Deaths involving buprenorphine: a compendium of French cases

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.

Patterns of use and adverse events reported among persons who regularly inject buprenorphine: a systematic review

Background and Aims

Given the ongoing opioid crisis, novel interventions to treat severe opioid use disorder (OUD) are urgently needed. Injectable opioid agonist therapy (iOAT) with diacetylmorphine or hydromorphone is effective for the treatment of severe, treatment-refractory OUD, however barriers to implementation persist. Intravenous buprenorphine for the treatment of OUD (BUP iOAT) has several possible advantages over traditional iOAT, including a safety profile that might enable take-home dosing. We aimed to characterize injecting practices among real-world populations of persons who regularly inject buprenorphine, as well as associated adverse events reported in order to inform a possible future BUP iOAT intervention.

Methods

We conducted a systematic review. We searched MEDLINE, EMBASE, and PsycINFO from inception through July 2020 and used backwards citation screening to search for publications reporting on dose, frequency among persons who regularly inject the drug, or adverse events associated with intravenous use of buprenorphine. The review was limited to English language publications and there was no limitation on study type. Study quality and risk of bias was assessed using the Mixed Methods Appraisal Tool. Narrative synthesis was used in reporting the results.

Results

Eighty-eight studies were included in our review. Regular injection of buprenorphine was identified across diverse settings world-wide. Daily dose of oral buprenorphine injected was < 1–12 mg. Frequency of injection was 0–10 times daily. Adverse events could be characterized as known side effects of opioids/buprenorphine or injection-related complications. Most studies were deemed to be of low quality.

Conclusions

Extramedical, intravenous use of buprenorphine, continues to be documented. BUP iOAT may be feasible and results may inform the development of a study to test the efficacy and safety of such an intervention. Future work should also examine acceptability among people with severe OUD in North America. Our review was limited by the quality of included studies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12954-022-00695-5.

Gender differences among persons entering medication treatment for opioid use disorder in the community

BACKGROUND AND OBJECTIVES

We evaluated gender differences among persons initiating medications for opioid use disorder (MOUD).

METHODS

Analyses of baseline assessments for a study evaluating the impact of MOUD on outcomes included: demographics, DSM-5 diagnoses, depression severity, quality of life (QoL), and medication history (N = 125).

RESULTS

When compared to men, women had a greater prevalence of generalized anxiety and posttraumatic stress disorders; and worse psychological QoL. Women were less likely to be prescribed psychiatric medications.

DISCUSSION AND CONCLUSIONS

Women may benefit from tailored multidisciplinary programs with MOUD.

SCIENTIFIC SIGNIFICANCE

This study identified that women with OUD seeking MOUD in the community had greater sedative hypnotic nonprescribed medication use and psychiatric comorbidity than men, all of which can contribute to poorer retention on MOUD and higher risk of morbidity and mortality. Thus, concurrent psychiatric disorder screening and treatment integrated with MOUD may improve retention on MOUD, opioid relapse and overdose for women.

Buprenorphine abuse and health risks in Iran: A systematic review

INTRODUCTION

Buprenorphine maintenance treatment (BMT) is widely used in Iran, and its use is growing continuously. We reviewed studies on buprenorphine use, non-prescribed use, use disorder and treatment-seeking for it, buprenorphine-associated poisoning, and mortality in Iran in the current systematic review.

METHODS

An Iranian database (Scientific Information Database; SID) and three International electronic databases (PubMed, Scopus, and Web of Science) were searched for publications up to August 2020 for the relevant data. Opportunistic methods (Contact with experts and backward citation tracking) were also used for this purpose. Identified records were screened for eligibility criteria, and data of included studies were extracted. For context, the trend of BMT in the country was also examined.

RESULTS

Ten studies were found on the prevalence of non-prescribed buprenorphine use, seven were on the regular use and use disorder, and two studies on buprenorphine poisoning. The last 12-month prevalence of non-prescribed use was lower than 0.5 % in the general population, university, and high school students. The indicator was 2.5 % among persons who use drugs in a 2018 national study. The proportion of buprenorphine poisoning was 4.9 % among all illicit substance poisoning cases admitted to a hospital. The proportion of buprenorphine poisoning cases among all acute pediatric drug poisoning cases increased from 1.2 % to 2.5 % in a 3-year study.

CONCLUSION

Despite the expansion of BMT in Iran in the last decade, the adverse health consequences associated with buprenorphine are infrequent, when compared to other opioids used in Iran, suggesting the safety of BMT for future expansion.

Development and validation of a rapid liquid chromatography/tandem mass spectrometry method to quantitate gabapentin and buprenorphine in human serum

RATIONALE

Gabapentin has shown initial promise as an opioid-sparing medication in pain patients as well as a treatment for opioid withdrawal and liquid chriomatography/tandem mass spectrometry (LC/MS/MS) is often used for clinical monitoring. Despite reports of validated tandem mass spectrometric methods for the determination of gabapentin and buprenorphine, mechanisms for the collision-induced fragmentation have not been adequetely described.

METHODS

A rapid analytical method has been developed to determine gabapentinoid, gabapentin, and the partial opioid agonist, buprenorphine, in 20 μL of human serum using LC/MS/MS with a chromatographic run time of 2 min. A simplified sample cleanup procedure using methanol precipitation of serum proteins/lipids followed by evaporation and reconstitution in mobile phase was demonstrated. Gabapentin and buprenorphine were detected following positive ion electrospray ionization using multiple-reaction monitoring. The internal standard approach was used for quantitation with labeled gabapentin-D10 and buprenorphine-D4 serving as internal standards. Using organic reaction principals and stable isotope labels, collision-induced fragmentation mechanisms for both gabapentin and buprenorphine are proposed. The method was validated according to the FDA Guidance for Industry - Bioanalytical Method Validation.

RESULTS

Accuracy was demonstrated by error values ≤15% for buprenorphine and ≤6% for gabapentin. The inter-day precision was ≤4.88% and 15.59% for gabapentin and buprenorphine and the intra-day precision was ≤5.20% and 11.65% for gabapentin and buprenorphine. The lower limit of quantitation corresponded to 10 ng/mL for gabapentin and 1 ng/mL for buprenorphine in serum. Recoveries were 104 ± 2.55% and 85 ± 2.03% for gabapentin and buprenorphine, respectively.

CONCLUSIONS

Concentrations of gabapentin and buprenorphine were determined for five authentic human serum samples to further validate the utility of the method and applicable to therapeutic drug monitoring beyond its use as a drug screening assay. Furthermore, new mechanisms for the collision-induced dissociation of gabapentin and buprenorphine have been proposed.

Buprenorphine-Related Deaths in North Carolina from 2010-2018

Buprenorphine is a commonly prescribed medication for the treatment of opioid-use disorder. As prescriptions increase in North Carolina, buprenorphine is more frequently encountered statewide in routine postmortem casework. Between 2010 and 2018, there were 131 select cases investigated by the Office of the Chief Medical Examiner where buprenorphine was detected in peripheral blood and considered a primary cause of death, with no other opioids present and no other non-opioid substances found in the lethal range. The decedents ranged in age from 14 to 64 years, with 67% male. The mean/median peripheral blood concentrations were 4.1/2.1 ng/mL for buprenorphine and 7.8/3.4 ng/mL for the metabolite, norbuprenorphine. These postmortem blood concentrations overlap antemortem therapeutic concentrations in plasma reported in the literature for opioid-dependent subjects receiving sublingual maintenance therapy. The pathologist considered scene findings, prescription history, autopsy findings, toxicological analysis, and decedent behavior prior to death to conclude a drug-related cause of death. Many of the deaths were complicated by the presence of other central nervous system depressants along with contributory underlying cardiovascular and respiratory disease. The three most prevalent additive substances were alprazolam, ethanol, and gabapentin, found in 67, 36, and 32 cases out of 131, respectively. Interpreting buprenorphine involvement in a death is complex, and instances may be under-estimated in epidemiological data because of the lack of a defined toxic or lethal range in postmortem blood along with its good safety profile. As expansion to access of opioid-use disorder treatment becomes a priority, awareness of the challenges of postmortem interpretation is needed as increased use and diversion of buprenorphine are inevitable.

Characteristics and circumstances of death related to buprenorphine toxicity in Australia

BACKGROUND

Buprenorphine is a semi-synthetic opioid used in the treatment of opioid dependence and chronic pain. The current study aimed to determine the characteristics and circumstances of all recorded cases of buprenorphine-related toxicity death in Australia; determine toxicology and organ pathology; and compare these profiles to cases of death due to buprenorphine-related traumatic injury.

METHODS

All cases of buprenorphine-related drug toxicity death were retrieved from the National Coronial Information System (2000-2019), as were all cases of buprenorphine-related traumatic injury. Information was collected on cause of death, case characteristics, toxicology and major organ pathology.

RESULTS

A total of 314 cases of drug toxicity and 55 of traumatic injury were identified. Toxicity cases were significantly older (40.5 v 36.1 years), more likely to have a history of chronic pain (OR 2.95), less likely to have a history of injecting drug use (OR 0.09), but more likely to have injected buprenorphine proximal to death (OR 4.90). There were no group differences in buprenorphine or norbuprenorphine toxicology. Toxicity cases were more likely to have hypnosedatives (OR 2.08) and other opioids (OR 4.69) present, but less likely to have psychostimulants (OR 0.26) and THC (OR 0.45). Toxicity cases were more likely to be obese (OR 4.05), have pre-existing cardiovascular disease (OR 4.02) and heavier hearts (412.1 v 355.2 g).

CONCLUSIONS

Buprenorphine-related toxicity death cases differed from trauma deaths in their characteristics, toxicology and disease. Fatal buprenorphine toxicity is associated with older age, concurrent use of depressants and cardiovascular disease.

Associations between prescribed benzodiazepines, overdose death and buprenorphine discontinuation among people receiving buprenorphine

BACKGROUND AND AIMS

Benzodiazepines are commonly prescribed to patients with opioid use disorder receiving buprenorphine treatment, yet may increase overdose risk. However, prescribed benzodiazepines may improve retention in care by reducing buprenorphine discontinuation and thus may prevent relapse to illicit opioid use. We aimed to test the association between benzodiazepine prescription and fatal opioid overdose, non-fatal opioid overdose, all-cause mortality and buprenorphine discontinuation.

DESIGN AND SETTING

This was a retrospective cohort study using five individually linked data sets from Massachusetts, United States government agencies.

PARTICIPANTS

We studied 63 389 Massachusetts residents aged 18 years or older who received buprenorphine treatment between January 2012 and December 2015.

MEASUREMENTS

Filled benzodiazepine prescription during buprenorphine treatment was the main independent variable. The primary outcome was time to fatal opioid overdose. Secondary outcomes were time to non-fatal opioid overdose, all-cause mortality and buprenorphine discontinuation. We defined buprenorphine discontinuation as having a 30-day gap without another prescription following the end date of the previous prescription. We used Cox proportional hazards models to calculate hazards ratios that tested the association between receipt of benzodiazepines and all outcomes, restricted to periods during buprenorphine treatment.

FINDINGS

Of the 63 345 individuals who received buprenorphine, 24% filled at least one benzodiazepine prescription during buprenorphine treatment. Thirty-one per cent of the 183 deaths from opioid overdose occurred when individuals received benzodiazepines during buprenorphine treatment. Benzodiazepine receipt during buprenorphine treatment was associated with an increased risk of fatal opioid overdose adjusted hazard ratio (HR) = 2.92, 95% confidence interval (CI) = 2.10-4.06, non-fatal opioid overdose, adjusted HR = 2.05, 95% CI, 1.68-2.50, all-cause mortality, adjusted HR = 1.90, 95% CI, 1.48-2.44 and a decreased risk of buprenorphine discontinuation, adjusted HR = 0.87, 95% CI, 0.85-0.89.

CONCLUSIONS

Benzodiazepine receipt appears to be associated with both increased risk of opioid overdose and all-cause mortality and decreased risk of buprenorphine discontinuation among people receiving buprenorphine.

Behavioral Pharmacology of Drugs Acting at Mu Opioid Receptors

Despite the therapeutic utility of opioids for relieving pain, other behavioral effects, including their potential for abuse and overdose, can be quite detrimental to individuals as well as society and have contributed to the ongoing opioid crisis. The dramatic escalation in overdose deaths over the last 15 years was initially driven by abuse of prescription opioids, although abuse of heroin, fentanyl, and fentanyl analogs has been increasing, largely due to increased availability and lower cost compared with prescription opioids. All of these opioids share pharmacological properties, acting as agonists at mu opioid receptors, and produce similar behavioral effects, including abuse-related, pain-relieving, dependence-producing, and respiratory-depressant effects. Despite their similarities, opioids are not pharmacologically identical. In fact, drugs that act at mu opioid receptors, including abused opioids, can vary on a number of dimensions, including pharmacological efficacy, drug-receptor interactions, receptor selectivity, and pharmacokinetics. Overall, these differences impact behavioral effects of drugs acting at mu opioid receptors, and this chapter describes variations in those behavioral effects and how these differences continue to provide new strategies that can be developed to address the ongoing opioid epidemic.

Determination of buprenorphine, naloxone and phase I and phase II metabolites in rat whole blood by LC-MS/MS

Buprenorphine and buprenorphine/naloxone combination are maintenance treatments used worldwide. However, since their marketing, despite ceiling respiratory effects, poisonings and fatalities have been attributed to buprenorphine misuse and overdose. Therefore, to better understand the mechanisms of buprenorphine-related toxicity in vivo, experimental investigations have been conducted, mainly in the rat. We developed a liquid chromatographic-tandem mass spectrometric (LC-MS/MS) method with electrospray ionization for the simultaneous quantification of buprenorphine, naloxone and their metabolites (norbuprenorphine, buprenorphine glucuronide, norbuprenorphine glucuronide and naloxone glucuronide) in rat whole blood. Compounds were extracted from whole blood by protein precipitation and chromatographically separated using gradient elution of aqueous ammonium formate and methanol in a Raptor Biphenyl core-shell column (100 mm x 3,0 mm x 2,7 μm). Following electrospray ionization, quantification was carried out in the multiple reaction monitoring (MRM) mode by the tandem mass spectrometer API 3200 system. The LC-MS/MS method was validated according to the currently accepted criteria for bioanalytical method validation. The method required small sample volumes (50 μL) and was sensitive with limits of quantification of 6.9, 6.2, 3.6, 3.3, 1.3 and 57.7 ng/mL for buprenorphine, norbuprenorphine, buprenorphine glucuronide, norbuprenorphine glucuronide, naloxone and naloxone glucuronide respectively. The upper limit of quantification was 4000 ng/ml for all the studied compounds. Trueness (88-115 %), repeatability and intermediate precision (both <15%) were in accordance with the international recommendations. The procedure was successfully used to quantify these compounds in the whole blood sample from one rat 24 h after the intravenous administration of buprenorphine/naloxone (30.0/7.5 mg/kg).

Methocinnamox Produces Long-Lasting Antagonism of the Behavioral Effects of µ-Opioid Receptor Agonists but Not Prolonged Precipitated Withdrawal in Rats

A novel µ-opioid receptor antagonist, methocinnamox (MCAM), attenuates some abuse-related and toxic effects of opioids. This study further characterized the pharmacology of MCAM in separate groups of rats using procedures to examine antinociception, gastrointestinal motility, and withdrawal in morphine-dependent rats. Antinociceptive effects of opioid receptor agonists were measured before and after MCAM (1-10 mg/kg) using warm water tail withdrawal and sensitivity to mechanical stimulation in inflamed paws (complete Freund's adjuvant). Before MCAM, morphine, fentanyl, and the κ-opioid receptor agonist spiradoline dose dependently increased tail-withdrawal latency from 50°C water; MCAM attenuated the antinociceptive effects of morphine and fentanyl, but not spiradoline. Morphine increased sensitivity to mechanical stimulation and decreased gastrointestinal motility, and MCAM blocked both effects. These antagonist effects of 10 mg/kg MCAM were persistent, lasting for 2 weeks or longer. Withdrawal emerged after discontinuation of morphine treatment or administration of 10 mg/kg MCAM or 17.8 mg/kg naloxone; other than the day of antagonist administration when withdrawal signs were greater in rats that received antagonist compared with rats that received vehicle, there was no difference among groups in directly observable withdrawal signs or decreased body weight. These results confirm that MCAM is a selective µ-opioid receptor antagonist with an exceptionally long duration of action, likely due to pseudoirreversible binding. Despite its sustained antagonist effects, the duration of withdrawal precipitated by MCAM is not different from that precipitated by naloxone, suggesting that the long duration of antagonism provided by MCAM could be particularly effective for treating opioid abuse and overdose. SIGNIFICANCE STATEMENT: The opioid receptor antagonist MCAM attenuates some abuse-related and toxic effects of opioids. This study demonstrates that MCAM selectively antagonizes multiple effects mediated by µ-opioid receptor agonists for 2 weeks or longer, and like naloxone, MCAM precipitates withdrawal in morphine-dependent rats. Despite this persistent antagonism, withdrawal signs precipitated by MCAM are not significantly different from signs precipitated by naloxone or occurring after discontinuation of morphine, suggesting that using MCAM for opioid abuse or overdose would not produce sustained withdrawal.

Overdose Risk and Client Characteristics Associated With the Injection of Buprenorphine at a Medically Supervised Injecting Center in Sydney, Australia

Background: Buprenorphine and buprenorphine/naloxone (BNX) were developed to improve the safety profile of opioid substitution treatment (OST) and reduce diversion and injection, yet continue to be injected, despite the risk of harm. Previous studies examining injection of these substances have relied on self-reported injection and overdose. Using data from the Uniting Medically Supervised Injecting Center (MSIC) in Sydney, this study aimed to assess the overdose risk associated with the use of buprenorphine and BNX and identify factors associated with injecting. Methods: Client data routinely collected from MSIC, a drug consumption room where clients can legally inject drugs under supervision, was used. Odds ratios (OR) to assess the risk of overdose and their associated 95% confidence intervals (95%CI) were calculated and compared to other substances. Univariate analysis using χ-square and multivariate logistic regressions were used to determine characteristics associated with buprenorphine and BNX injection. Results: Data from 1,020,782 injections by 15,832 individuals were analyzed. Risk of overdose was low for buprenorphine compared to other substances (OR 0.16; 95%CI: 0.07-0.19) and no overdoses occurred when BNX was injected. Injection of both buprenorphine and BNX was associated with male gender, homelessness, no income/reliance upon government payments, and prior imprisonment. Conclusions: Buprenorphine and BNX continue to be injected, albeit in small numbers. This is the first study to report on injection and overdose risk using direct observation, and has confirmed the lower overdose risk. MSIC clients who inject buprenorphine and BNX tend to be marginalized and may benefit from targeted harm reduction measures.

Treatment of opioid dependence with buprenorphine: current update

Opioid maintenance treatment is the first-line approach in opioid dependence. Both the full opioid agonist methadone (MET) and the partial agonist buprenorphine (BUP) are licensed for the treatment of opioid dependence. BUP differs significantly from MET in its pharmacology, side effects, and safety issues. For example, the risk of respiratory depression is lower than with MET. The risk of diversion and injection of BUP have been reduced by also making it available as a tablet containing the opioid antagonist naloxone. This review summarizes the clinical effects of BUP and examines possible factors that can support decisions regarding the use of BUP or MET in opioid-dependent people.

Poly-Drug Use of Prescription Medicine among People with Opioid Use Disorder in China: A Systematic Review and Meta-Analysis

BACKGROUND

Opioid use disorder (OUD) causes substantial public health and social problems worldwide. Poly-drug use is common in people with OUD and increases morbidity and mortality. Investigation of the patterns and characteristics of poly-drug use of prescription medicine among opioid users is needed to develop appropriate prevention and intervention strategies.

OBJECTIVES

To estimate the prevalence of poly-drug use of prescription medicine among people with OUD in China using meta-analysis.

METHODS

We searched relevant epidemiological studies published before February 2017 in English and Chinese databases. The quality of included studies was assessed using the Agency for Healthcare Research and Quality scale. The pooled prevalences of prescription medicine use among people with OUD were estimated.

RESULTS

We included 80 eligible studies in the meta-analysis. The main prescription medicines were benzodiazepines (BZDs) and prescription opioid analgesics. The pooled prevalence of unclassified BZDs and prescription opioids was 40.6% and 23.2%, respectively. Diazepam was the most frequently co-used BZD (32.6%), followed by triazolam (32.1%), and estazolam (9.2%). Tramadol was the most commonly used prescription opioid (27.3%), followed by methadone (16.8%), buprenorphine (12.6%), pethidine (8.9%), morphine (6.5%), dihydroetorphine (3.9%), and codeine-containing cough syrup (3.7%). BZDs were mainly used for self-medication (56.1%), whereas prescription opioids were primarily coused for nonmedical purposes (69.4%).

CONCLUSIONS

The results demonstrate that prescription medicine use is widespread among opioid users in China. There needs to be more consideration of poly-drug use, and early interventions and management strategies are needed to prevent poly-drug use among opioid users in China.

Buprenorphine prescription, misuse and service provision: a global perspective

Buprenorphine, a partial μ-opioid agonist and κ-opioid antagonist, is recommended as safe and effective maintenance treatment for opioid dependence. It offers the possibility of management in primary care settings. However, its prescription has led to diversion for illicit recreational use and resulted in medical complications and, rarely, fatal overdose in combination with other sedatives. The outcome of buprenorphine maintenance programmes varies from country to country and it is determined by the local therapeutic traditions, regulatory restrictions and existing service provision for opioid misusers. This article addresses the pharmacology of buprenorphine, the benefits and drawbacks of its prescription, service provision for opioid misuse around the world, policy recommendations, and prescribing training requirements.

What every psychiatrist should know about buprenorphine in substance misuse

Buprenorphine is prescribed as a treatment for opioid dependence (Barnett et al, 2001; Lintzeris et al, 2002). Methadone substitute prescribing is the primary maintenance treatment in Britain and is well established (Ward, 1997). Despite the advantages of methadone maintenance there are associated disadvantages, including potential death following overdose, the inconvenience of daily dosing, the risk of the drug being used by others and stigma (Walsh, 1994).

Pain Management of Patients with Substance Abuse in the Ambulatory Setting

PURPOSE OF REVIEW

Abuse of illicit substances and prescription opioids is a growing problem that presents challenges for pain management in the inpatient and outpatient setting. With future patient care models shifting toward shorter hospital stays and more same-day surgeries, it is crucial that clinicians learn to manage this patient population and strike a balance between the overtreatment of pain that can subsequently worsen tolerance and addiction, and the undertreatment of pain that can lead to pseudoaddiction.

RECENT FINDINGS

Through recognition of maladaptive behaviors, use of screening programs, and pain contracts, physicians in the outpatient setting can improve their oversight and shepherding of these patients. In the inpatient setting, regularly scheduled rather than PRN opioids are recommended for chronic opioid users, and good communication with the patient's outpatient prescriber of pain medications is essential. For surgical patients on chronic opioid therapy, making a multimodal plan in advance of the day of surgery that may incorporate NSAIDs, tricyclics, gabapentinoids, anticonvulsants, opioid tapering, and regional anesthesia can help alleviate high postoperative pain control requirements. In conjunction with such medication management, setting realistic expectations for pain control with preoperative counseling may be highly beneficial. For postoperative pain refractory to other strategies, the use of inpatient low-dose ketamine infusions is a novel approach that is gaining popularity, but this does require monitoring by a dedicated pain service.

Buprenorphine-Related Complications in Elderly Hospitalised Patients: A Case Series

We report a case series of buprenorphine-related respiratory and neurological depression in opioid-naïve elderly hospitalised patients who received buprenorphine for acute pain management at our institution over a 24-month period. All six patients had risk factors for respiratory depression such as advanced age, concurrent comorbidities, or the ingestion of other potential central nervous system depressants. All patients required escalation of management with additional monitoring, with some transferred to a high dependency or intensive care unit. Five patients had attempted naloxone reversal with varying results. Our cases highlight the fact that while buprenorphine has been demonstrated to have a ceiling effect in relation to respiratory depression in healthy volunteers, it remains an important side-effect and may result in significant respiratory depression in patients with reduced respiratory or neurological reserve. Difficulties with buprenorphine's reversal using naloxone are described. We recommend additional caution when considering buprenorphine for acute pain management in elderly opioid-naïve patients, especially if they have comorbidities or are taking other central nervous system depressants. When buprenorphine is used in patients with risk factors, we recommend additional monitoring and education about potential adverse respiratory effects and their management.

Do all screening immunoassay positive buprenorphine samples need to be confirmed?

Background Interference from opiates in the Microgenics CEDIA® Buprenorphine assay is known to produce false-positive buprenorphine screening immunoassay results necessitating confirmatory buprenorphine testing by chromatography/mass spectrometry methods. Method We reviewed data on falsely positive buprenorphine immunoassay screen (cut-off ≥ 5  µg/L) but negative for buprenorphine by gas chromatography mass spectrometry (cut-off ≥ 5  µg/L) and had a positive opiate immunoassay result (cut-off ≥ 300  µg/L). The results were collected over three months, and the data were evaluated to determine whether there is an opiate immunoassay screen concentration below which a false-positive buprenorphine result will not occur. Results We found that cross-reactivity in the CEDIA® buprenorphine immunoassay by opiates at concentrations <2000  µg/L will not cause a false-positive buprenorphine result. After changing our practice to not proceed with confirmatory buprenorphine gas chromatography mass spectrometry assay when the opiate screening concentration is below an even more conservative cut-off of <1500  µg/L, we estimate a potential cost-saving of AU$ 17,810 per year without compromising clinical care. Conclusion Samples with CEDIA® opiate immunoassay result <2000  µg/L and a positive CEDIA® buprenorphine immunoassay screen do not require confirmatory testing for buprenorphine.

Mechanisms of tramadol-related neurotoxicity in the rat: Does diazepam/tramadol combination play a worsening role in overdose?

Poisoning with opioid analgesics including tramadol represents a challenge. Tramadol may induce respiratory depression, seizures and serotonin syndrome, possibly worsened when in combination to benzodiazepines. Our objectives were to investigate tramadol-related neurotoxicity, consequences of diazepam/tramadol combination, and mechanisms of drug-drug interactions in rats. Median lethal-doses were determined using Dixon-Bruce's up-and-down method. Sedation, seizures, electroencephalography and plethysmography parameters were studied. Concentrations of tramadol and its metabolites were measured using liquid-chromatography-high-resolution-mass-spectrometry. Plasma, platelet and brain monoamines were measured using liquid-chromatography coupled to fluorimetry. Median lethal-doses of tramadol and diazepam/tramadol combination did not significantly differ, although time-to-death was longer with combination (P=0.04). Tramadol induced dose-dependent sedation (P<0.05), early-onset seizures (P<0.001) and increase in inspiratory (P<0.01) and expiratory times (P<0.05). The diazepam/tramadol combination abolished seizures but significantly enhanced sedation (P<0.01) and respiratory depression (P<0.05) by reducing tidal volume (P<0.05) in addition to tramadol-related increase in respiratory times, suggesting a pharmacodynamic mechanism of interaction. Plasma M1 and M5 metabolites were mildly increased, contributing additionally to tramadol-related respiratory depression. Tramadol-induced early-onset increase in brain concentrations of serotonin and norepinephrine was not significantly altered by the diazepam/tramadol combination. Interestingly neither pretreatment with cyproheptadine (a serotonin-receptor antagonist) nor a benserazide/5-hydroxytryptophane combination (enhancing brain serotonin) reduced tramadol-induced seizures. Our study shows that diazepam/tramadol combination does not worsen tramadol-induced fatality risk but alters its toxicity pattern with enhanced respiratory depression but abolished seizures. Drug-drug interaction is mainly pharmacodynamic but increased plasma M1 and M5 metabolites may also contribute to enhancing respiratory depression. Tramadol-induced seizures are independent of brain serotonin.

Buprenorphine infrequently found in fatal overdose in New York City

BACKGROUND

Buprenorphine is an opioid agonist medication that is both safe and effective in the treatment of opioid use disorders and the prevention of opioid overdoses. Despite this, media coverage has highlighted public concerns about the potential safety consequences of buprenorphine misuse and diversion. To address the possible contribution of buprenorphine to overdose mortality, we systematically tested post mortem blood specimens from decedents who had died of an unintentional drug overdoses in 2013.

METHODS

We retrospectively tested consecutive drug overdose cases that occurred from June through October 2013. Cases with available blood specimens were tested for buprenorphine and norbuprenorphine using liquid chromatography-tandem mass spectrometry. Toxicology results were linked to death certificates and case files from New York City Vital Statistics and New York City Office of the Chief Medical Examiner.

RESULTS

Of the 98 unintentional drug overdose fatalities tested, only 2 (2.0%) tested positive for buprenorphine metabolites. All 98 unintentional fatalities involved multiple substances.

CONCLUSIONS

Buprenorphine was infrequently found in drug overdose deaths in New York City. Since the safety and efficacy of buprenorphine are well documented, and overdoses resulting from buprenorphine treatment or diversion are very rare, facilitating access to buprenorphine treatment is strongly recommended.

A review of pharmacogenetic studies of substance-related disorders

BACKGROUND

Substance-related disorders (SRDs) are a major cause of morbidity and mortality worldwide. Family, twin, and adoption studies have demonstrated the substantial heritability of SRDs. To determine the impact of genetic variation on risk for SRD and the response to treatment, researchers have conducted a number of secondary data analyses and quasi-experimental studies that target one or more candidate gene variants.

METHODS

This review examines studies in which candidate polymorphisms were examined as mediator variables to identify pharmacogenetic effects on subjective responses to drug administration or cues or outcomes of medication trials for SRDs. Efforts to use a meta-analytic approach to quantify these effects are premature because the number of available studies using similar methods and outcomes is limited, so the present review is qualitative.

RESULTS

Findings from these studies provide preliminary evidence of clinically relevant pharmacogenetic effects. However, independent replication of these findings has been sparse.

CONCLUSIONS

Although this growing body of literature has produced conflicting results, improved statistical controls may help to clarify the findings. Additionally, the use of empirically derived sub-phenotypes (i.e., which serve to differentiate distinct groups of affected individuals) may also help to identify genetic mediators of pharmacologic response in relation to SRDs. The identification of genetic mediators can inform clinical care both by identifying risk factors for SRDs and predicting adverse events and therapeutic outcomes associated with specific pharmacotherapies.

Transporter-Mediated Disposition of Opioids: Implications for Clinical Drug Interactions

Opioid-related deaths, abuse, and drug interactions are growing epidemic problems that have medical, social, and economic implications. Drug transporters play a major role in the disposition of many drugs, including opioids; hence they can modulate their pharmacokinetics, pharmacodynamics and their associated drug-drug interactions (DDIs). Our understanding of the interaction of transporters with many therapeutic agents is improving; however, investigating such interactions with opioids is progressing relatively slowly despite the alarming number of opioids-mediated DDIs that may be related to transporters. This review presents a comprehensive report of the current literature relating to opioids and their drug transporter interactions. Additionally, it highlights the emergence of transporters that are yet to be fully identified but may play prominent roles in the disposition of opioids, the growing interest in transporter genomics for opioids, and the potential implications of opioid-drug transporter interactions for cancer treatments. A better understanding of drug transporters interactions with opioids will provide greater insight into potential clinical DDIs and could help improve opioids safety and efficacy.

Illicit use of opioid substitution drugs: prevalence, user characteristics, and the association with non-fatal overdoses

BACKGROUND AND AIMS

Diversion of opioid substitution drugs (OSD) is of public concern. This study examined the prevalence, frequency, and predictors of illicit OSD use in a group of injecting drug users (IDUs) and assessed if such use was associated with non-fatal overdoses.

METHODS

Semi-annual cross-sectional interviews conducted in Oslo, Norway (2006-2013), from 1355 street-recruited IDUs. Hurdle, logistic, and multinomial regression models were employed.

RESULTS

Overall, 27% reported illicit OSD use in the past four weeks; 16.8% methadone, 12.5% buprenorphine, and 2.9% both drugs. Almost 1/10 reported at least one non-fatal overdose in the past four weeks, and roughly 1/3 reported such experience in the past year. Use of additional drugs tended to be equally, or more prevalent among illicit OSD users than other IDUs. In terms of illicit OSD use being a risk factor for non-lethal overdoses, our results showed significant associations only for infrequent buprenorphine use (using once or less than once per week). Other factors associated with non-fatal overdoses included age, education, homelessness, as well as the benzodiazepines, stimulants, and heroin use.

CONCLUSIONS

Users of diverted OSD may represent a high-risk population, as they used more additional drugs and used them more frequently than other IDUs. However, illicit OSD use may be less harmful than previously assumed. After accounting for an extensive set of covariates, only infrequent illicit buprenorphine use, but not methadone use, was associated with non-fatal overdoses.

New developments in the management of opioid dependence: focus on sublingual buprenorphine-naloxone

Opioid maintenance therapy is a well-established first-line treatment approach in opioid dependence. Buprenorphine, a partial opioid agonist, has been found by numerous studies to be an effective and safe medication in the treatment of opioid dependence. At present, buprenorphine is available as a monodrug or in a fixed 4:1 ratio combination with naloxone. A diminished risk of diversion and abuse for the buprenorphine-naloxone combination is likely but not firmly established. Conventional formulations are given sublingually to avoid the hepatic first-pass effect. A novel film tablet is available only in the US and Australia. Other novel, sustained-release formulations (implant, depot) are currently being developed and tested. Recent studies, including a Cochrane meta-analysis, suggest that the retention with buprenorphine is lower than for methadone, but that buprenorphine may be associated with less drug use. Higher doses of buprenorphine are associated with better retention rates. Buprenorphine has a ceiling effect at the opioid receptor with regard to respiratory depression, and may cause fewer fatal intoxications than methadone. Possible antidepressant effects of buprenorphine and its use in comorbid psychiatric patients has not been studied in much detail. Clinical implications are discussed.

Would legalizing illicit opioids reduce overdose fatalities? Implications from a natural experiment

Overdose is the leading cause of premature mortality among heroin users. We examine whether the provision of regulated and quality-controlled heroin to users in specified doses would reduce heroin overdose rates. We also address this in the context of the epidemic of prescription opioid use and deaths seen in recent years in the United States and internationally. We explore the extent to which any change in legal access to heroin would affect overdose rates, and note that this depends upon the validity of the two main assumptions that variations in illicit drug purity and/or the presence of drug contaminants are major causes of overdose. Toxicological and demographic data from studies of heroin overdose deaths do not support these assumptions. The surge in the use of pharmaceutical opioids provides an example of the legal delivery of opioids of known dosage and free of contaminants, where overdose deaths can be examined to test these assumptions. Rates of fatal opioid overdose have escalated, with increased rates of prescribing of pharmaceutical opioids. On the basis of the experience with prescription opioids, unregulated legal heroin access would not reduce overdose rates.

Comparison of toxicity associated with nonmedical use of benzodiazepines with buprenorphine or methadone

BACKGROUND

Polysubstance use is prevalent in individuals using buprenorphine or methadone nonmedically, with benzodiazepines being a common co-ingestant. The objective of this study was to compare the severity of buprenorphine and methadone toxicity with concomitant use of benzodiazepines.

METHODS

A retrospective analysis of buprenorphine and methadone cases from November 1, 2002 to December 31, 2010 reported to the American Association of Poison Control Centers' National Poison Data System (NPDS) was conducted.

INCLUSION CRITERIA

age ≥ 18 years, nonmedical use of methadone with benzodiazepines (methadone-BZD) or buprenorphine with benzodiazepines (BUP-BZD), and case followed to a documented outcome. Cases with co-ingestants other than benzodiazepines were excluded. Clinical effects, treatments, disposition and final medical outcomes were evaluated.

RESULTS

There were 692 methadone-BZD cases and 72 BUP-BZD cases. Clinical effects in methadone-BZD and BUP-BZD groups were lethargy (71.1%, 59.7%), respiratory depression (29.0%, 15.3%), coma (22.4%, 5.6%), respiratory arrest (4.5%, 0), hypotension (11.8%, 2.8%) and cardiac arrest (1.9%, 0), respectively. Patients in the methadone-BZD group were four-times more likely to receive naloxone (60.4% vs 15.3%) or be intubated (16.3% vs 4.2%) than in the BUP-BZD group. Hospitalization rates were highest for methadone-BZD patients with 67.3% receiving medical admissions compared to 43.3% of BUP-BZD patients. Outcomes were more serious for methadone-BZD cases (p<0.0001); while there were no BUP-BZD deaths, exposure to methadone-BZD yielded 16 deaths.

CONCLUSIONS

Nonmedical use of benzodiazepines with methadone is associated with higher hospitalization rates, greater ICU utilization rates and considerably worse medical outcomes when compared to nonmedical use of benzodiazepines with buprenorphine.

Opioid-related mortality and filled prescriptions for buprenorphine and methadone

INTRODUCTION AND AIMS

To assess opioid-related mortality and correlation with filled prescriptions for buprenorphine and methadone.

DESIGN AND METHODS

A register study, including data from the Swedish Forensic Pathology and Forensic Toxicology databases 2003-2010, the Prescribed Drug Register and the National Patient Register.

RESULTS

A total of 1301 deaths, assessed as related to buprenorphine, methadone or heroin, or a combination of them, were studied. The largest number of fatalities was related to intake of heroin (n = 776), followed by methadone (n = 342) and buprenorphine (n = 168). The total annual number of fatal cases related to the studied drugs more than doubled (116 to 255) during the study period. There were increases in mortality related to both buprenorphine and methadone: from 1 to 49 cases for buprenorphine, and from 19 to 81 cases for methadone. Only one-fifth of the fatal cases had a filled prescription for the maintenance drug assessed as the cause of death.

DISCUSSION AND CONCLUSION

This study showed that most fatalities were not related to filled prescriptions of maintenance drugs, and a substantial illicit use of buprenorphine and methadone resulting in deaths was revealed. To prevent opioid toxicity deaths it is important to make efforts not only to reduce drug diversion from maintenance programs, but also to improve the control of drug trafficking and other illegal sources.

Buprenorphine and norbuprenorphine determination in mice plasma and brain by gas chromatography-mass spectrometry

A gas chromatography tandem mass spectrometry method for quantification of buprenorphine (BUP) and norbuprenorphine (NBUP) in brain and plasma samples from mice was developed and validated. Analytes were extracted from the brain or plasma by solid phase extraction and quantified within 20 minutes. Calibration was achieved by linear regression with a 1/x weighting factor and d₄-buprenorphine internal standard. All products were linear from 1 to 2000 ng/mL with a correlation of determination >0.99. Assay accuracy and precision of back-calculated standards were within ±10%. The lower limit of quantification for both BUP and NBUP from the brain and plasma was 1 ng/mL. This sensitive and specific method can be used for the investigation of BUP mechanism of action and clinical profile.

Mortality among clients seeking treatment for buprenorphine abuse in Finland

BACKGROUND

It is unclear whether buprenorphine abuse is associated with a similar risk of death to other substance abuse. This study examined all-cause mortality rates and causes of deaths among clients seeking treatment for buprenorphine abuse.

METHODS

Structured clinical interviews were conducted with 4685 clients between January 1998 and August 2008. Records of deaths that occurred among these clients were extracted from the Official Causes of Death Register in Finland. Standardized mortality ratios (SMRs) with 95% confidence intervals (CI) were computed using national mortality rates over a 13-year follow-up to examine excess mortality. Kaplan-Meier survival analysis was used to compare survival between buprenorphine and other clients.

RESULTS

Sixty-one of 780 (7.8%) clients who sought treatment for buprenorphine abuse and 408 of 3905 (10.4%) other clients died during the 13-year follow-up period. The most common cause of death was drug-related in buprenorphine (n=25, 41.0%) and other clients (n=142, 34.8%). Survival rates were similar among buprenorphine and other clients (log-rank χ[df=1](2)=0.215, p=0.643). The SMR was 3.0 (95% CI 2.3-3.8) and 3.1 (95% CI 2.8-3.4) for buprenorphine and other clients, respectively. Excess mortality was highest among women aged 20-29 years, and more pronounced in buprenorphine clients (SMR 27.9 [95% CI 12.6-49.0]) compared to other clients (SMR 14.0 [95% CI 9.3-19.6]).

CONCLUSIONS

Clients seeking treatment for buprenorphine abuse had a three times higher mortality rate than the national average, with the excess risk highest among female clients. Overall mortality rates were similar among clients seeking treatment for buprenorphine and other substance abuse.

Pharmacotherapies for treating opioid use disorder

Opioid use disorder (OUD) is a major public health problem in the United States. It has resulted in devastating consequences for people with this condition, including psychosocial and legal problems, in addition to contraction of infectious diseases such as HIV and hepatitis B and C. Furthermore, this disease can cause fatalities from drug overdoses and drug-drug interactions. OUD shatters families and destroys relationships. Effective treatment is crucial in order to curtail the consequences of this condition. The objective of this article is to provide a review of the pharmacotherapies currently being used to treat OUD.

Risks, management, and monitoring of combination opioid, benzodiazepines, and/or alcohol use

The concurrent use of opioids, benzodiazepines (BZDs), and/or alcohol poses a formidable challenge for clinicians who manage chronic pain. While the escalating use of opioid analgesics for the treatment of chronic pain and the concomitant rise in opioid-related abuse and misuse are widely recognized trends, the contribution of combination use of BZDs, alcohol, and/or other sedative agents to opioid-related morbidity and mortality is underappreciated, even when these agents are used appropriately. Patients with chronic pain who use opioid analgesics along with BZDs and/or alcohol are at higher risk for fatal/nonfatal overdose and have more aberrant behaviors. Few practice guidelines for BZD treatment are readily available, especially when they are combined clinically with opioid analgesics and other central nervous system-depressant agents. However, coadministration of these agents produces a defined increase in rates of adverse events, overdose, and death, warranting close monitoring and consideration when treating patients with pain. To improve patient outcomes, ongoing screening for aberrant behavior, monitoring of treatment compliance, documentation of medical necessity, and the adjustment of treatment to clinical changes are essential. In this article, we review the prevalence and pharmacologic consequences of BZDs and/or alcohol use among patients with pain on chronic opioid therapy, as well as the importance of urine drug testing, an indispensable tool for therapeutic drug monitoring, which helps to ensure the continued safety of patients. Regardless of risk or known aberrant drug-related behaviors, patients on chronic opioid therapy should periodically undergo urine drug testing to confirm adherence to the treatment plan.

Urine specimen detection of concurrent nonprescribed medicinal and illicit drug use in patients prescribed buprenorphine

Patients being treated with buprenorphine usually have a history of opioid dependence and may be predisposed to misuse of drugs. Concurrent drug misuse increases the risk of life-threatening drug interactions. This retrospective data analysis observed which nonprescribed and illicit drugs were most commonly detected in the urine of patients from pain management clinics taking buprenorphine with or without a prescription. GC, LC/MS and LC-MS-MS were used to quantify 20,929 urine specimens. The most prevalent illicit drug used in both the groups (prescribed and nonprescribed buprenorphine) was marijuana, followed by cocaine. The most prevalent nonprescribed medications abused by both the groups were benzodiazepines, followed by oxycodone and hydrocodone. The overall prevalence of illicit and nonprescribed drug use was significantly higher in subjects who used buprenorphine without a prescription versus prescribed use. Of the concurrent use of marijuana and cocaine with buprenorphine, cocaine is most concerning since it decreases exposure to buprenorphine (lower area under the concentration-time curve and maximum concentration). The concurrent use of nonprescribed benzodiazepines with buprenorphine can cause excess sedation leading to respiratory depression and even death. These findings highlight the importance of educating patients about these potential toxicities. Furthermore, pain providers should consider expanding the spectrum of drugs that they monitor in patients under treatment.

Quantitative paper spray mass spectrometry analysis of drugs of abuse

An ambient method for rapid monitoring and quantitation of drugs of abuse in dried blood spots was developed using paper spray tandem mass spectrometry (PS-MS).

Metabolic and toxicological considerations of the opioid replacement therapy and analgesic drugs: methadone and buprenorphine

INTRODUCTION

Methadone and buprenorphine are maintenance replacement therapies for opioid dependence; they are also used for pain management. Methadone and buprenorphine (to a lesser extent) have seen sharp increases in mortality associated with their use. They have distinct routes of metabolism (mostly cytochrome P450 dependent), and distinct pharmacologic activity of metabolites. As such, metabolism may play a role in differences in their toxicity.

AREAS COVERED

This article reviews peer-reviewed literature obtained from PubMed searches and literature referenced within. The review considers first an overview of drug use and mortality over the past decade. It then provides extensive detail on the in vitro and in vivo human metabolism of methadone and buprenorphine. Using both human and experimental animal studies it then presents the pharmacodynamic activity of parent drug and metabolites at the mu-opioid receptor, as P-glycoprotein substrates and plasma/brain concentration ratios, and activity at the hERG K(+) channel. Lessons learned from drug interaction studies in humans are then examined in an attempt to bring together the combined information.

EXPERT OPINION

The use and misuse of these drugs contributes to the epidemic in opioid-associated mortalities. A better understanding of metabolism-, transport- and co-medication-induced changes will contribute to their safer use.

Opioid agonist treatments and heroin overdose deaths in Baltimore, Maryland, 1995-2009

OBJECTIVES

We examined the association between the expansion of methadone and buprenorphine treatment and the prevalence of heroin overdose deaths in Baltimore, Maryland from 1995 to 2009.

METHODS

We conducted a longitudinal time series analysis of archival data using linear regression with the Newey-West method to correct SEs for heteroscedasticity and autocorrelation, adjusting for average heroin purity.

RESULTS

Overdose deaths attributed to heroin ranged from a high of 312 in 1999 to a low of 106 in 2008. While mean heroin purity rose sharply (1995-1999), the increasing number of patients treated with methadone was not associated with a change in the number of overdose deaths, but starting in 2000 expansion of opioid agonist treatment was associated with a decline in overdose deaths. Adjusting for heroin purity and the number of methadone patients, there was a statistically significant inverse relationship between heroin overdose deaths and patients treated with buprenorphine (P = .002).

CONCLUSIONS

Increased access to opioid agonist treatment was associated with a reduction in heroin overdose deaths. Implementing policies that support evidence-based medication treatment of opiate dependence may decrease heroin overdose deaths.