Modeling drug passage into human milk

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.

Transfer of monoclonal antibodies into breastmilk in neurologic and non-neurologic diseases

OBJECTIVE

To review currently available data on the transfer of monoclonal antibodies (mAbs) in the breastmilk of women receiving treatment for neurologic and non-neurologic diseases.

METHODS

We systematically searched the medical literature for studies referring to 19 selected mAb therapies frequently used in neurologic conditions and "breastmilk," "breast milk," "breastfeeding," or "lactation." From an initial list of 288 unique references, 29 distinct full-text studies met the eligibility criteria. One additional study was added after the literature search based on expert knowledge of an additional article. These 30 studies were reviewed. These assessed the presence of our selected mAbs in human breastmilk in samples collected from a total of 155 individual women.

RESULTS

Drug concentrations were typically low in breastmilk and tended to peak within 48 hours, although maximum levels could occur up to 14 days from infusion. Most studies did not evaluate the breastmilk to maternal serum drug concentration ratio, but in those evaluating this, the highest ratio was 1:20 for infliximab. Relative infant dose, a metric comparing the infant with maternal drug dose (<10% is generally considered safe), was evaluated for certolizumab (<1%), rituximab (<1%), and natalizumab (maximum of 5.3%; cumulative effects of monthly dosing are anticipated). Importantly, a total of 368 infants were followed for ≥6 months after exposure to breastmilk of mothers treated with mAbs; none experienced reported developmental delay or serious infections.

CONCLUSIONS

The current data are reassuring for low mAb drug transfer to breastmilk, but further studies are needed, including of longer-term effects on infant immunity and childhood development.

Safety of potential breast milk exposure to IFN-β or glatiramer acetate: One-year infant outcomes

Objective

To determine whether potential breast milk exposure to interferon-beta (IFN-β) or glatiramer acetate (GA) is safe for the infant.

Methods

We identified 74 infants born to 69 women with MS who breastfed under IFN-β (n = 39), GA (n = 34), or both (n = 1). Women had been enrolled into the German Multiple Sclerosis and Pregnancy Registry during pregnancy. Data were obtained from standardized, telephone-administered questionnaires completed by the mother during pregnancy and at 1, 3, 6, and 12 months postpartum and the infant's take-home medical record.

Results

The median duration of exposed breastfeeding was 8.5 months (wide interquartile range: 4.9–12.7 months). Physical growth curves during the first year of life were consistent with national, sex-specific growth curves. Median body measurements were consistent with national medians. Most children (n = 71, 96%) had normal motor and language development. Gross motor delay was reported in 3 children, of whom 1 remained delayed at last follow-up (3.9 years old) and 2 were normal by 0.9 and 4.1 years old. The proportion of children hospitalized at least once (girls n = 2, 7%, and boys n = 6, 14%) and the proportion of children with at least one episode of systemic antibiotic use during the first year of life (girls n = 7, 23%, and boys n = 8, 18%) are consistent with national averages.

Conclusion

Potential breast milk exposure to IFN-β or GA did not increase the risk of common adverse infant outcomes in the first year of life. Taken together with the benefits of breastfeeding and low biological plausibility of risk, women with MS who wish to resume IFN-β or GA postpartum can be encouraged to breastfeed.

The pre- and post-authorisation data published by the European medicines agency on the use of biologics during pregnancy and lactation

AIMS

The effects of biologics on reproduction/lactation are mostly unknown although many patients that receive biologics are women of reproductive age. The first objective of this study was to investigate the publicly available data on pregnancy/lactation before and after marketing authorization in Europe of biologics for the indications of rheumatologic inflammatory autoimmune diseases and inflammatory bowel disease. Secondary objectives included the assessment of the clinical relevance of the provided data and comparison of initial and post-authorization data.

METHODS

Initial and post-authorization data were extracted from the European Public Assessment Reports and the latest versions of Summary of Product Characteristics using publicly available documents on the European Medicines Agency's website. Four sections were categorized regarding pregnancy outcomes: pre-clinical/animal studies, human female fertility, pregnancy-related outcomes and congenital malformations in the human fetus. Three sections were categorized regarding lactation outcomes: pre-clinical/animal studies, excretion in human breast milk and absorption in children through breastfeeding. The clinical applicability of each category was scored by specified criteria, based on scientific literature, and further as defined by the authors.

RESULTS

For the 16 included biologics, post-authorization data were delivered only for adalimumab, certolizumab pegol, etanercept and infliximab. For the 12 remaining biologics limited data on pregnancy and lactation during the post-marketing period of 2-21 years were available.

CONCLUSIONS

In this article several suggestions are provided for improving a multidisciplinary approach to these issues. The initiation of suitable registries by marketing authorization holders and data transparency for clinicians and academics are highly endorsed.

Non-clinical Models to Determine Drug Passage into Human Breast Milk

BACKGROUND

Successful practice of clinical perinatal pharmacology requires a thorough understanding of the pronounced physiological changes during lactation and how these changes affect various drug disposition processes. In addition, pharmacokinetic processes unique to lactation have remained understudied. Hence, determination of drug disposition mechanisms in lactating women and their babies remains a domain with important knowledge gaps. Indeed, lack of data regarding infant risk during breastfeeding far too often results in discontinuation of breastfeeding and subsequent loss of all the associated benefits to the breastfed infant. In the absence of age-specific toxicity data, human lactation data alone are considered insufficient to rapidly generate the required evidence regarding risks associated with medication use during lactation.

METHODS

Systematic review of literature to summarize state-of-the art non-clinical approaches that have been developed to explore the mechanisms underlying drug milk excretion.

RESULTS

Several studies have reported methods to predict (to some extent) milk drug excretion rates based on physicochemical properties of the compounds. In vitro studies with primary mammary epithelial cells appear excellent approaches to determine transepithelial drug transport rates across the mammary epithelium. Several of these in vitro tools have been characterized in terms of transporter expression and activity as compared to the mammary gland tissue. In addition, with the advent of physiology-based pharmacokinetic (PBPK) modelling, these in vitro transport data may prove instrumental in predicting drug milk concentration time profiles prior to the availability of data from clinical lactation studies. In vivo studies in lactating animals have proven their utility in elucidating the mechanisms underlying drug milk excretion.

CONCLUSION

By combining various non-clinical tools (physicochemistry-based, in vitro and PBPK, in vivo animal) for drug milk excretion, valuable and unique information regarding drug milk concentrations during lactation can be obtained. The recently approved IMI project ConcePTION will address several of the challenges outlined in this review.

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.

Ivermectin concentration in breastmilk of a woman with Strongyloides stercoralis and human T-lymphotropic virus-I co-infection

Ivermectin is a widely used drug for the treatment of various neglected tropical diseases, such as lymphatic filariasis, onchocerciasis, and strongyloidiasis among others. Despite its excellent safety profile, there are few published studies of the use of ivermectin in children, pregnant and nursing women. In the present study, we report clinical data on ivermectin concentrations in breastmilk of a woman with Strongyloides stercoralis and HTLV-I coinfection. Ivermectin levels in breastmilk ranged from 1.4 to 20.8 ng/ml, with a mean of 9.26 ng/ml after a single dose of 200 µg/kg. We estimated the possible ivermectin exposure of the infant to be 1.1 µg/kg, 0.55% of the weight-adjusted percentage of the maternal dose. This value is largely under the threshold established by the World Health Organization for safe breastfeeding. Our results bolster previous findings on the secretion of ivermectin into breastmilk in healthy volunteers. The findings from this case study do not support exclusion of lactating women or interrupting lactation to accommodate it.

Quantifying breast milk intake by term and preterm infants for input into paediatric physiologically based pharmacokinetic models

Despite the many benefits of breast milk, mothers taking medication are often uncertain about the risks of drug exposure to their infants and decide not to breastfeed. Physiologically based pharmacokinetic models can contribute to drug‐in‐milk safety assessments by predicting the infant exposure and subsequently, risk for toxic effects that would result from continuous breastfeeding. This review aimed to quantify breast milk intake feeding parameters in term and preterm infants using literature data for input into paediatric physiologically based pharmacokinetic models designed for drug‐in‐milk risk assessment. Ovid MEDLINE and Embase were searched up to July 2, 2019. Key study reference lists and grey literature were reviewed. Title, abstract and full text were screened in nonduplicate. Daily weight‐normalized human milk intake (WHMI) and feeding frequency by age were extracted. The review process retrieved 52 studies. A nonlinear regression equation was constructed to describe the WHMI of exclusively breastfed term infants from birth to 1 year of age. In all cases, preterm infants fed with similar feeding parameters to term infants on a weight‐normalized basis. Maximum WHMI was 152.6 ml/kg/day at 19.7 days, and weighted mean feeding frequency was 7.7 feeds/day. Existing methods for approximating breast milk intake were refined by using a comprehensive set of literature data to describe WHMI and feeding frequency. Milk feeding parameters were quantified for preterm infants, a vulnerable population at risk for high drug exposure and toxic effects. A high‐risk period of exposure at 2–4 weeks of age was identified and can inform future drug‐in‐milk risk assessments.

Mother-child transfer rates of organohalogen compounds up to four years of age

BACKGROUND

Breastfed children absorb persistent and toxic chemicals such as organohalogen compounds (OHCs) during the entire lactation period. Nursing is a main contributor to the burden of these pollutants in the first years of life, hence further assessments on the OHC load processes are needed.

OBJECTIVES

To identify the determinants of OHC increase in children at four years of age, considering concentration gains, maternal venous concentrations and breastfeeding time.

METHODS

Concentrations of 19 organochlorine compounds (OCs) and 14 polybrominated diphenyl ethers (PBDEs) were analyzed in maternal venous (n = 466), cord blood (n = 326) and children venous serum at four years of age (n = 272) in the Asturias INMA cohort representing the Spanish general population. Data were evaluated considering the socio-demographic and individual information collected at recruitment and follow up surveys, as well as the OHC physical-chemical constants.

RESULTS

The four years-old children concentration gains of the most abundant OHCs showed strong correlations (R² = 0.65-0.93) with the maternal concentrations during pregnancy and lactation period. The child gain/maternal transfer rates of most correlated pollutants were similar.

DISCUSSION

Between 65 and 93% of the variance of OCs in four years-old children was explained by the maternal concentrations during pregnancy and the lactation period. The compounds with log(Kow) > 3.7 (hydrophobic) showed analogous child gain/maternal transfer rates indicating similar processes of membrane lipid dissolution and passive diffusion from the epithelial cells into the milk. Molecular weight of these pollutants did not influence on these rates. Compounds with low log(Koa) such as hexachlorobenzene are more volatile and less retained, involving lower child gain/maternal transfer rates. These results may be useful to anticipate the increase of the concentrations of OCs in children using the maternal concentration of these compounds during pregnancy and the planned lactation period and to implement prophylactic measures in mothers with high venous pollutant concentrations.

Impact of lactation on pharmacokinetics of meloxicam in goats

Use of drug in lactating animal should be carefully considered due to its possibility of changes in pharmacokinetics as well as drug penetration in milk. The aim of this study was to assess the effect of lactation on pharmacokinetics of meloxicam after IV and IM administrations in goats. A crossover design (2 × 2) was used for each lactating and nonlactating group of goats with a 3-week washout period. Meloxicam (0.5 mg/kg) was administered into the jugular vein and upper gluteal muscle by IV and IM routes, respectively. The plasma and milk drug concentrations were determined by high-performance liquid chromatography with diode array detector, and the pharmacokinetic analysis was carried out by noncompartmental analysis. The pharmacokinetic parameters of meloxicam in lactating and nonlactating goats were not significantly different. The IM bioavailability of meloxicam was relatively lower in lactating (75.3 ± 18.6%) than nonlactating goats (103.8 ± 34.7%); however, the difference was not statistically significant. Moreover, AUC ratio between milk and plasma, which represent drug milk penetration, for both IV and IM administrations was less than 1 (about 0.3). In conclusion, pharmacokinetic parameters of meloxicam are not significantly altered by lactation for either the IV or IM routes of administration and this drug does not require a different dosage regimen for lactating animals.

Minimal breast milk transfer of rituximab, a monoclonal antibody used in neurological conditions

Objective

To determine the transfer of rituximab, an anti-CD20 monoclonal antibody widely used for neurologic conditions, into mature breast milk.

Methods

Breast milk samples were collected from 9 women with MS who received rituximab 500 or 1,000 mg intravenous once or twice while breastfeeding from November 2017 to April 2019. Serial breast milk samples were collected before infusion and at 8 hours, 24 hours, 7 days, and 18–21 days after rituximab infusion in 4 patients. Five additional patients provided 1–2 samples at various times after rituximab infusion.

Results

The median average rituximab concentration in mature breast milk was low at 0.063 μg/mL (range 0.046–0.097) in the 4 patients with serial breast milk collection, with an estimated median absolute infant dose of 0.0094 mg/kg/d and a relative infant dose (RID) of 0.08% (range 0.06%–0.10%). Most patients had a maximum concentration at 1–7 days after infusion. The maximum concentration occurred in a woman with a single breast milk sample and was 0.29 μg/mL at 11 days postinfusion, which corresponds with an estimated RID of 0.33%. Rituximab concentration in milk was virtually undetectable by 90 days postinfusion.

Conclusions

We determined minimal transfer of rituximab into mature breast milk. The RID for rituximab was less than 0.4% and well below theoretically acceptable levels of less than 10%. Low oral bioavailability would probably also limit the absorption of rituximab by the newborn. In women with serious autoimmune neurologic conditions, monoclonal antibody therapy may afford an acceptable benefit to risk ratio, supporting both maternal treatment and breastfeeding.

Opioids in Breast Milk: Pharmacokinetic Principles and Clinical Implications

Safety of maternal drug therapy during breastfeeding may be assessed from estimated levels of drug exposure of the infant through milk. Pharmacokinetic (PK) principles predict that the lower the clearance is, the higher the infant dose via milk will be. Drugs with low clearance (<1 mL/[kg·min]) are likely to cause an infant exposure level greater than 10% of the weight-adjusted maternal dose even if the milk-to-plasma concentration ratio is 1. Most drugs cause relatively low-level exposure below 10% of the weight-adjusted maternal dose, but opioids require caution because of their potential for severe adverse effects. Furthermore, substantial individual variations of drug clearance exist in both mother and infant, potentially causing drug accumulation over time in some infants even if an estimated dose of the drug through milk is small. Such PK differences among individuals are known not only for codeine and tramadol through pharmacogenetic variants of CYP2D6 but also for non-CYP2D6 substrate opioids including oxycodone, indicating difficulties of eliminating PK uncertainty by simply replacing an opioid with another. Overall, opioid use for pain management during labor and delivery and subsequent short-term use for 2-3 days are compatible with breastfeeding. In contrast, newly initiated and prolonged maternal opioid therapy must follow a close monitoring program of the opioid-naive infants. Until more safety data become available, treatment duration of newly initiated opioids in the postpartum period should be limited to 2-3 days in unsupervised outpatient settings. Opioid addiction treatment with methadone and buprenorphine during pregnancy may continue into breastfeeding, but infant conditions must be monitored.

Use of an antiemetic to shorten the length of labor in nulliparous women, exploring a potential role of an old drug: A randomized controlled trial

OBJECTIVE

To assess whether metoclopramide is effective in shortening the duration of the first stage of labor in primiparous women.

METHODS

The present randomized, double-blind, placebo-controlled trial was conducted at King Faisal Hospital, Saudi Arabia (between July 30, 2013, and September 1, 2016), and sequentially recruited young nulliparous women admitted in spontaneous active labor with or without ruptured membranes. Eligible participants were randomly assigned to receive a slow intravenous injection of either metoclopramide or placebo and consistently managed according to the local institutional intrapartum protocol and received identical monitoring and supportive care. The primary outcome was the cervical dilatation rate.

RESULTS

Fifty-nine women were included in the metoclopramide group and 52 in the placebo group. The first stage of labor was significantly shorter in the metoclopramide group (203 minutes vs 230 minutes in the placebo group, P=0.019), with a faster cervical dilatation rate (2.4 ± 0.4 cm/h vs 1.9 ± 0.5 cm/h in the placebo group, P<0.001) and shorter interval from treatment administration until full cervical dilatation. There was a significantly higher probability of faster delivery among women who were treated with metoclopramide (log-rank test, χ² =5.997, P=0.014).

CONCLUSION

Metoclopramide safely reduced the duration of the first stage of labor and was not associated with major maternal or neonatal adverse outcomes. CLINICALTRIALS.GOV: NCT01937234.

Sleep Pharmacotherapy for Common Sleep Disorders in Pregnancy and Lactation

Sleep disturbances are common in pregnancy, and sleep disorders may worsen or present de novo in the course of gestation. Managing a pregnant patient is complicated by the risk of teratogenicity, pharmacokinetic changes, and the dynamic nature of pregnancy. Although nonpharmacologic interventions are likely safest, they are often ineffective, and a patient is left dealing with frustrations of the sleep disturbance, as well as the negative outcomes of poor sleep in pregnancy. As with any other condition in pregnancy, management requires an understanding of pregnancy physiology, knowledge of the impact of a given condition on pregnancy or fetal and neonatal outcomes, and an ability to weigh the risk of the exposure to an untreated, or poorly treated condition, against the risk of a given drug. In partnership with the pregnant patient or couple, options for therapy should be reviewed in the context of the impact of the condition on pregnancy and offspring outcomes, while understanding that data (positive or negative) on the impact of therapy on perinatal outcomes are lacking. This article reviews the epidemiology of sleep disorders in pregnancy, general principles of prescribing in pregnancy and lactation, and safety surrounding therapeutic options in pregnancy.

Pharmacogenomic Testing In Pediatrics: Navigating The Ethical, Social, And Legal Challenges

For the past several years, the implementation of pharmacogenetic (PGx) testing has become widespread in several centers and clinical practice settings. PGx testing may be ordered at the point-of-care when treatment is needed or in advance of treatment for future use. The potential benefits of PGx testing are not limited to adult patients, as children are increasingly using medications more often and at earlier ages. This review provides some background on the use of PGx testing in children as well as mothers (prenatally and post-natally) and discusses the challenges, benefits, and the ethical, legal, and social implications of providing PGx testing to children.

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.

Breast milk paclitaxel excretion following intravenous chemotherapy-a case report

Breast cancer can be diagnosed during pregnancy and in the peri-partum period, and the potential exposure of a foetus or neonate to chemotherapy is of concern to mothers and clinicians. Paclitaxel is a commonly used agent in breast cancer, but little is known about its excretion in breast milk. Breastfeeding during chemotherapy has been traditionally cautioned against due to the risk of neonatal exposure to chemotherapy agents, however, data are limited. We measured serum and breast milk concentrations of paclitaxel in a 33-year-old woman with an early breast cancer diagnosed during pregnancy and treated with weekly paclitaxel 80 mg/m². We found breast milk paclitaxel levels drop below the minimum quantifiable dose at 72 h following chemotherapy, with a relative infant dose of 0.091%. Breast milk excretion of paclitaxel following a dose of 80 mg/m² is negligible at 72 h, and this may be a safe time to recommence breastfeeding following exposure.

Exposure of Infants to Isoniazid via Breast Milk After Maternal Drug Intake of Recommended Doses Is Clinically Insignificant Irrespective of Metaboliser Status. A Physiologically-Based Pharmacokinetic (PBPK) Modelling Approach to Estimate Drug Exposure of Infants via Breast-Feeding

Isoniazid is a first-line anti-tuberculosis drug recommended for treatment of drug-susceptible Mycobacterium tuberculosis infections. Breast-feeding is not contra-indicated while undergoing isoniazid therapy, even though isoniazid was found to migrate into breast milk, leading to infant drug exposure. Exposure assessment of isoniazid in infants exposed to the drug via breast milk has so far not accounted for the polymorphic expression of the isoniazid metabolising enzyme N-acetyltransferase 2. The aim of this study was to re-visit the safety assessment of maternal isoniazid therapy for infants exposed to the drug via breast milk, while accounting for fast and slow metabolisers in the adult and infant population, as well as for slower metabolism in small infants than in adults. We applied a physiologically-based pharmacokinetic (PBPK) modelling approach to estimate mother and infant external and internal drug exposure non-invasively. Validity of our PBPK models was confirmed through comparison of simulated results with experimental data. Highest recommended oral doses for mothers are daily 300 mg or 900 mg every 3 days. Simulation of maternal intake of 300 mg resulted in oral exposures of 0.58 (95%CI: 0.42-0.69) mg/day and 1.49 (1.22-1.50) mg/day for infants of fast and slow metabolising mothers, respectively. Oral exposures of infants within the first 24 h after maternal intake of 900 mg were 1.75 (1.25-2.06) mg/day and 4.46 (4.00-4.50) mg/day. Maximal drug concentrations in infant plasma ranged between 0.04 and 0.78 mg/L for the two dosing regimens. We therefore conclude that infant exposure to isoniazid via breast milk after maternal drug intake of highest recommended doses is very low. We expect that such low exposure levels most likely do not cause any clinically significant adverse effects in nursed infants.

Drugs in lactation

Although most medications can be taken safely during breastfeeding, potential risks of infant toxicity do exist because all medications will be excreted into the breast milk to some extent. The amount of medication excreted in the milk depends mainly on (i) within-drug variation, such as dosing; (ii) between-drug variation including chemical characteristics of the medication; and (iii) host factors, such as maternal pharmacokinetics (PK), including variations of pregnancy-associated changes and their post-partum recovery. Neonatal drug exposure is usually assessed by calculating an expected total infant daily dose through breast milk and comparing it to the normal therapeutic dose. However, clinical PK studies in this population are challenging to conduct. Recently, research methods using population PK analyses and physiologically-based PK modeling and simulation techniques have been recognized as a complementary approach to the conventional PK studies in this field. These efforts are important for rational risk assessment balancing the toxicity risk against the benefits of human milk. Health benefits of lactation for both mother and child are significant and a decision to withhold from this should not be taken lightly. In case limited information is present, additional expertise from pharmacists or clinical pharmacologist with expertise in this area should be sought.

Transfer of rosuvastatin into breast milk: liquid chromatography-mass spectrometry methodology and clinical recommendations

Introduction

Rosuvastatin reduces concentrations of total cholesterol (TC) and is used for the management of hypercholesterolemia and prevention of acute coronary syndromes. There are no published reports estimating infant exposure to rosuvastatin through breast milk.

Purpose

The aims of this study were to quantify concentrations of rosuvastatin in human milk and plasma from a lactating woman taking rosuvastatin and to investigate potential infant exposure.

Materials and methods

A 38-year-old breastfeeding mother was commenced on rosuvastatin 20 mg daily for secondary prevention of an acute coronary syndrome. Eight maternal breast milk samples and a single plasma sample were collected over a 24-hour period. The samples were quantified using a sensitive liquid chromatography–mass spectrometry (LC-MS/MS) method.

Results

The average concentration of rosuvastatin in breast milk was 30.84 ng/mL, and a peak concentration of 58.59 ng/mL occurred at 17 hours after oral administration. Although the milk-to-plasma (M/P) ratio was 16.49 at 14 hours, the theoretical infant dosage (TID) and relative infant dose (RID) were 0.005 mg/kg/day and 1.50%, respectively.

Conclusion

The findings suggest that only small amounts of rosuvastatin pass into breast milk. Should the maternal condition necessitate treatment, consideration could be given to the use of rosuvastatin during breastfeeding provided the infant is monitored.

Estimation of Atenolol Transfer Into Milk and Infant Exposure During Its Use in Lactating Women

BACKGROUND

Atenolol lactation information is limited, and controversy exists over the safety of its use during breastfeeding. In this study, important parameters including milk-to-plasma ratio, ratio of infant plasma to maternal plasma, infant daily dosage, and relative infant dose were investigated. The findings from this study add information to existing data about atenolol transfer in human milk. This may help guide health professionals in decision making regarding the safety of beta blockers used by mothers during breastfeeding. Research aim: The aims of the study were to quantify concentrations of atenolol in human plasma and milk, to evaluate atenolol pharmacokinetics in lactating women, and to investigate subsequent infant exposure to atenolol via mother's milk.

METHODS

In this prospective, longitudinal observational study, participants were lactating mothers ( N = 3), 1 to 4 months postpartum, who had been taking atenolol for therapeutic reasons, and one 4-month-old breastfed infant. Eight milk samples were collected over 24 hr at different time points, together with a single blood sample from each lactating mother and the infant, and quantified using a new sensitive liquid chromatography mass spectrometry method developed for this study.

RESULTS

Peak milk concentrations of atenolol were observed in the women at 4 hr (T_max) after oral administration. The dose-normalized maximum concentrations (C_max) of all patients were similar. The mean milk-to-plasma ratio of the patients who were taking 25 to 100 mg of atenolol was 8.57%. In the mother-infant pair study, the ratio (%) of infant plasma drug concentration to maternal plasma drug concentration observed (18.87%) was similar to the relative infant dose estimated (18.20%). The relative infant dose values (13.96%-18.20%) for all patients were within 10% to 25% of maternal dosage.

CONCLUSION

Atenolol use during breastfeeding should be undertaken with some precaution. If clinically indicated, an alternate beta blocker may be preferred.

Physiologically-based pharmacokinetic modelling of infant exposure to efavirenz through breastfeeding

Background: Very little is known about the level of infant exposure to many drugs commonly used during breastfeeding. The aim of this study was to develop a physiologically-based pharmacokinetic (PBPK) model for predicting infant exposure to maternal efavirenz through breastmilk. Methods: A breastfeeding PBPK model combining whole-body maternal and infant sub-models was constructed from drug-specific and system parameters affecting drug disposition using mathematical descriptions. The model was validated against published data on the pharmacokinetics of efavirenz in nursing mother-infant pairs. Further simulations were conducted to assess exposure in the context of the 400 mg reduced dose of efavirenz as well as best- and worse-case scenarios. Results: The model adequately described efavirenz pharmacokinetics, with over 80% of observed data points (203 matched breast milk and plasma pairs) within the predictive interval. All parameters were within 2-fold difference of clinical data. Median (range) predicted versus observed breast milk AUC0-24, Cmax and Cmin at the standard 600 mg dose were 75.0 (18.5-324) versus 68.5 (26.3-257) µg.hr/mL, 4.56 (1.17-16.0) versus 5.39 (1.43-18.4) µg/mL, and 2.11 (0.38-12.3) versus 1.68 (0.316-9.57) µg/mL, respectively. Predicted plasma AUC0-24, Cmax and Cmin at 400 mg reduced dose were similar to clinical data from non-breastfeeding adults. Model-predicted infant plasma concentrations were similar to clinical data, 0.15 (0.026–0.78) μg/mL at the 400 mg maternal dose in pooled analysis, approximately 25% lower than simulated exposure at 600 mg. The maximum exposure index was observed in the youngest infants, 5.9% (2.2-20) at 400 mg and 8.7% (3.2-29) at 600 mg. Thirteen and 36% of 10 days-1 month old infants were predicted to have exposure index above the 10% recommended threshold at 400 mg and 600 mg maternal dose, respectively. Conclusions: This application of PBPK modelling opens up opportunities for expanding our understanding of infant exposure to maternal drugs through breastfeeding.

Guide for Drug Selection During Pregnancy and Lactation: What Pharmacists Need to Know for Current Practice

OBJECTIVE

To provide guidance for clinicians on risk assessment of medication use during pregnancy and lactation.

DATA SOURCES

Authors completed PubMed searches to identify articles focused on the use of medications in pregnancy, including fetal development, drug transfer across the placenta, trimester exposure, chronic conditions in pregnancy, medications in lactation, and lactation and chronic disease.

STUDY SELECTION AND DATA EXTRACTION

Articles were reviewed to provide overall guidance to medication selection during pregnancy. The following information was reviewed: medication use in pregnancy, including fetal development, drug transfer across the placenta, trimester exposure, chronic conditions in pregnancy, medications in lactation, and lactation and chronic disease.

DATA SYNTHESIS

This article will provide an overview of medication safety considerations during pregnancy and lactation. Information was interpreted to help clinicians predict the potential risk and benefit in each patient to make an evidence-based decision. The article concludes with guidance on risk assessment and how pharmacists may support fellow health care providers and their patients when considering medication use.

CONCLUSIONS

Information about the effects of medication use during reproductive periods is limited. With the removal of the Food and Drug Administration pregnancy categories, clinicians will be relying on pharmacists to aid in the appropriate selection of therapies for patients. It is critical that pharmacists keep abreast of resources available and be able to assess data to help prescribers and their patients.

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.

Evaluation of the Safety of Drugs and Biological Products Used During Lactation: Workshop Summary

This report serves as a summary of a 2-day public workshop sponsored by the US Food and Drug Administration (FDA) to discuss the safety of drugs and biological products used during lactation. The aim of the workshop was to provide a forum to discuss the collection of data to inform the potential risks to breastfed infants with maternal use of medications during lactation. Discussions included the review of current approaches to collect data on medications used during lactation, and the considerations for future approaches to design and guide clinical lactation studies. This workshop is part of continuing efforts to raise the awareness of the public for women who choose to breastfeed their infants.