Cocaine abstinence during the "critical period" of a contingency management trial predicts future abstinence in people with cocaine use disorder.

BACKGROUND: Contingency Management (CM) is being piloted as a treatment for stimulant use disorder in several US states, highlighting the need for treatment optimization. One important goal of optimization is decreasing drug use during the early stages of treatment, which has predicted success in other interventions. However, this "critical period" has not been reported in CM trials. The purpose of this analysis was to determine if, after accounting for baseline abstinence and incentive condition, abstinence in a CM trial for people with Cocaine Use Disorder (CUD) could be predicted by cocaine use during a first-week critical period. METHODS: Eighty-seven participants with CUD were randomized to receive contingent high or low value incentives for cocaine abstinence or were in a non-contingent control group. Generalized estimating equations (GEE) were used to analyze urine test results over 36 timepoints during the 12-week intervention. To assess for a critical period, the first three visits were included in the GEE as a covariate for remaining urine test results. RESULTS: Participants who provided more negative samples during the critical period were significantly more likely to produce a negative urine sample during the remainder of the trial, though some effects of group remained after controlling for the critical period. CONCLUSIONS: These results indicate that a critical period exists for CM trials, and it can explain a substantial amount of future performance. Early contact with an abstinence-contingent high magnitude alternative reinforcer may explain additional performance beyond the critical period, further justifying the use of high magnitude alternative reinforcers.

A randomised, double-blind, sham-controlled study of left prefrontal cortex 15 Hz repetitive transcranial magnetic stimulation in cocaine consumption and craving.

BACKGROUND: Cocaine use disorder (CUD) is a global health issue with no effective treatment. Repetitive Transcranial Magnetic Stimulation (rTMS) is a recently proposed therapy for CUD. METHODS: We conducted a single-center, randomised, sham-controlled, blinded, parallel-group research with patients randomly allocated to rTMS (15 Hz) or Sham group (1:1) using a computerised block randomisation process. We enrolled 62 of 81 CUD patients in two years. Patients were followed for eight weeks after receiving 15 15 Hz rTMS/sham sessions over the left dorsolateral prefrontal cortex (DLPFC) during the first three weeks of the study. We targeted the DLFPC following the 5 cm method. Cocaine lapses in twice a week urine tests were the primary outcome. The secondary outcomes were craving severity, cocaine use pattern, and psychometric assessments. FINDINGS: We randomly allocated patients to either an active rTMS group (32 subjects) or a sham treatment group (30 subjects). Thirteen (42%) and twelve (43.3%) of the subjects in rTMS and sham groups, respectively, completed the full trial regimen, displaying a high dropout rate. Ten/30 (33%) of rTMS-treated patients tested negative for cocaine in urine, in contrast to 4/27 of placebo controls (p = 0.18, odd ratio 2.88, CI 0.9-10). The Kaplan-Meier survival curve did not state a significant change between the treated and sham groups in the time of cocaine urine negativisation (p = 0.20). However, the severity of cocaine-related cues mediated craving (VAS peak) was substantially decreased in the rTMS treated group (p<0.03) after treatment at T1, corresponding to the end of rTMS treatment. Furthermore, in the rTMS and sham groups, self-reported days of cocaine use decreased significantly (p<0.03). Finally, psychometric impulsivity parameters improved in rTMS-treated patients, while depression scales improved in both groups. CONCLUSIONS: In CUD, rTMS could be a useful tool for lowering cocaine craving and consumption. TRIAL REGISTRATION: The study number on clinicalTrials.gov is NCT03607591.

Sleep time differs among people who co-use cocaine and cannabis compared to people who only use cocaine.

OBJECTIVE: People who use cocaine experience numerous sleep problems and often use cannabis to mitigate these problems. However, co-using cocaine and cannabis may result in worse sleep outcomes when compared to using cocaine only. The current study examined group differences in subjective sleep outcomes among people who use cocaine and people who co-use cocaine and cannabis. METHODS: Participants were 82 individuals with cocaine use disorder who were enrolled in a randomized clinical trial for cocaine treatment. Sleep outcomes, assessed at baseline prior to treatment, were measured with the Saint Mary's Hospital Sleep Questionnaire and included total sleep time, perceived sleep quality, difficulty falling asleep, and daytime alertness. Analysis of covariance and Kruskal-Wallis tests were used to compare sleep outcomes between participants with urine samples that tested positive for both cocaine and cannabis at baseline, those who tested positive for cocaine only, and those who tested negative for all drugs. RESULTS: Total reported sleep time was highest among those with a drug negative urine, followed by those with a cocaine positive urine and those who tested positive for cocaine and cannabis. There were no differences in perceived sleep quality, difficulty falling asleep, or daytime alertness between groups. CONCLUSIONS: People who co-use cocaine and cannabis may report reduced sleep time relative to those who only use cocaine. Co-use of cannabis may exacerbate sleep difficulties in people who use cocaine by decreasing total sleep time, although it is important to note that the groups each reported similar sleep quality. Implications for treatment and directions for future research are discussed.

A Positive Cocaine Urine Toxicology Test and the Effect on Intraoperative Hemodynamics Under General Anesthesia.

BACKGROUND: Cocaine has a short biological half-life, but inactive urine metabolites may be detectable for a week following use. It is unclear if patients who test positive for cocaine but have a normal electrocardiogram and vital signs have a greater percentage of hemodynamic events intraoperatively. METHODS: A total of 328 patients with a history of cocaine use who were scheduled for elective noncardiac surgery under general anesthesia were enrolled. Patients were categorized into cocaine-positive versus cocaine-negative groups based on the results of their urine cocaine toxicology test. The primary aim of this study was to evaluate whether asymptomatic cocaine-positive patients had similar percentages of intraoperative hemodynamic events, defined as (1) a mean arterial blood pressure (MAP) of <65 or >105 mm Hg and (2) a heart rate (HR) of <50 or >100 beats per minute (bpm) compared to cocaine-negative patients. The study was powered to assess if the 2 groups had an equivalent mean percent of intraoperative hemodynamic events within specific limits using an equivalence test of means consisting of 2 one-sided tests. RESULTS: The cocaine-positive group had a blood pressure (BP) that was outside the set limits 19.4% (standard deviation [SD] 17.7%) of the time versus 23.1% (SD 17.7%) in the cocaine-negative group (95% confidence interval [CI], 0.5-7.0). The cocaine-positive group had a HR outside the set limits 9.6% (SD 16.2%) of the time versus 8.2% (SD 14.9%) in the cocaine-negative group (95% CI, 4.3-1.5). Adjusted for age, sex, body mass index (BMI), smoking status, and the presence of comorbid hypertension, renal disease, and psychiatric illness, the cocaine-positive and cocaine-negative patients were similar within a 7.5% margin of equivalence for MAP data (ß coefficient = 2%, P = .003, CI, 2-6) and within a 5% margin of equivalence for HR data (ß coefficient = 0.2%, P < .001, CI, 4-3). CONCLUSIONS: Asymptomatic cocaine-positive patients undergoing elective noncardiac surgery under general anesthesia have similar percentages of intraoperative hemodynamic events compared to cocaine-negative patients.

Effects of time-based administration of abstinence reinforcement targeting opiate and cocaine use.

Polydrug use is a common problem among patients in opioid-substitution treatment. Polydrug use has been reduced by administering abstinence-reinforcement contingencies in a sequence, such that a single drug is targeted until abstinence is achieved, and then an additional drug is targeted. The present study examined effects of administering abstinence-reinforcement contingencies sequentially based on time rather than on achieved abstinence. Participants accessed paid work (about $10/hr maximum) in the Therapeutic Workplace by providing urine samples 3 times per week. The urine samples were tested for opiates and cocaine. During an induction period, participants earned maximum pay independent of drug abstinence. Then, maximum pay depended upon urine samples that were negative for opiates. Two weeks later, maximum pay depended upon urine samples that were negative for both opiates and cocaine. Opiate and cocaine abstinence increased following administration of the respective contingencies. The time-based administration of abstinence reinforcement increased opiate and cocaine abstinence.

Screening Electrocardiograms in Cocaine-Positive Chest Pain-Free Psychiatric Patients Requiring Medical Screening.

BACKGROUND: The current practice at a large urban academic emergency department (ED) is to obtain screening electrocardiograms (ECGs) as part of the medical screening on all psychiatric patients who test positive for cocaine. OBJECTIVE: We sought to examine the impact of an ECG in the medical screening of chest pain-free psychiatric patients who test positive for cocaine. METHODS: An institutional review board-approved retrospective chart review from January 2014 to December 2015 was performed on charts of adult ED patients requiring medical screening before transfer to a psychiatric facility. Patients who tested positive for cocaine on urine drug screens were included in this study. Patients with chest pain or those who did not have an ECG recorded were excluded. Outcomes evaluated included disposition and subsequent cardiac work-up. RESULTS: One thousand nine hundred sixty-eight ED patients were identified who tested positive for cocaine on a urine toxicology screen, and 853 met the inclusion criteria. ECGs were normal in 812 patients (95% [95% confidence interval 93-96%]) and abnormal in 41 patients (5% [95% confidence interval 4-7%]). Of 41 patients with abnormal ECGs, 4 were admitted for cardiac work-up. Two patients had positive troponin values in the ED, 2 had cardiology consultations, and 3 had further cardiac stress testing, all of which were negative or nondiagnostic. No cardiac catheterizations were performed. CONCLUSIONS: Most ED patients with recent cocaine use but without chest pain have a normal ECG. Of the minority with an abnormal ECG, no cases of acute myocardial ischemia or infarction were identified.

Abstinence-contingent wage supplements to promote drug abstinence and employment: a randomised controlled trial.

BACKGROUND: Poverty, unemployment and substance abuse are inter-related problems. This study evaluated the effectiveness of abstinence-contingent wage supplements in promoting drug abstinence and employment in unemployed adults in outpatient treatment for opioid use disorder. METHODS: A randomised controlled trial was conducted in Baltimore, MD, from 2014 to 2019. After a 3-month abstinence initiation and training period, participants (n=91) were randomly assigned to a usual care control group that received employment services or to an abstinence-contingent wage supplement group that received employment services plus abstinence-contingent wage supplements. All participants were invited to work with an employment specialist to seek employment in a community job for 12 months. Abstinence-contingent wage supplement participants could earn training stipends for working with the employment specialist and wage supplements for working in a community job, but had to provide opiate and cocaine-negative urine samples to maximise pay. RESULTS: Abstinence-contingent wage supplement participants provided significantly more opiate and cocaine-negative urine samples than usual care control participants (65% vs 45%; OR=2.29, 95% CI 1.22 to 4.30, p=0.01) during the 12-month intervention. Abstinence-contingent wage supplement participants were significantly more likely to have obtained employment (59% vs 28%; OR=3.88, 95% CI 1.60 to 9.41, p=0.004) and lived out of poverty (61% vs 30%; OR=3.77, 95% CI 1.57 to 9.04, p=0.004) by the end of the 12-month intervention than usual care control participants. CONCLUSION: Abstinence-contingent wage supplements can promote drug abstinence and employment. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov NCT02487745.

Within-treatment frequency of use versus abstinence as a predictor of longitudinal post-treatment follow-up assessments of drug use.

BACKGROUND: Abstinence is a widely-used endpoint in clinical trials of stimulant use disorders. A quantitative measure of frequency of use may be a more sensitive endpoint; however, it is important to establish that it is associated with post-treatment drug use. We examine and compare how within-treatment abstinence and frequency of use are related to two post-treatment longitudinal measures of drug use. METHODS: For each of three existing stimulant use disorder clinical trial datasets, we examined the association between within-treatment frequency of use (based on urine screens), within-treatment abstinence, and post-treatment follow-up assessments of drug use (urine screens and reported days of use). In joint analyses that simultaneously model the effects of within-treatment abstinence and frequency of use, it is possible to discern their relative importance as predictors of post-treatment drug use during the 12 months following the end of treatment. RESULTS: Results indicate a quantitative measure of within-treatment frequency of use was associated with longitudinal post-treatment follow-up assessments of drug use. Results from joint analyses of post-treatment follow-up drug use assessed by urine screens suggest that within-treatment frequency of use, rather than abstinence per se, is predictive of post-treatment drug use. However, results from joint analyses of self-report of days of use are equivocal. CONCLUSION: Results lend support to the use of a quantitative measure of within-treatment drug use as an alternative to complete abstinence. They suggest that some within-treatment use that fall short of complete abstinence may potentially represent clinically important improvements given their association with post-treatment drug use.

A Recombinant Humanized Anticocaine Monoclonal Antibody Alters the Urinary Clearance of Cocaine and Its Metabolites in Rats.

A recombinant humanized anticocaine monoclonal antibody, h2E2, has shown potential in the preclinical phases for the treatment of cocaine abuse. The standard tests for cocaine usage are the detection of benzoylecgonine (BE) and cocaine in the urine. This includes workplace drug screens as well as in clinical trials for potential treatments of cocaine abuse. By sequestering cocaine into the plasma compartment, h2E2 prevents cocaine from entering the brain. Due to the altered disposition of cocaine in the presence of h2E2, we investigated the effects of h2E2 on cocaine and metabolite levels in the urine of rats to clarify the use of BE as an endpoint measurement for effectiveness in future clinical trials. The urine concentrations of cocaine and metabolites were considerably altered in the presence of h2E2. After a single injection of h2E2 (120 mg/kg) and cocaine hydrochloride (0.56 mg/kg), the concentration of cocaine and BE excreted into the urine of rats decreased by 92% and 91%, respectively, from vehicle controls. Due to the significant decrease in urinary excretion, BE is not an appropriate indicator of cocaine usage in the presence of h2E2. Another endpoint measurement must be selected for the measurement of cocaine usage in the upcoming clinical trials of h2E2. In contrast to the effects on cocaine and BE urinary excretion, there was a 3-fold increase in ecgonine methyl ester (EME) in the presence of h2E2. Therefore, we conclude that EME is a more appropriate measurement of cocaine intake in the presence of h2E2.

Making risky decisions to take drug: Effects of cocaine abstinence in cocaine users.

Risky decision-making is characteristic of drug users, but little is known about the effects of circumstances, such as abstinence, on risky choice behavior in human drug users. We hypothesized that cocaine users would make more risky choices for cocaine (defined as taking a chance to receive a large number of cocaine doses as opposed to choosing to receive a fixed amount of cocaine) after 3 or 7 days of cocaine abstinence, compared to 1 day of cocaine abstinence. Six male nontreatment-seeking current cocaine smokers were enrolled in a 21-day inpatient within-subject study. Participants repeatedly smoked six 25 mg doses of cocaine during a training session and were instructed that they would be making decisions about smoking this dose throughout the study. After 1, 3 and 7 days of cocaine abstinence, participants completed a computerized task in which they repeatedly decided between receiving a guaranteed number of cocaine doses (between 1 and 5; fixed option) or receiving a chance (0.13 to 0.75) to smoke a larger number of cocaine doses (probabilistic option). After completing the computerized task, one of the participants' choices was randomly implemented and they smoked either the fixed number of cocaine doses or had the specified chance to smoke the greater number of doses. Contrary to our hypothesis, 5 of the 6 participants made fewer risky choices after 3 and 7 days of cocaine abstinence compared to one day of abstinence suggesting greater risk-aversion. Thus, even during cocaine abstinence cocaine users make rational decisions related to their drug use.

Opioid and cocaine use among primary care patients on buprenorphine-Self-report and urine drug tests.

BACKGROUND: Urine drug tests (UDTs) are recommended to monitor patients treated for opioid use disorder in primary care. The aims are to (1) estimate the frequency of self-report and UDT results of opioid and cocaine use and (2) evaluate the association between treatment time with non-disclosure of opioid or cocaine use and having a positive UDT. METHODS: We conducted a retrospective review of patients enrolled in a primary care-based buprenorphine program between January 2011-April 2013. We describe three clinical visits types: no disclosure of opioid/cocaine use and positive UDT; disclosure of opioid or cocaine use and a negative or positive UDT; and no disclosure of opioid or cocaine use and a negative UDT. We fit generalized estimating equations logistic regression models to evaluate whether treatment time is associated with non-disclosure of opioids or cocaine use and a positive UDT. RESULTS: Among all UDT results (n = 1755) from 130 patients, 10% were positive for illicit opioids and 4% for cocaine. Among UDTs with illicit opioid or cocaine positive results, in 57% and 76% of these scenarios, the patient did not disclose. The odds of non-disclosure and having a positive UDT was higher in the first 180 days for opioids and 90 days for cocaine. CONCLUSION: Among primary care patients treated with buprenorphine, a small but substantial percentage of UDTs were cocaine or opioid positive. As treatment time increased, non-disclosure was less common but persisted even after six months. Among primary care patients treated with buprenorphine, UDTs contribute information to optimize clinical care.

Presence of Parent Cocaine in the Absence of Benzoylecgonine in Urine.

Cocaine (COC) is widely abused and associated with significant adverse effects. Forensic and clinical laboratories often test for COC intake through detection of the primary metabolite, benzoylecgonine (BZE) in urine. Testing for BZE alone may result in false-negative determinations in situations where COC is recently administered or metabolism is impaired. To our knowledge, no data have been provided demonstrating the utility of adding parent COC to urine confirmation testing in routine analyses. For this study, random urine specimens from patients undergoing treatment for pain management and/or addiction were collected over six months from 800 clinics across 39 states. A total of 7,587 urine specimens tested positive for a COC marker (COC and/or BZE). A positive result was determined using a liquid chromatography-tandem mass spectrometry (LC-MS-MS) method with a limit of quantitation of 50 ng/mL. Of the positive specimens, 26% and 97% were positive for COC and BZE, respectively. Positive BZE-only specimens represented 74% of total positive specimens. However, 231 of the 7,587 urine specimens (3% of positive specimens) were positive for COC in the absence of BZE. The 231 COC-only positive specimens were collected from 206 patients, and two of these patients provided four COC-only positive specimens. Of a select group of COC-only specimens tested by both LC-MS-MS and immunoassay (IA) (N = 32), 81% were negative by IA, demonstrating the limitation of screening with BZE-specific IAs. A false-negative COC result can have profound impacts such as a delay in patient referral to addiction treatment, unintentional prescribing of a controlled substance to a patient actively abusing an illicit substance, or undetected cocaine use in the workplace. This study highlights the importance of testing for COC in addition to BZE in forensic and healthcare settings.

Illicit drug use and work in a model therapeutic workplace.

BACKGROUND: The link between illicit drug use and impaired employee performance in the workplace has been assumed, but the relation has not been demonstrated clearly in research. This study was an evaluation of the relations between cocaine and opiate use, attendance, and performance in a job skills training program in a population with high rates of drug use. METHODS: Out-of-treatment injection drug users (N = 42) attended a model therapeutic workplace where they could earn a maximum pay of around $10 per hour, 4 h every weekday, for 30 weeks. At the workplace, participants could complete practice trials on computer-based typing and keypad training programs. Participants were asked to provide urine samples thrice weekly, which were tested for opiates and cocaine. RESULTS: Participants worked for more hours on a program that resulted in a flat hourly wage when their urine was negative for opiates and cocaine than when their urine was opiate and cocaine positive. Attendance was positively associated with opiate-negative samples during the study. When participants attended the workplace, however, their performance was not related to drug use. Participants completed the same number of practice trials, performed at the same accuracy, and typed at the same speed when they were positive and negative for cocaine and opiates. CONCLUSIONS: Contrary to common expectations, this study failed to show that the use of opiates or cocaine affected in-training performance, even though opiate and cocaine use predicted reduced attendance under some circumstances.

The cocaine cutting agent levamisole is frequently detected in cocaine users.

Cocaine use in Australia is increasing, with approximately 2.5% of the surveyed population having used cocaine. In the USA, levamisole, a widely used anti-helminthic veterinary drug has been increasingly detected as a cutting agent in cocaine seizures. Levamisole is known to cause agranulocytosis in humans. We ascertained the prevalence of levamisole-adulterated cocaine, detectable in the urine from patients that had undergone a pathology request for a urine drug screen. We assayed routinely requested urines that were positive for cocaine on immunoassay with liquid chromatography high resolution quadrupole time of flight mass spectrometry (LC-QToF). We investigated available urine samples from a period of 2 years that had a positive result for cocaine. In addition, we examined samples that were below the cut-off for cocaine on immunoassay. Specimens were analysed for the presence of levamisole and other 'unknown' drugs. In the period under investigation the laboratory examined 3665 urine samples for cocaine: 1.4% (n = 51) of the samples were positive for cocaine by immunoassay and half of these (n = 26, 51%) were further examined by LC-QToF. In addition, we examined 10 samples that were negative by immunoassay (as defined by AS/NZS 4308:2008). Levamisole was detected in the urine of cocaine users in approximately 75% of cases. Other illicit drugs were also frequently found in this cohort. The most common illicit drugs detected were methamphetamine, ecstasy and cannabis. Australian cocaine is widely adulterated with levamisole. Cocaine users are at risk of levamisole related health problems in addition to the problems related to cocaine.

Effect of ß-blocker Therapy on Hospital Readmission and Mortality in Heart Failure Patients With Concurrent Cocaine Use.

BACKGROUND: ß-Blockers are first-line agents for reduction in symptoms, hospitalization, and mortality in patients with heart failure having reduced ejection fraction (HFrEF). However, the safety and efficacy of continuous ß-blocker therapy (BBT) in patients who actively use cocaine remain controversial, and available literature is limited. We aimed to evaluate the effect of BBT on hospital readmission and mortality in patients having HFrEF with concurrent cocaine use. METHODS: We conducted a retrospective study of patients with a diagnosis of HFrEF between 2011 and 2014 based on International Classification of Diseases 9-Clinical Modification codes. We included patients aged 18 and older who tested positive for cocaine on a urine toxicology test obtained at the time of index admission. Patients were followed for 1 year. Multivariate logistic regression was used to assess the effect of BBT on the 30-day, all-cause and heart failure-related readmissions. RESULTS: The 30-day readmission rates for BBT versus no BBT groups were 20% versus 41% (odds ratio [OR]: 0.17, 95% confidence interval [CI] = 0.05-0.56, P = .004) for heart failure-related readmissions and 25% versus 46% (OR: 0.19, 95% CI = 0.06-0.64, P = .007) for all-cause readmissions. CONCLUSION: The BBT reduced 30-day, all-cause and heart failure-related readmission rate but not 1-year mortality in patients having HFrEF with concurrent cocaine use.

Addressing discordant quantitative urine buprenorphine and norbuprenorphine levels: Case examples in opioid use disorder.

INTRODUCTION: Urine adulteration is a concern among patients treated for opioid use disorder. Quantitative urine testing for buprenorphine (B) and norbuprenorphine (NB), and the appropriate interpretation of B and NB levels, can facilitate constructive conversations with patients that may lead to modifications in the treatment plan, and strengthening of the patient-provider relationship. CASE SUMMARY: Three cases are presented in which discordant urine B and NB levels were recognized. Each patient was submerging buprenorphine/naloxone strips in their urine to mask ongoing illicit drug use. The authors used an approach to addressing intentional adulteration of urine samples that adheres to the principles of harm-reduction, the centrality of the patient-provider relationship, and the acknowledgment that ongoing illicit drug use and subsequent dishonesty about disclosure may be common among persons with substance use disorders. Each of the three patients ultimately endorsed diluting their urine, which allowed for strengthening of the patient-provider relationship and modifications to their treatment plans. Two of the three patients stabilized and achieved abstinence, while the third was eventually referred to a methadone treatment program. CONCLUSION: Providers should routinely monitor B and NB levels, rather than qualitative screening alone, and discordant levels should elicit a timely conversation with the patient. The authors use of a nonjudgmental approach to address urine adulteration, including giving patients an opportunity to reflect on potential solutions, has been effective at helping patients and providers to reestablish a therapeutic alliance and maintain retention in treatment.

Comparison of Cocaine/Crack Biomarkers Concentrations in Oral Fluid, Urine and Plasma Simultaneously Collected From Drug Users.

The use of oral fluid (OF) as an alternative specimen for drug analysis has become very popular in forensic toxicology. Many clinical studies have evaluated the correlations between concentrations of cocaine and its metabolites in OF and other matrices, but results have shown high variability. In addition, there are no data available regarding the correlations between biomarkers of crack-cocaine use in different matrices. This study evaluated the relationship between concentrations of cocaine/crack-cocaine biomarkers in OF, urine and plasma samples collected from cocaine users. All samples were analyzed for the presence of cocaine (COC), benzoylecgonine (BZE) and anhydroecgonine (AEC) by a validated liquid chromatography-mass spectrometry method. Median COC, BZE and AEC concentrations ranged from 4.20 to 33.26 ng/mL, from 13.03 to 3,615.86 ng/mL and from 7.40 to 1,892.5 ng/mL across matrices, respectively. The relationship between drug concentrations in OF versus plasma (OF/P) and OF versus urine (OF/U) was evaluated by their coefficients of determination (R2). Least-squares regression analyses demonstrated significant correlations between OF/P and OF/U for cocaine and BE (P < 0.05), with R2 = 0.17, 0.07 for cocaine and R2 = 0.73, 0.45 for BE, respectively. The correlation coefficients (r) found for BZE, COC and AEC in OF/P and OF/U were 0.85 and 0.67 (P < 0.05); 0.41 and 0.26 (P < 0.05); and 0.30 and -0.37 (P > 0.05), respectively. Many factors contribute to the variability of drug correlation ratios in studies involving random samples, including uncertainty about the time of last administration and dosage. Overall, we found significant R2 values for COC and BZE in OF/P and OF/U, but not for AEC. Despite the good correlations found in some cases, especially for BZE, the large variation in drug concentrations seen in this work suggests that OF concentrations should not be used to estimate concentrations of COC, BZE or AEC in plasma and/or urine.

Reduced interhemispheric executive control network coupling in men during early cocaine abstinence: A pilot study.

BACKGROUND: Individuals who use cocaine have fewer cognitive resources needed to maintain abstinence. This is evidenced by blunted brain function during cognitive control tasks and reduced communication between brain regions associated with cognitive function. For instance, relapse vulnerability is heightened in individuals with less communication between the right and left frontoparietal executive control network (ECN). Given that recent cocaine use enhances such communication, it is plausible that recency of cocaine use influences interhemispheric ECN communication. However, it is unclear whether ECN communication weakens over the course of early cocaine abstinence, which may then enhance relapse risk. METHODS: In ten men with cocaine use disorder, we conducted a preliminary assessment of the relationship between the number of days since last cocaine use (1-3days) and interhemispheric ECN coupling using resting state functional magnetic resonance imaging (fMRI). RESULTS: Reduced interhemispheric ECN coupling was associated with increasing days since last cocaine use; weaker coupling was also associated with lower urine cocaine metabolite concentrations. This association was more prominent in prefrontal than parietal ECN-subregions. CONCLUSIONS: Preliminary results indicate that resting state interhemispheric ECN coupling weakens within the first few days following last cocaine use. Because of the known link between reduced ECN interhemispheric coupling and relapse vulnerability, these results suggest that relapse risk may increase the longer an individual abstains during an early quit attempt. Treatments focused on reversing this coupling deficit may facilitate abstinence.