Co-use Of Opioids Research Articles

Correlates of Current Methamphetamine Use and Opioid Co-Use Among Latina Women in a Low-Income Community

ABSTRACT Using data from Proyecto SALTO, a 15-year follow-up study of a cohort of Mexican American women in a low-income community in San Antonio, Texas, this study examines emerging patterns of current methamphetamine (MA) use, including opioid co-use, among this understudied population. A bivariate analysis compared individuals with and without current MA use and identified sociodemographic correlates and co-occurring mental health and substance use. A secondary analysis compared those with current MA use, opioid use, and concurrent MA and opioid use. Nineteen percent of the sample had current MA use. MA use was associated with having a lower income (OR = 7.04–1.93, SE = 1.59–5.46), residential instability (OR = 5.19, SE = 1.99), and suicidal ideation (OR = 2.62, SE = 0.93). Participants with MA use had more than four times the odds of using opioids than those without MA use. Women with concurrent MA and opioid use differed in sociodemographics and behavioral risks compared to those with only MA or only opioid use. These findings explore the social, mental health, and structural inequities that exacerbate risks and harms associated with high-risk substance use among marginalized Latino populations. Prevention and intervention strategies should adopt a holistic approach that considers and addresses polysubstance use, mental health, and the sociocultural contexts in which individuals live.

Benzodiazepine Adverse Reaction Cases Age 50 and Older Reported to the U.S. Poison Centers: Healthcare Use and Major Medical Effects

Background: Despite widespread consensus on the need to reduce benzodiazepine (BZD) use in older adults, prescription rates in the U.S. have paradoxically increased over the past few decades. Objective: We examined (1) the characteristics of the BZD adverse reaction cases in patients aged 50 and older that were admitted to a healthcare facility (HCF) and experienced major effects/death, and (2) the associations between the concomitant use of opioids and/or antidepressants and HCF admission and major effects/death among BZD cases. Methods: We used the 2015–2022 National Poison Data System (NPDS), which contained data from 55 America’s Poison Centers. We fitted two multivariable logistic regression models to examine the associations between the co-use of opioids and/or antidepressants and HCF admission and major effects/death. Results: Of the BZD cases that were examined (N = 1979), 14.9% or 295 cases were admitted to healthcare facilities, and 8.5% of those who were followed up (77 out of 893 cases) experienced major effects or death. The number of co-used substances, co-use of opioids and antidepressants, atypical antipsychotics, anticonvulsants, muscle relaxants, and Gabapentin were associated with greater odds of healthcare admission. Co-use of opioids and healthcare admission were associated with greater odds of major effects/death. Conclusions: Adverse reactions and healthcare admissions are likely to be prevented when healthcare providers limit and carefully monitor BZD prescribing, especially for those who are on other medications, including prescription opioids and antidepressants.

Gabapentinoids Increase the Potency of Fentanyl and Heroin and Decrease the Potency of Naloxone to Antagonize Fentanyl and Heroin in Rats Discriminating Fentanyl.

Despite a significant decrease in the number of prescriptions for opioids, the opioid crisis continues, fueled in large part by the availability of the phenylpiperidine mu opioid receptor (MOR) agonist fentanyl. In contrast, the number of prescriptions for and the off-label use of gabapentinoids (gabapentin and pregabalin) has increased dramatically, with gabapentinoids commonly detected in opioid overdose victims. Although gabapentinoids can decrease the potency of the opioid receptor antagonist naloxone to reverse heroin-induced hypoventilation in male rats, the specificity and nature of interaction between gabapentinoids and MOR agonists and any potential sex difference in those interactions are not well characterized. Gabapentinoids were studied in female and male rats discriminating fentanyl (0.0032 mg/kg, i.p.) or cocaine (3.2 mg/kg, i.p.). Alone, neither gabapentin nor pregabalin significantly increased fentanyl- or cocaine-appropriate responding. In rats discriminating fentanyl, each gabapentinoid dose-dependently shifted the fentanyl and heroin discrimination dose-effect functions to the left, whereas naloxone dose-dependently shifted the fentanyl and heroin discrimination dose-effect functions to the right. Each gabapentinoid (100 mg/kg) significantly decreased the potency of naloxone to antagonize the discriminative stimulus effect of fentanyl or heroin. In contrast, each gabapentinoid dose-dependently shifted the cocaine and d-methamphetamine discrimination dose-effect functions to the right. There were no significant sex differences in this study. These results suggest that gabapentinoids impact the misuse of opioids, the co-use of opioids and stimulant drugs, and the increasing number of overdose deaths in individuals using opioids, stimulant drugs, and gabapentinoids in mixtures. SIGNIFICANCE STATEMENT: The number of prescriptions for and the off-label use of gabapentinoids (gabapentin and pregabalin) has increased dramatically, with gabapentinoids commonly detected in opioid overdose victims. This study reports that in rats gabapentinoids increase the potency of fentanyl and heroin to produce discriminative stimulus effects while decreasing the potency of naloxone to antagonize those effects of fentanyl and heroin. These results can help guide policies for regulating gabapentinoids and treating opioid misuse and overdose.

Detecting univariate, bivariate, and overall effects of drug mixtures using Bayesian kernel machine regression

ABSTRACT Background: Innovative analytic approaches to drug studies are needed to understand better the co-use of opioids with non-opioids among people using illicit drugs. One approach is the Bayesian kernel machine regression (BKMR), widely applied in environmental epidemiology to study exposure mixtures but has received far less attention in substance use research. Objective: To describe the utility of the BKMR approach to study the effects of drug substance mixtures on health outcomes. Methods: We simulated data for 200 individuals. Using the Vale and Maurelli method, we simulated multivariate non-normal drug exposure data: xylazine (mean = 300 ng/mL, SD = 100 ng/mL), fentanyl (mean = 200 ng/mL, SD = 71 ng/mL), benzodiazepine (mean = 300 ng/mL, SD = 55 ng/mL), and nitazene (mean = 200 ng/mL, SD = 141 ng/mL) concentrations. We performed 10,000 MCMC sampling iterations with three Markov chains. Model diagnostics included trace plots, r-hat values, and effective sample sizes. We also provided visual relationships of the univariate and bivariate exposure-response and the overall mixture effect. Results: Higher levels of fentanyl and nitazene concentrations were associated with higher levels of the simulated health outcome, controlling for age. Trace plots, r-hat values, and effective sample size statistics demonstrated BKMR stability across multiple Markov chains. Conclusions: Our understanding of drug mixtures tends to be limited to studies of single-drug models. BKMR offers an innovative way to discern which substances pose a greater health risk than other substances and can be applied to assess univariate, bivariate, and cumulative drug effects on health outcomes.

Unmet needs and harm reduction preferences of syringe services program participants: differences by co-use of illicit opioids and methamphetamine

BackgroundThe current fourth wave of the United States opioid overdose epidemic is characterized by the co-use of opioids and stimulants, including illicit opioids and methamphetamine. The co-use of these two drugs, known as “goofballing,” is associated with higher risk for several adverse outcomes, including more frequent injections, greater health risks, and higher morbidity. Considering these differences, this unique subpopulation of people who inject drugs (PWID) may also have unique unmet needs and harm reduction preferences.MethodsWe collected self-reported data from participants (N = 50) of a syringe services program (SSP), including basic needs and harm reduction preferences. Using bivariate analyses, we examined differences between SSP participants who do and do not co-use illicit opioids and methamphetamine. Co-use was defined as reporting the use of both drugs, which may or may not have been used simultaneously.ResultsIn the overall sample, the mean level of need was highest for bus passes or other transportation, a person who can help you get the services you need, medication for opioid use disorder, and a job or job training. Additionally, all participants reported being either interested or very interested in fentanyl test strips, safe consumption sites, delivery of syringe service supplies, and delivery of naloxone. Those who endorsed co-use had a greater need for food, healthcare, substance use disorder treatment, a support person to help them access needed services, and bus passes or transportation.ConclusionsUnmet needs were prevalent, and the desire for more harm reduction services was high among these PWID. Results also suggest people who co-use illicit opioids and methamphetamine may have the greatest unmet needs and desire for additional harm reduction services.

Longitudinal patterns of use of stimulants and opioids in the AIDS linked to the IntraVenous experience cohort, 2005–2019

BackgroundOverdoses involving opioids and stimulants are on the rise, yet few studies have examined longitudinal trends in use of both substances. We sought to describe use and co-use of opioids and stimulants, 2005–2019, in the AIDS Linked to the Intravenous Experience (ALIVE) cohort – a community-based cohort of people with a history of injection drug use living in or near Baltimore, MD. MethodsWe included 2083 ALIVE participants, who had at least two visits during the study period. Our outcome was based on self-reported use of opioids and stimulants in the prior 6 months. We estimated prevalence of 4 categories of use (neither stimulants nor opioids, only stimulants, only opioids, stimulants and opioids), using a non-parametric multi-state model, accounting for the competing event of death and weighting for informative loss to follow-up. All analyses were stratified by enrollment cohort, with the main analysis including participants who enrolled prior to 2015 and a sub-analysis including participants who enrolled 2015–2018. ResultsIn the main analysis, prevalence of using stimulants and opioids decreased from 38 % in 2005 to 12 % 2013 but stabilized from 2014 onwards (13–19 %). The prevalence of using only stimulants (7–11 %) and only opioids (5–10 %) was stable across time. Participants who reported using both were more likely to report homelessness, depression, and other substance use (e.g., marijuana and heavy alcohol use) than participants in the other use categories. On average, 65 % of visits with use of both were followed by a subsequent visit with use of both; of participants transitioning out of using both, 13% transitioned to using neither. ConclusionsWhile use of stimulants and opioids declined in the cohort through 2013, a meaningful proportion of participants persistently used both. More research is needed to understand and develop strategies to mitigate harms associated with persistent use of both stimulants and opioids.

Opioid and methamphetamine co-use: associations with economic vulnerabilities and interpersonal victimization among SUD program clients

ABSTRACT Increases in methamphetamine use among individuals seeking treatment for opioid use disorder (OUD) have implications for substance use disorder (SUD) treatment. Secondary data from 28,358 adults (18+) in a multi-year evaluation of publicly funded SUD treatment was analyzed. A significant linear trend showed an increase in opioid and methamphetamine co-use over time. In the multinomial logistic regression, recent co-use of opioids and methamphetamine was significantly associated with being female, younger age, being White, living in a metropolitan community, greater economic hardship, using more substances (other than opioids and methamphetamine) relative to the other drug use patterns. Past-12-month interpersonal victimization was associated with co-use of opioids and methamphetamine relative to individuals who did not use opioids-methamphetamine and individuals who used opioids, no methamphetamine.

Ventilatory Effects of Fentanyl, Heroin, and d-Methamphetamine, Alone and in Mixtures in Male Rats Breathing Normal Air .

The number of drug overdoses and deaths has increased significantly over the past decade and co-use of opioids and stimulants is associated with greater likelihood of overdose and decreased likelihood of accessing treatment, compared with use of opioids alone. Potential adverse effects of opioid/stimulant mixtures, particularly methamphetamine, are not well characterized. Two structurally different drugs with agonist properties at µ-opioid receptors (MOR), fentanyl and heroin, and d-methamphetamine, alone and in mixtures, were assessed for their effects on ventilation in rats breathing normal air. Whole-body phethysmography chambers were equipped with a tower and swivel allowing infusions to indwelling intravenous catheters. After a 45-minute habituation period, saline, fentanyl, heroin, or d-methamphetamine, alone and in mixtures, was administered. Five minutes later, the opioid receptor antagonist naloxone or vehicle was injected. Fentanyl (0.0032-0.1 mg/kg) and heroin (0.32-3.2 mg/kg) decreased ventilation [frequency (f) and tidal volume (VT)] in a dose-related manner whereas d-methamphetamine (0.1-3.2 mg/kg) increased f to >400% of control and decreased VT to <60% of control, overall increasing minute volume (product of f and VT) to >240% of control. When combined, d-methamphetamine (0.1-3.2 mg/kg) attenuated the ventilatory depressant effects of fentanyl (0.1 mg/kg) and heroin (3.2 mg/kg). d-Methamphetamine did not alter the potency of naloxone to reverse the ventilatory depressant effects of fentanyl or heroin. These studies demonstrate that d-methamphetamine can attenuate the ventilatory depressant effects of moderate doses of opioid receptor agonists while not altering the potency of naloxone to reverse opioid hypoventilation. SIGNIFICANCE STATEMENT: Co-use of opioids and stimulants is associated with greater likelihood of overdose and decreased likelihood of accessing treatment, compared with use of opioids alone. Potential adverse effects of opioid/stimulant mixtures are not well characterized. This study reports that 1) d-methamphetamine attenuates the ventilatory depressant effects of moderate doses of two structurally different opioid receptor agonists, fentanyl and heroin, and 2) d-methamphetamine does not alter potency or effectiveness of naloxone to reverse the ventilatory depressant effects of these opioid receptor agonists.

The Impact of Longitudinal Substance Use Patterns on the Risk of Opioid Agonist Therapy Discontinuation: A Repeated Measures Latent Class Analysis

AbstractPolysubstance use is prevalent among individuals on opioid agonist treatment (OAT), yet past studies have focused primarily on distinct substances and their association with OAT retention. Data was collected from two prospective cohorts between 2005 and 2020 in Vancouver, Canada. Among 13,596 visits contributed by 1445 participants receiving OAT, we employed repeated measures latent class analysis using seven indicators and identified four longitudinal substance use classes. Using marginal structural Cox modeling, we found that compared to the primarily crack use class, the two opioid and stimulant use classes carried a higher risk of OAT discontinuation, while the primarily cannabis and crack use class had a lower OAT discontinuation risk. Our findings highlight the need for integrated treatment strategies to manage the co-use of opioids and stimulants during receipt of OAT and suggest future research should explore the potential of cannabis as a harm reduction strategy or adjunctive treatment to OAT.Word count: 150/150.

Alcohol Use Among Treatment-Seeking Individuals With Opioid Use Disorder.

Individuals in the United States with opioid use disorder (OUD) have high rates of co-occurring alcohol use disorder. However, there is limited research on co-use patterns among opioid and alcohol use. The present study examined the relationship between alcohol and opioid use in treatment-seeking individuals with an OUD. The study used baseline assessment data from a multisite, comparative effectiveness trial. Participants with an OUD who had used nonprescribed opioids in the last 30 days (n = 567) reported on their alcohol and opioid use during the past 30 days using the Timeline Followback. Two mixed-effects logistic regression models were used to assess the effect of alcohol use and binge alcohol use (≥4 drinks/day for women and ≥5 drinks/day for men) on opioid use. The likelihood of same-day opioid use was significantly lower on days in which participants drank any alcohol (p < .001) as well as on days in which participants reported binge drinking (p = .01), controlling for age, gender, ethnicity, and years of education. These findings suggest that alcohol or binge alcohol use is associated with significantly lower odds of opioid use on a given day, which was not related to gender or age. The prevalence of opioid use remained high on both alcohol use and non-alcohol use days. In line with a substitution model of alcohol and opioid co-use, alcohol may be used to treat symptoms of opioid withdrawal and possibly play a secondary and substitutive role in individuals with OUD substance use patterns.

Community overdose surveillance: Fentanyl involvement in overdose deaths in rural Michigan

PurposeExamine fatal overdose toxicology trends to contribute toward understanding the outreach and treatment needs of people who use drugs in rural areas. MethodsWe describe toxicology results from overdose deaths that occurred between January 1, 2018, and December 31, 2020, in 11 rural counties in Michigan, a state with relatively high rates of overdose mortality. One-way ANOVA with Tukey's HSD posthoc tests were used to test statistically significant differences in the frequency of substances detected between years. FindingsDecedents (N = 107) were male (72.9%), White (96.3%), non-military (96.3%), unemployed (71.0%), married (73.9%), and had a mean age of 47 years old. The number of observed overdose deaths increased considerably from 2019 to 2020, with an increase of 72.4%. Fentanyl was the most common substance detected and had a 94% increase during the three-year period to present in 70% of all the deaths in these counties in 2020. Among the deaths we examined where cocaine was detected, 69% also contained fentanyl, and in deaths where methamphetamine was detected, 77% also contained fentanyl. ConclusionFindings could inform rural health and outreach initiatives aimed at reducing overdose risks by providing education on the risks of stimulant and opioid couse but also the widespread saturation of illicit drugs that contain fentanyl. Lowthreshold harm reduction interventions are discussed amid limited prevention and treatment resources in rural communities.

Strategies Used to Manage Chronic Pain in HIV-Disease: Comparing Persons Prescribed Opioids Versus Persons not Receiving Opioids.

Chronic pain is common in people living with HIV (PLWH), causes substantial disability and is associated with limitations in daily activities. Opioids are commonly prescribed for pain treatment among PLWH, but evidence of sustained efficacy is mixed. There is little information available on how PLWH who have chronic pain use multimodal strategies in pain management. The current cross-sectional study examined background characteristics, self-reported pain, and the use of other pain treatments among 187 PLWH with chronic pain and depressive symptoms who were and were not prescribed opioids. Approximately 20.9% of participants reported using prescription opioids at the time of the study interview. These individuals were significantly more likely to report having engaged in physical therapy or stretching, strengthening or aerobic exercises in the previous 3 months, recent benzodiazepine use, and receiving disability payments. There were no significant differences in pain characteristics (pain-related interference, average pain severity, and worst pain severity) between the two groups. Those not prescribed opioids were more likely to report better concurrent physical functioning and general health, and fewer physical role limitations, but higher depression symptom severity. Our findings suggest that many PLWH with chronic pain and depressive symptoms express high levels of pain with deficits in physical function or quality of life despite their use of opioids. The high rate of co-use of opioids and benzodiazepines (30.8%) is a concern because it may increase risk of overdose. An integrated care approach that includes a variety of effective non-pharmacologic treatment strategies such as physical therapy may be beneficial in reducing the reliance on opioids for pain management.

Potency-Enhancing Synthetics in the Drug Overdose Epidemic: Xylazine ("Tranq"), Fentanyl, Methamphetamine, and the Displacement of Heroin in Philadelphia and Tijuana.

Multiple transformations-referred to as "waves" in a panoply of recent public health and law enforcement publications-have rendered North American drug markets increasingly toxic since the early 2010s. The introduction of exceptionally potent synthetic sedatives and stimulants is initiating a new generation of drug injectors into co-use of opioids and methamphetamine, catapulting rates of deadly overdoses and infectious diseases. Drawing on extensive participant-observation research in Philadelphia (2007-present) and Tijuana (2018-present), we document the experience of street-based drug users across these two North American cities to focus on regional shifts in narcotics supplies and endpoint user preferences. We link the dramatic proliferation of fentanyl, methamphetamine, xylazine, and Mexican white powder heroin to: 1) pre-existing drug supply networks on the western and eastern coasts of the North American subcontinent; 2) material characteristics of local heroin supplies in pre-fentanyl opiate markets (Mexican black tar vs. Colombian off-white powder heroin); and 3) racialized repression/incarceration of drug sellers and users on both sides of the Mexico-US border. The article combines economic and medical anthropology to develop an ethnographically-informed political economy approach to an urgent public health challenge among street-based drug users with the highest overdose mortality rates in the US Northeastern Rust Belt and the Northwestern Mexican borderland metroplex anchored by Tijuana. It foregrounds street users' experiences in real time amidst rapidly shifting narcotics supply chains, linking market-driven logics of profit-seeking to the war on drugs' prohibitionist policy context, highlighting increasing toxic impacts on vulnerable sectors across regions.

259 Outcomes and Resource Utilization of Patients Presenting to the Emergency Department With Opioid and Benzodiazepine Poisoning

Recent literature shows many overdose deaths are associated with co-use of opioids and other drugs, such as benzodiazepines. However, the literature is sparse surrounding the characteristics and associated factors of people with co-use. Additionally, there are limited data evaluating treatment, outcomes, costs, disposition, and resource utilization related to co-users compared to those who use opioids alone.

Designer Benzodiazepines' Activity on Opioid Receptors: A Docking Study.

Previous studies have reported that benzodiazepines (BZDs) seem to enhance euphoric and reinforcing properties of opioids in opioid users so that a direct effect on opioid receptors has been postulated, together with a possible synergistic induction of severe side effects due to co use of BDZs and opioids. This is particularly worrisome given the appearance on the market of designer benzodiazepines (DBZDs), whose activity/toxicity profiles are scarcely known. This study aimed to evaluate, through computational studies, the binding affinity (or lack thereof) of 101 DBZDs identified online on the kappa, mu, and delta opioid receptors (K, M, DOR); and to assess whether their mechanism of action could include activation of the latter. MOE® was used for the computational studies. Pharmacophore mapping based on strong opioids agonist binders' 3D chemical features was used to filter the DBZDs. Resultant DBZDs were docked into the crystallised 3D active conformation of KOR (PDB6B73), DOR (PDB6PT3) and MOR (PDB5C1M). Co-crystallised ligands and four strong agonists were used as reference compounds. A score (S, Kcal/mol) representative of the predicted binding affinity, and a description of ligand interactions were obtained from MOE®. The docking results, filtered for S < -8.0 and the interaction with the Asp residue, identified five DBZDs as putative binders of the three ORs : ciclotizolam, fluloprazolam, JQ1, Ro 48-6791, and Ro 48-8684. It may be inferred that at least some DBZDs may have the potential to activate opioid receptors. This could mediate/increase their anxiolytic, analgesic, and addiction potentials, as well as worsen the side effects associated with opioid co-use.

Real-Time Monitoring of Cannabis and Prescription Opioid Co-Use Patterns, Analgesic Effectiveness, and the Opioid-Sparing Effect of Cannabis in Individuals With Chronic Pain

Despite a rapid expansion of cannabis use for pain management, how cannabis and prescription opioids are co-used and whether co-use improves analgesia and promotes reduction of opioid use in the daily lives of individuals with chronic pain is poorly understood. Based upon ecological momentary assessment (EMA), the present study examined 1) how pain and use of opioids and/or cannabis in the previous moment is associated with individuals’ choice of opioids and/or cannabis in the next moment, 2) the effects of co-use on pain severity and pain relief, and 3) whether daily total opioid consumption differs on days when people only used opioids versus co-used. Adults with chronic pain (N = 46) using both opioids and cannabis who were recruited online completed a 30-day EMA. Elevated pain did not increase the likelihood of co-use in subsequent momentary assessments. Switching from sole use of either opioids and cannabis to co-use was common. Neither co-use nor sole use of either cannabis or opioids were associated with reductions in pain in the next moment. However, participants reported the highest daily perceived pain relief from co-use compared to cannabis and opioid use only. Post hoc analysis suggested recall bias as a potential source of this discrepant findings between momentary versus retrospective assessment. Lastly, there was no evidence of an opioid-sparing effect of cannabis in this sample. The present study shows preliminary evidence on cannabis and opioid co-use patterns, as well as the effects of co-use on pain and opoid dose in the real-world setting. PerspectiveThis article presents the overall patterns and effects of co-using cannabis and prescription opioids among individuals with chronic pain employing ecological momentary assessment. There were conflicting findings on the association between co-use and analgesia. Co-use was not associated with a reduction in daily opioid consumption in this sample.

Dopamine Supersensitivity: A Novel Hypothesis of Opioid-Induced Neurobiological Mechanisms Underlying Opioid-Stimulant Co-use and Opioid Relapse.

Emergent harms presented by the co-use of opioids and methamphetamine highlight the broader public health challenge of preventing and treating opioid and stimulant co-use. Development of effective therapeutics requires an understanding of the physiological mechanisms that may be driving co-use patterns, specifically the underlying neurobiology of co-use and how they may facilitate (or be leveraged to prevent) continued use patterns. This narrative review summarizes largely preclinical data that demonstrate clinically-meaningful relationships between the dopamine and opioid systems with direct implications for opioid and stimulant co-use. Synthesized conclusions of this body of research include evidence that changes in the dopamine system occur only once physical dependence to opioids develops, that the chronicity of opioid exposure is associated with the severity of changes, and that withdrawal leaves the organism in a state of substantive dopamine deficit that persists long after the somatic or observed signs of opioid withdrawal appear to have resolved. Evidence also suggests that dopamine supersensitivity develops soon after opioid abstinence and results in increased response to dopamine agonists that increases in magnitude as the abstinence period continues and is evident several weeks into protracted withdrawal. Mechanistically, this supersensitivity appears to be mediated by changes in the sensitivity, not quantity, of dopamine D2 receptors. Here we propose a neural circuit mechanism unique to withdrawal from opioid use with implications for increased stimulant sensitivity in previously stimulant-naïve or inexperienced populations. These hypothesized effects collectively delineate a mechanism by which stimulants would be uniquely reinforcing to persons with opioid physical dependence, would contribute to the acute opioid withdrawal syndrome, and could manifest subjectively as craving and/or motivation to use that could prompt opioid relapse during acute and protracted withdrawal. Preclinical research is needed to directly test these hypothesized mechanisms. Human laboratory and clinical trial research is needed to explore these clinical predictions and to advance the goal of developing treatments for opioid-stimulant co-use and/or opioid relapse prevention and withdrawal remediation.

Patterns of and Rationale for the Co-use of Methamphetamine and Opioids: Findings From Qualitative Interviews in New Mexico and Nevada.

IntroductionMethamphetamine use and methamphetamine-involved deaths have increased dramatically since 2015, and opioid-related deaths now frequently involve methamphetamine. Nevada and New Mexico are states with elevated rates of opioid and methamphetamine use. In this paper, we report results from a qualitative analysis that examined patterns of methamphetamine and opioid co-use over participants' lifespan, factors that influence those patterns, and implications for health outcomes among users.MethodsProject AMPED was a multisite, mixed-methods study of methamphetamine use in Northern New Mexico and Northern Nevada. Between December 2019 and May 2020, qualitative interview participants were asked to describe their patterns of and reasons for co-administration of opioids and methamphetamine.ResultsWe interviewed 21 people who reported using methamphetamine in the past 3 months. Four primary patterns of methamphetamine and opioid co-use were identified: [1] using both methamphetamine and heroin, either simultaneously or sequentially (n = 12), [2] using methamphetamine along with methadone (n = 4), [3] using prescription opioids and methamphetamine (n = 1), and [4] using only methamphetamine (n = 4). Among those who used methamphetamine and heroin simultaneously or sequentially, motivations drew from a desire to enhance the effect of one drug or another, to feel the “up and down” of the “perfect ratio” of a goofball, or to mitigate unwanted effects of one or the other. Among those who used methamphetamine and methadone, motivations focused on alleviating the sedative effects of methadone.ConclusionTo address the emergent trend of increasing methamphetamine-related deaths, researchers, health care professionals, and community health workers must acknowledge the decision-making processes behind co-use of opioids and methamphetamine, including the perceived benefits and harms of co-use. There is an urgent need to address underlying issues associated with drug use-related harms, and to design interventions and models of treatment that holistically address participants' concerns.

Modeling Stimulant and Opioid Co-use in Rats Provided Concurrent Access to Methamphetamine and Fentanyl.

Concurrent use of stimulants (e.g., methamphetamine) and opioids (e.g., fentanyl) has become increasingly common in recent years and continues to pose an enormous health burden, worldwide. Despite the prevalence, relatively little is known about interactions between the reinforcing effects of stimulants and opioids in this pattern of polysubstance use. The goals of the current study were to evaluate the relative reinforcing and relapse-related effects of methamphetamine and fentanyl using a concurrent access, drug-vs.-drug choice procedure. Male Sprague-Dawley rats were first allowed to acquire self-administration for either 0.1 mg/kg/infusion methamphetamine or 0.0032 mg/kg/infusion fentanyl, independently, after which concurrent access to both drugs was provided. When training doses of methamphetamine and fentanyl were concurrently available, a subset of rats self-administered both drugs, either within a session or alternating across sessions, whereas the remaining rats responded exclusively for one drug. When the cost of the preferred drug was increased (i.e., unit dose reduced), or the cost of the non-preferred drug was decreased (i.e., unit dose increased), choice was largely allocated toward the cheaper alternative. Following extinction of responding, methamphetamine- and fentanyl-paired cues reinstated responding on both levers. Responding reinstated by a priming injection of methamphetamine or fentanyl allocated more responding to the lever previously reinforced by the priming drug. The current studies suggest that choice of methamphetamine and fentanyl is largely allocated to the cheaper alternative, although more co-use was observed than would be expected for economic substitutes. Moreover, they lay the groundwork for more fully evaluating interactions between commonly co-abused drugs (e.g., stimulants and opioids) in order to better understand the determinants of polysubstance use and develop effective treatment strategies for individuals suffering from a polysubstance use disorder.

Morphine Exposure Reduces Nicotine-Induced Upregulation of Nicotinic Receptors and Decreases Volitional Nicotine Intake in a Mouse Model.

IntroductionNicotine addiction remains a primary health concern as tobacco smoking remains the number one cause of preventable death in America. At the same time, America is still facing the threat of the opioid epidemic. While the prevalence of smoking combustible cigarettes or electronic nicotine delivery systems in the United States varies between 12% and 35%, the smoking rates among the opioid use dependent (OUD) population is 74%–97%. We examined changes in brain reward mechanisms in which co-use of nicotine and opioids may result in enhanced reward and reinforcement.Aims and MethodsAdult male and female α4-mCherryα6-GFP mice (C57BL/6J) were used in conditioned place preference (CPP) and microscopy assays to examine reward-related behavior and nicotinic acetylcholine receptor (nAChR) upregulation following treatments with saline, nicotine, morphine, or nicotine plus morphine. Following this, separate mice were trained in e-Vape self-administration assays to examine morphine’s impact on nicotine reinforcement.ResultsWe observed that nicotine and morphine coexposure in a CPP assay did not produce enhanced reward-related behavior when compared with nicotine or morphine alone. In parallel we observed coexposure reduced nicotine-induced upregulation of nAChRs on ventral tegmental area dopamine and GABA neurons. Additionally, we observed that concurrent morphine exposure reduced nicotine (plus menthol) vapor self-administration in male and female mice.ConclusionsWhile nicotine use is high among OUD individuals, our CPP assays suggest coexposure not only fails to enhance reward-related behavior but also reduces nicotine-induced changes in ventral tegmental area neurobiology. Our self-administration assays suggest that morphine exposure during nicotine acquisition reduces nicotine reinforcement-related behavior.ImplicationsWhile some may postulate that the co-use of opioids and nicotine may be driven by reward-related mechanisms, our data indicate that opioid exposure may hinder nicotine intake due to reduced upregulation of nAChRs critical for nicotine reward and reinforcement. Thus, the high co-use in OUD individuals may be a result of other mechanisms and this warrants further investigations into nicotine and opioid co-use.