Estimated infant exposure to enantiomer-specific methadone levels in breastmilk

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.

Pharmacological and non-pharmacological treatments for the Neonatal Abstinence Syndrome (NAS)

Neonatal abstinence syndrome is defined by signs and symptoms of withdrawal that infants develop after intrauterine maternal drug exposure. All infants with documented in utero opioid exposure, or a high pre-test probability of exposure should have monitoring with a standard assessment instrument such as a Finnegan Score. A Finnegan score of >8 is suggestive of opioid exposure, even in the absence of declared use during pregnancy. At least half of infants in most locales can be treated without the use of pharmacologic means. For this reason, symptom scores will drive the decision for pharmacologic therapy. Nevertheless, all infants, regardless of initial manifestations, should be first be managed with non-pharmacologic approaches which in turn, should not be considered as the sole alternative to drug therapy, but rather, as the base upon which all patients are treated. Those who continue to have symptoms despite supportive care should be pharmacologically treated, which in the most severe cases, is life-saving.

Breastfeeding Intention Compared With Breastfeeding Postpartum Among Women Receiving Medication-Assisted Treatment

BACKGROUND:

Women taking methadone or buprenorphine are encouraged to breastfeed if stable without polysubstance use.

RESEARCH AIM:

We aimed to determine the difference between stated intention to breastfeed prenatally in women taking methadone or buprenorphine compared with breastfeeding at discharge and 2 months postpartum. Secondary outcomes were determining whether breastfeeding was more common in women taking buprenorphine, in women without hepatitis C infection, and in women without a history of heroin use, and whether breastfeeding reduced the need for pharmacological treatment of neonatal opioid withdrawal syndrome.

METHODS:

This was a retrospective cohort study of 228 women enrolled in a perinatal substance abuse treatment program. Electronic medical records were reviewed to abstract data on mother-infant dyads. Chi-square tests were used to analyze our outcomes.

RESULTS:

Women taking buprenorphine had a higher prevalence of breastfeeding compared with women taking methadone (83% [ n = 100] vs. 71% [ n = 76]; χ² = 4.35, p = .03), despite no difference in their prenatal intention to breastfeed (87% vs. 81%; χ² = 1.28, p = .25). Only 31% ( n = 38) of women taking buprenorphine and 19.6% ( n = 21) of women taking methadone exclusively breastfed at discharge (χ² = 5.43, p = .06). Exclusively breastfed infants required less pharmacological treatment for neonatal opioid withdrawal syndrome compared with formula-fed infants (15.8% [ n = 21] vs. 47.4% [ n = 38]; χ² = 19.72, p < .05).

CONCLUSION:

Despite most women reporting a high prenatal intention to breastfeed, exclusive breastfeeding at hospital discharge postpartum was low. Breastfeeding was associated with a decreased likelihood of pharmacological treatment for neonatal opioid withdrawal syndrome.

Changes in the blood level, efficacy, and safety of tacrolimus in pregnancy and the lactation period in patients with systemic lupus erythematosus

OBJECTIVES

We investigated the efficacy and safety of tacrolimus (TAC) by monitoring its serum concentration for mothers and infants in pregnant patients with systemic lupus erythematosus (SLE).

METHODS

We measured trough concentrations of TAC in 25 pregnant patients with SLE to assess influence of TAC on the disease activity. Additionally, we measured the concentrations of TAC in umbilical arterial blood, breast milk, and breastfed infants to investigate the safety of TAC for the mothers and infants.

RESULTS

The trough concentrations of TAC in the mothers significantly decreased in the second trimester as compared with those before pregnancy. However, the decrease in the trough concentrations of TAC did not lead to the deterioration of SLE. When examined, the doses of TAC were significantly lower in the second trimester and postpartum in the deteriorating group than those in the non-deteriorating group. There were no adverse events by TAC in mothers and fetuses. The concentrations of TAC in the umbilical cord blood were lower than those in the maternal blood. The relative infant dose in breastfed infants of TAC was < 1%. The level of TAC in infant bloods was below detectable limits.

CONCLUSION

These findings suggest that TAC is one of the most effective and safest immunosuppressive drugs for use in pregnant patients with SLE.

Corrected QT Interval and Methadone Dose and Concentrations in Pregnant and Postpartum Women

BACKGROUND

Methadone is a standard treatment for opioid dependence in pregnancy; however, its impact on maternal corrected QT interval (QTc) has not been evaluated. We studied the association between methadone dose and enantiomer-specific plasma concentrations and QTc among pregnant and postpartum women and newborns. We assessed the relevance of QTc screening guidelines for pregnant women and infants.

METHODS

From 2006 to 2008, plasma methadone concentrations were measured during pregnancy, postpartum, and in cord blood in women treated for opioid dependence at a single treatment program. Electrocardiograms (ECGs) were obtained at peak methadone concentrations in mothers and within 48 hours of birth for infants. Pearson correlations were performed at each time point for QTc and R-methadone, S-methadone, and total methadone concentrations and ratio of R-methadone/S-methadone concentrations.

RESULTS

Mean (SD) daily methadone dose for the 25 women was 94.2 (39.1) mg during pregnancy and 112.5 (46.6) mg postpartum. During the third trimester, higher methadone dose and R-methadone concentration correlated with longer QTc (Pearson r = 0.67, P < .001 and Pearson r = 0.49, P = .02, respectively), while S-methadone concentration, R-methadone/S-methadone concentration ratio, and total methadone concentration did not. Postpartum, QTc did not significantly correlate with dose or enantiomer concentrations. Infant QTc did not correlate with maternal dose at delivery or enantiomer-specific cord methadone concentrations. In pregnant and postpartum women, 13% and 17%, respectively, had QTc ≥ 450 ms, as did 19% of infants.

CONCLUSIONS

QTc correlated with dose and R-methadone concentration during the third trimester. However, longer QTc was common among women during and after pregnancy. Given the relatively high rate of QTc > 450 ms, an ECG before and after methadone initiation is advisable for pregnant and postpartum women.

Maternal Buprenorphine Maintenance and Lactation

BACKGROUND

In addition to the well-known benefits of human milk and breastfeeding for the mother and infant, breastfeeding may mitigate neonatal abstinence syndrome severity in prenatally opioid-exposed infants. However, lack of conclusive data regarding the extent of the presence of buprenorphine and active metabolites in human milk makes the recommendation of breastfeeding for buprenorphine-maintained women difficult for many providers.

OBJECTIVE

This study seeks to determine the concentrations of buprenorphine and its active metabolites (norbuprenorphine, buprenorphine-glucuronide, and norbuprenorphine-glucuronide) in human milk, maternal plasma, and infant plasma of buprenorphine-maintained women and their infants.

METHODS

Up to 10 buprenorphine-maintained women provided paired breast milk and plasma samples at 2, 3, 4, 14, and 30 days postdelivery, and 9 infants provided plasma samples on day 14 of life. All samples were analyzed via liquid chromatography tandem mass spectrometry to determine concentrations of buprenorphine, norbuprenorphine, buprenorphine-glucuronide, and norbuprenorphine-glucuronide by a fully validated method.

RESULTS

Concentrations of buprenorphine and metabolites are low in human milk and maternal plasma. Breastfed infant plasma concentrations of buprenorphine were low or undetectable and metabolite concentrations undetectable at 14 days of infant age. There were significant correlations between maternal buprenorphine dose and maternal plasma and human milk buprenorphine concentrations.

CONCLUSION

These data find low concentrations of buprenorphine and metabolites in human milk and lend support to the recommendation for lactation among stable buprenorphine-maintained women. However, the correlation between maternal dose and maternal plasma and human milk buprenorphine concentrations bears further study.

Breastfeeding and Opiate Substitution Therapy: Starting to Understand Infant Feeding Choices

INTRODUCTION

Despite research demonstrating the safety and benefit of breastfeeding in opioid substitution therapy, few women in treatment breastfeed. Understanding the factors contributing to the choices women on opioid substitution therapy make about infant feeding is important.

OBJECTIVES

The aim of this study was to better understand and support infant feeding choices and breastfeeding experiences in women on opioid substitution therapy.

METHODS

A systematic review was conducted on five databases: (1) Ovid MEDLINE(R) without revisions, (2) Ovid MEDLINE(R) In-Process & Other Non-Indexed Citations, (3) EMBASE, (4) CINAHL, and (5) FRANCIS. From 1081 articles, 46 articles were reviewed.

RESULTS

The literature supports breastfeeding as an appropriate and safe option for women on opioid substitution treatment. Breastfeeding and rooming-in reduce neonatal abstinence. Women face barriers to breastfeeding due to societal stigma and the lack of patient and health-care provider education.

CONCLUSIONS

Efforts are needed to increase the knowledge that women and health-care professionals have about the safety and benefits of breastfeeding.

Forensic Investigation of Methadone Concentrations in Deceased Breastfed Infants

There is a paucity of data to aid in assessing whether postmortem methadone findings in breastfed infants are clinically and/or toxicologically significant. Two cases are reported in which methadone was detected in deceased neonates whose mothers were enrolled in methadone maintenance programs and were breastfeeding. In addition to a complete autopsy and toxicological testing for alcohol, prescription medications, and drugs of abuse, pharmacogenetic analysis was performed for variants in genes related to methadone metabolism and response. In both cases, the postmortem methadone concentration measured in neonatal heart blood was higher than the maximum serum methadone concentration reported in living breastfed infants whose mothers were receiving methadone. However, additional analysis of antemortem blood indicated postmortem redistribution of methadone. Pharmacogenetic results were suggestive of a potential predisposition to methadone toxicity based on studies in adults; the significance of these findings in breastfed neonates requires further research. The medical cause of death was unascertained in both cases.

Lactation and the Substance-Exposed Mother-Infant Dyad

Pregnant and postpartum women with substance use disorders have very unique needs and can present challenges to healthcare providers who are not familiar with how to evaluate and respond properly to their necessities. One such situation frequently arises when women with substance use disorders wish to breast-feed. There are many benefits and challenges to this practice that are specific to this population, and treating practitioners are often unclear on how to address them. The purpose of this article is to identify barriers to lactation in substance-exposed dyads and to provide strategies to mitigate these barriers and for promoting lactation in appropriate women with substance use disorders who wish to breast-feed.

Maternal and neonatal hair and breast milk in the assessment of perinatal exposure to drugs of abuse

Perinatal exposure to one or more drugs of abuse can affect the neonate temporarily or permanently. In addition to meconium, the evaluation of perinatal exposure to drugs of abuse has been achieved by testing biological matrices coming from the newborn (neonatal hair) and from the pregnant or nursing mother (maternal hair and breast milk). These matrices have the advantage of noninvasive collection and account for a sizable time window of active and passive exposure. Sensitive and specific analytical methods are required to determine minute amounts of drugs of abuse and metabolites in these matrices. The present manuscript reviews the newest analytical methods developed to detect drugs of abuse as well as ethanol biomarkers in maternal and neonatal hair and breast milk.

ABM clinical protocol #21: guidelines for breastfeeding and substance use or substance use disorder, revised 2015

A central goal of The Academy of Breastfeeding Medicine is the development of clinical protocols for managing common medical problems that may impact breastfeeding success. These protocols serve only as guidelines for the care of breastfeeding mothers and infants and do not delineate an exclusive course of treatment or serve as standards of medical care. Variations in treatment may be appropriate according to the needs of an individual patient.

Neonatal abstinence syndrome

Neonatal abstinence syndrome (NAS) is a result of the sudden discontinuation of fetal exposure to substances that were used or abused by the mother during pregnancy. Withdrawal from licit or illicit substances is becoming more common among neonates in both developed and developing countries. NAS continues to be an important clinical entity throughout much of the world. NAS leads to a constellation of signs and symptoms involving multiple systems. The pathophysiology of NAS is not completely understood. Urine or meconium confirmation may assist the diagnosis and management of NAS. The Finnegan scoring system is commonly used to assess the severity of NAS; scoring can be helpful for initiating, monitoring, and terminating treatment in neonates. Nonpharmacological care is the initial treatment option, and pharmacological treatment is required if an improvement is not observed after nonpharmacological measures or if the infant develops severe withdrawal. Morphine is the most commonly used drug in the treatment of NAS secondary to opioids. An algorithmic approach to the management of infants with NAS is suggested. Breastfeeding is not contraindicated in NAS, unless the mother is taking street drugs, is involved in polydrug abuse, or is infected with HIV. Future studies are required to assess the long-term effects of NAS on children after prenatal exposure.

Breastfeeding and Methadone Therapy: The Maternal Experience

BACKGROUND

Despite evidence of low transfer of methadone into breast milk and the potential physical and psychological benefits that breastfeeding offers for methadone-exposed mothers and infants, the rate of breastfeeding initiation in this population is about half that reported nationally. This study describes the perceptions surrounding breastfeeding decisions and management among pregnant and postpartum women taking methadone.

METHODS

Seven pregnant women and 4 postpartum women enrolled in methadone maintenance programs participated in semistructured, audiotaped interviews and focus groups, respectively, about their breastfeeding experiences. Transcripts were analyzed and coded using qualitative content analysis.

RESULTS

Three major content categories were identified: (1) fears, barriers, and misconceptions about breastfeeding while taking methadone; (2) motivation and perceived benefits of breastfeeding; and (3) sources of information, support, and anxiety about general breastfeeding management and breastfeeding while taking methadone. Lack of support from the health care community and misinformation about the dangers of combining breastfeeding and methadone therapy represented significant, yet modifiable, barriers to breastfeeding success in methadone-exposed women.

CONCLUSIONS

Interventions to increase the prevalence of breastfeeding among women taking methadone should address identified logistical, educational, and psychological barriers and consider inclusion of women themselves, partners, peers, and clinicians. In particular, clinicians who care for methadone-exposed mothers and infants should be educated on therapeutic communication, up-to-date breastfeeding contraindications, and the health benefits of breastfeeding in this population.

Management of neonatal abstinence syndrome from opioids

Most infants at risk for neonatal abstinence syndrome have opioid plus another drug exposure; polypharmacy is the rule rather than the exception. Scales for evaluation of neonatal abstinence syndrome are primarily based for opioid withdrawal. A standard protocol to treat neonatal abstinence syndrome has not been developed. Institute nonpharmacologic strategies for all neonates at risk. The American Academy of Pediatrics recommends mechanism-directed therapy (treat opioid withdrawal with an opioid) as the first-line therapy. Second-line medications are currently under evaluation.

Pharmacologic evidence to support clinical decision making for peripartum methadone treatment

RATIONALE

Limited pharmacological data are available to guide methadone treatment during pregnancy and postpartum.

OBJECTIVES

Study goals were to (1) characterize changes in methadone dose across childbearing, (2) determine enantiomer-specific methadone withdrawal kinetics from steady state during late pregnancy, (3) assess enantiomer-specific changes in methadone level/dose (L/D) ratios across childbearing, and (4) explore relationships between CYP2B6, CYP2C19, and CYP3A4 single-nucleotide polymorphisms and maternal dose, plasma concentration, and L/D.

METHODS

Methadone dose changes and timed plasma samples were obtained for women on methadone (n = 25) followed prospectively from third trimester of pregnancy to 3 months postpartum.

RESULTS

Participants were primarily white, Medicaid insured, and multiparous. All women increased their dose from first to end of second trimester (mean peak increase = 23 mg/day); 71 % of women increased from second trimester to delivery (mean peak increase = 19 mg/day). Half took a higher dose 3 months postpartum than at delivery despite significantly larger clearance during late pregnancy. Third trimester enantiomer-specific methadone half-lives (range R-methadone 14.7-24.9 h; S-methadone, 8.02-18.9 h) were about half of those reported in non-pregnant populations. In three women with weekly 24-h methadone levels after delivery, L/D increased within 1-2 weeks after delivery. Women with the CYP2B6 Q172 variant GT genotype have consistently higher L/D values for S-methadone across both pregnancy and postpartum.

CONCLUSIONS

Most women require increases in methadone dose across pregnancy. Given the shorter half-life and larger clearances during pregnancy, many pregnant women may benefit from split methadone dosing. L/D increases quickly after delivery and doses should be lowered rapidly after delivery.