A locus coeruleus to dorsal hippocampus pathway mediates cue-induced reinstatement of opioid self-administration in male and female rats

Opioid use disorder is a chronic relapsing disorder encompassing misuse, dependence, and addiction to opioid drugs. Long term maintenance of associations between the reinforcing effects of the drug and the cues associated with its intake are a leading cause of relapse. Indeed, exposure to the salient drug-associated cues can lead to drug cravings and drug seeking behavior. The dorsal hippocampus (dHPC) and locus coeruleus (LC) have emerged as important structures for linking the subjective rewarding effects of opioids with environmental cues. However, their role in cue-induced reinstatement of opioid use remains to be further elucidated. In this study, we showed that chemogenetic inhibition of excitatory dHPC neurons during re-exposure to drug-associated cues significantly attenuates cue-induced reinstatement of morphine-seeking behavior. In addition, the same manipulation reduced reinstatement of sucrose-seeking behavior but failed to alter memory recall in the object location task. Finally, intact activity of tyrosine hydroxylase (TH) LC-dHPCTh afferents is necessary to drive cue induced reinstatement of morphine-seeking as inhibition of this pathway blunts cue-induced drug-seeking behavior. Altogether, these studies show an important role of the dHPC and LC-dHPCTh pathway in mediating cue-induced reinstatement of opioid seeking.

Processing abnormalities in monetary outcome evaluations among male individuals with opioid use disorder: evidence from feedback-related negativity

Background: Numerous studies have highlighted the pivotal role of alterations in the monetary reward system in the development and maintenance of substance use disorder (SUD). Although these alterations have been well documented in various forms of SUD, the electrophysiological mechanisms specific to opioid use disorder (OUD) remain underexplored. Understanding these mechanisms is critical for developing targeted interventions and advancing theories of addiction specific to opioid use.Objectives: To explore abnormalities in monetary reward outcome processing in males with OUD. We hypothesized that control individuals would show higher feedback-related negativity (FRN) to losses, unlike those in the OUD group, where FRN to losses and gains would not differ significantly.Methods: Fifty-seven participants (29 male individuals with OUD [heroin] and 28 male controls) were evaluated. A combination of the monetary incentive delay task (MIDT) and event-related potential (ERP) technology was used to investigate electrophysiological differences in monetary reward feedback processing between the OUD and healthy control groups.Results: We observed a significant interaction between group (control vs. OUD) and monetary outcome (loss vs. gain), indicated by p < .05 and η2p = 0.116. Specifically, control participants showed stronger negative FRN to losses than gains (p < .05), unlike the OUD group (p > .05).Conclusion: This study's FRN data indicate that males with OUD show altered processing of monetary rewards, marked by reduced sensitivity to loss. These findings offer electrophysiological insights into why males with OUD may pursue drugs despite potential economic downsides.

Sleep Health Among Adults in Outpatient Opioid Use Disorder Treatment: A Systematic Review

The current systematic review synthesized available original research on objective and self-reported sleep health dimensions among adults aged 18 to 50 years in outpatient treatment for opioid use disorder (OUD). A comprehensive search was conducted using multiple electronic databases followed by screening 2,738 records published in English from the inception of each database to September 14, 2021. Quality was assessed with the Mixed Methods Appraisal Tool (version 2001). Fifty nine studies-50 descriptive (21 longitudinal, 18 cross-sectional, and 11 case control), seven interventional (five non-randomized), and two mixed/multi method designs-were included, comprising 18,195 adults with mean ages ranging from 23 to 49 years (mean age = 37.5 [SD = 5.9] years; 54.4% female) with OUD and 604 comparison participants without OUD. Studies were predominantly observational with various designs with self-report and objective measures with participants at various points in treatment. More work is needed to understand the multidimensional depth of sleep health in adults with OUD. Optimizing sleep health in adults with OUD may improve their addiction trajectory and should be a priority in practice and research. [Journal of Psychosocial Nursing and Mental Health Services, 62(1), 19-26.].

Chronic heroin use disorder and the brain: Current evidence and future implications

The incidence of chronic heroin use disorder, including overdose deaths, has reached epidemic proportions. Here we summarise and evaluate our knowledge of the relationship between chronic heroin use disorder and the brain through a narrative review. A broad range of areas was considered including causal mechanisms, cognitive and neurological consequences of chronic heroin use and novel neuroscience-based clinical interventions. Chronic heroin use is associated with limited or very limited evidence of impairments in memory, cognitive impulsivity, non-planning impulsivity, compulsivity and decision-making. Additionally, there is some evidence for certain neurological disorders being caused by chronic heroin use, including toxic leukoencephalopathy and neurodegeneration. However, there is insufficient evidence on whether these impairments and disorders recover after abstinence. Whilst there is a high prevalence of comorbid psychiatric disorders, there is no clear evidence that chronic heroin use per se causes depression, bipolar disorder, PTSD and/or psychosis. Despite the growing burden on society from heroin use, knowledge of the long-term effects of chronic heroin use disorder on the brain remains limited. Nevertheless, there is evidence for progress in neuroscience-based interventions being made in two areas: assessment (cognitive assessment and neuroimaging) and interventions (cognitive training/remediation and neuromodulation). Longitudinal studies are needed to unravel addiction and neurotoxic mechanisms and clarify the role of pre-existing psychiatric symptoms and cognitive impairments.

A limited access oral oxycodone paradigm produces physical dependence and mesocorticolimbic region-dependent increases in DeltaFosB expression without preference

The abuse of oral formulations of prescription opioids has precipitated the current opioid epidemic. We developed an oral oxycodone consumption model consisting of a limited access (4 h) two-bottle choice drinking in the dark (TBC-DID) paradigm and quantified dependence with naloxone challenge using mice of both sexes. We also assessed neurobiological correlates of withdrawal and dependence elicited via oral oxycodone consumption using immunohistochemistry for DeltaFosB (ΔFosB), a transcription factor described as a molecular marker for drug addiction. Neither sex developed a preference for the oxycodone bottle, irrespective of oxycodone concentration, bottle position or prior water restriction. Mice that volitionally consumed oxycodone exhibited hyperlocomotion in an open field test and supraspinal but not spinally-mediated antinociception. Both sexes also developed robust, dose-dependent levels of opioid withdrawal that was precipitated by the opioid antagonist naloxone. Oral oxycodone consumption followed by naloxone challenge led to mesocorticolimbic region-dependent increases in the number of ΔFosB expressing cells. Naloxone-precipitated withdrawal jumps, but not the oxycodone bottle % preference, was positively correlated with the number of ΔFosB expressing cells specifically in the nucleus accumbens shell. Thus, limited access oral consumption of oxycodone produced physical dependence and increased ΔFosB expression despite the absence of opioid preference. Our TBC-DID paradigm allows for the study of oral opioid consumption in a simple, high-throughput manner and elucidates the underlying neurobiological substrates that accompany opioid-induced physical dependence.

Sex and heredity are determinants of drug intake in a novel model of rat oral oxycodone self-administration

The steady rise in prescription opioids such as oxycodone has led to a virulent epidemic of widespread abuse and deaths in the United States; approximately 80% of affected individuals initiate the habitual use of oxycodone by using prescription oral oxycodone. Given the importance of drug pharmacokinetics in determining abuse potential, we designed an oral operant oxycodone self-administration (SA) procedure in rats to model drug intake by most human users/abusers of oxycodone. Key aspects of the model include limited initial drug intake followed by increasing drug concentrations during extended 4-h sessions on alternating days. Sex and genetic predisposition are major determinants of human opiate abuse. Therefore, we studied females in seven inbred strains (WLI, WMI, LEW, DSS, F344, BN and SHR) and both sexes in three of these strains. All strains increased intake across serially increasing doses (0.025-0.2 mg/ml; p < 0.001): the range of intakes at the final concentration of oxycodone was 0.72 ± 0.17-4.84 ± 1.42 mg/kg (mean ± SEM) - a 6.7-fold difference across strains. In LEW, WLI and WMI strains, oxycodone intake increased significantly across all sessions in both sexes. However, in LEW and WMI male rats but not WLI, daily oxycodone intake was significantly lower across all 4-h sessions than females (p < 0.005). The estimated heritability in oxycodone intake was in the range of 0.21-0.41. In summary, our novel operant oral oxycodone SA model captures the strong abuse potential of oral oxycodone and shows dose, sex and strain-specific drug intake that is significantly dependent on heredity.

Impaired working memory performance in opioid-dependent patients is related to reduced insula gray matter volume: a voxel-based morphometric study

Opioid-dependent patients frequently show deficits in multiple cognitive domains that might impact on their everyday life performance and interfere with therapeutic efforts. To date, the neurobiological underpinnings of those deficits remain to be determined. We investigated working memory performance and gray matter volume (GMV) differences in 17 patients on opioid maintenance treatment (OMT) and 17 healthy individuals using magnetic resonance imaging and voxel-based morphometry. In addition, we explored associations between substance intake, gray matter volume, and working memory task performance. Patients on OMT committed more errors during the working memory task than healthy individuals and showed smaller insula and putamen GMV. The duration of heroin use prior to OMT was associated with working memory performance and insula GMV in patients. Neither the substitution agent (methadone and buprenorphine) nor concurrent abuse of illegal substances during the 3 months prior to the experiment was significantly associated with GMV. Results indicate that impaired working memory performance and structural deficits in the insula of opioid-dependent patients are related to the duration of heroin use. This suggests that early inclusion into OMT or abstinence-oriented therapies that shorten the period of heroin abuse may limit the impairments to GMV and cognitive performance of opioid-dependent individuals.

Functional evaluation of NK1 antagonism on cue reactivity in opiate dependence; An fMRI study

BACKGROUND

Opiate addiction is a major health challenge with substantial societal cost. Though harm minimisation strategies have been effective, there is a growing need for new treatments for detoxification and relapse prevention. Preclinical research has found neurokinin 1 (NK1) receptors have prominent effects on opiate reward and reinforcement, and human studies have found NK1 antagonism led to reductions in craving and withdrawal. However, its effect on brain mechanisms in opiate addiction has not yet been examined.

METHODS

This study aims to assess the impact of NK1 antagonist aprepitant on heroin cue-elicited changes in blood-oxygenation level dependent (BOLD) signal in opiate dependent individuals undergoing detoxification. Participants will attend two scanning sessions and receive a single dose of aprepitant (320 mg) and a placebo in a randomised, cross-over design. During functional magnetic resonance imaging participants will undergo two runs of a cue reactivity task, which consists of passive viewing of drug cues or neutral cues in a block design fashion. We hypothesise that NK1 antagonism will attenuate the BOLD response to drug cues in the caudate nucleus and amygdala. Regions of interest were selected based on NK1 receptor density and their role in cue reactivity and craving.

Tolerance to Opioid-Induced Respiratory Depression in Chronic High-Dose Opioid Users: A Model-Based Comparison With Opioid-Naïve Individuals

Chronic opioid consumption is associated with addiction, physical dependence, and tolerance. Tolerance results in dose escalation to maintain the desired opioid effect. Intake of high-dose or potent opioids may cause life-threatening respiratory depression, an effect that may be reduced by tolerance. We performed a pharmacokinetic-pharmacodynamic analysis of the respiratory effects of fentanyl in chronic opioid users and opioid-naïve subjects to quantify tolerance to respiratory depression. Fourteen opioid-naïve individuals and eight chronic opioid users received escalating doses of intravenous fentanyl (opioid-naïve subjects: 75-350 µg/70 kg; chronic users: 250-700 µg/70 kg). Isohypercapnic ventilation was measured and the fentanyl plasma concentration-ventilation data were analyzed using nonlinear mixed-effects modeling. Apneic events occurred in opioid-naïve subjects after a cumulative fentanyl dose (per 70 kg) of 225 (n = 3) and 475 µg (n = 6), and in 7 chronic opioid users after a cumulative dose of 600 (n = 2), 1,100 (n = 2), and 1,800 µg (n = 3). The time course of fentanyl's respiratory depressant effect was characterized using a biophase equilibration model in combination with an inhibitory maximum effect (Emax ) model. Differences in tolerance between populations were successfully modeled. The effect-site concentration causing 50% ventilatory depression, was 0.42 ± 0.07 ng/mL in opioid-naïve subjects and 1.82 ± 0.39 ng/mL in chronic opioid users, indicative of a 4.3-fold sensitivity difference. Despite higher tolerance to fentanyl-induced respiratory depression, apnea still occurred in the opioid-tolerant population indicative of the potential danger of high-dose opioids in causing life-threatening respiratory depression in all individuals, opioid-naïve and opioid-tolerant.

Bidirectional Relationship between Opioids and Disrupted Sleep: Putative Mechanisms

Millions of Americans suffer from opiate use disorder, and over 100 die every day from opioid overdoses. Opioid use often progresses into a vicious cycle of abuse and withdrawal, resulting in very high rates of relapse. Although the physical and psychologic symptoms of opiate withdrawal are well-documented, sleep disturbances caused by chronic opioid exposure and withdrawal are less well-understood. These substances can significantly disrupt sleep acutely and in the long term. Yet poor sleep may influence opiate use, suggesting a bidirectional feed-forward interaction between poor sleep and opioid use. The neurobiology of how opioids affect sleep and how disrupted sleep affects opioid use is not well-understood. Here, we will summarize what is known about the effects of opioids on electroencephalographic sleep in humans and in animal models. We then discuss the neurobiology interface between reward-related brain regions that mediate arousal and wakefulness as well as the effect of opioids in sleep-related brain regions and neurotransmitter systems. Finally, we summarize what is known of the mechanisms underlying opioid exposure and sleep. A critical review of such studies, as well as recommendations of studies that evaluate the impact of manipulating sleep during withdrawal, will further our understanding of the cyclical feedback between sleep and opioid use. SIGNIFICANCE STATEMENT: We review recent studies on the mechanisms linking opioids and sleep. Opioids affect sleep, and sleep affects opioid use; however, the biology underlying this relationship is not understood. This review compiles recent studies in this area that fill this gap in knowledge.

Anhedonia in chronic pain and prescription opioid misuse

BACKGROUND

Both acute and chronic pain can disrupt reward processing. Moreover, prolonged prescription opioid use and depressed mood are common in chronic pain samples. Despite the prevalence of these risk factors for anhedonia, little is known about anhedonia in chronic pain populations.

METHODS

We conducted a large-scale, systematic study of anhedonia in chronic pain, focusing on its relationship with opioid use/misuse, pain severity, and depression. Chronic pain patients across four distinct samples (N = 488) completed the Snaith-Hamilton Pleasure Scale (SHAPS), measures of opioid use, pain severity and depression, as well as the Current Opioid Misuse Measure (COMM). We used a meta-analytic approach to determine reference levels of anhedonia in healthy samples spanning a variety of countries and diverse age groups, extracting SHAPS scores from 58 published studies totaling 2664 psychiatrically healthy participants.

RESULTS

Compared to healthy samples, chronic pain patients showed higher levels of anhedonia, with ~25% of patients scoring above the standard anhedonia cut-off. This difference was not primarily driven by depression levels, which explained less than 25% of variance in anhedonia scores. Neither opioid use duration, dose, nor pain severity alone was significantly associated with anhedonia. Yet, there was a clear effect of opioid misuse, with opioid misusers (COMM ⩾13) reporting greater anhedonia than non-misusers. Opioid misuse remained a significant predictor of anhedonia even after controlling for pain severity, depression and opioid dose.

CONCLUSIONS

Study results suggest that both chronic pain and opioid misuse contribute to anhedonia, which may, in turn, drive further pain and misuse.

Opioids and the Hypothalamic-Pituitary-Gonadal (HPG) Axis

CONTEXT

Hypogonadism is a well-established consequence of opioid use. It has been reported in both men and women, although more widely studied in men.

EVIDENCE ACQUISITION

PubMed was searched for articles in English until December 2019 for opioids and hypogonadism. Bibliography of retrieved articles was searched for relevant articles.

EVIDENCE SYNTHESIS

The prevalence of opioid-induced hypogonadism (OIH) varies between studies but was reported to be 69% in a recent systematic review. There is large heterogeneity in the studies, with different factors shown to have stronger association with hypogonadism such as specific types of opioids, higher doses, and longer durations of use. The consequences of OIH include sexual dysfunction, depression, decreased quality of life, and low bone density. There is paucity of randomized controlled trials assessing the efficacy of testosterone replacement therapy (TRT) for OIH in men, and even less studies on treating OIH in women. TRT studies in men reported varying outcomes with some studies favoring and others showing no clear benefit of TRT on different measures.

CONCLUSIONS

Despite the high prevalence of OIH, it remains underrecognized and undertreated with multiple endocrine and metabolic consequences. A reasonable approach in patients using opioids includes informing them of this complication and its potential consequences, screening for signs and symptoms of hypogonadism then sex hormone levels if prolonged opioid use > 3 months, and treating patients diagnosed with hypogonadism, if and when clinically indicated, with sex hormones if chronic opioids are planned to be continued for ≥ 6 months.

Assessment of Probable Opioid Use Disorder Using Electronic Health Record Documentation

IMPORTANCE

Electronic health records are a potentially valuable source of information for identifying patients with opioid use disorder (OUD).

OBJECTIVE

To evaluate whether proxy measures from electronic health record data can be used reliably to identify patients with probable OUD based on Diagnostic and Statistical Manual of Mental Disorders (Fifth Edition) (DSM-5) criteria.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective cross-sectional study analyzed individuals within the Geisinger health system who were prescribed opioids between December 31, 2000, and May 31, 2017, using a mixed-methods approach. The cohort was identified from 16 253 patients enrolled in a contract-based, Geisinger-specific medication monitoring program (GMMP) for opioid use, including patients who maintained or violated contract terms, as well as a demographically matched control group of 16 253 patients who were prescribed opioids but not enrolled in the GMMP. Substance use diagnoses and psychiatric comorbidities were assessed using automated electronic health record summaries. A manual medical record review procedure using DSM-5 criteria for OUD was completed for a subset of patients. The analysis was conducted beginning from June 5, 2017, until May 29, 2020.

MAIN OUTCOMES AND MEASURES

The primary outcome was the prevalence of OUD as defined by proxy measures for DSM-5 criteria for OUD as well as the prevalence of comorbidities among patients prescribed opioids within an integrated health system.

RESULTS

Among the 16 253 patients enrolled in the GMMP (9309 women [57%]; mean [SD] age, 52 [14] years), OUD diagnoses as defined by diagnostic codes were present at a much lower rate than expected (291 [2%]), indicating the necessity for alternative diagnostic strategies. The DSM-5 criteria for OUD can be assessed using manual medical record review; a manual review of 200 patients in the GMMP and 200 control patients identifed a larger percentage of patients with probable moderate to severe OUD (GMMP, 145 of 200 [73%]; and control, 27 of 200 [14%]) compared with the prevalence of OUD assessed using diagnostic codes.

CONCLUSIONS AND RELEVANCE

These results suggest that patients with OUD may be identified using information available in the electronic health record, even when diagnostic codes do not reflect this diagnosis. Furthermore, the study demonstrates the utility of coding for DSM-5 criteria from medical records to generate a quantitative DSM-5 score that is associated with OUD severity.

CE: Opioid Use Disorder: Pathophysiology, Assessment, and Effective Interventions

Opioid use disorder (OUD) is a chronic, relapsing disease. Genetic variability, dysregulated stress system response, and history of opioid experimentation or escalating exposure all contribute to the likelihood of developing OUD, which produces complex brain changes that make it difficult to stop opioid use. Understanding the neurobiology of OUD helps nurses anticipate the behaviors of patients with OUD and approach them with empathy. Here, the authors discuss the pathophysiology of OUD, available screening tools, medical treatments, and behavioral interventions that have demonstrated efficacy in reducing substance use.

The role of the gut microbiome in opioid use

Although the gut and brain are separate organs, they communicate with each other via trillions of intestinal bacteria that collectively make up one's gut microbiome. Findings from both humans and animals support a critical role of gut microbes in regulating brain function, mood, and behavior. Gut bacteria influence neural circuits that are notably affected in addiction-related behaviors. These include circuits involved in stress, reward, and motivation, with substance use influencing gut microbial abnormalities, suggesting significant gut-brain interactions in drug addiction. Given the overwhelming rates of opioid overdose deaths driven by abuse and addiction, it is essential to characterize mechanisms mediating the abuse potential of opioids. We discuss in this review the role of gut microbiota in factors that influence opioid addiction, including incentive salience, reward, tolerance, withdrawal, stress, and compromised executive function. We present clinical and preclinical evidence supporting a bidirectional relationship between gut microbiota and opioid-related behaviors by highlighting the effects of opioid use on gut bacteria, and the effects of gut bacteria on behavioral responses to opioids. Further, we discuss possible mechanisms of this gut-brain communication influencing opioid use. By clarifying the relationship between the gut microbiome and opioid-related behaviors, we improve understanding on mechanisms mediating reward-, motivation-, and stress-related behaviors and disorders, which may contribute to the development of effective, targeted therapeutic interventions in opioid dependence and addiction.

Behavioral preference for viewing drug v. pleasant images predicts current and future opioid misuse among chronic pain patients

BACKGROUND

The USA is currently enduring an opioid crisis. Identifying cost-effective, easy-to-implement behavioral measures that predict treatment outcomes in opioid misusers is a crucial scientific, therapeutic, and epidemiological goal.

METHODS

The current study used a mixed cross-sectional and longitudinal design to test whether a behavioral choice task, previously validated in stimulant users, was associated with increased opioid misuse severity at baseline, and whether it predicted change in opioid misuse severity at follow-up. At baseline, data from 100 prescription opioid-treated chronic pain patients were analyzed; at follow-up, data were analyzed in 34 of these participants who were non-misusers at baseline. During the choice task, participants chose under probabilistic contingencies whether to view opioid-related images in comparison with affectively pleasant, unpleasant, and neutral images. Following previous procedures, we also assessed insight into choice behavior, operationalized as whether (yes/no) participants correctly self-reported the image category they chose most often.

RESULTS

At baseline, the higher choice for viewing opioid images in direct comparison with pleasant images was associated with opioid misuse and impaired insight into choice behavior; the combination of these produced especially elevated opioid-related choice behavior. In longitudinal analyses of individuals who were initially non-misusers, higher baseline opioid v. pleasant choice behavior predicted more opioid misuse behaviors at follow-up.

CONCLUSIONS

These results indicate that greater relative allocation of behavior toward opioid stimuli and away from stimuli depicting natural reinforcement is associated with concurrent opioid misuse and portends vulnerability toward future misuse. The choice task may provide important medical information to guide opioid-prescribing practices.

Cingulo-hippocampal effective connectivity positively correlates with drug-cue attentional bias in opioid use disorder

Individuals with opioid use disorder (OUD) often relapse when exposed to opioid-related cues. Previous functional magnetic resonance imaging (fMRI) studies have identified neuronal corticolimbic changes related to drug cue reactivity in OUD. However, the corresponding manner in which brain regions interact is still unclear. Effective (directional) connectivity was analyzed using dynamic causal modeling of fMRI data acquired from 27 OUD participants (13 with OUD and 14 with OUD and cocaine use disorder [OUD+CUD]), while performing an opioid-word Stroop task. Participants were shown opioid and neutral words presented in different colors and were instructed to indicate word color but ignore word meaning. The effects of opioid words relative to neutral words on effective connectivity and on behavioral reaction time were defined as modulatory change and attentional bias, respectively. For all the 27 participants, left anterior cingulate cortex (ACC) to right hippocampus effective connectivity exhibited the largest modulatory change, which was positively correlated with attentional bias. The findings for the ACC to hippocampus EC were consistent across OUD and CUD found in a previous study.

The role of the endogenous neurotransmitters associated with neuropathic pain and in the opioid crisis: The innate pain-relieving system

Neuropathic pain is a chronic pain caused by central and peripheral nerve injury, long-term diabetes or treatment with chemotherapy drugs, and it is dissimilar to other chronic pain conditions. Chronic pain usually seriously affects the quality of life, and its drug treatment may result in increased costs of social and medical care. As in the USA and Canada, in Europe, the demand for pain-relieving medicines used in chronic pain has also significantly increased, but most European countries are not experiencing an opioid crisis. In this review, the role of various endogenous transmitters (noradrenaline, dopamine, serotonin, met- and leu-enkephalins, β-endorphin, dynorphins, cannabinoids, ATP) and various receptors (α₂, μ, etc.) in the innate pain-relieving system will be discussed. Furthermore, the modulation of pain processing pathways by transmitters, focusing on neuropathic pain and the role of the sympathetic nervous system in the side effects of excessive opioid treatment, will be explained.

Calculated Decisions: Clinical opiate withdrawal scale (COWS)

The COWS is used to quantify the severity of opiate withdrawal.

Changes in cardiac vagal tone as measured by heart rate variability during naloxone-induced opioid withdrawal

BACKGROUND

Heart rate variability (HRV) is of interest to researchers due to its potential utility as a marker for both physiological and psychological stress. Sympatholytics are used to treat opioid withdrawal, but little information about the parasympathetic system's role in mediating withdrawal symptoms exists. The goal of the current study was to evaluate changes in HRV during opioid withdrawal to provide a better understanding of the autonomic effects of opioid withdrawal.

METHODS

Ten male participants (mean age = 46.4 years) received intramuscular naloxone (mean dose =0.26 mg) to confirm opioid dependence. The presence and severity of withdrawal symptoms were assessed using subjective and objective measures (Wang et al., 1974). Electrocardiography (ECG) was measured continuously, and HRV was analyzed in 2-minute segments before naloxone injection (at baseline) and after participants were in moderate withdrawal (Wang Test score ≥10). Heart rate, blood pressure, pupil diameter, and respiratory rate were also examined.

RESULTS

Pupil diameter significantly increased after naloxone administration relative to baseline (t(9) = 5.562, p = 0.000). Both high frequency (HF) HRV (Z = -2.803, p = 0.005) and root mean square of successive differences (RMSSD) HRV (Z = -2.090, p = 0.037) were significantly lower during withdrawal relative to baseline. Increases in heart rate (Z = -2.090, p = 0.032) and systolic pressure (t(9) = 8.099, p = 0.0000) from baseline to withdrawal also were significant.

CONCLUSIONS

These preliminary data indicate that a large reduction in cardiac vagal tone occurs during naloxone-induced withdrawal. This finding underscores the need for further research into the role of the parasympathetic nervous system in opioid withdrawal.

The chippers, the quitters, and the highly symptomatic: A 12-month longitudinal study of DSM-5 opioid- and cocaine-use problems in a community sample

BACKGROUND

Individual trajectories of drug use and drug-related problems are highly heterogeneous. There is no standard taxonomy of these trajectories, but one could be developed by defining natural categories based on changes in symptoms of substance-use disorders over time.

METHODS

Our study was conducted in a community sample in Baltimore, Maryland. At baseline, all participants were using opioids and/or cocaine, but none were in treatment. Drug use and symptomatology were assessed again at 12 months (N = 115).

RESULTS

We defined Quitters as participants who had not used for at least 30 days at follow-up (17%). For the remaining participants, we performed longitudinal cluster analysis on DSM symptom-counts, identifying three trajectory clusters: newly or persistently Symptomatic (40%) participants, Chippers (21.5%) with few symptoms, and Converted Chippers (21.5%) with improved symptom counts. Logistic regression showed that profiles of Quitters did not resemble Chippers, but instead resembled Symptomatic participants, having high probability of disorderly home neighborhood, nonwhite race, and negative mood. Quitters tended to have two protective factors: initiating opioid-agonist treatment during the study (r_effect = 0.25, CL95 0.02-0.48) and lack of polydrug use (r_effect = 0.25, CL95 0.004-0.49). Converted Chippers tended to be white, with orderly home neighborhoods and less negative mood (r_effects 0.24 to 0.31, CL95 0.01-0.54).

CONCLUSIONS

Changes in DSM symptomology provided a meaningful measure of individual trajectories. Quitters shared psychosocial characteristics with Symptomatic participants, but not with participants who continued to use with few symptoms. This suggests that Quitters abstained out of necessity, not because their problems were less severe.

The relationship between pupil diameter and other measures of opioid withdrawal during naloxone precipitated withdrawal

BACKGROUND

Understanding mechanisms of physiological opioid withdrawal symptoms can inform treatment strategies. This secondary analysis evaluated the association between mydriasis (dilated pupils), a commonly-assessed opioid withdrawal metric, with self- and observer-rated opioid withdrawal severity.

METHOD

Ninety-five participants with opioid physical dependence were stabilized with morphine before receiving an injection of the opioid antagonist naloxone to precipitate withdrawal. Pupil diameter, the Subjective Opiate Withdrawal Scale (SOWS), and the Clinical Opiate Withdrawal Scale (COWS) were collected at baseline and in 15-minute intervals for 120 min following naloxone administration. Pearson product-moment correlations and linear regressions characterized the relationships between pupil measurements (baseline and peak naloxone-induced) and self- and observer-rated measures of withdrawal. Repeated-measures ANOVAs tested whether self and observer-rated withdrawal severity corresponded to unique patterns in pupil changes.

RESULTS

Baseline pupil diameter significantly correlated with SOWS and COWS peak scores. Peak naloxone-induced pupil diameter significantly correlated with SOWS scores only. Peak changes in pupil from baseline did not correspond to peak changes in self- and observer-rated withdrawal scales.

CONCLUSIONS

This study suggests that pupil diameter measurements were more closely associated with acute opioid withdrawal severity than changes in pupil diameter. Prospective research examining the mechanisms underlying the relationship between pupil diameter and opioid withdrawal severity are warranted.

Implications of the Opioid Epidemic for the Clinical Gastroenterology Practice

PURPOSE OF REVIEW

The opioid epidemic in the USA has led to a rise in opioid-related gastrointestinal (GI) side effects that are often difficult to diagnose and treat. The aim of this report is to discuss opioid pathophysiology, opioid-related GI side effects, clinical presentation, and diagnostic criteria and to review the current pharmacotherapy available.

RECENT FINDINGS

Opioid-related GI disorders are increasingly recognized and include, but are not limited to, opioid-induced esophageal dysfunction (OIED), gastroparesis, opioid-induced constipation (OIC), narcotic bowel syndrome (NBS), acute post-operative ileus, and anal sphincter dysfunction. Treatment of these conditions is challenging. OIC has the most available pharmacotherapy for treatment, including classical laxatives, peripherally acting μ-receptor antagonists (PAMORAs), novel therapies (lubiprostone, prucalopride- 5-HT agonist), and preventative therapies (PR oxycodone/naloxone). The gastrointestinal effects of opioid therapy are variable and often debilitating. While medical management for some opioid-related GI side effects exists, limiting or completely avoiding opioid use for chronic non-cancer pain will mitigate these effects most effectively.

Outcomes associated with hospital admissions for accidental opioid overdose in British Columbia: a retrospective cohort study

OBJECTIVES

To study the association between accidental opioid overdose and neurological, respiratory, cardiac and other serious adverse events and whether risk of these adverse events was elevated during hospital readmissions compared with initial admissions.

DESIGN

Retrospective cohort study.

SETTING

Population-based study using linked administrative data in British Columbia, Canada.

PARTICIPANTS

The primary analysis included 2433 patients with 2554 admissions for accidental opioid overdose between 2006 and 2015, including 121 readmissions within 1 year of initial admission. The secondary analysis included 538 patients discharged following a total of 552 accidental opioid overdose hospitalizations and 11 040 matched controls from a cohort of patients with ≥180 days of prescription opioid use.

OUTCOME MEASURES

The primary outcome was encephalopathy; secondary outcomes were adult respiratory distress syndrome, respiratory failure, pulmonary haemorrhage, aspiration pneumonia, cardiac arrest, ventricular arrhythmia, heart failure, rhabdomyolysis, paraplegia or tetraplegia, acute renal failure, death, a composite outcome of encephalopathy or any secondary outcome and total serious adverse events (all-cause hospitalisation or death). We analysed these outcomes using generalised linear models with a logistic link function.

RESULTS

3% of accidental opioid overdose admissions included encephalopathy and 25% included one or more adverse events (composite outcome). We found no evidence of increased risk of encephalopathy (OR 0.57; 95% CI 0.13 to 2.49) or other outcomes during readmissions versus initial admissions. In the secondary analysis, <5 patients in each cohort experienced encephalopathy. Risk of the composite outcome (OR 2.15; 95% CI 1.48 to 3.12) and all-cause mortality (OR 2.13; 95% CI 1.18 to 3.86) were higher for patients in the year following overdose relative to controls.

CONCLUSIONS

We found no evidence that risk of encephalopathy or other adverse events was higher in readmissions compared with initial admissions for accidental opioid overdose. Risk of serious morbidity and mortality may be elevated in the year following an accidental opioid overdose.

US Emergency Department Visits for Acute Harms From Prescription Opioid Use, 2016-2017

OBJECTIVES

To estimate the number of US emergency department visits for prescription opioid harms by patient characteristics, intent, clinical manifestations, and active ingredient.

METHODS

We used data from medical record-based surveillance from a nationally representative 60-hospital sample.

RESULTS

Based on 7769 cases, there were 267 020 estimated emergency department visits annually (95% confidence interval [CI] = 209 833, 324 206) for prescription opioid harms from 2016 to 2017. Nearly half of visits (47.6%; 95% CI = 40.8%, 54.4%) were attributable to nonmedical opioid use, 38.9% (95% CI = 32.9%, 44.8%) to therapeutic use, and 13.5% (95% CI = 11.0%, 16.0%) to self-harm. Co-implication with other pharmaceuticals and concurrent illicit drug and alcohol use were common; prescription opioids alone were implicated in 31.5% (95% CI = 27.2%, 35.8%) of nonmedical use visits and 19.7% (95% CI = 15.7%, 23.7%) of self-harm visits. Unresponsiveness or cardiorespiratory failure (30.0%) and altered mental status (35.7%) were common in nonmedical use visits. Gastrointestinal effects (30.4%) were common in therapeutic use visits. Oxycodone was implicated in more than one third of visits across intents.

CONCLUSIONS

Morbidity data can help target interventions, such as dispensing naloxone to family and friends of those with serious overdose, and screening and treatment of substance use disorder when opioids are prescribed long-term.

Preparing student pharmacists to identify opioid misuse, prevent overdose and prescribe naloxone

BACKGROUND AND PURPOSE

All 50 states have implemented policies to improve access to naloxone through community pharmacies. Many states require naloxone-based training for pharmacists before participating in these activities. The purpose of this study was to determine the effects of an opioid misuse and overdose training program on students' knowledge, self-efficacy, and value of pharmacists' role in preventing overdose.

EDUCATIONAL ACTIVITY AND SETTING

The training program was implemented with third-year professional pharmacy students. Students participated in a 50-min lecture followed by a two-hour hands-on laboratory activity. Students took a pre-survey immediately before the lecture and a post-survey immediately following the laboratory activity.

FINDINGS

Seventy students completed the pre- and post-surveys. Students showed a significant (p < 0.05) gain in self-efficacy and value after completing the training program, and a significant gain in knowledge from six of the eight related survey items. There was a significant correlation between students' self-efficacy and perceived value of the pharmacists' role in preventing opioid overdose.

SUMMARY

A training program implemented for third-year pharmacy students increases students' knowledge, self-efficacy, and perceived value. Specifically, the strong correlation seen between self-efficacy and perceived value after completing the training program is important to note as we prepare future pharmacists for their role in fighting the opioid epidemic.

Prefrontal cortex response to drug cues, craving, and current depressive symptoms are associated with treatment outcomes in methadone-maintained patients

Methadone maintenance is an effective treatment for opioid use disorder, yet many methadone-maintained patients (MMPs) continue to struggle with chronic relapse. The current study evaluated whether functional near-infrared spectroscopy (fNIRS) could identify prefrontal cortex (PFC) markers of ongoing opioid use in MMPs, and whether clinical measures of depression and self-report measures of craving would also be associated with opioid use. MMPs (n = 29) underwent a drug cue reactivity paradigm during fNIRS measurements of PFC reactivity. Self-reported opioid craving (measured by a visual analog scale; 0-100) was collected before and after drug cue reactivity, and depressive symptoms were assessed via the 17-item Hamilton Depression Rating Scale (HAM-D). Hierarchical regression and partial correlations were used to evaluate associations between weekly urine drug screens over a 90-day follow-up period and fNIRS, craving, and HAM-D assessments. Neural response to drug cues in the left lateral PFC, controlling for age, sex, and days in treatment was significantly associated with percent opioid-negative urine screens during follow-up (∆F1, 24 = 13.19, p = 0.001, ∆R2 = 0.30), and correctly classified 86% of MMPs as either using opioids, or abstaining from opioids (χ2(4) = 16.28, p = 0.003). Baseline craving (p < 0.001) and HAM-D assessment (p < 0.01) were also associated with percent opioid-negative urine screens. Combining fNIRS results, baseline craving scores, and HAM-D scores created a robust predictive model (∆F3, 22 = 16.75, p < 0.001, ∆R2 = 0.59). These data provide preliminary evidence that the fNIRS technology may have value as an objective measure of treatment outcomes within outpatient methadone clinics. Depressive symptoms and drug craving were also correlated with opioid use in MMPs.

Rostral and Caudal Ventral Tegmental Area GABAergic Inputs to Different Dorsal Raphe Neurons Participate in Opioid Dependence

Both the ventral tegmental area (VTA) and dorsal raphe nucleus (DRN) are involved in affective control and reward-related behaviors. Moreover, the neuronal activities of the VTA and DRN are modulated by opioids. However, the precise circuits from the VTA to DRN and how opioids modulate these circuits remain unknown. Here, we found that neurons projecting from the VTA to DRN are primarily GABAergic. Rostral VTA (rVTA) GABAergic neurons preferentially innervate DRN GABAergic neurons, thus disinhibiting DRN serotonergic neurons. Optogenetic activation of this circuit induces aversion. In contrast, caudal VTA (cVTA) GABAergic neurons mainly target DRN serotonergic neurons, and activation of this circuit promotes reward. Importantly, μ-opioid receptors (MOPs) are selectively expressed at rVTA→DRN GABAergic synapses, and morphine depresses the synaptic transmission. Chronically elevating the activity of the rVTA→DRN pathway specifically interrupts morphine-induced conditioned place preference. This opioid-modulated inhibitory circuit may yield insights into morphine reward and dependence pathogenesis.

Sleep Management Among Patients with Substance Use Disorders

Sleep and substance use disorders commonly co-occur. Insomnia is commonly associated with use and withdrawal from substances. Circadian rhythm abnormalities are being increasingly linked with psychoactive substance use. Other sleep disorders, such as sleep-related breathing disorder, should be considered in the differential diagnosis of insomnia, especially in those with opioid use or alcohol use disorder. Insomnia that is brief or occurs in the context of active substance use is best treated by promoting abstinence. A referral to a sleep medicine clinic should be considered for those with chronic insomnia or when another intrinsic sleep disorder is suspected.

Mindfulness-based interventions modulate structural network strength in patients with opioid dependence

Mindfulness-based interventions (MBI) are increasingly used in the treatment of patients with mental disorders, in particular in individuals presenting with affective disorders or in patients exhibiting abnormal levels of impulsive behavior. MBI have been also offered to patients with substance use disorders, where such treatment options may yield considerable clinical effects. Neural effects associated with MBI have been increasingly acknowledged, but is unknown whether MBI exert specific effects on brain structure in patients with substance use disorders. In this study, we investigated 19 inpatients with opioid dependence receiving treatment-as-usual (TAU, n = 9) or additional MBI (n = 10). Structural magnetic resonance imaging data were acquired before and after four weeks of treatment. Source-based morphometry was used to investigate modulation of structural networks after treatment. Both treatment modalities led to significant clinical improvement. Patients receiving MBI showed a significant change in distress tolerance levels. An increase in bilateral striatal/insular and prefrontal/cingulate network strength was found in patients receiving MBI compared to individuals receiving TAU. Prefrontal/cingulate cortical network strength was associated with impulsivity levels. These findings suggest that MBI can have a recognizable role in treatment of substance use disorders and that neural effects of MBI may be captured in terms of frontostriatal structural network change.

Computational modeling of opioid-induced synaptic plasticity in hippocampus

According to a broad range of research, opioids consumption can lead to pathological memory formation. Experimental observations suggested that hippocampal glutamatergic synapses play an indispensable role in forming such a pathological memory. It has been suggested that memory formation at the synaptic level is developed through LTP induction. Here, we attempt to computationally indicate how morphine induces pathological LTP at hippocampal CA3-CA1 synapses. Then, based on simulations, we will suggest how one can prevent this type of pathological LTP. To this purpose, a detailed computational model is presented, which consists of one pyramidal neuron and one interneuron both from CA3, one CA1 pyramidal neuron, and one astrocyte. Based on experimental findings morphine affects the hippocampal neurons in three primary ways: 1) disinhibitory mechanism of interneurons in CA3, 2) enhancement of NMDARs current by μ Opioid Receptor (μOR) activation and 3) by attenuation of astrocytic glutamate reuptake ability. By utilizing these effects, simulations were implemented. Our results indicate that morphine can induce LTP by all aforementioned possible mechanisms. Based on our simulation results, attenuation of pathologic LTP achieved mainly by stimulation of astrocytic glutamate transporters, down-regulation of the astrocytic metabotropic glutamate receptors (mGlurs) or by applying NMDAR’s antagonist. Based on our observations, we suggest that astrocyte has a dominant role in forming addiction-related memories. This finding may help researchers in exploring drug actions for preventing relapse.

Letter to the Editor: Substance use disorder—Substance-induced disorder clinics for pain-medication addictions and addicted patients' pains: futuristic need for pain physicians sub-specializing in addiction-medicine

no abstract

Erectile dysfunction and quality of life in men receiving methadone or buprenorphine maintenance treatment. A cross-sectional multicentre study

BACKGROUND

Erectile dysfunction (ED) is common among men on opioid replacement therapy (ORT), but most previous studies exploring its prevalence and determinants yielded contrasting findings. Moreover, the impact of ED on patients' quality of life (QoL) has been seldom explored.

OBJECTIVE

To explore the prevalence and determinants of ED in men on ORT, and the impact on QoL.

METHODS

In a multicentre cross-sectional study, we recruited 797 consecutive male patients on methadone and buprenorphine treatment, collected data on demographic, clinical, and psychopathological factors, and explored their role as predictors of ED and QoL through univariate and multivariate analysis. ED severity was assessed with a self-assessment questionnaire.

RESULTS

Nearly half of patients in our sample were sexually inactive or reported some degree of ED. Some demographic, clinical and psychopathological variables significantly differed according to the presence or absence of ED. Multivariate regression analysis indicated that age, employment, smoke, psychoactive drugs, opioid maintenance dosage, and severity of psychopathological factors significantly influenced the risk and severity of ED. QoL was worse in patients with ED and significantly correlated with ED severity. Age, education, employment, opioid maintenance dosage, ED score, and severity of psychopathology significantly influenced QoL in the multivariate analysis.

CONCLUSIONS

ED complaints can be explored in male opioid users on ORT through a simple and quick self-assessment tool. ED may have important effects on emotional and social well-being, and may affect outcome.

The Opioid Crisis in Missouri: A Call to Action for Physicians, Legislators, and Society

Opioid overdose deaths in the United States increased sharply over the last decade leading the President to declare a national emergency. The neurobiology of opioid addiction is explored in conjunction with the historical events preceding the current epidemic. A patient-centric perspective is provided along with rationale for contemporary Medical Assisted Therapy (MAT) options to safely reduce overdose deaths and other preventable consequences of prescription misuse and heroin abuse. A multidisciplinary medical provider approach is essential, in addition to legislative efforts to reduce current regulatory burdens that reduce access to MAT in many settings. This review introduces a new Missouri Medicine series intended to explore key concepts to simultaneously reduce opioid prescribing, while effectively managing acute and chronic pain across complex healthcare settings.

Estimating State Transitions for Opioid Use Disorders

AIM

The aim was to estimate transitions between periods in and out of treatment, incarceration, and legal supervision, for prescription opioid (PO) and heroin users.

METHODS

We captured all individuals admitted for the first time for publicly funded treatment for opioid use disorder (OUD) in California (2006 to 2010) with linked mortality and criminal justice data. We used Cox proportional hazards and competing risks models to assess the effect of primary PO use (v. heroin) on the hazard of transitioning among 5 states: (1) opioid detoxification treatment; (2) opioid agonist treatment (OAT); (3) legal supervision (probation or parole); (4) incarceration (jail or prison); and (5) out-of-treatment. Transitions were conditional on survival, and death was modeled as an absorbing state.

RESULTS

Both primary PO (n = 11,733) and heroin (n = 19,926) users spent most of their median 2.3 y of observation out of treatment. Primary PO users were significantly younger (median age 30 v. 34 y), and a higher percentage were female (43.1% v. 31.5%; P < 0.001), white (74.6% v. 63.1%; P < 0.001), and had completed high school (31.8% v. 18.9%; P < 0.001). When compared to primary heroin users, PO users had a higher hazard of transitioning from detoxification to OAT (Hazard Ratio (HR), 1.65; 95% CI, 1.54 to 1.77), and had a lower hazard of transitioning from out-of-treatment to either detoxification (0.75 [0.70, 0.81]) or OAT (0.90 [0.85, 0.96]).

CONCLUSION

Our findings can be applied directly in state transition modeling to improve the validity of health economic evaluations. Although PO users tended to remain in treatment for longer durations than heroin users, they also tended to remain out of treatment for longer after transitioning to an out-of-treatment state. Despite the proven effectiveness of time-unlimited treatment, individuals with OUD spend most of their time out of treatment.

A comparison of bone quality and its determinants in young opioid-dependent women with healthy control group

BACKGROUND

Little is known about bone quality and its determinants in patients with opioid addiction. The goal of this study was to compare bone quality and its determinants in young opioid addicted women with a local group of young healthy women.

METHOD

Using cross-sectional design, 104 women (mean age 29.9 yrs, range: 20-40 yrs, SD=7.8) with previous opioid addiction and current methadone substitution (3-30mg, daily) for 1-16 weeks were compared to 117 healthy women (mean age 31.0 yrs, range: 20-40 yrs, SD=5.9). Bone quality was examined with quantitative ultrasound. Anthropometric characteristics (body weight, fat free mass (FFM), fat mass) were obtained by bioelectrical impedance analysis. Substance use and other risk factors for low bone quality were assessed by questionnaire-based interviews.

RESULTS

More than one-quarter (34%) of patients had osteopenia (n=31) or osteoporosis (n=4), compared to 16% of the healthy control group having osteopenia (n=18). Bivariate correlation analysis demonstrated that age, body weight, and FFM correlated with bone quality (p<0.05) in healthy women, which were not found in patients. Multivariate analyses showed that in healthy controls, the determinants of bone quality were age, body height, physical activity, and BMI, but in patients, the determinant of bone quality was duration of drug intake.

CONCLUSIONS

Long-term opioid dependence in young women may lead to low bone quality. Efforts to increase awareness of low bone quality in young opioid addicted women should be considered so that effective treatment may be employed to lower future fracture risk.

Opioid Addiction: Social Problems Associated and Implications of Both Current and Possible Future Treatments, including Polymeric Therapeutics for Giving Up the Habit of Opioid Consumption

BACKGROUND

Detoxification programmes seek to implement the most secure and compassionate ways of withdrawing from opiates so that the inevitable withdrawal symptoms and other complications are minimized. Once detoxification has been achieved, the next stage is to enable the patient to overcome his or her drug addiction by ensuring consumption is permanently and completely abandoned, only after which can the subject be regarded as fully recovered.

METHODS

A systematic search on the common databases of relevant papers published until 2016 inclusive.

RESULTS AND CONCLUSION

Our study of the available oral treatments for opioid dependence has revealed that no current treatment can actually claim to be fully effective. These treatments require daily oral administration and, consequently, regular visits to dispensaries, which in most cases results in a lack of patient compliance, which causes fluctuations in drug plasma levels. We then reviewed alternative treatments in the available scientific literature on polymeric sustained release formulations. Research has been done not only on release systems for detoxification but also on release systems for giving up the habit of taking opioids. These efforts have obtained the recent authorization of polymeric systems for use in patients that could help them to reduce their craving for drugs.

Cannabidiol: Swinging the Marijuana Pendulum From 'Weed' to Medication to Treat the Opioid Epidemic

Epidemics require a paradigm shift in thinking about all possible solutions. The rapidly changing sociopolitical marijuana landscape provides a foundation for the therapeutic development of medicinal cannabidiol to address the current opioid abuse crisis.

Opiate withdrawal syndrome in buprenorphine abusers admitted to a rehabilitation center in Tunisia

BACKGROUND

Illicit use of high dosage buprenorphine has been well documented in several countries, including Tunisia.

OBJECTIVES

The aim of this survey is to assess the buprenorphine withdrawal syndrome time course, and how it may be affected by the population characteristics among subjects admitted to a rehabilitation center in Tunisia.

METHODS

A prospective research has permitted study of the socio-demographic characteristics and assessment of buprenorphine withdrawal syndrome among 32 subjects admitted for buprenorphine dependence by using the clinical opiate withdrawal scale. An ANOVA was conducted to examine the effect of different factors on the withdrawal scores.

RESULTS

32 subjects were included. Among them 30 were males, 27 had been injecting buprenorphine, 16 were poly-drug abusers and 2 had a history of mental disorders. Buprenorphine withdrawal syndrome was of a mild intensity and had a delayed onset. Withdrawal mean scores varied between 0 and 9, and maximum values were reached at day 21. These scores varied significantly over time (p<0,001). The sex v time interaction and the mode of consumption of buprenorphine had significant effects on the withdrawal scores (p<0,001). The poly-drug consumption and the history of mental disorders did not have any significant effect on the withdrawal scores.

CONCLUSION

This study has permitted description of buprenorphine withdrawal syndrome among patients going through a detoxification treatment at a rehabilitation center. Understanding this syndrome would help elaborate effective and suitable buprenorphine dependence management plans.

Multifaceted impairments in impulsivity and brain structural abnormalities in opioid dependence and abstinence

BACKGROUND

Chronic opioid exposure, as a treatment for a variety of disorders or as drug of misuse, is common worldwide, but behavioural and brain abnormalities remain under-investigated. Only a small percentage of patients who receive methadone maintenance treatment (MMT) for previous heroin misuse eventually achieve abstinence and studies on such patients are rare.

METHOD

The Cambridge Neuropsychological Test Automated Battery and T1 weighted magnetic resonance imaging (MRI) were used to study a cohort of 122 male individuals: a clinically stable opioid-dependent patient group receiving MMT (n = 48), an abstinent previously MMT maintained group (ABS) (n = 24) and healthy controls (n = 50).

RESULTS

Stable MMT participants deliberated longer and placed higher bets earlier in the Cambridge Gambling Task (CGT) and showed impaired strategic planning compared with healthy controls. In contrast, ABS participants showed impairment in choosing the least likely outcome, delay aversion and risk adjustment on the CGT, and exhibited non-planning impulsivity compared with controls. MMT patients had widespread grey matter reductions in the orbitomedial prefrontal cortex, caudate, putamen and globus pallidus. In contrast, ABS participants showed midbrain-thalamic grey matter reductions. A higher methadone dose at the time of scanning was associated with a smaller globus pallidus in the MMT group.

CONCLUSIONS

Our findings support an interpretation of heightened impulsivity in patients receiving MMT. Widespread structural brain abnormalities in the MMT group and reduced brain structural abnormality with abstinence suggest benefit of cessation of methadone intake. We suggest that a longitudinal study is required to determine whether abstinence improves abnormalities, or patients who achieve abstinence have reduced abnormalities before methadone cessation.

The Evolution of Recommended Naloxone Dosing for Opioid Overdose by Medical Specialty

INTRODUCTION

Opioid abuse and opioid overdose deaths have increased significantly over the past decade. Naloxone is a potentially life-saving medication that can reverse opioid-induced respiratory depression, though precipitated opioid withdrawal can pose acute risks to the patient and medical personnel. The optimal naloxone dose is unclear and few studies address this question.

METHODS

A convenience sample of commonly available references were queried for the recommended IV naloxone dose. When dosing recommendations were different for opioid-tolerant patients these were also recorded.

RESULTS

Twenty-five references were located. 48% recommended a starting dose ≤ 0.05 mg while 36% recommend a dose ten-fold higher. More than half of medical toxicology and general medical sources recommended a low-dose strategy with a starting dose lower than 0.05 mg IV.

CONCLUSION

There are variations in the recommended doses for naloxone with ranges spanning an order of magnitude. Further exploration is needed to determine the dose that balances reversal of respiratory depression with mitigation of withdrawal.

Effects of Antisocial Personality, Cocaine and Opioid Dependence, and Gender on Eye Movement Control

Substance-dependent patients have been reported to exhibit abnormal smooth pursuit and saccadic eye movements. However, contrasts of the effects of different substances and the effects of comorbid psychiatric symptoms such as antisocial personality have rarely been performed. Separate analyses examined the effects of cocaine dependence, opioid dependence, or antisocial personality disorder. In each analysis, sex was included as an additional grouping factor. The dependent measures were the gain of smooth pursuit eye movement and the delay and accuracy of saccadic eye movement. Analyses of covariance indicated that both cocaine dependence and antisocial personality, but not opiate dependence, were associated with a significant reduction in gain of smooth pursuit eye movement. Cocaine dependence and antisocial personality also slowed the onset of saccadic eye movements, but only in men. No group differences were found in the accuracy of saccadic eye movements. The results suggest that the neurophysiological effects of cocaine dependence and antisocial personality overshadow the effects of heroin. The significance of these findings for visual attention and reading skill has yet to be assessed.

Efficacy and Safety of Methadone as a Second-Line Opioid for Cancer Pain in an Outpatient Clinic: A Prospective Open-Label Study

INTRODUCTION

Most clinical reports on methadone rotation describe outcomes in hospitalized patients. The few studies that have included outpatients are retrospective. The aim of this study was to assess the efficacy and safety of methadone as a second-line opioid in adult patients with advanced cancer after rotation in routine clinical practice at a palliative care outpatient clinic.

PATIENTS AND METHODS

This was a prospective, open-label study of 145 patients whose treatment was rotated from other opioids to methadone. Informed consent was obtained in all cases. The main outcome measure was change in the variable "worst pain" at day 28. Pain and pain interference were assessed with the Brief Pain Inventory, with side effects evaluated according to the Common Terminology Criteria for Adverse Events version 3.0. Pain levels were evaluated at study entry and at days 3, 7, 9, 14, 21, and 28.

RESULTS

Rotation to methadone was performed for the following reasons: poor pain control (77.9%), opioid side effects (2.1%), or both (20%). The mean daily oral morphine equivalent dose before rotation was 193.7 mg. The median worst and average pain scores decreased significantly (p < .0001) from baseline to day 28: The median worst pain score decreased from 9 (interquartile range [IQR]: 8-10) to 6 (IQR: 3-8), and the median average pain score decreased from 6 (IQR: 5-7) to 4 (IQR: 2-5). The proportions of patients with moderate to severe worst and average pain decreased by 30.3% and 47.5%, respectively, by day 28. No increase in opioid toxicity was observed during the study.

CONCLUSION

In outpatients with advanced cancer, rotation to methadone as a second-line opioid was efficacious and safe when using a tiered scheme with close follow-up by experienced health professionals.

IMPLICATIONS FOR PRACTICE

The results of this study, conducted prospectively under real clinical conditions, support the efficacy and safety of oral methadone as a second-line opioid in ambulatory patients with cancer. Moreover, these findings corroborate previously reported outcomes in retrospective outpatient studies and prospective studies that evaluated inpatient populations. Although more research into methadone rotation strategies is still needed, this study describes a successful tiered scheme of oral methadone rotation that was proven safe and effective during follow-up.

Naloxone Administration in US Emergency Departments, 2000-2011

Rates of opioid overdose and opioid-related emergency department (ED) visits have increased dramatically. Naloxone is an effective antidote to potentially fatal opioid overdose, but little is known about naloxone administration in ED settings. We examined trends and correlates of naloxone administration in ED visits nationally from 2000 to 2011. Using data from the National Hospital Ambulatory Medical Care Survey, we examined ED visits involving (1) the administration of naloxone or (2) a diagnosis of opioid overdose, abuse, or dependence. We assessed patient characteristics in these visits, including concomitant administration of prescription opioid medications. We used logistic regression to identify correlates of naloxone administration. From 2000 to 2011, naloxone was administered in an estimated 1.7 million adult ED visits nationally; 19 % of these visits recorded a diagnosis of opioid overdose, abuse, or dependence. An estimated 2.9 million adult ED visits were related to opioid overdose, abuse, or dependence; 11 % of these visits involved naloxone administration. In multivariable logistic regression models, patient age, race, and insurance and non-rural facility location were independently associated with naloxone administration. An opioid medication was provided in 14 % of visits involving naloxone administration. Naloxone was administered in a minority of ED visits related to opioid overdose, abuse, or dependence. Among all ED visits involving naloxone administration, prescription opioids were also provided in one in seven visits. Further work should explore the provider decision-making in the management of opioid overdose in ED settings and examine patient outcomes following these visits.

[A significance of measurement of breathing nervous regulation, respiratory resistance and spirometry in clinical toxicology - retrospective review]

The exogenous central nervous system depressants such opioides, alcohol and carbon monoxide may affect nervous respiratory regulation and lead to disturbances in respiratory system efficiency. The aim of this study was to evaluate the breathing nervous regulation and ventilatory efficiency in patients treated in Clinical Toxicology, UJCM in Krakow in the period 1994- 2000.

METHODS

There were 385 persons under examination: 144 alcohol abusers and 70 opiate abusers (group I), 91 persons treated because of acute carbon monoxide poisoning (group II) and 80 healthy persons - control group. The examinations performed before and after treatment included measurements of respiratory pattern parameters, occlusion pressure and evaluation of ventilatory efficiency determined on the basis of “flow-volume” loop results, spirometry and the measurements of respiratory tract resistance.

RESULTS

The central respiratory drive (VT/T(in) index) and the parasympathetic control of breathing cycle (T(in)/ T(tot) index) were similar in alcohol and opiate abusers in the initial examination but in abusers classified to methadone maintenance treatment programme the VT/T(in) index was elevated. After treatment the values of both indices were similar. In the group of acute CO poisoned patients the disturbances in breathing regulation were connected with increased value of the VT/Tin parameter and the diminished of T(in)/T(tot) value. After treatment in the slightly CO poisoned patients the both respiratory pattern components were comparable to the healthy control group but in the moderately and severely poisoned group the VT/T(in) index was elevated and the T(in)/T(tot) index was lessened compared to the controls. The values of respiratory resistance were higher than upper level of normal values (except participants of methadone programme). The bronchial obturation was most often stated disturbance in respiratory system efficiency, especially in alcohol abusers. Ventilatory parameters in moderate and severe CO poisoned were significantly lower than in the slightly poisoned patients.

CONCLUSION

Presented methods of evaluation of respiratory system efficiency and nervous breathing regulation are of special value and should be implemented in clinical toxicology as essential to diagnosis and monitoring, especially in case of alcohol and drug dependent patients and in patients poisoned with central nervous system depressants.

Report: Demographic profiles and sleep quality among patients on methadone maintenance therapy (MMT) in Malaysia

Poor sleep quality was frequently reported by opioid dependence patients during methadone maintenance therapy (MMT). The study investigated a sample of patients on MMT to investigate the severity and prevalence of sleep problems in MMT patients. We evaluated sleep quality and disturbances of 119 Malay male patients from MMT clinics in Kelantan, Malaysia between March and July 2013 using the Pittsburgh Sleep Quality Index (PSQI)-Malay version. Patients' demographic, clinical data, past drug history and methadone treatment variables were recorded. Patients averaged 37.5 years of age (SD 6.79) and their mean age of first time illicit drug use was 19.3 years (SD 4.48). Their mean age of entering MMT was 34.7 years (SD 6.92) and the mean duration in MMT was 2.8 years (SD 2.13). The mean current daily dosage of methadone was 77.8 mg (SD 39.47) and ranged from 20 to 360 mg. The mean global PSQI score was 5.6 (SD 2.79) and 43.7% patients were identified as 'poor sleepers' (global PSQI scores >5). This study confirms the poor overall sleep quality among patients on MMT. The prevalence and severity of sleep problems in MMT patients should not be underestimated.