Buprenorphine may not be as safe as you think: a pediatric fatality from unintentional exposure

Trends in opioid exposures among young children reported to United States poison centers from 2016 to 2023

INTRODUCTION

The objective of this study was to update and expand on previous studies of opioid exposures among young children reported to America's Poison Centers®, and to describe how fentanyl and medications for opioid use disorder have contributed.

METHODS

This retrospective study investigated 34,632 reports of single-substance opioid exposure from 2016 to 2023 involving pediatric patients aged one month to six years old. Descriptive statistics, tests for data normality, and significance testing were performed where applicable.

RESULTS

Of 34,632 reported exposures, 96.7% were unintentional. The median age of exposure was 2.0 years (IQR 1.33-3.0 years). Reported exposures decreased by 57.5% over the study period (r = -0.96; P <0.001). However, there was a 300% absolute increase in deaths and major effects (r = 0.96; P <0.001). Exposures resulting in minor, no effect, not followed, or unable to follow decreased 66.2% (r = -0.99; P <0.001). Buprenorphine was most frequently involved, comprising 23.4% of reported exposures. Buprenorphine (OR 1.93; P <0.001) and methadone (OR 14.98; P <0.001) were associated with an increased risk of severe effects when compared to other prescription drugs (OR: 1). There was an absolute increase of 512% over time in reports of heroin, fentanyl, synthetic non-pharmaceutical opioids (r = 0.92; P <0.001), which were also associated with severe effects (OR 20.1; P <0.001).

DISCUSSION

Pediatric opioid exposures have previously been reported to be relatively stable. It is likely the 57.5% reduction is exaggerated due to underreporting from health care providers. However, decreases in exposures are presumed to be balanced throughout the dataset and, therefore, without differential impact on other points of analysis. Our study highlights the continued need for enhanced poisoning prevention strategies.

CONCLUSIONS

The relative severity of poisonings reported to poison centers worsened over the study period. The opioids implicated have shifted away from hydrocodone, oxycodone, and tramadol, and towards fentanyl and buprenorphine.

Assessment of the potential of novel and classical opioids to induce respiratory depression in mice

BACKGROUND AND PURPOSE

Opioid-induced respiratory depression limits the use of μ-opioid receptor agonists in clinical settings and is the main cause of opioid overdose fatalities. The relative potential of different opioid agonists to induce respiratory depression at doses exceeding those producing analgesia is understudied despite its relevance to assessments of opioid safety. Here we evaluated the respiratory depressant and anti-nociceptive effects of three novel opioids and relate these measurements to their in vitro efficacy.

EXPERIMENTAL APPROACH

Respiration was measured in awake, freely moving male CD-1 mice using whole body plethysmography. Anti-nociception was measured using the hot plate test. Morphine, oliceridine and tianeptine were administered intraperitoneally, whereas methadone, oxycodone and SR-17018 were administered orally. Receptor activation and arrestin-3 recruitment were measured in HEK293 cells using BRET assays.

KEY RESULTS

Across the dose ranges examined, all opioids studied depressed respiration in a dose-dependent manner, with similar effects at the highest doses, and with tianeptine and oliceridine showing reduced duration of effect, when compared with morphine, oxycodone, methadone and SR-17018. When administered at doses that induced similar respiratory depression, all opioids induced similar anti-nociception, with tianeptine and oliceridine again showing reduced duration of effect. These data were consistent with the in vitro agonist activity of the tested compounds.

CONCLUSION AND IMPLICATIONS

In addition to providing effective anti-nociception, the novel opioids, oliceridine, tianeptine and SR-17018 depress respiration in male mice. However, the different potencies and kinetics of effect between these novel opioids may be relevant to their therapeutic application in different clinical settings.

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 practical review of buprenorphine utilization for the emergency physician in the era of decreased prescribing restrictions

INTRODUCTION

Opioid abuse and overdose deaths have reached epidemic proportions in the last couple decades. In response to rational prescribing initiatives, utilization of prescription opioids has decreased; however, the number of deaths due to opioid overdoses continues to rise, largely driven by fentanyl analogues in adulterated heroin. Solutions to the opioid crisis must be multifaceted and address underlying opioid addiction. In recent years, buprenorphine has become a cornerstone in the treatment of opioid use disorder (OUD) and initiation of therapy in the emergency department (ED) has become increasingly common. There have also been calls by many organizations to remove the requirement for additional training and X-waiver to prescribe buprenorphine. In April 2021, the Biden Administration eased prescribing restrictions on the drug. These initiatives are expected to increase ED utilization of the buprenorphine. The purpose of this paper is to provide an updated overview of the role and use of buprenorphine in the ED setting so physicians may adapt to the changing practice environment.

OBJECTIVES

This is a narrative review describing the role of buprenorphine in the ED. A PubMed search was conducted using the keywords "opioid epidemic" "buprenorphine," and "medication assisted therapy", and "emergency department". All the articles that contained information on the opioid epidemic, medication assisted therapy, and the biological effects of buprenorphine, that were also relevant to pain management and the ED, were included in the review.

DISCUSSION

Multiple studies have pointed to the effective use of buprenorphine as a treatment for OUDs in ED patients and are superior to standard care; however, there are various barriers to its use in the ED setting.

CONCLUSION

Emergency physicians can influence opioid related morbidity and mortality, by familiarizing themselves with the use of buprenorphine to treat opioid withdrawal and addiction, particularly now that prescribing restrictions have been eased. Further ED research is necessary to assess the optimal use of buprenorphine in this care setting.

Veterinary-Prescribed Buprenorphine Ingestion in a 2-Year-Old Girl

INTRODUCTION

Ingestion of buprenorphine by young children is on the rise and can lead to life-threatening consequences and death. Exposure most often occurs when a child acquires the medication intended for adult use. However, buprenorphine is also prescribed by veterinarians and may be sent home, typically in non-child-resistant packaging, to be administered to the family pet.

CASE

A previously healthy 2-year-old girl weighing 11.36 kg was found with a 1-mL syringe containing 0.6 mg/mL of buprenorphine in her mouth. The syringe had been in a plastic bag provided to the family by their veterinarian for the family dog. She was hospitalized for 24 hours but remained asymptomatic and was discharged healthy. This type of exposure to buprenorphine has not previously been described in the literature.

CONCLUSIONS

Having this unsecured medication in the home increases the potential risk of exposure for young children and associated health consequences. Pediatricians should be aware of the potential dangers that veterinary pharmaceuticals can pose and educate parents about proper storage of medications. In addition, veterinarians should take extra precautions when dispensing these medications to pet owners with children.

Low intrinsic efficacy for G protein activation can explain the improved side effect profiles of new opioid agonists

Biased agonism at G protein-coupled receptors describes the phenomenon whereby some drugs can activate some downstream signaling activities to the relative exclusion of others. Descriptions of biased agonism focusing on the differential engagement of G proteins versus β-arrestins are commonly limited by the small response windows obtained in pathways that are not amplified or are less effectively coupled to receptor engagement, such as β-arrestin recruitment. At the μ-opioid receptor (MOR), G protein-biased ligands have been proposed to induce less constipation and respiratory depressant side effects than opioids commonly used to treat pain. However, it is unclear whether these improved safety profiles are due to a reduction in β-arrestin-mediated signaling or, alternatively, to their low intrinsic efficacy in all signaling pathways. Here, we systematically evaluated the most recent and promising MOR-biased ligands and assessed their pharmacological profile against existing opioid analgesics in assays not confounded by limited signal windows. We found that oliceridine, PZM21, and SR-17018 had low intrinsic efficacy. We also demonstrated a strong correlation between measures of efficacy for receptor activation, G protein coupling, and β-arrestin recruitment for all tested ligands. By measuring the antinociceptive and respiratory depressant effects of these ligands, we showed that the low intrinsic efficacy of opioid ligands can explain an improved side effect profile. Our results suggest a possible alternative mechanism underlying the improved therapeutic windows described for new opioid ligands, which should be taken into account for future descriptions of ligand action at this important therapeutic target.

Buprenorphine Treatment for Adolescents and Young Adults With Opioid Use Disorders: A Narrative Review

: In the past decade, a new cohort of adolescents and young adults with opioid use disorders (OUD) has emerged. While medications and psychosocial treatments are available, few adolescents and young adults with OUD can access and remain in treatment. Effective, practical, and scalable treatment paradigms for this young population are needed. Buprenorphine is a medication with unique pharmacological and regulatory characteristics that make it a promising component of adolescent and young adult OUD treatment models. Three randomized controlled trials and multiple observational studies have evaluated the use of buprenorphine to treat this population. However, data from these studies have not been consolidated into an up-to-date summary that may be useful to clinicians. The objective of this narrative review is to inform clinical practice by summarizing results of primary and secondary analyses from randomized controlled clinical trials and observational studies that have evaluated the use of buprenorphine to treat adolescents and young adults with OUD. Based on results from these studies, we encourage the conceptualization of OUD among youth as a chronic medical condition requiring a long-term management strategy. This includes treatment with buprenorphine in conjunction with medication-prescribing protocols that do not necessarily require daily clinic attendance for observed medication adherence. However, more study of treatment delivery models, addressing such issues as medication adherence and intensity requirements, is needed to determine practices that optimize outcomes for youth.

Buprenorphine Overdose in Young Children: An Underappreciated Risk

The escalation of the opioid crisis has led to an increase in the treatment of opioid use disorder. In particular, recent legislation has allowed for office-based treatment with buprenorphine, a partial µ-opioid agonist that is believed to be safer than methadone due to a ceiling effect on respiratory depression in adults. An increasing number of children are being exposed to buprenorphine as more adults in US households receive take-home prescriptions. The ceiling effect seen in adults does not seem to apply to young children, and intoxication with severe symptoms including fatalities can occur. This article outlines the pharmacology of buprenorphine and reviews the current literature on overdose in children. We conclude with practical recommendations for limiting potential exposure and damage to children from accidental buprenorphine overdose.

Mind the Gaps: Ontogeny of Human Brain P-gp and Its Impact on Drug Toxicity

Available data on human brain P-glycoprotein ontogeny during infancy and childhood are limited. This review discusses the current body of data relating to maturation of human brain P-glycoprotein including transporter expression levels in post-mortem human brain samples, in vivo transporter activity using probe substrates, surrogate marker endpoints, and extrapolations from animal models. Overall, the data tend to confirm that human brain P-glycoprotein activity keeps developing after birth, although with a developmental time frame that remains unclear. This knowledge gap is a concern given the critical role of brain P-glycoprotein in drug safety and efficacy, and the vulnerable nature of the pediatric population. Future research could include the measurement of brain P-glycoprotein activity across age groups using positron emission tomography or central pharmacodynamic responses. For now, caution is advised when extrapolating adult data to children aged younger than 2 years for drugs with P-glycoprotein-dependent central nervous system activity.

Pharmacologic Treatment of Opioid Use Disorder: a Review of Pharmacotherapy, Adjuncts, and Toxicity

Opioid use disorder continues to be a significant source of morbidity and mortality in the USA and the world. Pharmacologic treatment with methadone and buprenorphine has been shown to be effective at retaining people in treatment programs, decreasing illicit opioid use, decreasing rates of hepatitis B, and reducing all cause and overdose mortality. Unfortunately, barriers exist in accessing these lifesaving medications: users wishing to start buprenorphine therapy require a waivered provider to prescribe the medication, while some states have no methadone clinics. As such, users looking to wean themselves from opioids or treat their opioid dependence will turn to alternative agents. These agents include using prescription medications, like clonidine or gabapentin, off-label, or over the counter drugs, like loperamide, in supratherapeutic doses. This review provides information on the pharmacology and the toxic effects of pharmacologic agents that are used to treat opioid use disorder. The xenobiotics reviewed in depth include buprenorphine, clonidine, kratom, loperamide, and methadone, with additional information provided on lofexidine, akuamma seeds, kava, and gabapentin.

Unit-Dose Packaging and Unintentional Buprenorphine-Naloxone Exposures

BACKGROUND AND OBJECTIVES

Buprenorphine accounts for the most opioid-related pediatric hospital admissions when compared with other opioid analgesics. Since 2010, several manufacturers began distributing their buprenorphine products with unit-dose packaging (UDP). Our main objective in this study is to evaluate the impact of UDP on unintentional pediatric buprenorphine-naloxone poison center exposures.

METHODS

This is an observational surveillance study in which the Researched Abuse, Diversion, and Addiction-Related Surveillance System Poison Center Program is used. The main outcome was cases of unintentional ingestions involving children <6 years old and buprenorphine-naloxone (combination) products. The study was split into 3 periods: pre-UDP (first quarter 2008 through fourth quarter 2010), transition to UDP (first quarter 2011 through fourth quarter 2012), and post-UDP (first quarter 2013 through fourth quarter 2016).

RESULTS

Overall, there were 6217 exposures to combination products. In the pre-UDP period, there were 20.57 pediatric unintentional exposures per 100 000 prescriptions dispensed; in the transition to UDP period, there were 8.77 pediatric unintentional exposures per 100 000 prescriptions dispensed; and in the post-UDP period, there were 4.36 pediatric unintentional exposures per 100 000 prescriptions dispensed. This represents a 78.8% (95% confidence interval: 76.1%-81.3%; P < .001) relative decrease from the pre-UDP period.

CONCLUSIONS

The shift from non-UDP to UDP in over 80% of buprenorphine-naloxone products was associated with a significant decrease in unintentional pediatric exposures reported to poison centers. Packaging controls should be a mainstay in the approach to the prevention of unintentional buprenorphine pediatric exposures as well as exposures to other prescription opioids.

Pregnancy Increases Norbuprenorphine Clearance in Mice by Induction of Hepatic Glucuronidation

Norbuprenorphine (NBUP) is the major active metabolite of buprenorphine (BUP) that is commonly used to treat opiate addiction during pregnancy; it possesses 25% of BUP's analgesic activity and 10 times BUP's respiratory depression effect. To optimize BUP's dosing regimen during pregnancy with better efficacy and safety, it is important to understand how pregnancy affects NBUP disposition. In this study, we examined the pharmacokinetics of NBUP in pregnant and nonpregnant mice by administering the same amount of NBUP through retro-orbital injection. We demonstrated that the systemic clearance (CL) of NBUP in pregnant mice increased ∼2.5-fold compared with nonpregnant mice. Intrinsic CL of NBUP by glucuronidation in mouse liver microsomes from pregnant mice was ∼2 times greater than that from nonpregnant mice. Targeted liquid chromatography tandem-mass spectrometry proteomics quantification revealed that hepatic Ugt1a1 and Ugt2b1 protein levels in the same amount of total liver membrane proteins were significantly increased by ∼50% in pregnant mice versus nonpregnant mice. After scaling to the whole liver with consideration of the increase in liver protein content and liver weight, we found that the amounts of Ugt1a1, Ugt1a10, Ugt2b1, and Ugt2b35 protein in the whole liver of pregnant mice were significantly increased ∼2-fold compared with nonpregnant mice. These data suggest that the increased systemic CL of NBUP in pregnant mice is likely caused by an induction of hepatic Ugt expression and activity. The data provide a basis for further mechanistic analysis of pregnancy-induced changes in the disposition of NBUP and drugs that are predominately and extensively metabolized by Ugts.

Pediatric Poisoning by Ingestion: Developmental Overview and Synopsis of National Trends

The American Association of Poison Control Centers' National Poison Data Surveillance System provides real-time toxico-surveillance and epidemiologic trends, and pediatric ingestions comprise most of those reports. The sequences in social and physical developmental milestones from young childhood to adolescence reveal the vulnerability of these age groups to a wide variety of potential poisonous ingestions. Most pediatric ingestions are exploratory. Some common agents associated with pediatric fatalities include disc batteries, laundry detergent "pods," opioid analgesics, acetaminophen, benzodiazepines, and amphetamines. The pediatric provider can be a valuable resource at all points throughout a child's life, offering anticipatory guidance to caregivers targeting developmental changes associated with poisonous ingestions. [Pediatr Ann. 2017;46(12):e443-e448.].

Opioid use disorder and misuse: A review of the epidemiology and medical implications for pediatric anesthesiologists

This educational review presents an overview of opioid use disorder, misuse and overdose among adolescents, and the clinical implications for anesthesiologists. It provides definitions, discusses the epidemiology worldwide, (focusing on North America), and emphasizes the clinical implications of patients with chronic opioid exposure, including perioperative pain management, as well as opioid overdose and prolonged use of opioids after acute exposure. In the USA, opioid use disorder and negative outcomes related to opioids rose dramatically from 1999-2010; concomitantly heroin use and fatal overdoses have increased as heroin use is associated with the disordered use of licit opioids. Among adolescents and young adults, opioid use disorder is significant, with continued increases in disordered use specifically among young adults. Acute opioid intoxication may have multiple medical implications in addition to respiratory depression, and children are susceptible to acute intoxication via accidental ingestion of prescription opioids. Novel opioid formulations, such as acetyl fentanyl, with unpredictable pharmacology may also be present in acute intoxication. Chronically, opioid use presents challenges for safe and adequate pain management, in the presence of opioid-induced hyperalgesia and differential tolerance as well as mental health issues including depression and anxiety. Predictors of prolonged opioid use in adolescents and adults after surgery is an area of ongoing research. Young patients encountered by pediatric anesthesiologists may be involved in diversion and disordered use of opioids. Increased awareness among anesthesiologists is important, as perioperative discussions often provide an opportunity to detect at risk patients.

Unintentional methadone and buprenorphine exposures in children: Developing prevention messages

OBJECTIVES

To develop key messages for methadone and buprenorphine safety education material based on an analysis of calls to the NYC Poison Control Center (NYC PCC) and designed for distribution to caregivers of young children.

METHODS

Retrospective review of all calls for children 5 years of age and younger involving methadone or buprenorphine from January 1, 2000, to June 15, 2014. A data abstraction form was completed for each case to capture patient demographics, exposure and caller sites, caller relation to patient, qualitative information regarding the exposure scenario, the product information, if naloxone was given, and the medical outcome of the case.

RESULTS

A total of 123 cases were identified. The ages of the children ranged from 4 days to 5 years; 55% were boys. All exposures occurred in a home environment. The majority of the calls were made to the NYC PCC by the doctor (74%) or nurse (2%) at a health care facility. Approximately one-fourth of the calls came from the home and were made by the parent (22%) or grandparent (2%). More than one-half of the exposures involved methadone (64%). Naloxone was administered in 28% of cases. Approximately one-fourth of the children did not experience any effect after the reported exposure, one-half (51%) experienced some effect (minor, moderate, or major), and there was 1 death (1%). More than one-half of the children were admitted to the hospital, with 40% admitted to critical care and 13% to noncritical care. Approximately 23% were treated and released from the hospital, and 20% were lost to follow-up or never arrived to the hospital. The remaining 4% were managed on site without a visit to the hospital.

CONCLUSION

Exposures to methadone and buprenorphine are dangerous with some leading to serious health effects. Safe storage and disposal instructions are needed for homes where children may be present.

P-gp/ABCB1 exerts differential impacts on brain and fetal exposure to norbuprenorphine

Norbuprenorphine is the major active metabolite of buprenorphine which is commonly used to treat opiate addiction during pregnancy. Norbuprenorphine produces marked respiratory depression and was 10 times more potent than buprenorphine. Therefore, it is important to understand the mechanism that controls fetal exposure to norbuprenorphine, as exposure to this compound may pose a significant risk to the developing fetus. P-gp/ABCB1 and BCRP/ABCG2 are two major efflux transporters regulating tissue distribution of drugs. Previous studies have shown that norbuprenorphine, but not buprenorphine, is a P-gp substrate. In this study, we systematically examined and compared the roles of P-gp and BCRP in determining maternal brain and fetal distribution of norbuprenorphine using transporter knockout mouse models. We administered 1mg/kg norbuprenorphine by retro-orbital injection to pregnant FVB wild-type, Abcb1a-/-/1b-/-, and Abcb1a-/-/1b-/-/Abcg2-/- mice on gestation day 15. The fetal AUC of norbuprenorphine was ∼64% of the maternal plasma AUC in wild-type mice, suggesting substantial fetal exposure to norbuprenorphine. The maternal plasma AUCs of norbuprenorphine in Abcb1a-/-/1b-/- and Abcb1a-/-/1b-/-/Abcg2-/- mice were ∼2 times greater than that in wild-type mice. Fetal AUCs in Abcb1a-/-/1b-/- and Abcb1a-/-/1b-/-/Abcg2-/- mice were also increased compared to wild-type mice; however, the fetal-to-maternal plasma AUC ratio remained relatively unchanged by the knockout of Abcb1a/1b or Abcb1a/1b/Abcg2. In contrast, the maternal brain-to-maternal plasma AUC ratio in Abcb1a-/-/1b-/- or Abcb1a-/-/1b-/-/Abcg2-/- mice was increased ∼30-fold compared to wild-type mice. Protein quantification by LC-MS/MS proteomics revealed significantly higher amounts of P-gp protein in the wild-type mice brain than that in the placenta. These results indicate that fetal exposure to norbuprenorphine is substantial and that P-gp has a minor impact on fetal exposure to norbuprenorphine, but plays a significant role in restricting its brain distribution. The differential impacts of P-gp on norbuprenorphine distribution into the brain and fetus are likely, at least in part, due to the differences in amounts of P-gp protein expressed in the blood-brain and blood-placental barriers. BCRP is not as important as P-gp in determining both the systemic and tissue exposure to norbuprenorphine. Finally, fetal AUCs of the metabolite norbuprenorphine-β-d-glucuronide were 3-7 times greater than maternal plasma AUCs, while the maternal brain AUCs were <50% of maternal plasma AUCs, suggesting that a reversible pool of conjugated metabolite in the fetus may contribute to the high fetal exposure to norbuprenorphine.

The New Kid on the Block--Incorporating Buprenorphine into a Medical Toxicology Practice

Buprenorphine represents a safe and effective therapy for treating opioid dependence, alleviating craving and withdrawal symptoms in opioid-dependent patients. Buprenorphine has a "blocking" effect against the action of other opioids at the mu-receptor, preventing not only opioid-induced euphoria, but CNS and respiratory depressant effects as well. Buprenorphine was approved for the treatment of opioid dependence in 2002 after the passage of Drug Abuse Treatment Act 2000 (DATA 2000) which allowed clinicians to treat opioid-dependent patients with specifically named opioid agonist therapies in an office setting. Buprenorphine programs reduce the prevalence of HIV and hepatitis C and reduce criminal behaviors associated with illicit drug use. Patients stabilized on buprenorphine have increased employment, enhanced engagement with social services, and better overall health and well-being.

Clinical effects of unintentional pediatric buprenorphine exposures: experience at a single tertiary care center

CONTEXT

Exploratory buprenorphine ingestions in young children have been associated with clinically significant toxicity. However, detailed data on the clinical presentation and management of these patients are lacking. In an attempt to obtain more comprehensive data, we sought to examine a single center cohort of patients with report of buprenorphine exposure and provide descriptive analysis of rates of respiratory depression, time to respiratory depression, interventions, disposition, and outcomes.

STUDY DESIGN

We performed a retrospective cohort study at a single pediatric tertiary care center of children between the age of 6 months and 7 years of age hospitalized between 1 January 2006 and 1 September 2014 with report of buprenorphine or buprenorphine/naloxone exposure. Patients with possible exposure to more than one agent were excluded. We extracted clinical findings, including time to respiratory depression, interventions, and disposition from the medical record.

RESULTS

Eighty-eight patients met the inclusion criteria. Seven patients were excluded. The median age was 24 months [IQR 18-30]. 20 patients (23%) received activated charcoal while 48 (55%) were treated with naloxone. 36 (41%) patients were admitted to the ICU. Observed clinical effects included respiratory depression (83%), oxygen saturation by pulse oximetry (SpO₂)< 93% (28%), depressed mental status (80%), miosis (77%), and emesis (45%). Median time from exposure to respiratory depression was 263 min [IQR 105-486]. The median hospital length of stay was 22 h [IQR 20-26] and was positively associated with estimated exposure dose (p = 0.002).

CONCLUSION

Pediatric patients exposed to buprenorphine are likely to exhibit signs and symptoms of opioid toxicity, including respiratory depression, altered mental status and miosis. Although the majority of patients developed signs of clinical toxicity within 8 h of reported exposure, the optimum duration of monitoring remains unclear.

Should the United States Government Repeal Restrictions on Buprenorphine/Naloxone Treatment?

Attention must be focused on needed changes to the current United States law that restricts physicians who prescribe buprenorphine for the detoxification or treatment of Opioid Use Disorder, to accepting no more than 100 patients. The current system does not provide comprehensive treatment as defined by the American Society of Addiction Medicine (ASAM) criteria. In addition, it suffers from both fragmentation and stigma and will require a significant change to comply with ASAM's call for integrated delivery of comprehensive addiction treatment. This commentary calls for the development and implementation of "best practice," by recommending caution in lifting the 100 patient limit until substantial achievement of this goal occurs. The authors call for an increase to 200 in the patient limit to be restricted to those physicians who are Board Certified in Addiction Medicine by the American Board of Addiction Medicine (ABAM) or in Addiction Psychiatry by the American Board of Psychiatry and Neurology (ABPN), or other responsible medical organizations. Any additional restriction lifting should follow a systemic evolution that rewards and documents competency. Such a system would involve the integration of treatment, treatment systems, and recovery with prescription medication. In addition, it should monitor emotional blunting, treatment progress and initiation of genetic addiction risk testing.

Severe and fatal pharmaceutical poisoning in young children in the UK

OBJECTIVE

Accidental poisoning in young children is common, but severe or fatal events are rare. This study was performed to identify the number of such events occurring in the UK and the medications that were most commonly responsible.

DESIGN

Analysis of national data sets containing information relating to severe and fatal poisoning in children in the UK.

DATA SOURCES

Office of National Statistics mortality data for fatal poisoning; Paediatric Intensive Care Audit Network admissions database and the National Poisons Information Service for severe non-fatal poisoning; Hospital Episode Statistics for admission data for implicated agents.

RESULTS

Between 2001 and 2013, there were 28 children aged 4 years and under with a death registered as due to accidental poisoning by a pharmaceutical product in England and Wales. Methadone was the responsible drug in 16 (57%) cases. In the UK, 201 children aged 4 years and under were admitted to paediatric intensive care with pharmaceutical poisoning between 2002 and 2012. The agent(s) responsible was identified in 115 cases, most commonly benzodiazepines (22/115, 19%) and methadone (20/115, 17%).

CONCLUSIONS

Methadone is the most common pharmaceutical causing fatal poisoning and a common cause of intensive care unit admissions in young children in the UK.

Where Is Buprenorphine Dispensed to Treat Opioid Use Disorders? The Role of Private Offices, Opioid Treatment Programs, and Substance Abuse Treatment Facilities in Urban and Rural Counties

POLICY POINTS

Buprenorphine is an effective opioid dependence treatment that has expanded access to care since its 2002 approval, but it can only be prescribed by physicians waivered to treat a limited number of individuals. We examined the impact of 2006 legislation that increased waivered physician patient limits from 30 to 100 on buprenorphine use, and found that 100-patient-waivered physicians were significantly associated with growth in buprenorphine use, with no such relationship for 30-patient-waivered physicians. Policies relaxing patient limits may be more effective in increasing buprenorphine use than alternatives such as opening new substance abuse treatment facilities or increasing the overall number of waivered physicians.

CONTEXT

Opioid use disorders are a significant public health problem. In 2002, the FDA approved buprenorphine as an opioid use disorder treatment when prescribed by waivered physicians who were limited to treating 30 patients at a time. In 2006, federal legislation raised this number to 100 patients. Although federal legislators are considering increasing these limits further and expanding prescribing privileges to nonphysicians, little information is available regarding the impact of such changes on buprenorphine use. We therefore examined the impact of the 2006 legislation-as well as the association between urban and rural waivered physicians, opioid treatment programs, and substance abuse treatment facilities-on buprenorphine distributed per capita over the past decade.

METHODS

Using 2004-2011 state-level data on buprenorphine dispensed and county-level data on the number of buprenorphine-waivered physicians and substance abuse treatment facilities using buprenorphine, we estimated a multivariate ordinary least squares regression model with state fixed effects of a state's annual total buprenorphine dispensed per capita as a function of the state's number of buprenorphine providers.

FINDINGS

The amount of buprenorphine dispensed has been increasing at a greater rate than the number of buprenorphine providers. The number of physicians waivered to treat 100 patients with buprenorphine in both rural and urban settings was significantly associated with increased amounts of buprenorphine dispensed per capita. There was no significant association in the growth of buprenorphine distributed and the number of physicians with 30-patient waivers.

CONCLUSIONS

The greater amounts of buprenorphine dispensed are consistent with the potentially greater use of opioid agonists for opioid use disorder treatment, though they also make their misuse more likely. The changes after the 2006 legislation suggest that policies focused on increasing the number of patients that a single waivered physician could safely and effectively treat could be more effective in increasing buprenorphine use than would alternatives such as opening new substance abuse treatment facilities or raising the overall number of waivered physicians.

Policies related to opioid agonist therapy for opioid use disorders: The evolution of state policies from 2004 to 2013

BACKGROUND

State Medicaid policies play an important role in Medicaid enrollees' access to and use of opioid agonists, such as methadone and buprenorphine, in the treatment of opioid use disorders. Little information is available, however, regarding the evolution of state policies facilitating or hindering access to opioid agonists among Medicaid enrollees.

METHODS

During 2013-2014, we surveyed state Medicaid officials and other designated state substance abuse treatment specialists about their state's recent history of Medicaid coverage and policies pertaining to methadone and buprenorphine. We describe the evolution of such coverage and policies and present an overview of the Medicaid policy environment with respect to opioid agonist therapy from 2004 to 2013.

RESULTS

Among our sample of 45 states with information on buprenorphine and methadone coverage, we found a gradual trend toward adoption of coverage for opioid agonist therapies in state Medicaid agencies. In 2013, only 11% of states in our sample (n = 5) had Medicaid policies that excluded coverage for methadone and buprenorphine, whereas 71% (n = 32) had adopted or maintained policies to cover both buprenorphine and methadone among Medicaid enrollees. We also noted an increase in policies over the time period that may have hindered access to buprenorphine and/or methadone.

CONCLUSIONS

There appears to be a trend for states to enact policies increasing Medicaid coverage of opioid agonist therapies, while in recent years also enacting policies, such as prior authorization requirements, that potentially serve as barriers to opioid agonist therapy utilization. Greater empirical information about the potential benefits and potential unintended consequences of such policies can provide policymakers and others with a more informed understanding of their policy decisions.

A review of buprenorphine diversion and misuse: the current evidence base and experiences from around the world

Outpatient opioid addiction treatment with sublingual buprenorphine pharmacotherapy has rapidly expanded in the United States and abroad, and, with this increase in medication availability, there have been increasing concerns about its diversion, misuse, and related harms. This narrative review defines the behaviors of diversion and misuse, examines how the pharmacology of buprenorphine alone and in combination with naloxone influence its abuse liability, and describes the epidemiological data on buprenorphine diversion and intravenous misuse, risk factors for its intravenous misuse, and the unintended consequences of misuse and diversion. Physician practices to prevent, screen for, and therapeutically respond to these behaviors, which are a form of medication nonadherence, are discussed, and gaps in knowledge are identified. Outpatient opioid addiction treatment with sublingual buprenorphine pharmacotherapy experiences from other countries that have varied health care systems, public policies, and access to addiction treatment are shared to make clear that diversion and misuse occur across the world in various contexts, for many different reasons, and are not limited to buprenorphine. Comparisons are made with other opioids with known abuse liability and medications with no known abuse. The objective was to facilitate understanding of diversion and misuse so that all factors influencing their expression (patient and provider characteristics and public policy) can be appreciated within a framework that also recognizes the benefits of addiction treatment. With this comprehensive perspective, further careful work can help determine how to minimize these behaviors without eroding the current benefits realized through improved addiction treatment access and expansion.

Efficacy and ligand bias at the μ-opioid receptor

In order to describe drug action at a GPCR, a full understanding of the pharmacological terms affinity, efficacy and potency is necessary. This is true whether comparing the ability of different agonists to produce a measurable response in a cell or tissue, or determining the relative ability of an agonist to activate a single receptor subtype and produce multiple responses. There is a great deal of interest in the μ-opioid receptor (MOP receptor) and the ligands that act at this GPCR not only because of the clinically important analgesic effects produced by MOP agonists but also because of their liability to induce adverse effects such as respiratory depression and dependence. Our understanding of the mechanisms underlying these effects, as well as the ability to develop new, more effective MOP receptor drugs, depends upon the accurate determination of the efficacy with which these ligands induce coupling of MOP receptors to downstream signalling events. In this review, which is written with the minimum of mathematical content, the basic meaning of terms including efficacy, intrinsic activity and intrinsic efficacy is discussed, along with their relevance to the field of MOP receptor pharmacology, and in particular in relation to biased agonism at this important GPCR.

Emergency hospitalizations for unsupervised prescription medication ingestions by young children

BACKGROUND

Emergency department visits and subsequent hospitalizations of young children after unsupervised ingestions of prescription medications are increasing despite widespread use of child-resistant packaging and caregiver education efforts. Data on the medications implicated in ingestions are limited but could help identify prevention priorities and intervention strategies.

METHODS

We used nationally representative adverse drug event data from the National Electronic Injury Surveillance System-Cooperative Adverse Drug Event Surveillance project and national retail pharmacy prescription data from IMS Health to estimate the frequency and rates of emergency hospitalizations for unsupervised prescription medication ingestions by young children (2007-2011).

RESULTS

On the basis of 1513 surveillance cases, 9490 estimated emergency hospitalizations (95% confidence interval: 6420-12,560) occurred annually in the United States for unsupervised prescription medication ingestions among children aged <6 years from 2007 through 2011; 75.4% involved 1- or 2-year old children. Opioids (17.6%) and benzodiazepines (10.1%) were the most commonly implicated medication classes. The most commonly implicated active ingredients were buprenorphine (7.7%) and clonidine (7.4%). The top 12 active ingredients, alone or in combination with others, were implicated in nearly half (45.0%) of hospitalizations. Accounting for the number of unique patients who received dispensed prescriptions, the hospitalization rate for unsupervised ingestion of buprenorphine products was significantly higher than rates for all other commonly implicated medications and 97-fold higher than the rate for oxycodone products (200.1 vs 2.1 hospitalizations per 100,000 unique patients).

CONCLUSIONS

Focusing unsupervised ingestion prevention efforts on medications with the highest hospitalization rates may efficiently achieve large public health impact.

Illicit buprenorphine use, interest in and access to buprenorphine treatment among syringe exchange participants

Poor access to buprenorphine maintenance treatment (BMT) may contribute to illicit buprenorphine use. This study investigated illicit buprenorphine use and barriers to BMT among syringe exchange participants. Computer-based interviews conducted at a New York City harm reduction agency determined: prior buprenorphine use; barriers to BMT; and interest in BMT. Of 102 opioid users, 57 had used illicit buprenorphine and 32 had used prescribed buprenorphine. When illicit buprenorphine users were compared to non-users: barriers to BMT ("did not know where to get treatment") were more common (64 vs. 36%, p<0.01); mean levels of interest in BMT were greater (3.37 ± 1.29 vs. 2.80 ± 1.34, p=0.03); and more participants reported themselves likely to initiate treatment (82 vs. 50%, p<0.01). Illicit buprenorphine users were interested in BMT but did not know where to go for treatment. Addressing barriers to BMT could reduce illicit buprenorphine use.

Sublingual buprenorphine as an analgesic in chronic pain: a systematic review

OBJECTIVE

There is growing interest in the use of sublingual buprenorphine for the treatment of chronic pain due to the unique pharmacology of buprenorphine, widespread use of the transdermal buprenorphine patch for chronic pain, and recent availability of sublingual buprenorphine tablets for the treatment of opioid dependence. The aim of this systematic review was to evaluate the evidence from clinical trials that have assessed the effectiveness of sublingual buprenorphine for chronic pain analgesia.

METHODS

Electronic searches of MEDLINE, Embase, CINAHL, Web of Science, and the Cochrane Database of Systematic Reviews were used to identify clinical trials of sublingual buprenorphine for the treatment of chronic pain.

RESULTS

Ten trials involving 1,190 patients were included in the review. Due to heterogeneity of studies, pooling of the results and meta-analysis were not possible. All studies reported that sublingual buprenorphine demonstrated some effectiveness as a chronic pain analgesic. The majority of studies were observational and of low quality.

CONCLUSIONS

Preliminary trials suggest a plausible role; however, due to a paucity of high-quality trials, the current evidence is insufficient to determine the effectiveness of sublingual buprenorphine for the treatment of chronic pain. Rigorous further trials are warranted.

Medication errors related to transdermal opioid patches: lessons from a regional incident reporting system

OBJECTIVE

A few cases of adverse reactions linked to erroneous use of transdermal opioid patches have been reported in the literature. The aim of this study was to describe and characterize medication errors (MEs) associated with use of transdermal fentanyl and buprenorphine.

METHODS

All events concerning transdermal opioid patches reported between 2004 and 2011 to a regional incident reporting system and assessed as MEs were scrutinized and characterized. MEs were defined as "a failure in the treatment process that leads to, or has the potential to lead to, harm to the patient".

RESULTS

In the study 151 MEs were identified. The three most common error types were wrong administration time 67 (44%), wrong dose 34 (23%), and omission of dose 20 (13%). Of all MEs, 118 (78%) occurred in the administration stage of the medication process. Harm was reported in 26 (17%) of the included cases, of which 2 (1%) were regarded as serious harm (nausea/vomiting and respiratory depression). Pain was the most common adverse reaction reported.

CONCLUSIONS

Of the reported MEs related to transdermal fentanyl and buprenorphine, most occurred during administration. Improved routines to ascertain correct and timely administration and educational interventions to reduce MEs for these drugs are warranted.

Oral transmucosal drug delivery for pediatric use

The formulation of medicines for children remains a challenge. An ideal pediatric formulation must allow accurate dose administration and be in a dosage form that can be handled by the target age group. It is also important to consider the choices and the amount of excipients used in the formulation for this vulnerable age group. Although oral formulations are generally acceptable to most pediatric patients, they are not suitable for drugs with poor oral bioavailability or when a rapid clinical effect is required. In recent years, oral transmucosal delivery has emerged as an attractive route of administration for pediatric patients. With this route of administration, a drug is absorbed through the oral mucosa, therefore bypassing hepatic first pass metabolism and thus avoiding drug degradation or metabolism in the gastrointestinal tract. The high blood flow and relatively high permeability of the oral mucosa allow a quick onset of action to be achieved. It is a simple and non-invasive route of drug administration. However, there are several barriers that need to be overcome in the development of oral transmucosal products. This article aims to provide a comprehensive review of the current development of oral transmucosal delivery specifically for the pediatric population in order to achieve systemic drug delivery. The anatomical and physiological properties of the oral mucosa of infants and young children are carefully examined. The different dosage forms and formulation strategies that are suitable for young patients are discussed.

Buprenorphine for opioid dependence: Are there really differences between the formulations?

Buprenorphine and buprenorphine/naloxone sublingual tablets were approved by the FDA in 2002. In 2010, the buprenorphine/naloxone sublingual film was approved to address concerns of diversion, time for tablet dissolution, and unintentional exposure in children with the tablet. This article will compare the buprenorphine sublingual formulations in terms of pharmacokinetics, safety, diversion and misuse, cost, and patient preference. It will explore current data suggesting advantages or disadvantages of the various formulations since conclusive data are minimally available.