragmatic considerations for the use of psychedelics in the postpartum period.

METHODS

We examined the available evidence for the treatment of PPD and the evidence for psychedelics in the treatment of MDD. We explored safety considerations in the use of psychedelics in the postpartum period.

RESULTS

There is increasing evidence for safety, and encouraging signals for efficacy, of psilocybin in the treatment of MDD. Psilocybin has been shown to catalyse a sense of 'reconnection' in participants with MDD. This effect in PPD, by fostering a sense of 'reconnection' for the mother, may allow for improved mood and maternal sensitivity towards the infant, which can positively impact maternal role gratification and the mother-infant relationship.

CONCLUSION

Psychedelic assisted therapy in PPD may have a positive effect on the mother-infant dyad and warrants further examination.

Safety of breast feeding during rituximab treatment in multiple sclerosis

BACKGROUND

There are limited data on the safety of breast feeding during rituximab therapy. Our objective is to determine exposure from breast feeding and biological effects of rituximab in breastfed infants.

METHODS

In our case series of six mother-infant pairs, the nursing mothers with relapsing-remitting multiple sclerosis received rituximab during breast feeding. As part of clinical follow-up, six serial breast milk samples, and blood samples from both mothers and infants, were collected and analysed.

RESULTS

The median average rituximab concentration (Cavg) in breast milk was 0.04 µg/mL and the estimated relative infant dose (RID) was 0.07%. The highest measured concentration of rituximab in the breast milk samples was 0.25 µg/mL, giving an estimated RID of 0.26%.All infant serum rituximab concentrations were below 0.01 µg/mL. The CD19 +B cell count values were within the 10th- 90th percentiles of reported normal ranges in healthy infants.

CONCLUSIONS

We found minimal transfer of rituximab into breast milk and could not reliably detect levels of rituximab in infant serum. B cell counts in infants were unaffected.

Allopregnanolone Concentrations in Breast Milk and Plasma from Healthy Volunteers Receiving Brexanolone Injection, With Population Pharmacokinetic Modeling of Potential Relative Infant Dose

Background and Objective

Women with postpartum depression (PPD) may expose their infants to antidepressants via breast milk. Brexanolone is the only FDA-approved antidepressant specifically indicated for the treatment of PPD. This open-label, phase Ib study of healthy lactating volunteers assessed pharmacokinetic (PK) properties of brexanolone and a population PK (PopPK) model determined the relative infant dose (RID) in breastfeeding mothers.

Methods

Twelve participants received a 60-h infusion of brexanolone (titration up to 90 µg/kg/h). Allopregnanolone concentration was measured in breast milk and plasma. The RID was computed using a nonlinear mixed-effects PopPK model of patients with PPD and healthy women (N = 156). Model results were extended across an integrated dataset of participants through day 7.

Results

Allopregnanolone concentration–time profiles were similar between breast milk and plasma (partition coefficient for concentration gradient [milk : plasma] 1.36). Mean (95% CI) C_max was 89.7 ng/mL (74.19–108.39), and median (95% CI) t_max was 47.8 h (47.8–55.8) in plasma. The overall PK profile was best described by a two-compartment model with linear elimination and distribution. Body weight was the only significant covariate identified. There were no apparent differences in PopPK AUC and C_max between participants with or without concomitant antidepressant treatment. Maximum RID was 1.3%.

Conclusion

The PopPK model successfully described the variability and concentration–time profiles of allopregnanolone in breast milk and plasma in healthy participants and in the plasma of brexanolone-treated patients with PPD. The rapid elimination of allopregnanolone from plasma and breast milk, and low RID, suggests the appropriateness of brexanolone weight-based dosing and supports other PK-related labeling recommendations.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40262-022-01155-w.

Neonatal Feeding Trajectories in Mothers With Bipolar Disorder Taking Lithium: Pharmacokinetic Data

Purpose: Women who take lithium during pregnancy and continue after delivery may choose to breastfeed, formula feed, or mix these options. The aim of the study was to evaluate the neonatal lithium serum concentrations based on these three feeding trajectories. Methods: We followed 24 women with bipolar disorder treated with lithium monotherapy during late pregnancy and postpartum (8 per trajectory). Lithium serum concentrations were determined by an AVL 9180 electrolyte analyser with a 0.10 mEq/L detection limit and a 0.20 mEq/L limit of quantification (LoQ). Results: There was complete lithium placental passage at delivery, with a mean ratio of lithium concentration in the umbilical cord to maternal serum of 1.12 ± 0.17. The median times to LoQ were 6-8, 7-8, and 53-60 days for formula, mixed, and exclusive breastfeeding respectively. The generalized log-rank testing indicated that the median times to LoQ differ according to feeding trajectory (p = 0.037). According to the multivariate analysis-adjusted lithium serum concentrations at birth, times to LoQ are, on average, longer under exclusive breastfeeding (formula, p = 0.015; mixed, p = 0.012). No lithium accumulation was observed in infants under either exclusive or mixed breastfeeding. During the lactation follow-up, there was no acute growth or developmental delays in any neonate or infant. Indeed, lithium concentrations in the three trajectories declined in all cases. However, the time needed to reach the LoQ was much longer for those breastfeeding exclusively. Conclusions: In breastfeed infant no sustained accumulation of lithium and no adverse effects on development or growth were observed.

First-in-human pharmacokinetics of tamoxifen and its metabolites in the milk of a lactating mother: a case study

BackgroundBreast cancer represents the most frequent neoplasm diagnosed in women of childbearing age. When the tumour is oestrogen receptor-positive, tamoxifen is among the recommended endocrine treatments. Lactating women are advised not to breastfeed while receiving tamoxifen. However, information about tamoxifen transfer into breast milk is lacking.MethodsWe measured the concentration of tamoxifen and its metabolites by liquid chromatography-tandem mass spectrometry in the milk of a nursing mother that was treated for pregnancy-associated breast cancer diagnosed a few months after delivery. She was advised not to breastfeed her child and she collected milk samples for 23 days while the baby was fed with formula.ResultsTamoxifen concentrations in milk increased reaching a maximum of 214 nM. The two active metabolitesZ-4-hydroxy-tamoxifen and Z-endoxifen, could not be quantified in milk the first days after tamoxifen intake, but increased over time and reached clinically significant levels after day 18.ConclusionThis study demonstrates for the first time in human that tamoxifen and its metabolites transfer into milk. Since tamoxifen has a complete oral bioavailability, a long half-life (>7 days) and may interfere with the normal development of the infant, mothers should not breastfeed during tamoxifen treatment.

Prediction of drug concentrations in milk during breastfeeding, integrating predictive algorithms within a physiologically-based pharmacokinetic model

There is a risk of exposure to drugs in neonates during the lactation period due to maternal drug intake. The ability to predict drugs of potential hazards to the neonates would be useful in a clinical setting. This work aimed to evaluate the possibility of integrating milk-to-plasma (M/P) ratio predictive algorithms within the physiologically-based pharmacokinetic (PBPK) approach and to predict milk exposure for compounds with different physicochemical properties. Drug and physiological milk properties were integrated to develop a lactation PBPK model that takes into account the drug ionization, partitioning between the maternal plasma and milk matrices, and drug partitioning between the milk constituents. Infant dose calculations that take into account maternal and milk physiological variability were incorporated in the model. Predicted M/P ratio for acetaminophen, alprazolam, caffeine, and digoxin were 0.83 ± 0.01, 0.45 ± 0.05, 0.70 ± 0.04, and 0.76 ± 0.02, respectively. These ratios were within 1.26-fold of the observed ratios. Assuming a daily milk intake of 150 ml, the predicted relative infant dose (%) for these compounds were 4.0, 6.7, 9.9, and 86, respectively, which correspond to a daily ingestion of 2.0 ± 0.5 mg, 3.7 ± 1.2 µg, 2.1 ± 1.0 mg, and 32 ± 4.0 µg by an infant of 5 kg bodyweight. Integration of the lactation model within the PBPK approach will facilitate and extend the application of PBPK models during drug development in high-throughput screening and in different clinical settings. The model can also be used in designing lactation trials and in the risk assessment of both environmental chemicals and maternally administered drugs.

Direct oral anticoagulant safety during breastfeeding: a narrative review

PURPOSE

There are limited data regarding the safety of direct oral anticoagulants (DOACs) during breastfeeding. The aim of the present study is to investigate the extent of excretion of DOACs into human milk according to the available clinical and experimental studies.

METHODS

On 16th January 2021, we systematically searched PubMed, Scopus, Embase, and Web of Science for all studies which investigated DOACs in breastfeeding without any time frame and language limitation. Search keywords were [breastfeeding, breast feeding, breastfed, lactation, milk secretion OR milk] AND [apixaban OR Eliquist OR rivaroxaban OR Xarelto OR edoxaban OR Savaysa OR dabigatran OR Pradaxa OR dabigatran etexilate OR dabigatran etexilate mesylate OR direct oral anticoagulant OR DOAC OR new oral anticoagulant OR NOAC]. Finally, we identified six articles which reported DOAC use during breastfeeding or lactation.

RESULTS AND CONCLUSION

According to the available limited data, dabigatran has the least excretion in human breast milk. Rivaroxaban and dabigatran both have acceptable milk excretion cutoffs, whereas apixaban milk excretion is greater than the maximum allowed range. Further well-designed studies with larger sample sizes are required to generate consistent comparable data and clarify benefits and risks of each DOAC during breastfeeding.

Bupivacaine Pharmacokinetics and Breast Milk Excretion of Liposomal Bupivacaine Administered After Cesarean Birth

Very little plasma bupivacaine was transferred into breast milk after liposomal bupivacaine wound infiltration in patients who had undergone cesarean delivery.

To evaluate bupivacaine concentrations in maternal plasma and transfer into breast milk in women undergoing liposomal bupivacaine infiltration in the transversus abdominis plane after cesarean birth.

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.

Hydroxyurea Exposure in Lactation: a Pharmacokinetics Study (HELPS)

Lactation is contraindicated for women with sickle cell anemia receiving hydroxyurea therapy, despite sparse pharmacokinetics data. In 16 women who were lactating volunteers, we documented hydroxyurea transferred into breastmilk with a relative infant dosage of 3.4%, which is below the recommended 5%-10% safety threshold. Breastfeeding should be permitted for women taking daily oral hydroxyurea.

Pharmacokinetics, Placental and Breast Milk Transfer of Antiretroviral Drugs in Pregnant and Lactating Women Living with HIV

BACKGROUND

Remarkable progress has been achieved in the identification of HIV infection in pregnant women and in the prevention of vertical HIV transmission through maternal antiretroviral treatment (ART) and neonatal antiretroviral drug (ARV) prophylaxis in the last two decades. Millions of women globally are receiving combination ART throughout pregnancy and breastfeeding, periods associated with significant biological and physiological changes affecting the pharmacokinetics (PK) and pharmacodynamics (PD) of ARVs. The objective of this review was to summarize currently available knowledge on the PK of ARVs during pregnancy and transport of maternal ARVs through the placenta and into the breast milk. We also summarized main safety considerations for in utero and breast milk ARVs exposures in infants.

METHODS

We conducted a review of the pharmacological profiles of ARVs in pregnancy and during breastfeeding obtained from published clinical studies. Selected maternal PK studies used a relatively rich sampling approach at each ante- and postnatal sampling time point. For placental and breast milk transport of ARVs, we selected the studies that provided ratios of maternal to the cord (M:C) plasma and breast milk to maternal plasma (M:P) concentrations, respectively.

RESULTS

We provide an overview of the physiological changes during pregnancy and their effect on the PK parameters of ARVs by drug class in pregnancy, which were gathered from 45 published studies. The PK changes during pregnancy affect the dosing of several protease inhibitors during pregnancy and limit the use of several ARVs, including three single tablet regimens with integrase inhibitors or protease inhibitors co-formulated with cobicistat due to suboptimal exposures. We further analysed the currently available data on the mechanism of the transport of ARVs from maternal plasma across the placenta and into the breast milk and summarized the effect of pregnancy on placental and of breastfeeding on mammal gland drug transporters, as well as physicochemical properties, C:M and M:P ratios of individual ARVs by drug class. Finally, we discussed the major safety issues of fetal and infant exposure to maternal ARVs.

CONCLUSIONS

Available pharmacological data provide evidence that physiological changes during pregnancy affect maternal, and consequently, fetal ARV exposure. Limited available data suggest that the expression of drug transporters may vary throughout pregnancy and breastfeeding thereby possibly impacting the amount of ARV crossing the placenta and secreted into the breast milk. The drug transporter's role in the fetal/child exposure to maternal ARVs needs to be better understood. Our analysis underscores the need for more pharmacological studies with innovative study design, sparse PK sampling, improved study data reporting and PK modelling in pregnant and breastfeeding women living with HIV to optimize their treatment choices and maternal and child health outcomes.

Clinical lactation studies and the role of pharmacokinetic modeling and simulation in predicting drug exposures in breastfed infants

The relative lack of information on medication use during breastfeeding is an ongoing problem for health professionals and mothers alike. Most nursing mothers are prescribed some form of medication, yet some mothers either discontinue breastfeeding or avoid medications entirely. Although regulatory authorities have proposed a framework for clinical lactation studies, data on drug passage into breastmilk are often lacking. Model-based approaches can potentially be used to estimate the passage of drugs into milk, predict exposures in breastfed infants, and identify drugs that need clinical lactation studies. When a human study is called for, measurement of the drug concentration in milk are often adequate to characterize safety. Data from these studies can be leveraged to further refine pharmacokinetic models with subsequent Monte Carlo simulations to estimate the spread of exposure values. Both clinical lactation studies and model-based approaches have some limitations and pitfalls which are discussed.

Unexpected drug residuals in human milk in Ankara, capital of Turkey

Background

Breast milk is a natural and unique nutrient for optimum growth and development of the newborn. The aim of this study was to investigate the presence of unpredictable drug residues in mothers’ milk and the relationship between drug residues and maternal-infant characteristics.

Methods

In a descriptive study, breastfed infants under 3 months of age and their mothers who applied for child health monitoring were enrolled for the study. Information forms were completed for maternal-infant characteristics, breastfeeding problems, crying and sleep characteristics of infants. Maternal and infant anthropometric measurements and maternal milk sample were taken. Edinburgh Postpartum Depression Scale was applied to mothers. RANDOX Infiniplex kit for milk was used for residual analysis.

Results

Overall, 90 volunteer mothers and their breastfed infants were taken into the study and the mean age of the mothers and their infants was 31.5 ± 4.2 years and 57.8 ± 18.1 days, respectively. Anti-inflammatory drug residues in breast milk were detected in 30.0% of mothers and all had tolfenamic acid. Overall, 94.4% had quinolone, 93.3% beta-lactam, 31.1% aminoglycoside and 13.3% polymycin residues. Drugs used during pregnancy or lactation period were not affected by the presence of residues. Edinburgh postpartum depression scores of mothers and crying and sleeping problems of infants were similar in cases with and without drug residues in breast milk. When controlling confounding factors, maternal body mass index alterations were detected to be significantly lower in mothers with anti-inflammatory drug residues in breast milk than in their counterparts (p = 0.017).

Conclusions

Our study suggests that there are unpredictable drug residues in the milk of many mothers. Anti-inflammatory drug exposure might affect maternal weight change during the postpartum period. Further studies are required to evaluate the impact of drug residues on maternal and infant health.

Clinical Lactation Studies of Lithium: A Systematic Review

Background: There is substantial evidence that postpartum prophylaxis with lithium lowers the rate of relapse in bipolar disorder. However, it is contraindicated during breastfeeding due to the high variability of the transfer into breast milk. Aims: We conducted a systematic review of the current evidence of studies assessing the transfer of lithium to lactating infants and short-term infant outcomes. Methods: An a priori protocol was designed based on PRISMA guidelines. Searches in PubMed and LactMed were conducted until September 2018. Studies assessing lithium pharmacokinetic parameters and short-term infant outcomes were included. Quality was assessed using a checklist based on international guidelines (i.e., FDA). Results: From 344 initial studies, 13 case reports/series with 39 mother-child dyads were included. Only 15% of studies complied with ≥50% of the items on the quality assessment checklist. Infants breastfeed a mean (SD) of 58.9 (83.3) days. Mean maternal lithium dose was 904 (293) mg/day, corresponding lithium plasma/serum concentration was 0.73(0.26) mEq/L, and breast milk concentration was 0.84(0.14) mEq/L. Mean infant lithium plasma/serum concentration was 0.23(0.26) mEq/L. Twenty-six (80%) infants had concentrations ≤0.30 mEq/L without adverse effects. Eight (20%) showed a transient adverse event (i.e., acute toxicity or thyroid alterations). All of them were also prenatally exposed to lithium monotherapy or polytherapy. Conclusion: The current evidence comes from studies with a degree of heterogeneity and of low-moderate quality. However, it identifies areas of improvement for future clinical lactation studies of lithium and provides support for some clinical recommendations.

Navigating monoclonal antibody use in breastfeeding women: Do no harm or do little good?

Many neurologic diseases disproportionately affect women, particularly during their reproductive years. For many of these diseases, monoclonal antibodies (mAbs) are becoming widely available as a treatment option, for example, in migraine, multiple sclerosis, and myasthenia gravis. Yet, despite how common pregnancy is (latest estimates suggest that 86% of US women ages 40-44 have given birth), there is a paucity of research on the safety of prescription medications, including mAbs, during the peripartum period. In this article, we focus on the safety of mAbs during breastfeeding. We summarize how pregnancy affects the trajectory of these diseases and explore the benefit derived from mAb therapies. We posit that as neurologists, we are uniquely poised to lead the study of peripartum safety for the mAbs now on the market and provide a framework for their future study.

Transfer of Candesartan Into Human Breast Milk

BACKGROUND

There are currently no data regarding the transfer of candesartan into human milk. This report provides data on this transfer, an estimation of the amount breastfed infants receive, and plasma concentrations from two breastfed infants.

CASES

Three breastfeeding mothers, all stabilized on candesartan (8-32 mg/d), provided milk and plasma samples over one dosing interval (24 hours). Two infant plasma samples were obtained. The amount the infants ingested was estimated to be 0.09% (95% CI 0.07-0.11) of the maternal dose (weight-adjusted). Candesartan was undetectable (less than 0.2 micrograms/L) in infant plasma samples.

CONCLUSION

A relative infant dose of 0.09% suggests that maternal benefit from candesartan at standard therapeutic doses may outweigh risk in breastfeeding healthy, term infants.

[Medications in breastfeeding: what evidence is there?]

Breastfeeding plays a fundamental role in the benefits for the health of the newborn child and the nursing mother. The use of medications during breastfeeding is a relevant issue, by virtue of the frequent need for pharmacological treatment in the postpartum period. The scope of this article was to conduct a review of the literature regarding the efficacy and safety of medications used during the breastfeeding period. A search was conducted in the PubMed (National Library of Medicine), ScienceDirect and Biblioteca Virtual em Saúde (BVS) databases for articles published in Portuguese, English and Spanish in the period from 1981 to 2016. This review discusses the risk of the use of medications during lactation and the effects that they may have on the breastfed infant. Few medications are contraindicated and others require care due the risk of adverse effects on breastfed infants or in the suppression of breast milk volume. Therefore, the dissemination of updated information for the health professional to adequately assess the risks and the benefits of the use of medications during breastfeeding is of vital importance, thereby contributing to avoid early weaning.

Balancing the Use of Medications While Maintaining Breastfeeding

Breast milk is the most beneficial nutrition a mother can give her infant. Fortunately, the dose of most drugs transferred into milk is small and does not lead to clinically significant effects on the infant. In almost all instances, the mother should be advised to continue breastfeeding. Certain medications are absolutely contraindicated, including anticancer agents, radioactive drugs, and those that inhibit milk production. However, most medications can be used safely. An improved understanding of the relationship between maternal and infant exposure to medications would provide a more enlightened understanding of the risk and benefit analysis for individual drugs.

Maternal Metyrapone Use During Breastfeeding: Safe for the Breastfed Infant

Context

Metyrapone is an inhibitor of endogenous adrenal corticosteroid synthesis, which has been proven to be a viable option in controlling maternal serum cortisol concentrations during pregnancy. The infant exposure to maternally ingested metyrapone through breast milk is, however, largely unknown.

Case Description

We report the excretion of metyrapone into breast milk and subsequent infant exposure from a lactating woman on 250 mg of metyrapone three times daily. Due to limited supply of breast milk, the infant was fed ∼50% breast milk and 50% formula. At steady state, the average concentrations in the studied breast milk and absolute and relative infant doses were 176 µg/L, 26.45 µg/kg/d, and 0.7%, respectively, for metyrapone, and 310 µg/L, 46.52 µg/kg/d, and 1.21% for its active metabolite metyrapol. The breastfed infant was found to have a plasma metyrapone concentration of 0.05 µg/L, with no evidence of disruption to his adrenocortical axis biochemically.

Conclusion

These findings indicate that maternal metyrapone use during breastfeeding did not pose a notable risk to this breastfed infant. The infants’ exposure to metyrapone was further minimized by avoiding nursing for 2 to 3 hours after each metyrapone dose.

Green sample preparations for the bioanalysis of drugs of abuse in complex matrices

The sample preparation is the most critical step involved in the bioanalytical process. When dealing with green analytical chemistry, sample preparation can be even more challenging. To fit the green analytical chemistry principles, efforts should be made toward the elimination or reduction of the use of toxic reagents and solvents, minimization of energy consumption and increased operator safety. The simplest sample preparations are more appropriate for liquid biological matrices with little interfering compounds such as urine, plasma and oral fluid. The same does not usually occur with complex matrices that require more laborious procedures. The present review discusses green analytical approaches for the analyses of drugs of abuse in complex biological matrices, such as whole blood, breast milk, meconium and hair.

Quality of Lactation Studies Investigating Antidepressants

Introduction: The aim of this study was to determine the quality of lactation studies investigating antidepressants in breast milk according to the Food and Drug Administration (FDA) draft guidelines and the article by Begg et al., 2002, published in the official journal of the International Lactation Consultant Association (ILCA). Materials and Methods: We used PubMed and LactMed^® for the literature search. Furthermore, cross references were searched for additional studies. Results: A total number of 60 articles were included for review. For selective serotonin reuptake inhibitors and venlafaxine, only two studies correctly assessed the absolute infant dose and milk to plasma ratio; one sertraline and one fluoxetine study. Of all tricyclic antidepressants, one study for amitriptyline and one for nortriptyline assessed these endpoints correctly. We found a lack of information on breast milk sampling methods in many studies. Concentrations needed for the calculations were based on single measurements instead of at least five measurements during one dose interval, and the relative infant dose was not normalized by maternal weight, or an average maternal weight of 70 kg was used as a standard. Discussion: We conclude that the quality of the current literature on this topic does not meet the standards of the FDA. Studies of higher quality are needed to determine the extent of drug transfer to breast milk for antidepressants, so an adequate recommendation about use of these drugs during lactation can be given.

Intravenous single administration of amiodarone and breastfeeding

Amiodarone treatment is contraindicated during breastfeeding. As the regional pharmacovigilance centre, we were contacted for information relative to the possibility of breastfeeding after single intravenous administration of 450 mg amiodarone to a breastfeeding woman. A monitoring of amiodarone concentration in plasma and milk was performed in the mother. At day 4, milk concentration of amiodarone reached a peak (233 μg/L) and milk to plasma ratio was determined to 3.5. Milk concentration was still detectable at day 10 (132 μg/L). The maximal relative infant dose was estimated to be 0.6% of the maternal weight-adjusted dosage, corresponding to 0.18% of the usual posology used in children by parenteral route. The review of the literature retrieved one publication suggesting that a single intravenous administration of 150 mg of amiodarone to a mother represents a negligible infant risk based on low breast milk concentration. The French National Pharmacovigilance database query did not disclose any case of side effects during breastfeeding after a single dose of amiodarone. A very limited exposition of breastfed newborns to amiodarone, as well as a low risk of side effects, is expected after a single administration of amiodarone to their mothers.

Antibiotics and lactation: An overview of relative infant doses and a systematic assessment of clinical studies

Breastfeeding is important for the development of the child. Many antibiotics are considered safe during breastfeeding. The aim of the study was to assess the quality of lactation studies with antibiotics using the FDA and International Lactation Consultant Association quality guidelines for lactation studies. The secondary goal was to determine the exposure of the breastfed infant to antibiotics in relation to bacterial resistance and the developing microbiome. A literature search was performed and the included studies were scored on methodology, parameters concerning maternal exposure to antibiotics, maternal plasma and milk sampling. The infant exposure has been calculated and expressed as a percentage of a normal infant therapeutic dose. Sixty-six studies were included in five antibiotic groups (broad-spectrum penicillin, cephalosporins, macrolides and lincosamides, quinolones and sulphonamides). Cephalosporins were the most studied group of antibiotics (n = 21). Fifteen studies met all the criteria of "mother exposure to antibiotic". Six studies met every criterion related to "plasma sampling". Only one case report met all listed criteria for lactation studies. The correct calculation of infant exposure to antibiotics via the milk:plasma ratio (AUC) varies between 13% for macrolides and 38% for broad-spectrum penicillin. The highest assessed exposure as a percentage of infant therapeutic dose was for metronidazole (11%). The studies meet to a limited extent with the quality standards for lactation research. The breastfed infants are exposed to a subtherapeutic concentration of antibiotics.

Drugs in Lactation

One impediment to breastfeeding is the lack of information on the use of many drugs during lactation, especially newer ones. The principles of drug passage into breastmilk are well established, but have often not been optimally applied prospectively. Commonly used preclinical rodent models for determining drug excretion into milk are very unreliable because of marked differences in milk composition and transporters compared to those of humans. Measurement of drug concentrations in humans remains the gold standard, but computer modeling is promising. New FDA labeling requirements present an opportunity to apply modeling to preclinical drug development in place of conventional animal testing for drug excretion into breastmilk, which should improve the use of medications in nursing mothers.

Pharmacokinetics of amlodipine besylate at delivery and during lactation

BACKGROUND

Amlodipine is rarely used in the treatment of pregnant hypertensive women due to limited pharmacokinetic data during pregnancy and the postpartum period.

OBJECTIVE

To evaluate the pharmacokinetics of amlodipine besylate in the peri-partum period including quantities of placental passage, breast milk excretion and infant exposure.

STUDY DESIGN

This was a prospective study of pregnant women who were prescribed 5 mg of amlodipine daily for treatment of chronic hypertension and delivered at term. Cord and maternal blood samples were collected at delivery. On postpartum day 2, six paired maternal plasma and breast milk samples were obtained at 4, 6, 8, 12, 15 and 24 h following amlodipine dosing. Infant plasma samples were collected 24-48 h after delivery. All samples were analyzed for amlodipine concentration. A one compartment, first-order model was used to calculate pharmacokinetic estimates for maternal plasma.

RESULTS

Of the 16 patients enrolled in the study, 11 had cord blood and maternal serum collected at delivery, of which only 6 produced sufficient breast milk for sampling. Amlodipine was detected in infant cord blood plasma with a mean concentration of 0.49 ± 0.29 ng/mL compared to mean maternal serum level of 1.27 ± 0.84 ng/mL. Amlodipine concentrations in both in breast milk and infant plasma were undetectable at the lower limit of assay detection (<0.1 ng/mL). In the immediate postpartum period, the amlodipine elimination half-life was 13.7 ± 4.9 h, the area under the curve was 53.4 ± 19.8 ng*h/mL and the peak concentration was 2.0 ± 1.0 ng/mL.

CONCLUSIONS

Amlodipine does cross the placenta in measurable quantities, but is not detected in breast milk or infant plasma at 24-48 h of life indicating that it is likely safe to use during the peripartum period.

Simple physicochemical properties related with lipophilicity, polarity, molecular size and ionization status exert significant impact on the transfer of drugs and chemicals into human breast milk

OBJECTIVES

The transfer of xenobiotic compounds into human breast milk has raised serious concerns in the last few years. The present study is aimed to assess whether simple physicochemical properties exert significant impact on human breast milk transfer of drugs and chemicals.

METHODS

A large data set of 375 xenobiotic compounds with available experimental milk to plasma (M/P) ratios was systematically compiled from the literature and explored with their physicochemical properties being further analyzed with respect to their extent to transfer into breast milk.

RESULTS

Xenobiotic compounds with increased breast milk transfer (M/P ≥ 1) were characterized by enhanced lipophilicity and decreased molecular size (p < 0.05). Enhanced polarity and hydrogen bonding capacity were more frequently observed in xenobiotic compounds with reduced breast milk transfer (p < 0.0001). Xenobiotic compounds presenting increased positive charge at pH 7.4 were characterized by enhanced breast milk transfer (p < 0.001). Xenobiotic compounds presenting increased negative charge at pH 7.4 were characterized by decreased breast milk transfer (p < 0.001).

CONCLUSIONS

The present study supports evidence that simple physicochemical properties related with lipophilicity, polarity, molecular size and ionization status exert significant impact on drugs and chemicals transport into human breast milk.

The quality of lactation studies including antipsychotics

THE AIM OF THE STUDY

The aim of this study is to determine the quality of lactation studies that investigated antipsychotics in breast milk according to the Food and Drug Administration (FDA) and International Lactation Consultant Association (ILCA) draft guidelines.

MATERIALS AND METHODS

We used the draft FDA and ILCA guidelines to review the quality of articles including antipsychotic use during breastfeeding. We used PubMed and Lactmed for the literature search. Furthermore, cross references were searched for additional studies.

RESULTS

Of the 51 studies, only one olanzapine and one quetiapine study calculated the milk to plasma ratio (M:P ratio), the Absolute Infant Dose (AID), and the Relative Infant Dose (RID) correctly. In the remaining studies, at least one of the three endpoints was not determined properly. No correct endpoints were calculated in studies containing chlorpromazine, chlorprothixene, clozapine, haloperidol, sulpiride, trifluoperazine, ziprasidone, zonisamide, and zuclopenthixol. This review investigated that there was a lack of information on the sampling methods of breast milk. Furthermore, the concentrations needed for the calculations of the three endpoints were mainly based on single measurements instead of at least five measurements during one dose interval. In many studies, the RID was not calculated correctly due to the fact that the RID was not normalized by the maternal weight or an average maternal weight of 70 kg was used as a standard.

CONCLUSION

Except for two studies, most studies about the safety of antipsychotic use during lactation did not meet the criteria of the draft FDA and ILCA guidelines. Further research is mandatory to assess the safety of using antipsychotics while breastfeeding.

Dietary Epicatechin Is Available to Breastfed Infants through Human Breast Milk in the Form of Host and Microbial Metabolites

Polyphenols play an important role in human health. To address their accessibility to a breastfed infant, we planned to evaluate whether breast milk (BM) (colostrum, transitional, and mature) epicatechin metabolites could be related to the dietary habits of mothers. The polyphenol consumption of breastfeeding mothers was estimated using a food frequency questionnaire and 24 h recalls. Solid-phase extraction-ultra performance liquid chromatography-tandem mass spectrometry (SPE-UPLC-MS/MS) was applied for direct epicatechin metabolite analysis. Their bioavailability in BM as a result of dietary ingestion was confirmed in a preliminary experiment with a single dose of dark chocolate. Several host and microbial phase II metabolites of epicatechin were detected in BM among free-living lactating mothers. Interestingly, a modest correlation between dihydroxyvalerolactone sulfate and the intake of cocoa products was observed. Although a very low percentage of dietary polyphenols is excreted in BM, they are definitely in the diet of breastfed infants. Therefore, evaluation of their role in infant health could be further promoted.

Modeling drug passage into human milk

Breastfeeding has positive health consequences for both the breastfed infant and the nursing mother.(1,2) Although information on drug use during lactation is available through sites such as LactMed,(3) available information is often incomplete. Unlike pregnancy, in which large numbers of pregnant women need to be studied to assure safety, measurement of drug concentrations in breastmilk in a relatively few subjects can provide valuable information to assess drug safety. This article reviews methods of measuring and predicting drug passage into breastmilk.

Antibiotics and Breastfeeding

During the breastfeeding period, bacterial infections can occur in the nursing mother, requiring the use of antibiotics. A lack of accurate information may lead health care professionals and mothers to suspend breastfeeding, which may be unnecessary. This article provides information on the main antibiotics that are appropriate for clinical use and the interference of these antibiotics with the infant to support medical decisions regarding the discontinuation of breastfeeding. We aim to provide information on the pharmacokinetic factors that interfere with the passage of antibiotics into breast milk and the toxicological implications of absorption by the infant. Publications related to the 20 most frequently employed antibiotics and their transfer into breast milk were evaluated. The results demonstrate that most antibiotics in clinical use are considered suitable during breastfeeding; however, the pharmacokinetic profile of each drug must be observed to ensure the resolution of the maternal infection and the safety of the infant.

Mirtazapine in pregnancy and lactation - A systematic review

Depression is common in pregnancy and associated with increased risk of adverse effects for the neonate. Treatment and prevention options include antidepressant therapy. The aim of this paper was to review the literature on safety of mirtazapine during pregnancy and lactation. In 31 papers a total of 390 cases of neonates exposed to mirtazapine during pregnancy or lactation have been described. There might be an association between mirtazapine and spontaneous abortion, however, this might be attributable to underlying psychiatric disease. An increased risk of major neonatal malformations associated with mirtazapine in pregnancy has not been reported. Although one study showed a nearly significant increase in occurrence of respiratory problems and hypoglycaemia, no indication of causality could be given. No other significant adverse effects on neonates were reported. Limited available data, four papers on 11 exposed neonates, suggest that use of mirtazapine during breastfeeding is safe due to a low relative infant dose. High plasma levels might be associated with increased body weight and sleep. However, the reported data are too scarce to come to a clear assessment of the risk of mirtazapine in lactation. No information is available on the use of mirtazapine in pregnancy and Poor Neonatal Adaptation Syndrome (PNAS) or neurobehavioral development at an age over one year. In conclusion, mirtazapine seems to be safe in pregnancy, especially regarding incidence of congenital malformations. There are not enough data available to come to a conclusion on the safety of mirtazapine during lactation.

Drugs in breastfeeding

Most commonly used drugs are relatively safe for breastfed babies. The dose received via milk is generally small and much less than the known safe doses of the same drug given directly to neonates and infants. Drugs contraindicated during breastfeeding include anticancer drugs, lithium, oral retinoids, iodine, amiodarone and gold salts. An understanding of the principles underlying the transfer into breast milk is important, as is an awareness of the potential adverse effects on the infant. Discussion with the mother about the possibility of either negative product information or ill-informed advice from others will reduce the confusion and anxiety that may be generated. Good resources about medicines and breastfeeding are available and include state-based medicines information services.

Is infant exposure to antiretroviral drugs during breastfeeding quantitatively important? A systematic review and meta-analysis of pharmacokinetic studies

Objectives

The objectives of this study were to summarize antiretroviral drug concentrations in breast milk (BM) and exposure of breast-fed infants.

Methods

This was a systematic review of pharmacokinetic studies of HIV-positive women taking antiretrovirals that measured drugs in BM. The quality of pharmacokinetic and laboratory methods was assessed using pre-defined criteria. Pooled ratios and 95% CIs were calculated using the generalized inverse variance method and heterogeneity was estimated by the I² statistic. PubMed Central, SCOPUS and LactMed databases were searched. No date or language restrictions were applied. Searches were conducted up to 10 November 2014. Clinical relevance was estimated by comparing ingested dose with the recommended therapeutic dose for each drug.

Results

Twenty-four studies were included. There was substantial variability in the clinical and laboratory methods used and in reported results. Relative to maternal plasma (MP), NRTIs accumulate in BM, with BM : MP ratios (95% CI estimates) from 0.89 to 1.21 (14 studies, 1159 paired BM and MP samples). NNRTI estimates were from 0.71 to 0.94 (17 studies, 965 paired samples) and PI estimates were from 0.17 to 0.21 (8 studies, 477 paired samples). Relative to the recommended paediatric doses, a breast-fed infant may ingest 8.4% (95% CI 1.9–15.0), 12.5% (95% CI 2.6–22.3) and 1.1% (95% CI 0–3.6) of lamivudine, nevirapine and efavirenz, respectively, via BM.

Conclusions

Transfer to untreated infants appears quantitatively important for some NRTIs and NNRTIs. The pharmacokinetic methods varied widely and we propose standards for the design, analysis and reporting of future pharmacokinetic studies of drug transfer during breastfeeding.

Lactation studies of anticonvulsants: a quality review

AIM

The aim of this review was to investigate the quality of the current literature on the transfer of anticonvulsants to breast milk to provide an overview of which anticonvulsants are in need of further research.

METHODS

We reviewed the quality of the available lactation studies for 19 anticonvulsants against the guidelines of the Food and Drug Administration (FDA) and the International Lactation Consultant Association (ILCA).

RESULTS

Except for one study on lamotrigine and one case report on gabapentin, no study on anticonvulsants had both the absolute infant dose (AID) and milk to plasma ratio (M : P) correctly assessed. Only one study on carbamazepine, phenytoin and vigabatrin was found that correctly assessed the AID. The main cause for this low number is the lack of essential details in published studies, since 25 of 62 studies were case reports, letters or abstracts. Other major shortcomings were the lack of information on sampling methods, the number of samples in a particular dose interval as well as the low number of study participants.

CONCLUSION

The quality of the current literature on the transfer of anticonvulsants to breast milk is low, except for lamotrigine, which makes it hard to draw conclusions about the safety of the use of anticonvulsants during the lactation period. Therefore, further research is needed.