Gender and strain contributions to the variability of buprenorphine-related respiratory toxicity in mice

An automated respiratory data pipeline for waveform characteristic analysis

Comprehensive and accurate analysis of respiratory and metabolic data is crucial to modelling congenital, pathogenic and degenerative diseases converging on autonomic control failure. A lack of tools for high-throughput analysis of respiratory datasets remains a major challenge. We present Breathe Easy, a novel open-source pipeline for processing raw recordings and associated metadata into operative outcomes, publication-worthy graphs and robust statistical analyses including QQ and residual plots for assumption queries and data transformations. This pipeline uses a facile graphical user interface for uploading data files, setting waveform feature thresholds and defining experimental variables. Breathe Easy was validated against manual selection by experts, which represents the current standard in the field. We demonstrate Breathe Easy's utility by examining a 2-year longitudinal study of an Alzheimer's disease mouse model to assess contributions of forebrain pathology in disordered breathing. Whole body plethysmography has become an important experimental outcome measure for a variety of diseases with primary and secondary respiratory indications. Respiratory dysfunction, while not an initial symptom in many of these disorders, often drives disability or death in patient outcomes. Breathe Easy provides an open-source respiratory analysis tool for all respiratory datasets and represents a necessary improvement upon current analytical methods in the field. KEY POINTS: Respiratory dysfunction is a common endpoint for disability and mortality in many disorders throughout life. Whole body plethysmography in rodents represents a high face-value method for measuring respiratory outcomes in rodent models of these diseases and disorders. Analysis of key respiratory variables remains hindered by manual annotation and analysis that leads to low throughput results that often exclude a majority of the recorded data. Here we present a software suite, Breathe Easy, that automates the process of data selection from raw recordings derived from plethysmography experiments and the analysis of these data into operative outcomes and publication-worthy graphs with statistics. We validate Breathe Easy with a terabyte-scale Alzheimer's dataset that examines the effects of forebrain pathology on respiratory function over 2 years of degeneration.

Buprenorphine differentially alters breathing among four congenic mouse lines as a function of dose, sex, and leptin status

The opioid buprenorphine alters breathing and the cytokine leptin stimulates breathing. Obesity increases the risk for respiratory disorders and can lead to leptin resistance. This study tested the hypothesis that buprenorphine causes dose-dependent changes in breathing that vary as a function of obesity, leptin status, and sex. Breathing measures were acquired from four congenic mouse lines: female and male wild type C57BL/6J (B6) mice, obese db/db and ob/ob mice with leptin dysfunction, and male B6 mice with diet-induced obesity. Mice were injected intraperitoneally with saline (control) and five doses of buprenorphine (0.1, 0.3, 1.0, 3.0, 10 mg/kg). Buprenorphine caused dose-dependent decreases in respiratory frequency while increasing tidal volume, minute ventilation, and respiratory duty cycle. The effects of buprenorphine varied significantly with leptin status and sex. Buprenorphine decreased minute ventilation variability in all mice. The present findings highlight leptin status as an important modulator of respiration and encourage future studies aiming to elucidate the mechanisms through which leptin status alters breathing.

Effects of opioids on respiration assessed by a contact-free unconstraint respiratory monitor with load cells under the bed in patients with advanced cancer

Nocturnal periodic breathing of chronic opioid users has been predominantly documented by the use of polysomnography. No previous studies have assessed the opioid effects of respiratory rhythms throughout the day without the use of physical restraint. We recently developed a contact-free unconstraint vital sign monitoring system with four load cells placed under the bed legs, which allows continuous measurements of respiratory change at the center of gravity on the bed. We aimed to reveal details of the patient's 24-h respiratory status under a monitoring system and to test the hypothesis that respiratory rhythm abnormalities are opioid dose-dependent and worsen during the night time. Continuous 48-h respiratory measurements were successfully performed in 51 patients with advanced cancer (12 opioid-free patients and 39 opioid-receiving patients). Medians of respiratory variables with minimal body movement artifacts were calculated for each 8-h split time period. Compared with opioid-free patients, opioid-receiving patients had slower respiratory rate with higher respiratory rate irregularity without changing tidal centroid shift regardless of the time period. Irregular ataxic breathing was only identified in opioid-receiving patients (33%, P = 0.023) whereas incidence rate of periodic breathing did not differ between the groups. Multivariate regression analyses revealed that opioid dose was an independent risk factor for occurrence of irregular breathing [odds ratio 1.81 (95% CI: 1.39-2.36), P < 0.001], and ataxic breathing [odds ratio 2.08 (95% CI: 1.60-2.71), P < 0.001]. Females developed the ataxic breathing at lower opioid dose compared with males. We conclude that respiratory rhythm irregularity is a predominant specific feature of opioid dose-dependent respiratory depression particularly in female patients with advanced cancer.NEW & NOTEWORTHY Through usage of a novel contact-free unconstraint vital sign monitoring system with four load cells placed under the bed legs allowing continuous measurements of respiratory changes of center of gravity on the bed, this study is the first to assess detailed respiratory characteristics throughout day and night periods without interference of daily activities in patients with advanced cancer receiving opioids. Respiratory rhythm irregularity is a predominant specific feature of opioid dose-dependent respiratory depression particularly in female patients with advanced cancer.

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.

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.