Effect of sustained high buprenorphine plasma concentrations on fentanyl-induced respiratory depression: A placebo-controlled crossover study in healthy volunteers and opioid-tolerant patients.

BACKGROUND: Opioid-induced respiratory depression driven by ligand binding to mu-opioid receptors is a leading cause of opioid-related fatalities. Buprenorphine, a partial agonist, binds with high affinity to mu-opioid receptors but displays partial respiratory depression effects. The authors examined whether sustained buprenorphine plasma concentrations similar to those achieved with some extended-release injections used to treat opioid use disorder could reduce the frequency and magnitude of fentanyl-induced respiratory depression. METHODS: In this two-period crossover, single-centre study, 14 healthy volunteers (single-blind, randomized) and eight opioid-tolerant patients taking daily opioid doses ≥90 mg oral morphine equivalents (open-label) received continuous intravenous buprenorphine or placebo for 360 minutes, targeting buprenorphine plasma concentrations of 0.2 or 0.5 ng/mL in healthy volunteers and 1.0, 2.0 or 5.0 ng/mL in opioid-tolerant patients. Upon reaching target concentrations, participants received up to four escalating intravenous doses of fentanyl. The primary endpoint was change in isohypercapnic minute ventilation (VE). Additionally, occurrence of apnea was recorded. RESULTS: Fentanyl-induced changes in VE were smaller at higher buprenorphine plasma concentrations. In healthy volunteers, at target buprenorphine concentration of 0.5 ng/mL, the first and second fentanyl boluses reduced VE by [LSmean (95% CI)] 26% (13-40%) and 47% (37-59%) compared to 51% (38-64%) and 79% (69-89%) during placebo infusion (p = 0.001 and < .001, respectively). Discontinuations for apnea limited treatment comparisons beyond the second fentanyl injection. In opioid-tolerant patients, fentanyl reduced VE up to 49% (21-76%) during buprenorphine infusion (all concentration groups combined) versus up to 100% (68-132%) during placebo infusion (p = 0.006). In opioid-tolerant patients, the risk of experiencing apnea requiring verbal stimulation following fentanyl boluses was lower with buprenorphine than with placebo (odds ratio: 0.07; 95% CI: 0.0 to 0.3; p = 0.001). INTERPRETATION: Results from this proof-of-principle study provide the first clinical evidence that high sustained plasma concentrations of buprenorphine may protect against respiratory depression induced by potent opioids like fentanyl.

Pharmacokinetics of buprenorphine in pregnant sheep after intravenous injection.

Buprenorphine is a semi-synthetic opioid, widely used in the maintenance treatment for opioid-dependent pregnant women. Limited data exist on the pharmacokinetics of buprenorphine in pregnancy. We conducted a pharmacokinetic study to determine the pharmacokinetics of intravenous buprenorphine in pregnant sheep. Fourteen pregnant sheep in late gestation received 10 µg/kg of buprenorphine as an intravenous bolus injection. Plasma samples were collected up to 48 h after administration. Buprenorphine and its metabolite, norbuprenorphine, were quantified from plasma using a LC/MS/MS method, with lower limits of quantification of 0.01 µg/L and 0.04 µg/L for buprenorphine and norbuprenorphine, respectively. The pharmacokinetic parameters were calculated using noncompartmental analysis. The pharmacokinetic parameters, median (minimum-maximum), were Cmax 4.31 µg/L (1.93-15.5), AUCinf 2.89 h*µg/L (1.72-40.2), CL 3.39 L/h/kg (0.25-6.02), terminal t½ 1.75 h (1.07-31.0), Vss 8.04 L/kg (1.05-49.3). Norbuprenorphine was undetected in all plasma samples. The median clearance in pregnant sheep was higher than previously reported for nonpregnant sheep and human (male) subjects. Our sensitive analytical method was able to detect long terminal half-lives for six subjects, and a wide between-subject variability in the study population. Significance statement: Buprenorphine is widely used for the treatment of opioid use disorder in pregnancy. However, limited data exist on the pharmacokinetics of buprenorphine during pregnancy. As this type of study cannot be done in humans due to ethical reasons, we conducted a study in pregnant sheep. This study provides pharmacokinetic data on buprenorphine in pregnant sheep and helps us to understand the pharmacokinetics of the drug in humans.

Factors Associated with Low Bone Density in Opioid Substitution Therapy Patients: A Systematic Review.

Background: Long-term opioid therapy is a risk factor for low bone mineral density (BMD). However, other factors may also contribute to low BMD. Several studies have examined the variables that might contribute to low BMD in patients receiving opioid replacement therapy (OST). However, to our knowledge, there was no systemic review conducted to address this particular issue. Thus, we reviewed the articles on the factors associated with low BMD in the population of opioid use disorder receiving substitution therapy. Methods: The articles that examined correlates or risk factors of low BMD in OST population were retrieved from OVID, SCOPUS, and PUBMED from inception until July 2020 by two independent investigators. Results: A total of 429 articles from three databases were retrieved initially. After screening based on eligibility criteria, five articles were included in the final analysis. The risk factors or correlates found to be significantly associated with low BMD in the OST population include male gender, low body mass index, low testosterone level, methadone or heroin use, and longer duration of heavy alcohol use. The review limitations include small sample sizes and inconsistent definition of variables. Conclusion: OST patients should be screened for BMD and its associated factors. Guidelines and training of practitioners involving in the OST service should be provided to increase the detection of low BMD in the OST population.

Pharmacogenomics biomarkers for personalized methadone maintenance treatment: The mechanism and its potential use.

Methadone has a wide pharmacokinetic interindividual variability, resulting in unpredicted treatment response. Pharmacogenomic biomarkers seem promising for personalized methadone maintenance treatment. The evidence supports the use of ABCB1 single-nucleotide polymorphism (SNP) 1236C>T with genotypes C/T or C/C (Jewish) and haplotypes AGCTT carrier, AGCGC heterozygote, or non-carrier (Caucasian), which have a predicted lower methadone dose requirement. In contrast, ABCB1 SNP 1236C>T with genotype T/T (Jewish); haplotypes AGCGC homozygote, AGCTT non-carrier (Caucasian), and ABCB1 3435C>T variant carrier; and haplotypes CGT, TTC, and TGT (Han Chinese) have a predicted higher methadone dose. For methadone plasma levels, ABCB1 diplotype non-CGC/TTT (Malay) predicted lower, and diplotype CGC/TTT (Malay), 3435C>T allelic carrier, haplotypes (CGT, TTC, TGT) (Han Chinese) predicted higher methadone levels. In terms of metabolism biomarkers, a lower methadone requirement was related to carriers of CYP2B6 genotypes *4(G/G) and *9(T/T) among Jewish patients, CYP2B6*9 genotype (T/T) and haplotypes (TA/TG); and CYP2C19 (*2/*2,*2/*3, and *3/*3; Han Chinese). Higher methadone dose was observed in CYP2C19*1 allelic carriers (Han Chinese) and CYP2D6 ultrarapid metabolizer (Caucasian). Lower methadone levels were reported in CYP2B6 SNPs, haplotypes TTT, and AGATAA (Han Chinese), CYP2C19 genotype *1/*1 (Han Chinese), allelic carrier *1xN (Caucasian), and CYP3A4 genotype *1/*1 (Caucasian). Carriers of CYP2B6 genotype *6/*6 (Caucasian), CYP2B6 haplotypes ATGCAG and ATGCTG (Han Chinese), and CYP3A4 genotype *1/*1B (Caucasian) had predicted higher methadone plasma levels. Specific pharmacokinetics biomarkers have potential uses for personalized methadone treatment in specific populations.

Association of Testosterone Levels and Steroid 5-Alpha-Reductase 2 Polymorphisms with Opioid Craving.

BACKGROUND/AIMS: Opioid dependence is a severe disease which is associated with a high risk of relapse, even in cases of successful withdrawal therapy. Studies have shown alterations of the hypothalamic-pituitary-gonadal axis in opioid-dependent patients, such as decreased testosterone serum levels in affected males. Sex hormones and the steroid 5-alpha-reductase 2 (SRD5A2) V89L polymorphism are associated with craving during alcohol withdrawal, but little is known about their impact on symptomatology of opioid dependence. METHODS: In this study, we analyzed 2 independent male cohorts of opioid-dependent patients for possible alterations in testosterone serum levels compared to non-opioid-dependent controls. In one of the cohorts, we additionally investigated associations of testosterone serum levels and 3 SRD5A2 polymorphisms with symptoms of opioid dependence, measured by the Heroin Craving Questionnaire (HCQ). RESULTS: In the patient groups, we found significantly decreased testosterone serum levels compared to the control groups. Furthermore, we found significant associations of both the testosterone serum levels and the SRD5A2 V89L polymorphism with opioid craving assessed by the HCQ. CONCLUSION: Our data show a possible role of testosterone metabolism in opioid dependence, which may be relevant for the establishment of future treatment strategies.

Opioid Overdose Deaths with Buprenorphine Detected in Postmortem Toxicology: a Retrospective Analysis.

BACKGROUND: Buprenorphine is a unique µ-opioid receptor partial agonist with avid receptor binding, nominal euphoric reward, and a ceiling effect on sedation and respiratory depression. Despite a pharmacologic profile that enhances safety, cases of fatal opioid overdose with buprenorphine on postmortem toxicology are reported, but details of these cases in the literature are limited. METHODS: A retrospective review of opioid-involved drug overdose fatalities in Rhode Island (RI) from 2016 to 2018 using the RI Department of Health State Unintentional Drug Overdose Reporting System (SUDORS) database. Deaths with buprenorphine on toxicology testing versus opioid-involved overdose deaths without buprenorphine were compared to assess the type and number of co-exposures. RESULTS: Of 534 opioid-involved deaths, 29 (5.4%) included buprenorphine and/or norbuprenorphine on toxicology. Most frequent co-exposures are as follows: fentanyl (75.9%), norfentanyl (72.4%), cocaine (41.4%), benzoylecgonine (41.4%), cannabinoids (31.0%), ethanol (31.0%), levamisole (31.0%), and free morphine (31.0%). An average number of co-exposures for fatalities with buprenorphine were 9.24 versus 6.68 in those without buprenorphine. In one case buprenorphine was the only drug listed to cause death; all other fatalities with buprenorphine on toxicology reported additional drugs contributing to death. CONCLUSION: Decedents with buprenorphine detected on toxicology testing commonly had documented polysubstance use. Although data are limited, buprenorphine may provide some risk mitigation against full agonist opioid overdose including fentanyl. Further work should explore the use of postmortem concentrations of buprenorphine, norbuprenorphine, and other opioid metabolites to determine the role of buprenorphine in fatal overdose pharmacology.

Evaluation of the Effects of High Intensity Interval Training on Cytokine Levels and Clinical Course in Treatment of Opioid Use Disorder. / Opioid Kullanim BozukluguTedavisinde Yüksek Yogunluklu Aralikli Egzersizin Sitokin Düzeyleri ve Klinik Seyir Üzerine Etkileri.

OBJECTIVE: Opioid use disorder (OpUD) is a biological and psychosocial disorder with limited treatment options. Addition of physical exercise to the pharmacological treatment has been proposed to be effective on reducing substance use and improving the quality of life. In this study we aimed to investigate the effects of a high-intensity interval training (HIIT) program on the serum levels of cortisol, insulin-like growth factor1 (IGF-1), interferon-gamma (IFN-γ), interleukin 17 (IL-17) and the clinical progress of inpatients with OpUD. METHOD: Our study enrolled 22 male inpatients diagnosed with OpUD on the basis of the DSM-5 criteria. Two groups of 11 individuals were formed as the exercise (EG) and the control (CG) groups. The EG conducted 5 sessions of a HIIT. Participant data were collected with Sociodemographic Questionnaire, the Addiction Profile Index (API), and the Barratt Impulsiveness Scale (BIS-11). Also, the Hamilton Depression Rating Scale (HAM-D), the Hamilton Anxiety Rating Scale (HAM-A) and the Substance Craving Scale (SCS) were used before and after the treatment program in order to evaluate the clinical progress. Blood samples were collected on the 5th and the 21st days for estimation of the serum cortisol, IGF-1, IFN-γ and the IL-17 levels. RESULTS: Comparison of the pre- and the post- treatment performances of the two groups on the HAM-D, the HAM-A and the SCS indicated a significant drop in the respective scores of the EG. Also, a significant increase was observed in the post-treatment IGF-1 level of the EG as compared to the CG. No differences were observed between the cortisol, IFN-γ and IL-17 levels of the EG and the CG. CONCLUSION: HIIT resulted in significant reduction in the symptoms of depression, anxiety and substance craving, and increased the serum IGF-1 levels. HIIT did not change serum cortisol, IFN-γ and IL-17 levels. We believe this research will contribute to the literature on the treatment of opioid depencence by emphasising the effects of HIIT on patients treated for OpUD.

Free Testosterone and Prolactin Levels and Sperm Morphology and Function Among Male Patients With Tramadol Abuse: A Case-Control Study.

BACKGROUND/PURPOSE: Tramadol abuse has become a crisis in Egypt and many other Middle Eastern countries. Tramadol abuse is associated with sexual dysfunction and male infertility, according to recent animal and human studies. The objective of this study was to compare tramadol abuse patients and healthy controls regarding free testosterone and prolactin levels and semen analysis. METHODS: Sixty patients with opiate use disorders attributed to tramadol (OUD-T) based on Diagnostic and Statistical Manual of Mental Disorders (Fifth Edition) diagnostic criteria and 30 healthy controls were included in the study. Sociodemographic and clinical data and urine, blood, and semen samples were collected from patients and controls for assessment. RESULTS: Compared with controls, OUD-T patients had higher prolactin and lower free testosterone levels. Patients with OUD-T were more likely to have lower sperm count and higher abnormal motility and forms of sperms compared with controls. CONCLUSIONS: Patients with OUD-T were found to be more likely to have lower free testosterone levels and lower sperm counts and vitality, and higher prolactin levels and sperm abnormal forms compared with controls.

Stress indices in methadone maintenance treatment - Cross sectional and follow up study.

To study the prevalence of perceived high stress among methadone maintenance treatment (MMT) patients, and whether stress can predict outcome, and whether stress may improve during treatment, we studied a sample of 107 MMT patients using Perceived Stress Scale (PSS) questionnaires. We studied if PSS scores on admission predict long-term retention, and we monitored stress indices (PSS, heart rate variability, saliva cortisol) on admission, 6 and 12 months later, to measure changes. Variables included demographic data, history of adverse events, and urine test. A sample of 79 (73.8%) males and 28 (26.2%) females whose age at opioid use onset was 22.1±7.2 years and age at study onset 50.5±10.8 years was studied for PSS. Both high and very-high PSS patients characterized (logistic regression) as abusing benzodiazepine, and with history of depressive symptoms. The very-high PSS group on admission (n=29) had shorter cumulative retention (1.8 years, 95%%CI 1.2-2.4) compared with 50 others (2.8 years, 95%%CI 2.3-3.3, p=0.03). Monitoring stress indices among 25 patients found that no-benzodiazepine and cocaine use on admission, opioid discontinuation after 6 months, and any substance discontinuation after a year were associated with stress reduction. Conclusion: stress level appears to normalize among MMT patients if no other substance is abused.

Genetic variants in NECTIN4 encoding an adhesion molecule are associated with continued opioid use.

Methadone is a synthetic opioid used as maintenance treatment for patients addicted to heroin. Skin irritation is one of the adverse events caused by opioid use. 344 methadone maintenance treatment (MMT) patients were recruited with records and measurements on methadone dose, plasma methadone concentrations, and treatment emergent symptom scales (TESS). 15 patients reported with skin irritation. Five SNPs located within the NECTIN4 genetic region were genotyped. The NECTIN4 gene within the adherens junction interaction pathway was associated with methadone dose in pathway-based genome wide association analyses (P = 0.0008). Three highly-linked SNPs, rs11265549, rs3820097, and rs4656978, were significantly associated with methadone dose (P = 0.0003), plasma concentrations of R,S-methadone (P = 0.0004) and TNF-α (P = 0.010) in all 344 MMT patients, and with self-report skin irritation symptom scores (P = 0.010) in the 15 MMT patients who reported with skin irritation. To identify the possible roles of plasma level of Nectin-4 in the responses to MMT and opioid use, additional age- and gender-matched 51 controls and 83 methadone-free abstinent former heroin users were recruited. Plasma level of Nectin-4 was the highest in MMT patients among the three groups. The results suggest involvement of genetic variants on NECTIN4 in methadone dose. Plasma Nectin-4 level is likely an indicator for continued use of opioids.

Discovery and validation of biomarkers to aid the development of safe and effective pain therapeutics: challenges and opportunities.

Pain medication plays an important role in the treatment of acute and chronic pain conditions, but some drugs, opioids in particular, have been overprescribed or prescribed without adequate safeguards, leading to an alarming rise in medication-related overdose deaths. The NIH Helping to End Addiction Long-term (HEAL) Initiative is a trans-agency effort to provide scientific solutions to stem the opioid crisis. One component of the initiative is to support biomarker discovery and rigorous validation in collaboration with industry leaders to accelerate high-quality clinical research into neurotherapeutics and pain. The use of objective biomarkers and clinical trial end points throughout the drug discovery and development process is crucial to help define pathophysiological subsets of pain, evaluate target engagement of new drugs and predict the analgesic efficacy of new drugs. In 2018, the NIH-led Discovery and Validation of Biomarkers to Develop Non-Addictive Therapeutics for Pain workshop convened scientific leaders from academia, industry, government and patient advocacy groups to discuss progress, challenges, gaps and ideas to facilitate the development of biomarkers and end points for pain. The outcomes of this workshop are outlined in this Consensus Statement.

Intravenous calcium Gluconate alleviates Lead-induced abdominal pain, a randomized clinical trial.

BACKGROUND: In 2016, in a lead poisoning outbreak in Iran, physicians reported thousands of opium users who presented to emergency departments (EDs) with intractable severe abdominal pain which did not respond to any narcotic medication. During the same period of time, we investigated the efficacy of intravenous calcium gluconate in alleviating lead-induced abdominal pain. METHODS: In a single-center, single blinded, randomized controlled trial, a convenient sample of adult opium-addicted patients who presented to an academic ED with abdominal pain and had an initial diagnosis of lead poisoning were included and randomly subjected to two treatment groups receiving conventional treatment (morphine 0.1 mg/kg + normal saline; group 1) and conventional treatment plus 1 g of intravenous calcium gluconate (group 2) to alleviate their abdominal pain. The visual analogue scale (VAS) was determined by each patient (0 to 100 mm) before treatment, and 15, 30, and 60 min after intervention. RESULTS: A total of 50 patients (25 in each group) were enrolled. Blood lead levels, VAS scores before treatment, and mean administered dose of morphine were similar between the two groups. After treatment, mean VAS score dropped to 64.7± 10.4 vs. 67.1± 10.9 at 15 min (P = 0.437), 64.6± 10.9 vs. 58.0 ± 11.2 at 30 min (P = 0.041), and 63.8± 10.7 vs. 53.6± 10.9 at 60 min (P = 0.002) in groups 1 and 2, respectively. CONCLUSION: Intravenous calcium gluconate administration along with morphine can improve abdominal pain in lead poisoning due to the ingestion of lead-contaminated opium. Further interventional studies are recommended to see if response to calcium salts in suspected lead-induced abdominal pain can rule in lead toxicity. TRIAL REGISTRATION: IRCT20171009036661N2. Registered 27 May 2018 - Retrospectively registered.

Female and male rats readily consume and prefer oxycodone to water in a chronic, continuous access, two-bottle oral voluntary paradigm.

The increasing abuse of opioids - such as oxycodone - poses major challenges for health and socioeconomic systems. Human prescription opioid abuse is marked by chronic, voluntary, oral intake and sex differences. To develop interventions, the field would benefit from a preclinical paradigm that similarly provides rodents with chronic, continuous, oral, voluntary and free-choice access to oxycodone. Here we show female and male rats voluntarily ingest and choose oxycodone over water and show both dependence and motivation to take oxycodone during a chronic oral voluntary, two-bottle choice, continuous access paradigm. Adult female and male Long-Evans rats were given unlimited, continuous homecage access to two bottles containing water (Control) or one bottle of water and one bottle of oxycodone dissolved in water (Experimental). Virtually all experimental rats voluntarily drank oxycodone (~10 mg/kg/day) and escalated their intake over 22 weeks. Females self-administered twice as much oxycodone by body weight (leading to higher blood levels of oxycodone) and engaged in more gnawing behavior of wooden blocks relative to males. Precipitated withdrawal revealed high levels of dependence in both sexes. Reflecting motivation to drink oxycodone, ascending concentrations of citric acid suppressed the intake of oxycodone (Experimental) and the intake of water (Control); however, Experimental rats returned to pre-citric acid preference levels whereas Controls rats did not. Pre-screening behaviors of rats on open field exploration predicted oxycodone intake. Thus, rats consumed and preferred oxycodone over time in this chronic two-bottle oral choice paradigm and both sexes displayed many features of human oxycodone abuse.

Determination of thallium in urine, blood, and hair in illicit opioid users in Iran.

CONTEXT: Heavy metals, including thallium and lead, are introduced to illicit drug users' body as a result of using drugs such as cocaine and heroin. OBJECTIVE: This study aimed to determine urine, blood, and hair thallium (Tl) concentrations in illicit opioid users along with the relevant clinical signs and symptoms consistent with thallotoxicosis and to compare them with the corresponding variables in the control non-opioid user group. MATERIALS AND METHODS: This case-control study was conducted on 50 illicit opioid users who had abused opioids continuously for more than a year, referred to Amirie Drug Abuse Treatment Clinic in Kashan, Iran. The control group included 50 non-opioid users. Thallium concentrations in urine, blood, and hair were assessed in both groups (n = 100) using electrothermal (graphite furnace) atomic absorption spectrometry (ET AAS, GF AAS). RESULTS: In the studied group, the median (interquartile range) concentrations of thallium in urine, blood, and hair were 54.8 ± 79.9 µg/L, 14.5 ± 11.1 µg/L, and 5.4 ± 3.7 µg/g, respectively; these values were 4.8 ± 5.2 µg/L, 2.5 ± 2.4 µg/L, and 1.4 ± 1.1 µg/g, respectively, in the control group. There were significant differences in urine, blood, and hair thallium concentrations between the study group and the control group (p < 0.001). There were significant correlations between duration of illicit opioid use and urine thallium concentrations (r = 0.394, p = 0.005) and hair thallium concentrations (r = 0.293, p = 0.039), but not with blood thallium concentrations (r = 0.246, p = 0.085). Urine and blood thallium concentrations of illicit opioid users with clinical signs and symptoms consistent with thallotoxicosis of weakness (p = 0.01), depression (p = 0.03), and headache (p = 0.03) were higher than users without these problems. DISCUSSION AND CONCLUSION: The results of the study showed that thallium concentrations in urine, blood, and hair in illicit opioid users were significantly higher than the comparable concentrations in the control group. This can be due to the use of illicit opioids adulterated with thallium. Also, this study showed long-term illicit opioid use may lead to thallium exposure. In addition, cigarette smoking was associated with increased thallium exposure.

Sexual dysfunction in tramadol hydrochloride use disorder male patients: a case-control study.

Evidence suggests that opioids can modulate gonadal function, with consequent decreased release of sex hormones. We attempted to investigate the sexual function of males using tramadol hydrochloride (HCL) and its relationship to levels of free testosterone, luteinizing hormone, and follicle stimulating hormone, and to compare them with heroin use disorder patients and healthy controls. Our sample consisted of 60 opiate use disorder patients (assessed by Structured Clinical Interview for DSM-IV Axis I) (30 heroin and 30 tramadol) and 30 healthy controls. Sexual dysfunction was assessed using the International Index of Erectile Function. Free testosterone, follicle stimulating hormone, and luteinizing hormone levels were measured in morning blood samples using enzyme-linked immunosorbent assay (ELISA). Results showed that there was a decrease of luteinizing hormone and free testosterone levels in opiate use disorder patients compared with healthy controls, with heroin-dependent patients having significantly lower levels than those using tramadol. Opiates' effect on follicle stimulating hormone had mixed results. Opioid-dependent patients (both tramadol HCL and heroin using patients) developed sexual dysfunction more than healthy controls, which was generalized, with erectile dysfunction being the most affected domain. These findings are of ultimate importance, considering the fact that people use opioids to enhance their sexual performance in many countries.

The role of 6-acetylmorphine in heroin-induced reward and locomotor sensitization in mice.

We have previously demonstrated that heroin's first metabolite, 6-acetylmorphine (6-AM), is an important mediator of heroin's acute effects. However, the significance of 6-AM to the rewarding properties of heroin still remains unknown. The present study therefore aimed to examine the contribution of 6-AM to heroin-induced reward and locomotor sensitization. Mice were tested for conditioned place preference (CPP) induced by equimolar doses of heroin or 6-AM (1.25-5 µmol/kg). Psychomotor activity was recorded during the CPP conditioning sessions for assessment of drug-induced locomotor sensitization. The contribution of 6-AM to heroin reward and locomotor sensitization was further examined by pretreating mice with a 6-AM specific antibody (anti-6-AM mAb) 24 hours prior to the CPP procedure. Both heroin and 6-AM induced CPP in mice, but heroin generated twice as high CPP scores compared with 6-AM. Locomotor sensitization was expressed after repeated exposure to 2.5 and 5 µmol/kg heroin or 6-AM, but not after 1.25 µmol/kg, and we found no correlation between the expression of CPP and the magnitude of locomotor sensitization for either opioid. Pretreatment with anti-6-AM mAb suppressed both heroin-induced and 6-AM-induced CPP and locomotor sensitization. These findings provide evidence that 6-AM is essential for the rewarding and sensitizing properties of heroin; however, heroin caused stronger reward compared with 6-AM. This may be explained by the higher lipophilicity of heroin, providing more efficient drug transfer to the brain, ensuring rapid increase in the brain 6-AM concentration.

Opioid Use and Rate of Nicotine Metabolism Among Pregnant Smokers.

INTRODUCTION: Smokers who use opioids smoke more cigarettes per day (CPD) than non-opioid users, which could be due to the effects of opioids on nicotine metabolism. Moreover, nicotine metabolism increases during pregnancy, potentially making quitting more difficult for pregnant smokers. We examined nicotine metabolism and its association with opioid use (OU) and CPD in pregnant smokers. METHODS: We recruited pregnant women who smoked at least 5 CPD for a clinical trial of smoking cessation. Plasma nicotine metabolite ratio (NMR; trans-3'-hydroxycotinine (3HC)/cotinine)-a biomarker of nicotine metabolism-OU (involving methadone, buprenorphine, fentanyl, oxycodone, or tramadol), and CPD were assessed at baseline. We used linear regression to examine the associations between log-transformed NMR, OU, and CPD, adjusting for race/ethnicity and menthol smoking. RESULTS: Among 129 pregnant smokers, 25 (19%) were opioid users; most were maintained on methadone (n = 14). Compared to non-OU smokers, OU smokers had higher median CPD (10.0 vs. 7.0, p = .0007), serum 3HC (81.0 vs. 42.0 ng/mL, p = .0001), and NMR (0.63 vs. 0.43, p < .0001). In addition, methadone-maintained smokers had a higher median NMR than non-OU smokers (0.66 vs. 0.43, p = .0004). Adjusting for covariates, log-transformed NMR was greater in OU smokers (p = .012), specifically methadone-maintained smokers (p = .024), than non-OU smokers. CONCLUSIONS: Our preliminary results show that OU is associated with a higher NMR in pregnant smokers. A larger study sample is needed to replicate this finding, examine potential mechanisms, and determine its clinical significance. IMPLICATIONS: Among pregnant smokers, we observed that nicotine metabolism was significantly faster among opioid users-the majority of whom were on methadone maintenance-compared to nonusers, which could have implications for smoking cessation. Further studies are needed to replicate this finding, evaluate potential mechanisms, and determine its clinical significance.

Assessment of the Utility of the Oral Fluid and Plasma Proteomes for Hydrocodone Exposure.

INTRODUCTION: Non-medical use and abuse of prescription opioids is a growing problem in both the civilian and military communities, with minimal technologies for detecting hydrocodone use. This study explored the proteomic changes that occur in the oral fluid and blood plasma following controlled hydrocodone administration in 20 subjects. METHODS: The global proteomic profile was determined for samples taken at four time points per subject: pre-exposure and 4, 6, or 168 hours post-exposure. The oral fluid samples analyzed herein provided greater differentiation between baseline and response time points than was observed with blood plasma, at least partially due to significant person-to-person relative variability in the plasma proteome. RESULTS: A total of 399 proteins were identified from oral fluid samples, and the abundance of 118 of those proteins was determined to be significantly different upon metabolism of hydrocodone (4 and 6 hour time points) as compared to baseline levels in the oral fluid (pre-dose and 168 hours). CONCLUSIONS: We present an assessment of the oral fluid and plasma proteome following hydrocodone administration, which demonstrates the potential of oral fluid as a noninvasive sample that may reveal features of hydrocodone in opioid use, and with additional study, may be useful for other opioids and in settings of misuse.

Altered monocyte phenotype and dysregulated innate cytokine responses among people living with HIV and opioid-use disorder.

BACKGROUND: Opioid-use disorders (OUD) and hepatitis C or B co-infection (HEP) are common among people living with HIV (PLHIV). The impact of OUD on innate and adaptive immunity among PLHIV with and without HEP is unknown. OBJECTIVES: To investigate the impact of OUD on monocyte and T-cell phenotypes, cytokine responses to lipopolysaccharide (LPS) and phytohemagglutinin (PHA), and plasma inflammatory markers, among PLHIV with and without HEP. METHODS: Cross-sectional study enrolling PLHIV receiving ART, with and without OUD. Flow cytometry determined monocyte and T-cell phenotypes; LPS and PHA-induced cytokine production was assessed following LPS and PHA stimulation by multiplex cytokine array; plasma IL-6, soluble CD163, and soluble CD14 were measured by ELISA. RESULTS: Twenty-two PLHIV with OUD and 37 PLHIV without OUD were included. PLHIV with OUD exhibited higher frequencies of intermediate (CD14CD16) and nonclassical (CD14CD16) monocytes when compared with PLHIV without OUD (P = 0.0025; P = 0.0001, respectively), regardless of HEP co-infection. Soluble CD163 and monocyte cell surface CD163 expression was increased among PLHIV with OUD and HEP, specifically. Regardless of HEP co-infection, PLHIV with OUD exhibited reduced production of IL-10, IL-8, IL-6, IL-1alpha, and TNF-alpha in response to LPS when compared with PLHIV without OUD; PHA-induced production of IL-10, IL-1alpha, IL-1beta, IL-6, and TNF-alpha were also reduced among individuals with OUD. CONCLUSION: OUD among PLHIV are associated with altered monocyte phenotypes and a dysregulated innate cytokine response. Defining underlying mechanisms of opioid-associated innate immune dysregulation among PLHIV should be prioritized to identify optimal OUD treatment strategies.

A comparison of blood toxicology in fatalities involving alcohol and other drugs in patients with an opioid use disorder treated with methadone, buprenorphine, and implant naltrexone.

Background: Methadone, buprenorphine, and implant naltrexone have comparable efficacy in preventing death from drug intoxication during treatment, but there may be differences between treatments in the specific drugs contributing to death and in the risk of death during different phases of treatment.Objective: The objective of this study was to compare concentrations of individual drugs in decedents for evidence that the three medications use to treat opioid use disorders differed in the protection they offered against fatal overdose.Methods: Fatalities with a primary or co-diagnosis of alcohol or other drug poisoning in patients treated with methadone (n = 66, 74.2% male), buprenorphine (n = 54, 74.1% male), or naltrexone (n = 28, 85.7% male) were identified by combining treatment (Monitoring of Drugs of Dependence System and clinical records) and mortality records (Western Australian Death Registry). Quantitative postmortem blood drug analysis data were obtained for drug-related deaths. The presence/absence of drugs were compared between the three medication groups and between phases of treatment (on-treatment/off-treatment).Results: Opioids (89.8%) and benzodiazepines (76.2%) were most commonly identified in postmortem blood. The three medication groups did not differ materially in the drugs present postmortem, except that alcohol was less prevalent in naltrexone-treated cases. Morphine or heroin intoxication was implicated in more patients dying off-treatment than on-treatment but levels of morphine and other drugs were comparable across the two phases.Conclusion: Comparisons of postmortem concentrations of specific drugs indicated that patients treated with methadone, buprenorphine, and implant naltrexone had comparable susceptibilities to lethal co-intoxication and that similar drug mixtures contributed to death.