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Opioid use disorder (OUD) treatment needs continue to outpace the capacity of existing treatment systems, with access to buprenorphine particularly constrained in many communities. Pharmacist involvement in medications for OUD (MOUD), including buprenorphine initiation and longitudinal management, has demonstrated feasibility and acceptability in select settings, yet widespread implementation remains limited by regulatory variability and fragmented care models. Pharmacies are highly accessible health care sites, and pharmacists’ scope of practice can be expanded through mechanisms such as collaborative pharmacy practice agreements (CPPAs)-a term used interchangeably in the literature with “collaborative practice agreement” and related variants-to support buprenorphine initiation and ongoing management. The CTN-0151 PharmValue project aims to develop a scalable, pharmacist-led CPPA model for MOUD that can be adapted across diverse state regulatory environments and pharmacy settings. Using a community-engaged research approach and a 50-state legal and regulatory review supplemented by a national expert survey, PharmValue will (1) engage community stakeholders to codevelop a model CPPA and care pathway for pharmacist-managed buprenorphine and (2) identify existing legal authorities and advocacy opportunities to expand pharmacist-managed MOUD care nationally. This protocol commentary describes the rationale, guiding frameworks, and key design decisions underlying the PharmValue model and outlines anticipated implementation challenges and future directions for evaluation and scale-up.

Related protocols: CTN-0151

Buprenorphine treatment for opioid use disorder (OUD) is highly effective in decreasing opioid use, risk of opioid overdose, and death, but retention is challenging. Buprenorphine does not always eliminate illicit opioid use and craving and does not treat stimulant or other substance co-use, nor common comorbid sleep problems. Tirzepatide, a glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) receptor agonist, may help address substance use and sleep problems. The National Drug Abuse Treatment Clinical Trials Network (CTN) is conducting a 9-site outpatient, intent-to-treat, two-arm, double-blind, randomized controlled trial: Evaluation of Tirzepatide as an Adjunct to Buprenorphine for the treatment of OUD (TAB). The primary objective is to evaluate the effect of tirzepatide, relative to placebo, as an adjunct to buprenorphine on retention and on substance-related and sleep outcomes in adults with OUD. The primary outcome is 6-month buprenorphine treatment retention. The key secondary outcome is proportion of illicit opioid-negative urine samples over the 6-month treatment period. Approximately 310 adults with moderate-severe OUD who recently started buprenorphine will be recruited and randomized 1:1 to tirzepatide or placebo, balancing on site and buprenorphine formulation (transmucosal vs extended-release). Participants will be administered study medication, receive Fitbits to track sleep, and attend weekly research visits through 6 months post-randomization with longer research visits occurring at 1, 3, and 6 months. A follow-up visit at week 30 will collect final safety measures. This paper describes the rationale and study design for TAB, the first randomized trial to test tirzepatide for the treatment of OUD.

Related protocols: CTN-0152

This is the primary outcomes paper for CTN-0133.

Background: Underrepresented communities in the Southwestern United States Borderlands region face disproportionate substance use disorder (SUD) burdens yet remain largely excluded from clinical trials. No existing resource integrates health beliefs, research literacy, and vulnerability frameworks to support diverse community engagement in SUD clinical trials.

Methods: We developed the Exploring Health Beliefs for Community Engagement and Diversity in Clinical Trials (EXPLORE) Toolkit through a multi-phase process (2021-2024) including systematic review of existing toolkits, domain development, platform design, individual interviews (n = 10), and two rounds of theater testing with community health workers serving Hispanic communities in Southern New Mexico (n = 60) and American Indian communities in Northern New Mexico (n = 25). Pre/post surveys assessed feasibility, acceptability, community interest, and research literacy. Ripple Effects Mapping evaluated the development process.

Results: Domain-specific toolkit importance ratings averaged 4.48-4.61 on a 5-point scale; 79% of participants rated the toolkit “very important” for promoting culturally competent research, and 64% were “very likely” to recommend it. Post-theater testing scores improved for perceived feasibility of conducting clinical research in participants’ communities (pre: 7.19 vs. post: 7.94, 10-point scale) and research terminology understanding (pre: 7.97 vs. post: 8.74). Qualitative themes included cultural appropriateness, the role of community gatekeepers, and confidentiality concerns in rural and border communities.

Conclusions: The EXPLORE Toolkit demonstrates promise for bridging researcher-community gaps in SUD clinical trials. Findings highlight the value of interdisciplinary, community-centered development and the need for ongoing cultural adaptation.

Find the EXPLORE Toolkit here!

Related protocols: CTN-0133

Background: Cannabis is the most commonly used drug in the United States, and among people who use cannabis, polysubstance use is common and understudied. We aimed to examine the association of tetrahydrocannabinol (THC) positive urine drug screen (+UDS) with the odds of submitting a cocaine + UDS during cocaine use disorder treatment.

Methods: We conducted a secondary data analysis of a previously reported double-blind, placebo-controlled clinical trial, CTN0048. Participants meeting criteria for opioid abuse/dependence were assigned to receive extended-release naltrexone and one of three conditions of buprenorphine (placebo, 4 mg/day, 16 mg/day) for 8 weeks. Generalized estimating equations (GEE) were used to analyze urine samples (Liu et al., 2018) collected over time, examining the association between THC + UDS and cocaine + UDS during treatment.

Results: Participants (n = 301) averaged 46 (SD = 8.64) years of age, were majority male (78.41 %), non-Hispanic (89.70 %), and African American (66.45 %). GEE results indicated that patients who submitted THC + UDS had significantly higher odds of submitting cocaine + UDS compared to participants who submitted THC-negative UDS across the 25 time points examined (OR = 1.47, 95 % CI = 1.21–1.79, p = 0.00). Time (OR = 0.9998, 95 % CI: 0.9997, 0.9999, p = 0.018) and the covariate of sex assigned at birth (OR = 1.77, 95 % CI = 1.13–2.77, p = 0.013) were also significant in the model, indicating very small decreases in the odds of submitting a cocaine + UDS over time for all patients and 77 % higher odds of submitting cocaine + UDS for females.

Conclusion: THC + UDS was associated with increased odds of submitting a cocaine + UDS during treatment. Further investigation is needed to discern whether decreasing THC use will result in reduced cocaine use; however, these results suggest that it may be beneficial to counsel patients on cannabis use cessation both before and during treatment for cocaine use, as it is related to cocaine use treatment outcomes.

Related protocols: CTN-0048

Background: This study examined sexual delay discounting (SDD) as a potential factor associated with the relationship between substance use and condomless anal sex (CAS) among Black and Latino men who have sex with men (MSM).

Methods: Baseline data were drawn from a multi-site HIV testing promotion trial (NIDA-CTN-0083) involving Black and Latino MSM across eight U.S. states and the District of Columbia. Past 90-day CAS and past 12-month substance use were assessed via self-report. SDD was measured using the Sexual Delay Discounting Task and summarized as area under the curve (AUC) values. K-means clustering identified four SDD profiles: high self-control, globally impulsive, immediate-impulsive, and delayed-impulsive. Ordinal logistic regression models examined associations among substance use, SDD profiles, and CAS.

Results: A total of 271 participants were included. Compared with the high self-control group, the odds of CAS were significantly higher among the delayed-impulsive (OR = 2.978, p = 0.001), immediate-impulsive (OR = 8.970, p < 0.001), and globally high-discounting groups (OR = 9.427, p < 0.001). Alcohol and illicit drug use were modeled separately. Although substance use showed no overall main effect, significant interactions indicated that illicit drug use was more strongly associated with CAS among immediate-impulsive (OR = 1.485, p = 0.039) and globally high-discounting participants (OR = 1.686, p = 0.004).

Conclusions: SDD profiles were associated with CAS and may shape how illicit drug use relates to sexual risk behavior among Black and Latino MSM. These findings highlight the importance of considering temporal impulsivity in HIV prevention efforts.

Related protocols: CTN-0083

American Indian and Alaska Native (AI/AN) communities experience a disproportionate burden of substance use disorders (SUDs) alongside persistent barriers to culturally responsive care and research participation. Despite this need, AI/AN populations remain underrepresented in substance use research, in part due to historical and ongoing systemic inequities, including research practices that have not adequately respected Tribal sovereignty or incorporated Indigenous knowledge systems. This commentary synthesizes research conducted within the National Institute on Drug Abuse (NIDA) Clinical Trials Network (CTN) focused on AI/AN communities, identifies key lessons learned from this body of work, and offers recommendations for future research.

First, we provide an overview of CTN-supported studies involving AI/AN populations, highlighting both the diversity of substance use patterns across communities and the feasibility of conducting rigorous, culturally responsive research. Second, we synthesize lessons learned from these studies and related literature, including the importance of long-term relationship building, the need for culturally responsive research frameworks, structural barriers to implementation, and workforce and infrastructure challenges. Third, we present recommendations for the field, emphasizing the central role of community-based participatory research (CBPR) and Tribal participatory research (TPR), the integration of Indigenous knowledge systems, and the importance of Tribal data sovereignty and community-led dissemination.

Collectively, this commentary argues that sustainable progress in addressing SUDs among AI/AN populations requires a fundamental shift toward community-engaged, culturally responsive, and equity-focused research partnerships. The experiences of the CTN AI/AN Special Interest Group demonstrate that such approaches are not only feasible but essential for advancing both scientific knowledge and community health.

Related protocols: CTN-0020-A-1, CTN-0033-Ot-1, CTN-0033-Ot-2, CTN-0033-Ot-3, CTN-0033-Ot-4, CTN-0033-Ot-5, CTN-0044-A2, CTN-0078-Ot, CTN-0096, CTN-0096-A-1, CTN-0118, CTN-0123, CTN-0129

Methadone is an essential tool for addressing opioid use disorder, especially with the prevalence of high-potency synthetic opioids in the drug supply. The current care delivery model in the United States with siloed methadone clinics has many limitations. Legislation has been proposed to expand access to methadone to office-based settings with pharmacy dispensing. Even with legal and regulatory changes, there are many practical barriers to implementation which include insurance coverage and patient cost, prior authorizations, and stocking of methadone.

Practical steps for clinicians and policymakers to take to overcome these barriers include ensuring insurance coverage for methadone, removing methadone from the algorithms that limit the amount of controlled substances pharmacies can order, and obtaining concentrated methadone formulations.

Related protocols: CTN-0131

Background and aims: US regulatory changes allowed for additional methadone take-home doses following COVID-19 onset. How dispensing practices changed and which factors drove variation remains unexplored. We determined daily methadone dispensing trajectories over six months before and after regulatory changes due to COVID-19 using state sequence analysis and explored correlates.

Design: Retrospective chart review of electronic health records.

Settings: Nine opioid treatment programs (OTPs) across nine US states.

Participants: Adults initiating treatment in 2019 (n = 328) vs. initiating 1 month after the COVID-19 regulatory changes of March 2020 (n = 376).

Measurements: Type of daily methadone medication encounter (in-clinic, weekend/holiday take-home, take-home, missed dose, discontinued) based on OTP clinic; cohort (pre vs. post-COVID-19); and patient substance use, clinical and sociodemographic characteristics.

Findings: Following COVID-19 regulatory changes, allotted methadone take-home doses increased from 3.5% to 13.8% of total person-days in treatment within the first 6 months in care. Clinic site accounted for the greatest variation in methadone dispensing (6.2% and 9.5% of the variation of discrepancy between sequences pre- and post-COVID-19, respectively). People who co-use methamphetamine had a greater increase in take-homes than people who did not use methamphetamine (from 3.7% pre-pandemic to 21.2% post-pandemic vs. 3.5% to 12.5%) and higher discontinuation (average 3.6 vs. 4.7 months among people who did not use methamphetamine pre-COVID-19; average 3.3 vs. 4.6 months post-COVID-19). In the post-COVID-19 cohort, females had a higher proportion of missed doses (17.2% vs. 11.9%) than males. People experiencing houselessness had a higher proportion of missed doses (19% vs. 12.3%) and shorter stays (average 3.5 vs. 4.5 months) when compared with those with stable housing.

Conclusion: Daily methadone dispensing trajectories in the US both before and following COVID-19 regulatory changes appeared to depend more on the opioid treatment programs’ practices than individual patient characteristics or response to treatment.

Related protocols: CTN-0112

Aims: This study, supported by the CTN Ohio Valley Node, aimed to identify substance use disorder (SUD) patterns and their association with T2DM health outcomes among patients with type 2 diabetes and hypertension.

Methods: Researchers used latent class analysis on electronic health records from the MetroHealth System (Cleveland, Ohio) to obtain the target SUD groups: i) only tobacco (TUD), ii) tobacco and alcohol (TAUD), and iii) tobacco, alcohol, and at least one more substance (PSUD). A matching program with Mahalanobis distance within propensity score calipers created the matched control groups: no SUD (NSUD) for TUD and TUD for the other two SUD groups. The numbers of participants for the target-control groups were 8009 (TUD), 1672 (TAUD), and 642 (PSUD).

Results: TUD was significantly associated with T2DM complications. Compared to TUD, the TAUD group showed a significantly higher likelihood for all-cause mortality (adjusted odds ratio (aOR) = 1.46) but not for any of the T2DM complications. Compared to TUD, the PSUD group experienced a significantly higher risk for cerebrovascular accident (CVA) (aOR = 2.19), diabetic neuropathy (aOR = 1.76), myocardial infarction (MI) (aOR = 1.76), and all-cause mortality (aOR = 1.66).

Conclusions: The findings of increased risk associated with PSUDs may provide insights for better management of patients with T2DM and hypertension co-occurrence.

Aims: This study aimed to examine within and between effects of the relationship between depression, using the Beck Depression Inventory (BDI), and cocaine craving, using the visual analog craving scale (VAS), over time.

Methods: Data from the NIDA Clinical Trial Network Study Cocaine Use Reduction with Buprenorphine (CTN-0048) were used in a secondary analysis (CTN-0148). Random-effects regression modelling was used to examine relationships between participants’ depressive symptoms and their cocaine craving over time.

Results: A total of 301 participants with past-year DSM-IV criteria for cocaine and opioid use disorder were analyzed (21.6% female, 10.3% Hispanic, 66.4% Black) being treated with placebo or buprenorphine+naloxone. Craving significantly decreased over time (B = −1.11, 95% CI [-1.21, −1.02], p < 0.001). Depression emerged as a significant within-person predictor of craving over time (B = 0.93, 95% CI [0.76, 1.09], p<0.001), indicating that when a person’s BDI score increased by one point from their own mean, their craving increased by 0.71 units. Between-person differences in average BDI did not have significant effects (p>0.05), indicating that depression scores across participants did not significantly predict differences in craving.

Conclusions: These findings highlight depression as a dynamic, time-varying clinical marker of heightened craving risk and suggest that monitoring and addressing increases in depressive symptoms during treatment may help mitigate craving spikes and potentially reduce vulnerability in returning to use.

Related protocols: CTN-0148

This is the primary outcomes paper for CTN-0101.

Background and aims:
Individuals who engage in illicit or nonmedical opioid use may have elevated risk of health and social consequences, including progression to opioid use disorder (OUD). Preventive interventions to reduce this risk are lacking. This trial tested the impact of a primary care-integrated collaborative care approach for reducing risky opioid use, defined as nonmedical use of prescription opioids or any use of illicit opioids.

Design: Cluster-randomized controlled trial randomized primary care providers (PCPs) and their patients into the Subthreshold Opioid Use Disorder Prevention (STOP) intervention or enhanced usual care (EUC).

Setting: Primary care clinics at 5 U.S. sites.

Participants:
PCPs and their patients were recruited January 2021–May 2023. A total of 119 PCP clusters (STOP=48, EUC=51) and 202 patients (STOP=88, EUC=114) enrolled. Eligible patients were adults (≥18 years) having current risky opioid use, without moderate–severe OUD. Patient participants were majority female (63.4%), white (70.8%) and non-Hispanic (96.5%), with a mean age of 55.7 [standard deviation (SD) = 12.7] years. At baseline, 63.4% of participants had moderate–severe pain (Brief Pain Inventory) and below average physical (79.2%) and mental (62.4%) health (SF-12).

Interventions: The STOP collaborative care intervention consisted of brief advice from the PCP about reducing risky opioid use, meetings with a clinic-embedded nurse care manager over 12 months and remote health coaching (2–6 sessions). Both groups received primary care treatment as usual and overdose risk reduction materials.

Measurements: The primary outcome was total days of risky opioid use, recorded from 6 monthly electronic surveys. A key secondary outcome was moderate–severe OUD at 6 and 12 months.

Findings: A total of 77 (87.5%) STOP and 107 (93.9%) EUC participants completed the 6-month assessment period. The primary outcome analysis used the Intention-to-Treat sample with multiple imputations of missing data. Mean days of risky opioid use at 180 days were lower in STOP than EUC [12.2 (SD = 27.73) vs. 15.5 (SD = 32.64)]; the difference between groups adjusted for baseline risky opioid use was not statistically significant (rate ratio 0.95, 95% confidence interval = 0.52–1.74). One STOP participant (1.1%) and 13 EUC participants (11.4%) developed moderate–severe OUD at 6 months, and 3 (3.4%) STOP and 6 (5.3%) EUC participants had moderate–severe OUD at 12 months (P<0.001).

Conclusions: This cluster-randomized controlled trial did not find evidence that the STOP intervention for reducing risky opioid use produced greater reductions over 6 months compared with enhanced usual care, though fewer intervention participants progressed to moderate–severe opioid use disorder. Patients had a high burden of pain and comorbidities that may present challenges to reducing opioid use.

Related protocols: CTN-0101

Substance use disorder (SUD) is a complex chronic condition requiring a multi-disciplinary approach to both research and treatment. Randomized controlled trials (RCTs) are gold standard methodologies for inferring causal relationships between an intervention and treatment outcomes but often face challenges in generalizability, scalability and real-world implementation. Target trial emulation (TTE) is a powerful methodological framework that uses observational or real-world data sources to emulate the methodology of these gold standard target trials to complement the learning from RCTs and enhance translation to real world evidence. An additional methodological innovation is the translational testing of clinical- and community-based digital health systems to provide new insights into SUD in the real world and provide scalable access to therapeutic resources.

To explore these methodological innovations in SUD research, the National Institute on Drug Abuse Center for the Clinical Trials Network convened a variety of experts for a virtual workshop titled “Target Trial Emulation in Observational Research and Translational Testing of Advanced Digital Health Tools for Substance Use Disorder Prevention and Treatment.” This article summarizes the discourse of the workshop, focused on three thematic areas: TTE using real-world healthcare data, SUD evidence from nationwide data sources that may be useful in TTE analyses, and translational testing of clinical- and community-based digital health systems. The workshop also highlighted various exemplars of digital health systems that demonstrate success in translational research addressing SUDs, key methodological and translational challenges, importance of rigorous study design, robust data linkages and expanding use of common data elements, and the integration of digital health tools to enhance causal inference and clinical impact. Future research directions are outlined to refine these approaches, address barriers, and maximize the utility of real-world data in shaping effective SUD prevention and treatment strategies.

Background: While medication for opioid use disorder (MOUD) is effective for a significant proportion of patients, many return to using opioids during treatment. Understanding which factors lead to successful treatment informs the development of implementation approaches that can improve outcomes. This manuscript and its accompanying website provide an applied introduction to interpretable machine learning for clinical investigators interested in predicting treatment response for people using MOUD.

Methods: This study, which uses data from CTN-0094, applied machine learning (ML) algorithms (K-Nearest Neighbors (KNN), logistic regression with and without regularization, Multivariate Additive Regression Splines (MARS), Support Vector Machines, Classification and Regression Trees (CART), Random Forest, Bayesian Additive Regression Trees (BART), Boosted Trees, Neural Networks) to predict failure of treatment in a collection of 2478 individuals who had participated in the three largest pragmatic, clinical trials of MOUD.

Results: All models produced Receiver Operating Characteristic Area Under the Curve (ROC AUC) estimates in the range of 0.62 to 0.67 using cross-validation data and the optimal model, random forest, achieved 0.65 using testing data. The algorithms nearly universally identified predictive features such as age, intravenous drug use days, study medication, and study site. Most algorithms also identified various aspects of smoking. Only the algorithms that detect complex non-linear trends identified details from timeline follow-back. One algorithm, BART, performed well while devaluing all treatment-specific details.

Conclusions: After explaining how to apply, compare, and contrast various ML workflows, the results show that while overall modeling performance is similar across the models developed, the use of different algorithms identifies different sets of predictive features. Previous research has not recognized some features as important for predicting treatment outcomes. A companion website introduces clinical investigators to the concepts and implementations this study presents. That site also provides a detailed annotated blueprint to fully replicate, or even expand, this work.

Related protocols: CTN-0094

Cocaine use disorder (CUD) is a major public health issue, and greater cocaine use severity has been associated with worse treatment retention and outcomes. Therefore, greater understanding of processes that influence cocaine use is needed. Both anhedonia (i.e., undervaluation of nondrug rewards) and cocaine demand (i.e., cocaine valuation) are related to cocaine use severity and thematically related to each other at face value, but no studies have directly compared these outcomes to our knowledge.

The present study represents a secondary analysis from a two-phase sequential, multiple assignment, randomized trial aimed at developing adaptive interventions for CUD (CTN-0130). We examined the relationship between anhedonia and cocaine demand and how these measures were related to cocaine use severity. Participants (N = 116) were treatment-seeking adults with CUD. All measures were taken at baseline before treatment initiation. Analyses revealed (a) moderate and very strong evidence of relationships between cocaine demand factors (i.e., persistence, amplitude) and anhedonia (PP values ≥ 77.8%); (b) positive association between cocaine demand (both persistence and amplitude) and measures of cocaine use severity, with the exception of one relationship, which was in the opposite direction; and (c) demand amplitude continued to be positively related to cocaine use severity, even when considering anhedonia.

Conclusions: Overall, findings from this study indicate cocaine demand relates to cocaine use severity more strongly than anhedonia.

Related protocols: CTN-0130

This is the Primary Outcomes Article for CTN-0130.

Fentanyl-related, cocaine-overdose deaths have drastically increased, yet research on how people who use cocaine perceive fentanyl adulteration is limited. This study developed the novel Adulterated Cocaine Purchasing Task, a modification of the original Cocaine Purchasing Task, to quantify how people respond to fentanyl adulteration in cocaine.

In the Adulterated Cocaine Purchasing Task, participants indicated how much cocaine they would purchase when cocaine had no (0%) versus some (10%) probability of fentanyl adulteration. Study aims were to (a) determine how possible fentanyl adulteration affects cocaine demand and (b) determine which individual characteristics predict continued demand for cocaine despite fentanyl adulteration.

This Amazon Mechanical Turk study included self-reported cocaine purchasers (N = 64), who completed self-report questionnaires (demographics, substance use history, depression/posttraumatic stress disorder symptoms, fentanyl knowledge quiz), and the Adulterated Cocaine Purchasing Task.

Results showed (a) that a greater probability of fentanyl adulteration (10%) lowered cocaine demand, but only for intensity (Q₀; amount of cocaine consumed when free; p < .001); (b) no effect on other demand indices (Omax, Pmax, essential value, breakpoint); (c) significantly more zero responders with 10% probability of fentanyl adulteration than 0%, p < .001; and (d) that opioid co-use, depression, age, posttraumatic stress disorder, fentanyl knowledge, and cocaine use severity did not moderate the relationship between fentanyl adulteration and intensity.

Conclusions: Overall, fentanyl adulteration reduced cocaine demand but only for volume preferred at minimal cost, not general motivational drive for use, illustrating the dangerous insensitivity to toxic contamination. The internal validity of the paradigm provides proof-of-concept for this approach to identify individuals at risk from fentanyl-adulterated cocaine.

Related protocols: CTN-0130