Transfer of buprenorphine into breast milk and calculation of infant drug dose

Microfluidic blood-milk barrier and physiologically based pharmacokinetic model to predict lofexidine secretion into breast milk

INTRODUCTION

Lofexidine (LUCEMYRA®) is the only FDA-approved, non-opioid, non-addictive treatment for opioid withdrawal symptoms, crucial for postpartum and pregnant women affected by the opioid crisis. Despite its clinical importance, data on its secretion into breast milk is limited. This study aims to develop a novel, microfluidic-based blood-milk-barrier on a chip model, a static human mammary cell transwell model, and a physiologically based pharmacokinetic (PBPK) lactation model to estimate the breast milk secretion of lofexidine, thereby ensuring maternal and infant safety and improving withdrawal management.

METHODS

A novel microfluidic device was developed to build a mammary epithelium-on-a-chip model, and a transwell plate was used to develop a static mammary epithelium using a human noncarcinogenic mammary epithelial cell (MEC) population that can form an integrated barrier with tight junctions. Both models were used to evaluate the transfer of lofexidine through the in vitro mammary cell barrier. The fraction of unbound lofexidine in the breast milk was determined by a Rapid Equilibrium Dialysis (RED) assay. Eleven approaches, including a novel, previously published in vitro to in vivo extrapolation (IVIVE) approach and various other approaches, were used to estimate milk-to-plasma (M/P) ratios of lofexidine. A whole-body lactation PBPK model was built using Simcyp® simulator v22 and used to predict the concentration-time profiles of lofexidine in both human plasma and breast milk.

RESULTS

A subpopulation of human normal mammary epithelial MCF10A cells (named MCF10A-TJ) was identified to form an integrated barrier that reaches trans-epithelial electrical resistance (TEER) values of over 1000 Ω·cm2 by culturing with in-house designed maintenance and boosting medium. The microfluidic device-based mammary epithelium-on-a-chip model generated slightly higher lofexidine permeability values than the static transwell mammary epithelial cell model. The predicted milk-to-plasma (M/P) ratio of lofexidine ranged from 0.40 to 15.88. Four approaches estimated an M/P ratio below 1, while seven predicted values above 1, mostly between 1.35 and 5.48. The whole-body lactation PBPK model predicted the concentration-time profile of lofexidine in breast milk, with an estimated M/P ratio of approximately 2.0. This value falls within the mid-range of the predictions obtained from all eleven methods.

CONCLUSION

This study introduces comprehensive and novel approaches to predict lofexidine secretion into breast milk. Most predictions suggest higher lofexidine concentration in milk than in plasma, raising potential safety concerns for opioid withdrawal management. Further pharmacokinetic clinical lactation studies are needed to validate these predictions.

Spontaneous umbilical cord entwinement in 1-day-old kittens

Case summary

A 1-year-old domestic shorthair queen with five neonates was referred for umbilical cord entwinement in three kittens 24 h after parturition. The owner noticed the kittens were stuck to each other 3 h before admission. Despite a conservative treatment approach, prolonged ischaemia led to dry gangrenous changes in one of the kitten's metatarsi.

Relevance and novel information

This and other neonatal complications in cats are rarely reported. Primiparity is a known factor contributing to postpartum complications. Furthermore, inexperienced owners require more assistance in mitigating these challenges. Therefore, further research and collaboration among breeders, owners and veterinary professionals are imperative in order to accurately determine the prevalence of this condition in kittens and develop effective strategies to address it.

Abnormal Morphology and Synaptogenic Signaling in Astrocytes Following Prenatal Opioid Exposure

In recent decades, there has been a dramatic rise in the rates of children being born after in utero exposure to drugs of abuse, particularly opioids. Opioids have been shown to have detrimental effects on neurons and glia in the central nervous system (CNS), but the impact of prenatal opioid exposure (POE) on still-developing synaptic circuitry is largely unknown. Astrocytes exert a powerful influence on synaptic development, secreting factors to either promote or inhibit synapse formation and neuronal maturation in the developing CNS. Here, we investigated the effects of the partial µ-opioid receptor agonist buprenorphine on astrocyte synaptogenic signaling and morphological development in cortical cell culture. Acute buprenorphine treatment had no effect on the excitatory synapse number in astrocyte-free neuron cultures. In conditions where neurons shared culture media with astrocytes, buprenorphine attenuated the synaptogenic capabilities of astrocyte-secreted factors. Neurons cultured from drug-naïve mice showed no change in synapses when treated with factors secreted by astrocytes from POE mice. However, this same treatment was synaptogenic when applied to neurons from POE mice, indicating a complex neuroadaptive response in the event of impaired astrocyte signaling. In addition to promoting morphological and connectivity changes in neurons, POE exerted a strong influence on astrocyte development, disrupting their structural maturation and promoting the accumulation of lipid droplets (LDs), suggestive of a maladaptive stress response in the developing CNS.

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.

Evaluation of the Hepatotoxicity of Buprenorphine in Rat Pups Born to an Exposed Mother During Lactation

AIMS

This study aimed to evaluate the hepatotoxicity of buprenorphine in lactating rat pups of buprenorphine-injected mothers. Buprenorphine (BUP), a semisynthetic opioid, is increasingly administrated as a first-line standard maintenance treatment for opioid dependence due to its high safety and efficacy compared to other opioids. Numerous studies have confirmed the safety of BUP maintenance treatment in addicted patients.

OBJECTIVES

This study was designed to assess the effects of BUP on the activities of liver enzymes, oxidative parameters, and liver histopathological changes in pups born to a mother exposed to this drug during lactation.

METHODS

BUP at a dose of 0.5 or 0.1 mg/kg was subcutaneously administrated to lactating rats for 28 days. At the end of the experiment, the pups were anesthetized, and blood samples were obtained from their hearts for measuring liver enzymes. Then the livers of the animals were dissected to measure oxidative stress parameters. In addition, the liver samples were fixed for histopathological evaluation.

RESULTS

The findings indicated a decrease in the activities of serum liver enzymes (ALT and AST) of the pups born to mothers exposed to 0.5 and 1 mg/kg of BUP during lactation. BUP could not change malondialdehyde (MDA), glutathione (GSH), nitric oxide (NO) levels, nor superoxide dismutase (SOD) activity in the liver tissue of animals. Some vacuolated hepatocytes with dark, eccentric nuclei, necrosis with karyolytic nuclei, mitotic figures, and multiple binucleated cells were seen in the pups which received 1 mg/kg of BUP.

CONCLUSION

In conclusion, BUP may induce liver dysfunction in pups born to mothers exposed to this drug during lactation.

Maternal care behavior and physiology moderate offspring outcomes following gestational exposure to opioids

The opioid epidemic has resulted in a drastic increase in gestational exposure to opioids. Opioid-dependent pregnant women are typically prescribed medications for opioid use disorders ("MOUD"; e.g., buprenorphine [BUP]) to mitigate the harmful effects of abused opioids. However, the consequences of exposure to synthetic opioids, particularly BUP, during gestation on fetal neurodevelopment and long-term outcomes are poorly understood. Further, despite the known adverse effects of opioids on maternal care, many preclinical and clinical studies investigating the effects of gestational opioid exposure on offspring outcomes fail to report on maternal care behaviors. Considering that offspring outcomes are heavily dependent upon the quality of maternal care, it is important to evaluate the effects of gestational opioid exposure in the context of the mother-infant dyad. This review compares offspring outcomes after prenatal opioid exposure and after reduced maternal care and integrates this information to potentially identify common underlying mechanisms. We explore whether adverse outcomes after gestational BUP exposure are due to direct effects of opioids in utero, deficits in maternal care, or a combination of both factors. Finally, suggestions for improving preclinical models of prenatal opioid exposure are provided to promote more translational studies that can help to improve clinical outcomes for opioid-dependent mothers.

An Examination of the Complex Pharmacological Properties of the Non-Selective Opioid Modulator Buprenorphine

The goal of this review is to provide a recent examination of the pharmacodynamics as well as pharmacokinetics, misuse potential, toxicology, and prenatal consequences of buprenorphine. Buprenorphine is currently a Schedule III opioid in the US used for opioid-use disorder (OUD) and as an analgesic. Buprenorphine has high affinity for the mu-opioid receptor (MOR), delta (DOR), and kappa (KOR) and intermediate affinity for the nociceptin (NOR). Buprenorphine's active metabolite, norbuprenorphine, crosses the blood-brain barrier, is a potent metabolite that attenuates the analgesic effects of buprenorphine due to binding to NOR, and is responsible for the respiratory depressant effects. The area under the concentration curves are very similar for buprenorphine and norbuprenorphine, which indicates that it is important to consider this metabolite. Crowding sourcing has identified a buprenorphine street value (USD 3.95/mg), indicating some non-medical use. There have also been eleven-thousand reports involving buprenorphine and minors (age < 19) at US poison control centers. Prenatal exposure to clinically relevant dosages in rats produces reductions in myelin and increases in depression-like behavior. In conclusion, the pharmacology of this OUD pharmacotherapy including the consequences of prenatal buprenorphine exposure in humans and experimental animals should continue to be carefully evaluated.

A review of the safety of buprenorphine in special populations

Rates of opioid misuse and opioid use disorder have been increasing in recent years. Buprenorphine has emerged as an appealing medication for its use not only as treatment for opioid use disorder, but also as an opioid for chronic pain that has a ceiling effect on risks associated with opioid therapy. As other opioid prescribing decreases, buprenorphine prescribing continues to increase. As a result, it is imperative to understand the safety and efficacy of its use in special populations. This review article will explore the safety and efficacy of buprenorphine when used in subjects with hepatic and renal impairment, the elderly, and pregnant women. While manufacturer labeling for buprenorphine products may caution against their use in these populations, further examination of available data indicates that buprenorphine can be used safely and effectively for both chronic pain and/or opioid use disorder in all four of these populations.

Oxidative stress and apoptotic index modifications in the hippocampus of rat pups born to mothers exposed to buprenorphine during lactation

Background

The effect of opioids administration during lactation on nervous system has not fully understood.

Objective

The aim of this study was to evaluate the buprenorphine (BUP) impact on oxidative stress indexes and apoptotic gene expression in the hippocampus of neonates exposed to this drug through breastfeeding.

Methods

Lactating female rats were subcutaneously injected with BUP (1 or 0.5 mg/kg). After 28 days, the pups were anesthetized, then their hippocampus were obtained for measurement of oxidative stress parameters [glutathione (GSH), thiobarbituric acid reactive substances (TBARS), total antioxidant capacity (TAC) and superoxide dismutase (SOD)] and gene expression of apoptotic indices (Bcl2, Bax and caspase 3).

Results

This study showed that BUP (0.5 and 1 mg/kg) could not markedly change oxidative stress indices levels and apoptotic markers expression in the hippocampus of pups versus controls.

Conclusion

This study did not find BUP effect on the apoptosis and oxidative stress indices in the hippocampus of pups born to mothers exposed to this drug during lactation.

Oxidative Stress Indices Changes in the Hearts of Rat Pups in Response to Maternal Buprenorphine Treatment during Gestation and Lactation

This study aimed to assess the effects of Buprenorphine (BUP) on oxidative parameters in pups born to mothers exposed to the drug during gestation and lactation. Pregnant and lactating rats received BUP, 0.5 or 0.1 mg/kg subcutaneously for 21 and 28 days, respectively. At the end of the study, the pups were anesthetized, and the hearts were dissected out to measure oxidative stress indices, including the levels of Malondialdehyde (MDA), Nitric oxide (NO), Glutathione (GSH), and the activity of Superoxide dismutase (SOD). Our findings indicated that BUP did not alter MDA, NO, GSH levels, nor SOD activity in the cardiac tissue of pups exposed to this drug during the fetal period and through breast milk. We suggest performing additional studies to determine the association between BUP and oxidative modifications in cardiac tissues of pups born to mothers under BUP therapy during gestation and lactation.

Alterations in Excitatory and Inhibitory Synaptic Development Within the Mesolimbic Dopamine Pathway in a Mouse Model of Prenatal Drug Exposure

The rise in rates of opioid abuse in recent years in the United States has led to a dramatic increase in the incidence of neonatal abstinence syndrome (NAS). Despite improved understanding of NAS and its acute symptoms, there remains a paucity of information regarding the long-term effects of prenatal exposure to drugs of abuse on neurological development. The primary goal of this study was to investigate the effects of prenatal drug exposure on synaptic connectivity within brain regions associated with the mesolimbic dopamine pathway, the primary reward pathway associated with drug abuse and addiction, in a mouse model. Our secondary goal was to examine the role of the Ca+2 channel subunit α2δ-1, known to be involved in key developmental synaptogenic pathways, in mediating these effects. Pregnant mouse dams were treated orally with either the opioid drug buprenorphine (commonly used in medication-assisted treatment for substance use patients), gabapentin (neuropathic pain drug that binds to α2δ-1 and has been increasingly co-abused with opioids), a combination of both drugs, or vehicle daily from gestational day 6 until postnatal day 11. Confocal fluorescence immunohistochemistry (IHC) imaging of the brains of the resulting wild-type (WT) pups at postnatal day 21 revealed a number of significant alterations in excitatory and inhibitory synaptic populations within the anterior cingulate cortex (ACC), nucleus accumbens (NAC), and medial prefrontal cortex (PFC), particularly in the buprenorphine or combinatorial buprenorphine/gabapentin groups. Furthermore, we observed several drug- and region-specific differences in synaptic connectivity between WT and α2δ-1 haploinsufficient mice, indicating that critical α2δ-1-associated synaptogenic pathways are disrupted with early life drug exposure.

Patientin mit Schwangerschaft, Borderline-Organisation und schwerer Polytoxikomanie

Zielsetzung Ziel dieser Arbeit war es, die Komplexität von Schwangerschaft und Sucht durch ein Fallbeispiel einer Patientin mit schwerer Polytoxikomanie, Borderline-Organisation sowie den Verlauf der Schwangerschaft und die frühe Phase nach der Geburt vorzustellen. Dabei ging es v. a. um die Frage, wie eine langfristige Behandlung mit einem mehrstufigen, multiprofessionellen und multimodalen Setting aussehen könnte. Die Arbeit zeigt zudem Konflikte an Schnittstellen auf und wie wichtig die Kommunikation innerhalb des Teams und fachübergreifend war.

Intervention Qualifizierte stationäre Entgiftungsbehandlung von Benzodiazepinen, Phenothiazin, Lyrica Venlafaxin und Reduktion von Methadon mit anschließender Umstellung auf Buprenorphin sowie ergänzender kombinierter ärztlicher, psychodynamischer Einzel- und Gruppentherapie und einem pflegerischen DBT-S Einzel- und Gruppensetting. Außerdem wurde schon während der Schwangerschaft zusätzlich zum stationären Behandlungsteam ein fächerübergreifendes Behandlungsteam aus Gynäkologen, Kinderärzten, Kinder- und Jugendpsychiatern sowie der Kinder- und Erwachsenenschutzbehörde (KESB, in Deutschland Jugendamt) zusammengestellt und schon zu Beginn wurde eine langfristige Behandlung mit stationärem, teilstationärem und ambulantem Intervall geplant.

Ergebnis Im Laufe der fast 3-jährigen Behandlung und 5 Jahre späteren katamnestischen Nachuntersuchung konnte zunächst unter 8 mg Buprenorphin eine Abstinenz von illegalen Substanzen erzielt werden. Im Verlauf sogar vollständige Abstinenz ohne Substitution. Dies konnte durch ein erneutes Interview und Drogenscreening im Jahr 2020 bestätigt werden. Außerdem konnte im Rahmen der fächerübergreifenden Arbeit ein stabiles soziales Umfeld und ein Wiedereinstieg ins Berufsleben erreicht werden.

Diskussion Trotz der anfänglich häufigen Rückfälle konnte durch den Erhalt der therapeutischen Beziehung (z. B. mittels Time-out auf die Akutstation, Verlängerung einer Wochenendbeurlaubung oder Neuverhandlung der Behandlungsvereinbarung) unter Fortsetzung der Einzelpsychotherapie und Bezugspflege mit Einbezug der Rückfälle, gegenseitiges Vertrauen und Wertschätzung geschaffen werden. Dafür war allerdings viel supervisorische Arbeit innerhalb des Teams, aber auch fächerübergreifend notwendig, da sich die extreme innerer Welt der Patientin häufig in unterschiedlicher Art und Weise im multiprofessionellen Team zeigte und dadurch zu Konflikten führte, die passager das Verlassen der Neutralität verlangten. Ferner waren für diese Art der Behandlung enorme Ressourcen notwendig sowohl zeitlich als auch personell.

Lactose-free infant formula does not change outcomes of neonatal abstinence syndrome (NAS): a randomized clinical trial

OBJECTIVE

To determine if lactose-free formula, compared to lactose-containing formula, decreases the cumulative morphine dose required to treat neonatal abstinence syndrome (NAS).

STUDY DESIGN

In a double-blind clinical trial, we randomized 74 infants (36-42 weeks gestation) at risk for developing NAS due to in-utero exposure to opioids to receive either lactose-free (Similac Sensitive®) or lactose-containing (Similac Advance®) infant formula. The primary outcome measure was the cumulative dose of morphine used for the treatment of NAS during the first 14 days of life.

RESULTS

Data on 69 (4 withdrew consent and 1 ineligible)/74 randomized infants were analyzed. Patient characteristics between the infant groups fed lactose-free (n = 34) vs. lactose-containing (n = 35) infant formula were similar except more common maternal heroin abuse in the latter group (p = 0.013). Cumulative morphine dose (20.7 ± 19.8 vs. 23 ± 23.5 mg, p = 0.61) between the two groups were similar.

CONCLUSION

Lactose-free vs. lactose-containing infant formula did not change the outcomes of infants with NAS.

Buprenorphine dosing for the treatment of opioid use disorder through pregnancy and postpartum

PURPOSE OF REVIEW

Opioid-related deaths are a leading cause of mortality during pregnancy through 12 months postpartum. Buprenorphine use during pregnancy is increasing, yet expert opinion on its dosing through the perinatal period is limited. We provide a review of the current clinical literature on buprenorphine dosing during pregnancy through 12 months postpartum. and present data from a retrospective chart review of patients at our institution describing trends in buprenorphine dosing during pregnancy and postpartum. Utilizing this information, we synthesize findings to provide clinical recommendations for providers.

RECENT FINDINGS

Existing literature during pregnancy reflects how many women increase and split total daily buprenorphine doses as gestational age advances.

SUMMARY

We present data from a retrospective chart review of patients at our institution describing trends in buprenorphine dosing during pregnancy and postpartum. Utilizing this information, we synthesize findings to provide clinical recommendations for providers. Changes in the total daily dose of buprenorphine used across pregnancy and through 12 months postpartum at the individual level do not follow consistent patterns, highlighting substantial individual variability. Altogether, buprenorphine dosing should be individualized through pregnancy and postpartum with frequent evaluations by providers and solicited input from patients.

Psychoactive substances in human breast milk: a review of analytical strategies for their investigation

WHO recommends breastfeeding for the first 6 months of newborn's life. Due to its physicochemical properties, breast milk may contain undesirable components originated from mother's feeding, medication and illicit drugs consumption. Some of these substances transferred from bloodstream to milk and delivered to the infant can cause harmful effects. For the last decades, analytical advances enabled the analysis of several substances in milk using different techniques. Thereby, it is possible to evaluate infant's level of exposure to these substances. This review presents the information published in the main scientific dissemination media about psychoactive drugs investigation in human breast milk, involving the sample preparation techniques and chromatographic validated methods developed in the past 10 years.

Effects of Partially Hydrolyzed Formula on Severity and Outcomes of Neonatal Abstinence Syndrome

OBJECTIVE

This study compares the effect of partially hydrolyzed formula (PHF) and standard formula (SF) on the severity and short-term outcomes of neonatal abstinence syndrome (NAS).

STUDY DESIGN

We performed a retrospective chart review of 124 opioid-dependent mothers and their term or near-term infants. Infants were categorized according to the predominant type of formula consumed during the hospital stay. Finnegan's scale was used to assess symptoms of withdrawal.

RESULTS

A total of 110 infants met our inclusion criteria. Thirty-four (31%) infants were fed predominantly PHF, 60 (54%) infants were fed SF, and 16 (15%) infants were fed maternal breast milk. There was no difference between the infants in the PHF and SF groups with respect to requirement of morphine (MSO₄) therapy, maximum dose of MSO₄ used, duration of MSO₄ treatment or length of hospital stay after performing multivariate analyses to control for type of drug used by the mother, maternal smoking, regular prenatal care, inborn status, and maximum Finnegan score prior to MSO₄ treatment.

CONCLUSION

Use of PHF failed to impact short-term outcomes in infants treated for NAS including maximum MSO₄ dose, duration of MSO₄ treatment, and length of hospital stay. A prospective randomized controlled trial may be indicated to confirm this finding.

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.

Supporting breastfeeding for women on opioid maintenance therapy: a systematic review

OBJECTIVE

Despite evidence to support breastfeeding, rates remain low in women on opioid maintenance therapy (OMT). The goal of this review was to synthesize current knowledge regarding interventions to promote breastfeeding in women on OMT.

STUDY DESIGN

A systematic search of databases including PubMed, CINAHL, PsycINFO, Embase, Scopus, Web of Science, and the Cochrane database of systematic reviews was conducted. Key words included breastfeeding, lactation, opioid use disorder, and opioid maintenance therapy. Risk of bias was assessed by two reviewers.

RESULT

Four quasi-experimental studies met inclusion criteria. Improved rates of breastfeeding reached statistical significance in all four. Three studies had moderate to serious risk of bias related to confounding variables. Interventions shared common features, including an integrated approach, a well-prepared multidisciplinary team, nonseparation of mother and newborn, and patient centered care.

CONCLUSIONS

Further research should explore barriers and facilitators to breastfeeding in this vulnerable population.

Breastmilk feeding for mothers and infants with opioid exposure: What is best?

With rare exception, breastfeeding is the optimal way to feed infants, and has special benefits for women and infants with perinatal opioid exposure. Infants breastfed and/or fed their mother's own breastmilk experience less severe opioid withdrawal symptoms, have shorter hospital stays, and are less likely to be treated with medication for withdrawal. The specific impact of mothers' milk feeding on opioid withdrawal may be related to the act of breastfeeding and associated skin-to-skin contact, qualities of breastmilk, healthier microbiome, small amounts of opioid drug in breastmilk, or a combination of these. Women with opioid use disorder face significant breastfeeding obstacles, including psychosocial, behavioral, concomitant medications, and tobacco use and thus may require high levels of support to achieve their breastfeeding goals. They often don't receive information to make informed infant feeding decisions. Hospital practices such as prenatal education, rooming-in and having a policy that minimizes barriers to breastfeeding are associated with increased breastfeeding rates.

Buprenorphine in Neonatal Abstinence Syndrome

Infants exposed in utero to opioids will demonstrate a withdrawal syndrome known as neonatal abstinence syndrome (NAS). Buprenorphine is a long-acting opioid with therapeutic use in medication-assisted treatment of opioid dependency in adults and adolescents. Emerging data from clinical trials and treatment cohorts demonstrate the efficacy and safety of sublingual buprenorphine for those infants with NAS who require pharmacologic treatment. Pharmacometric modeling will assist in defining the exposure-response relationships and facilitate dose optimization.

Opioid Use in Pregnancy, Neonatal Abstinence Syndrome, and Childhood Outcomes: Executive Summary of a Joint Workshop by the Eunice Kennedy Shriver National Institute of Child Health and Human Development, American College of Obstetricians and Gynecologists, American Academy of Pediatrics, Society for Maternal-Fetal Medicine, Centers for Disease Control and Prevention, and the March of Dimes Foundation

In April 2016, the Eunice Kennedy Shriver National Institute of Child Health and Human Development invited experts to a workshop to address numerous knowledge gaps and to review the evidence for the screening and management of opioid use in pregnancy and neonatal abstinence syndrome. The rising prevalence of opioid use in pregnancy has led to a concomitant dramatic fivefold increase in neonatal abstinence syndrome over the past decade. Experts from diverse disciplines addressed research gaps in the following areas: 1) optimal screening for opioid use in pregnancy; 2) complications of pregnancy associated with opioid use; 3) appropriate treatments for pregnant women with opioid use disorders; 4) the best approaches for detecting, treating, and managing newborns with neonatal abstinence syndrome; and 5) the long-term effects of prenatal opioid exposure on children. Workshop participants identified key scientific opportunities to advance the understanding of opioid use disorders in pregnancy and to improve outcomes for affected women, their children, and their families. This article provides a summary of the workshop presentations and discussions.

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.

The Association Between Breastfeeding and Length of Hospital Stay Among Infants Diagnosed with Neonatal Abstinence Syndrome: A Population-Based Study of In-Hospital Births

OBJECTIVE

The incidence of neonatal abstinence syndrome (NAS), a drug withdraw syndrome mainly associated with intrauterine opioid exposure, has increased considerably in the United States since 2000. Nonpharmacological options, including breastfeeding, may be effective at improving outcomes in this population. The objective of this population-based study was to examine the association between breastfeeding and length of hospital stay among infants diagnosed with NAS.

METHODS

This was a retrospective cohort study of singleton in-hospital births to resident mothers in Pennsylvania. Hospital discharge data from births occurring between 2012 through 2014 were linked with corresponding birth certificate data. International Classification of Diseases, Ninth Revision, Clinical Modification discharge diagnosis codes were used to identify NAS neonates (N = 3,725). Breastfeeding at discharge was used to determine breastfeeding status. Infant and maternal characteristics were compared by breastfeeding status and the association between breastfeeding and infant length of hospitalization was assessed.

RESULTS

Less than one-half of infants diagnosed with NAS were breastfed at discharge. Significant differences in infant birth weight and gestational age, and maternal education, marital status, prenatal care, smoking, and insurance status were found by breastfeeding status. A significant inverse relationship existed between breastfeeding and hospital length of stay for infants diagnosed with NAS. Specifically, length of hospitalization was reduced by 9.4% in the breastfed group compared to the nonbreastfed group.

CONCLUSION

Breastfeeding may be beneficial for infants diagnosed with NAS by shortening the length of hospital stay. Future prospective studies are warranted to further examine the benefits of breastfeeding and other nonpharmaceutical interventions in NAS populations.

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.

Caring for Opioid-dependent Pregnant Women: Prenatal and Postpartum Care Considerations

Pregnancy is an opportune time to identify opioid dependence, facilitate conversion to opioid maintenance treatment, and coordinate care with specialists in addiction medicine, behavioral health, and social services. Comprehensive prenatal care for opioid-dependent women involves the evaluation and the management of co-occurring psychiatric disorders, polysubstance use, infectious diseases, social stressors, and counseling regarding the importance of breastfeeding, contraception, and neonatal abstinence syndrome. Although the complex psychiatric, social, and environmental factors faced by this population pose significant challenges to obstetric care providers, the development of strong patient-provider relationships can facilitate the ability to deliver efficient and effective health care during pregnancy.

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.

Buprenorphine for the treatment of opioid dependence in pregnancy

The treatment of opioid dependence during pregnancy has historically consisted of either medication-assisted withdrawal or maintenance treatment with methadone. Buprenorphine maintenance treatment is emerging as a treatment during pregnancy with distinct benefits for the neonate and the pregnant woman. Buprenorphine is effective in decreasing the risk of relapse in pregnant women. In addition, prenatal use of buprenorphine appears to decrease the severity and duration of neonatal abstinence syndrome as compared with methadone maintenance. Management of buprenorphine includes initiation and maintenance treatment as well as careful planning for pain control during and after delivery and prevention of postpartum relapse risk. Only very small amounts of buprenorphine enter breast milk, making it a good option for those who elect to breast-feed. There is evidence that emerging collaborative care models are effective ways to deliver buprenorphine maintenance treatment, although more investigation is needed to generalize this to the obstetric setting.

The wellbeing of infants exposed to buprenorphine via breast milk at 4 weeks of age

BACKGROUND

Buprenorphine has been available in Australia since 2000 as an alternative pharmacotherapy to methadone for the treatment of opioid dependence. However, there is little information in the literature regarding the effect of buprenorphine on the wellbeing of infants exposed to buprenorphine via breast milk, following discharge from hospital.

OBJECTIVE

The aim of the present study was to examine the wellbeing of infants exposed to buprenorphine via breast milk up to 4 weeks postnatally.

METHODS

Approximately 4 weeks after birth, information on the feeding and sleeping patterns, skin color, infant elimination patterns and hydration, and Neonatal Abstinence Scores of infants (n = 7) exposed to buprenorphine via breast milk was collected via both observation and documentation.

RESULTS

Infants were progressing well, with normal sleep patterns and skin color, and 2 mothers had minor concerns regarding infant elimination patterns. Four infants were exclusively breastfed and 3 were receiving a supplement, with a range of 260 to 700 mL of formula over 24 hours. The sleep patterns following feeding ranged from 1.55 to 3.33 hours, with a median of 2.12 hours.

CONCLUSION

No adverse effects were detected in infants exposed to buprenorphine via breast milk up to 4 weeks postnatally. Further research using larger samples to assess possible developmental effects over longer periods of time is required.

Breastfeeding rates and the relationship between breastfeeding and neonatal abstinence syndrome in women maintained on buprenorphine during pregnancy

INTRODUCTION

Although a growing body of evidence suggests that buprenorphine is a safe alternative to methadone in the treatment of opioid-dependent pregnant women, little is known about breastfeeding in this population. The first objective of this study was to describe breastfeeding rates among opioid-dependent pregnant women maintained on buprenorphine in an integrated medical and behavioral health program. The second objective was to determine whether breastfeeding is related to the duration, severity, and frequency of pharmacologic treatment for neonatal abstinence syndrome (NAS).

METHODS

A retrospective chart review was conducted for all infants born to opioid-dependent pregnant women treated in the integrated buprenorphine program between December 2007 and August 2012.

RESULTS

Eighty-five maternal-infant pairs were identified. Sixty-five women (76%) chose to breastfeed their infants after birth; of the women who initiated breastfeeding in the hospital, 66% were still breastfeeding 6 to 8 weeks postpartum. Although the data suggest that infants who were breastfed had less severe NAS (mean peak NAS, 8.83 vs 9.65 on a modified Finnegan Scoring System) and were less likely to require pharmacologic treatment (23.1% vs 30.0%) than infants who were not breastfed, these results were not statistically significant.

DISCUSSION

More than three-quarters of the opioid-dependent pregnant women in this case series chose to breastfeed after birth. Although a direct comparison of care models is not possible, the integrated model of care potentially reduced some of the barriers to breastfeeding as the women accessed all their care in a single, infant-friendly setting. Further work is needed to definitively determine whether breastfeeding mitigates NAS.

Breastfeeding reduces the need for withdrawal treatment in opioid-exposed infants

AIM

To examine the rate and duration of breastfeeding in a cohort of women in opioid maintenance treatment (OMT) in Norway, as well as the effect of breastfeeding on the incidence and duration of neonatal abstinence syndrome (NAS).

METHODS

A national cohort of 124 women treated with either methadone or buprenorphine during pregnancy, and their neonates born between 1999 and 2009, was evaluated in three study parts. A standardized questionnaire was administered, and medical information from the hospitals and municipalities were collected to confirm self-reported data.

RESULTS

There were high initiation rates of breastfeeding (77%) for women in OMT, but also high rates of early cessation of breastfeeding. Breastfed neonates exposed to methadone prenatally had significantly lower incidence of NAS requiring pharmacotherapy (53% vs. 80%), and both the whole group of infants and the methadone-exposed neonates needed shorter pharmacological treatment of NAS (p < 0.05) than neonates who were not breastfed.

CONCLUSION

Breastfed neonates exposed to OMT medication prenatally, and methadone-exposed newborns in particular, have lower incidence of NAS and require shorter pharmacotherapy for NAS than infants who are not breastfed. The results add to the evidence regarding the benefits of breastfeeding for neonates prenatally exposed to OMT medications.

The transfer of drugs and therapeutics into human breast milk: an update on selected topics

Many mothers are inappropriately advised to discontinue breastfeeding or avoid taking essential medications because of fears of adverse effects on their infants. This cautious approach may be unnecessary in many cases, because only a small proportion of medications are contraindicated in breastfeeding mothers or associated with adverse effects on their infants. Information to inform physicians about the extent of excretion for a particular drug into human milk is needed but may not be available. Previous statements on this topic from the American Academy of Pediatrics provided physicians with data concerning the known excretion of specific medications into breast milk. More current and comprehensive information is now available on the Internet, as well as an application for mobile devices, at LactMed (http://toxnet.nlm.nih.gov). Therefore, with the exception of radioactive compounds requiring temporary cessation of breastfeeding, the reader will be referred to LactMed to obtain the most current data on an individual medication. This report discusses several topics of interest surrounding lactation, such as the use of psychotropic therapies, drugs to treat substance abuse, narcotics, galactagogues, and herbal products, as well as immunization of breastfeeding women. A discussion regarding the global implications of maternal medications and lactation in the developing world is beyond the scope of this report. The World Health Organization offers several programs and resources that address the importance of breastfeeding (see http://www.who.int/topics/breastfeeding/en/).

Buprenorphine use in pregnant opioid users: a critical review

Pregnancy in opioid users poses a number of problems to treating physicians. Most guidelines recommend maintenance treatment to manage opioid addiction in pregnancy, with methadone being the gold standard. More recently, buprenorphine has been discussed as an alternate medication. The use and efficacy of buprenorphine in pregnancy is still controversial. This article reviews the current database on the basis of a detailed and critical literature search performed in MEDLINE (206 counts). Most of the relevant studies (randomised clinical trials and one national cohort sample) were published in the last 2 years and mainly compared buprenorphine with methadone. Some studies are related to maternal outcomes, others to foetal, neonatal or older child outcomes. With respect to maternal outcomes, most studies suggest that buprenorphine has similar effects to methadone. Very few data from small studies discuss an effect of buprenorphine on neurodevelopment of the foetus. Neonatal abstinence syndrome is common in infants of both buprenorphine- and methadone-maintained mothers. As regards neonatal outcomes, buprenorphine has the same clinical outcome as methadone, although some newer studies suggest that it causes fewer withdrawal symptoms. Since hardly any studies have investigated the combination of buprenorphine with naloxone (which has been suggested to possibly have teratogenic effects) in pregnant women, a switch to buprenorphine monotherapy is recommended in women who become pregnant while receiving the combination product. These novel findings indicate that buprenorphine is emerging as a first-line treatment for pregnant opioid users.

Opioid addiction in pregnancy

The purpose of this review is to discuss the incidence, risks, pregnancy complications, and maintenance options for treatment of opioid addiction in pregnancy.

SUMMARY

Opioid dependence in pregnancy carries clear identifiable maternal and fetal risk. Providing care for patients with dependence is best done in a multidisciplinary care model addressing the particular needs of this population. There are limited data on maternal detoxification, with data still emerging surrounding the safety profile of this practice. Historically, methadone has been the recommended maintenance treatment; however, recent data on buprenorphine identify this as a safe and effective option. The majority of births from women with opioid dependence result in neonatal abstinence syndrome requiring prolonged neonatal hospitalization. Intrapartum pain management should not differ from the general obstetric population. Postpartum pain is magnified in this population, and particular attention should be focused on this issue. Breast-feeding is recommended regardless of maintenance dose, unless other conditions restricting breast-feeding are present. Comprehensive postpartum care and transition of care to addiction specialists are highly recommended.

TARGET AUDIENCE

Obstetricians and gynecologists, family physicians, addiction specialists.

LEARNING OBJECTIVES

After completing this CME activity, physicians should be better able to assess the treatment options available to patients with opioid addiction during pregnancy, compare the risk/safety profiles of methadone and buprenorphine, and evaluate the recommendations and current data surrounding breast-feeding while on opioid maintenance treatment.

Buprenorphine treatment of opioid-dependent pregnant women: a comprehensive review

AIMS

This paper reviews the published literature regarding outcomes following maternal treatment with buprenorphine in five areas: maternal efficacy, fetal effects, neonatal effects, effects on breast milk and longer-term developmental effects.

METHODS

Within each outcome area, findings are summarized first for the three randomized clinical trials and then for the 44 non-randomized studies (i.e. prospective studies, case reports and series and retrospective chart reviews), only 28 of which involve independent samples.

RESULTS

Results indicate that maternal treatment with buprenorphine has comparable efficacy to methadone, although difficulties may exist with current buprenorphine induction methods. The available fetal data suggest buprenorphine results in less physiological suppression of fetal heart rate and movements than methadone. Regarding neonatal effects, perhaps the single definitive conclusion is that prenatal buprenorphine treatment results in a clinically significant less severe neonatal abstinence syndrome (NAS) than treatment with methadone. The limited research suggests that, like methadone, buprenorphine is compatible with breastfeeding. Data available thus far suggest that there are no deleterious effects of in utero buprenorphine exposure on infant development.

CONCLUSIONS

While buprenorphine produces a less severe neonatal abstinence syndrome than methadone, both methadone and buprenorphine are important parts of a complete comprehensive treatment approach for opioid-dependent pregnant women.

Pharmacologic management of the opioid neonatal abstinence syndrome

Opioid use in pregnant women has increased over the last decade. Following birth, infants with in utero exposure demonstrate signs and symptoms of withdrawal known as the neonatal abstinence syndrome (NAS). Infants express a spectrum of disease, with most requiring the administration of pharmacologic therapy to ensure proper growth and development. Treatment often involves prolonged hospitalization. There is a general lack of high-quality clinical trial data to guide optimal therapy, and significant heterogeneity in treatment approaches. Emerging trends in the treatment of infants with NAS include the use of sublingual buprenorphine, transition to outpatient therapy, and pharmacogenetic risk stratification.

Estimated dose exposure of the neonate to buprenorphine and its metabolite norbuprenorphine via breastmilk during maternal buprenorphine substitution treatment

OBJECTIVE

The aim of the present study was to estimate the dose of buprenorphine and its primary metabolite norbuprenorphine that a breastfed infant would receive during maternal maintenance treatment with buprenorphine.

STUDY DESIGN

Seven pregnant opioid-dependent women taking buprenorphine (median, 7 mg/day; range, 2.4-24 mg) and who intended to breastfeed were recruited. After lactation was established, several milk samples were collected from each subject over a 24-hour dose interval, and buprenorphine and norbuprenorphine concentrations were measured by liquid chromatography-tandem mass spectrometry. The average concentration (C(avg)) across the dose interval was estimated as for both buprenorphine and norbuprenorphine (as buprenorphine equivalents). Absolute infant dose (AID), defined as C(avg) × daily milk intake, and relative infant dose (RID), defined as 100×AID/weight-adjusted maternal daily dose, via milk were calculated, assuming a milk intake of 0.15 L/kg/day. The infant's health and progress were assessed directly and by questionnaire on the study day.

RESULTS

Mean (95% confidence interval) norbuprenorphine concentration in milk and AID values (1.94 [0.79-3.08] μg/L and 0.29 [0.12-0.46] μg/kg/day, respectively) were approximately half those for buprenorphine (3.65[1.61-5.7] μg/L and 0.55 [0.24-0.85] μg/kg/day, respectively). Similarly, the mean RID values were 0.18% (0.11-0.25%) for norbuprenorphine and 0.38% (0.23-0.53%) for buprenorphine. The breastfed infants showed no adverse effects, were all in good health, and were progressing as expected.

CONCLUSION

Thus the dose of buprenorphine and norbuprenorphine received via milk is unlikely to cause any acute adverse effects in the breastfed infant.

Treatment of opioid dependence in the setting of pregnancy

Opioid dependence in the setting of pregnancy provides a distinct set of challenges for providers. Treatment plans must take into consideration psychiatric and medical comorbidities while balancing risks and benefits for the maternal-fetal dyad. Treatment is best offered through a comprehensive treatment program designed to effectively deliver opioid agonist maintenance treatment along with psychosocial and obstetric care. As misuse of prescription analgesics increases in the United States, identification of the problem in pregnancy will become more important because this misuse is expected to lead to an increased prevalence of opioid dependence in pregnancy. Buprenorphine as maintenance treatment of opioid dependence during pregnancy has promise and may offer some benefits, but more research is needed, especially regarding induction of actively addicted women during pregnancy. For the present, methadone maintenance remains the standard of care for agonist treatment of opioid dependence in pregnancy against which other treatments must be compared.

Opioid dependent and pregnant: what are the best options for mothers and neonates?

Pregnancy in opioid-dependent women is a major public health issue. Women who are afflicted by opioid addiction are a highly vulnerable group of patients frequently becoming pregnant unplanned and at risk of adverse pregnancy outcomes and peri-natal complications. Opioid agonist maintenance treatment is the best option for the majority of women. Ideally, early and closely monitored treatment in an interdisciplinary team approach including social workers, nurses, psychologists, psychiatrists, gynecologists, anesthesiologists, and pediatricians should be provided. The treatment of comorbid psychiatric conditions, the resolution of financial, legal, and housing issues, and the psychosocial support provided have a significant effect on optimizing pregnancy outcomes. This paper aims to update health professionals in the field of gynecology and obstetrics on the latest optimal treatment approaches for mothers suffering from opioid dependence and their neonates.

Management of women treated with buprenorphine during pregnancy

The management of pregnancy and delivery of a woman on opiate-substitution therapy with buprenorphine requires a coordinated team approach by social services, addiction medicine, obstetrics, and pediatrics. Her obstetrical care is further complicated by the unique pharmacology of buprenorphine and the issues of pain management. Obstetrical providers should be familiar with the complex issues surrounding the optimal care of these women.

Development and validation of a method for the determination of buprenorphine and norbuprenorphine in breast milk by gas chromatography-mass spectrometry

Buprenorphine (BUP) is used for the maintenance of opioid-addicted pregnant women. Because BUP and its main metabolite nor-BUP are excreted into breast milk, a sensitive and specific GC/MS method has been developed, optimized and validated for their determination in breast milk. BUP-d4 was used as internal standard. The sample preparation includes combination of protein precipitation with solid-phase extraction and derivatization (acetylation). The absolute recovery for both analytes was found to be higher than 87.3%. The limits of detection and quantification were 0.07 and 0.20 µg/L, respectively. The calibration curves were linear within the dynamic range 0.20-20.0 µg/L, with a correlation coefficient higher than 0.996. Intra- and inter-day accuracies were ranged from -7.06 to 4.50 and from -5.88 to 7.00%, respectively, while intra- and inter-day precision were less than 5.7 and 6.1%. The analytes were found to be stable in breast milk at 4 °C for one week, at -20 °C for one month, and after three freeze-thaw cycles. The method can be used for the determination of BUP and nor-BUP in breast milk of BUP-maintained mothers, in order to calculate the amount of drug that could pass to the newborn via breast milk and to avoid toxic consequences of breastfeeding.

Buprenorphine TTS for children--a review of the drug's clinical pharmacology

OBJECTIVE

The transdermal therapeutic system (TTS) with buprenorphine is currently being used 'off-label' to treat chronic pediatric pain. We compiled available pharmacokinetic (PK), pharmacodynamic (PD), and clinical pediatric data on buprenorphine to rationalize treatment regimens.

METHODS

We conducted a systematic biomedical literature review focusing on pediatric buprenorphine data.

RESULTS

There are few relevant pediatric buprenorphine data, particularly in children suffering chronic pain. There are no pediatric PK and PD data for children with chronic pain given sublingual or TTS formulations. Children given single dose buprenorphine have increased drug clearance referenced to bodyweight with a possible paradoxical longer duration of action. Buprenorphine metabolism is independent of renal function, which is advantageous in renal insufficiency. The risk of respiratory depression after buprenorphine is difficult to quantify. A concentration-response relationship for respiratory effects has not been described and it is unknown whether children have a ceiling effect similar to that described in healthy adult volunteers.

CONCLUSIONS

Buprenorphine is of interest in pediatric postoperative pain and cancer pain control because of its multiple administration routes, long duration of action, and metabolism largely independent of renal function. There is little reason to expect buprenorphine effects in children out of infancy are fundamentally different to those in adults. From the limited pediatric data available, it appears that buprenorphine has no higher adverse potential than the more commonly used opioids. There is an urgent need for focused PK, PD, and safety studies in children before use in children becomes more widespread.