Cocaine abuse sharply reduced in an effective methadone maintenance program

Forensic pathological study of methadone-related deaths in the Genoa (Italy) district: A six-year study

Methadone is a synthetic opioid, a pure agonist of the μ receptor. It is used for opioid maintenance therapy in heroin addiction. In recent years, Italian studies of incidence and prevalence have indicated an increase in the illegal sales of methadone and, consequently, an increase in deaths due to acute methadone intoxication as well. The present review is a prospective-observational study regarding epidemiological and toxicological analyses of methadone-related deaths recorded in the district of Genoa (Italy) from 2013 to 2018. The study includes a list of twenty-six people that have died from methadone toxicity: twenty-two males and four females. The concentration of methadone in the blood samples ranged from 181 to 4058.53 ng/mL, with an average of 964.29 ng/mL. Six subjects tested positive for methadone alone; twenty cases, however, presented drugs or substances in different concentrations in the blood samples. Illegal sales and consumption of methadone have a negative impact on the self-administration therapy of opioid addiction, inducing patients to increase their dosage or sell methadone in order to purchase illegal drugs. As shown in our study, this behaviour is associated with an increase in methadone-related deaths. Accordingly, careful monitoring of dosage administrated to patients is required in order to render the system safer.

Non-medical Cannabis Self-Exposure as a Dimensional Predictor of Opioid Dependence Diagnosis: A Propensity Score Matched Analysis

Background: The impact of increasing non-medical cannabis use on vulnerability to develop opioid use disorders has received considerable attention, with contrasting findings. A dimensional analysis of self-exposure to cannabis and other drugs, in individuals with and without opioid dependence (OD) diagnoses, may clarify this issue. Objective: To examine the age of onset of maximal self-exposure to cannabis, alcohol, cocaine, and heroin, in volunteers diagnosed with OD, using a rapidly administered instrument (the KMSK scales). To then determine whether maximal self-exposure to cannabis, alcohol, and cocaine is a dimensional predictor of odds of OD diagnoses. Methods: This outpatient observational study examined maximal self-exposure to these drugs, in volunteers diagnosed with DSM-IV OD or other drug diagnoses, and normal volunteers. In order to focus more directly on opioid dependence diagnosis as the outcome, volunteers who had cocaine dependence diagnoses were excluded. Male and female adults of diverse ethnicity were consecutively ascertained from the community, and from local drug treatment programs, in 2002-2013 (n = 574, of whom n = 94 had OD diagnoses). The age of onset of maximal self-exposure of these drugs was examined. After propensity score matching for age at ascertainment, gender, and ethnicity, a multiple logistic regression examined how increasing self-exposure to non-medical cannabis, alcohol and cocaine affected odds of OD diagnoses. Results: Volunteers with OD diagnoses had the onset of heaviest use of cannabis in the approximate transition between adolescence and adulthood (mean age = 18.9 years), and onset of heaviest use of alcohol soon thereafter (mean age = 20.1 years). Onset of heaviest use of heroin and cocaine was detected later in the lifespan (mean ages = 24.7 and 25.3 years, respectively). After propensity score matching for demographic variables, we found that the maximal self-exposure to cannabis and cocaine, but not to alcohol, was greater in volunteers with OD diagnoses, than in those without this diagnosis. Also, a multiple logistic regression detected that increasing self-exposure to cannabis and cocaine, but not alcohol, was a positive predictor of OD diagnosis. Conclusions/Importance: Increasing self-exposure to non-medical cannabis, as measured with a rapid dimensional instrument, was a predictor of greater odds of opioid dependence diagnosis, in propensity score-matched samples.

Changes in substance use in patients receiving opioid substitution therapy and resulting clinical challenges: a 17-year treatment case register analysis

BACKGROUND

Although the beneficial effects of opioid substitution for the reduction of heroin use are well established, its effect on other substance use is unclear. We aimed to evaluate short-term and long-term changes in substance use in opioid-dependent patients on opioid substitution therapy. We focused on frequent use of heroin, cocaine, benzodiazepines, and alcohol under naturalistic conditions (ie, with non-selected patients and clinical practice as usual) over 17 years.

METHODS

This was a treatment case register analysis. Data were obtained from the treatment case register of the canton of Zurich, Switzerland, which included information for 8962 patients (122 399 case report forms) who received substitution therapy with methadone or buprenorphine between 1998 and 2014. The main focus of our study was to evaluate long-term changes in frequent substance use of patients on opioid substitution therapy, together with the associations between individual, treatment, and environmental factors and substance use, including short-term changes at first treatment entry. Data were analysed using a generalised estimating equation that accounted for individual, treatment, and environmental factors. Frequent use was defined as substance use on at least 5 days per week.

FINDINGS

The most frequent use of heroin (odds ratio [OR] 5·30, 95% CI 4·63-6·08; p<0·0001), cocaine (2·30, 1·95-2·71; p<0·0001) and, to a lesser extent, benzodiazepines (1·34, 1·17-1·54; p<0·0001) and alcohol (1·21, 1·08-1·35; p=0·0007), was found in previously untreated individuals compared with patients already receiving treatment 6 months after starting opioid substitution therapy, corroborating a strong effect of initiating substitution therapy. Frequency of substance use was associated with the year of evaluation: frequent use of heroin (OR per decade 0·56, 0·52-0·60; p<0·0001) and cocaine (0·63, 0·58-0·68; p<0·0001) significantly decreased between 1998 and 2014, while frequent alcohol use increased (1·15, 1·08-1·23; p<0·0001). In 2014, frequent alcohol use was observed in 990 (22·5%) of 4400 patients on opioid substitution therapy.

INTERPRETATION

Frequent use of alcohol during opioid substitution therapy significantly increased during the observation period, whereas there was a decline in frequent use of heroin and cocaine. Given the high infection rates with hepatotoxic viruses and the increasing liver-related mortality rates in patients on opioid substitution therapy, these findings suggest that frequent alcohol use increasingly constitutes a therapeutic challenge in opioid substitution therapy.

FUNDING

None.

Association between methadone dose and concomitant cocaine use in methadone maintenance treatment: a register-based study

Background

Concomitant cocaine use is a major problem in clinical practice in methadone maintenance treatment (MMT) and may interfere with successful treatment. Data from European methadone populations is sparse. This register-based study sought to explore the association between prescribed methadone dose and concomitant cocaine and heroin use in the methadone population of Basel City.

Methods

The study included 613 methadone patients between April 1, 2003 and March 31, 2004. Anonymized data was taken from the methadone register of Basel City. For analysis of the prescribed methadone dose distribution, the patient sample was split into three methadone dosage groups: a low dose group (LDG) (n = 200; < 60 mg/day), a medium dose group (MDG) (n = 273; 60 to 100 mg/day), and a high dose group (HDG) (n = 140; > 100 mg/day). Concomitant drug use was based on self-report.

Results

Analysis showed a significant difference in self-reported cocaine use between groups (p < 0.001). Patients in the LDG reported significantly fewer cocaine consumption days compared to the MDG (p < 0.001) and the HDG (p < 0.05). Patients in the HDG reported significantly fewer heroin consumption days than those in the LDG (p < 0.01) and the MDG (p < 0.001). In logistic regression analysis, cocaine use was significantly associated with heroin use (OR 4.9).

Conclusions

Cocaine use in methadone patients may be associated with heroin use, which indicates the importance of prescribing appropriate methadone dosages in order to indirectly reduce cocaine use.

Treatment-like steady-state methadone in rats interferes with incubation of cocaine sensitization and associated alterations in gene expression

In a previous study, steady-state methadone treatment was found to prevent associative cocaine learning, as well as related decreases in mRNA expression of preprohypocretin/preproorexin (ppHcrt) in the lateral hypothalamus (LH) and dopamine D2 receptor (DR2) in the caudate-putamen (CP), and increases in mu-opioid receptor in the ventral striatum of rats. To investigate whether the same regimen of methadone exposure could prevent the incubation of cocaine sensitization and related alterations in gene expression, male Sprague-Dawley rats received 45 mg/kg/day steady-dose "binge" cocaine administration (IP) for 14 days followed by mini-pumps releasing 30 mg/kg/day methadone (SC). After 14 days of methadone, and a subsequent 10-day drug-free period, all rats were tested for sensitization (cocaine test dose: 15 mg/kg) and brain tissue was collected to quantify mRNA expression. Rats exposed to cocaine displayed cocaine-induced stereotypy at test, as well as enhanced ppHcrt mRNA in the LH and reduced DR2 mRNA in the CP. Importantly, these alterations were significantly reduced in rats treated with methadone following cocaine. These results suggest that steady-state methadone can interfere with the incubation of neuroadaptations underlying changes in behavioral responses to cocaine and cocaine-associated stimuli, and that these effects can be observed even after withdrawal from methadone.

Extreme marginalization: addiction and other mental health disorders, stigma, and imprisonment

Major well-defined medical problems that are, in part, the unfortunate outcome of a negative social environment may include specific addictive diseases and other mental health disorders, in particular the affective disorders of anxiety, depression, social phobia, and posttraumatic stress syndrome. This overview touches on the topic of extreme marginalization associated with addiction and other mental health disorders, along with arrest, imprisonment, and parole. All of these are characterized by a lasting stigma that hauntingly continues to affect each person suffering from any of these problems.

Pharmacotherapy in the treatment of addiction: methadone

Methadone maintenance treatment (MMT) is the most widely available pharmacotherapy for opioid addiction and has been shown to be an effective and safe treatment over a period of 40 years. Although women comprise approximately 40% of clients currently being treated in MMT programs, comparatively little research geared specifically toward this group has been published. This article begins with an overview of neurobiological studies on opioid addiction, including a discussion of gender differences, followed by a review of the pharmacology of methadone. The authors then examine the particular needs and differences of women being treated in MMTs, including co-dependence with other substances, women's health issues, and psychosocial needs unique to this population. Research shows that women have different substance abuse treatment needs in comparison to their male counterparts. One New York City MMT program that has attempted to address these differences is highlighted.

Steady-state methadone blocks cocaine seeking and cocaine-induced gene expression alterations in the rat brain

To elucidate the effects of steady-state methadone exposure on responding to cocaine conditioned stimuli and on cocaine-induced alterations in central opioid, hypocretin/orexin, and D2 receptor systems, male Sprague-Dawley rats received intravenous infusions of 1 mg/kg/inf cocaine paired with an audiovisual stimulus over three days of conditioning. Then, mini pumps releasing vehicle or 30 mg/kg/day methadone were implanted (SC), and lever pressing for the stimulus was assessed in the absence of cocaine and after a cocaine prime (20 mg/kg, IP). It was found that rats treated with vehicle, but not methadone, responded for the cocaine conditioned stimulus and displayed elevated mu-opioid receptor mRNA expression in the nucleus accumbens core and basolateral amygdala, reduced hypocretin/orexin mRNA in the lateral hypothalamus, and reduced D2 receptor mRNA in the caudate-putamen. This is the first demonstration that steady-state methadone administered after cocaine exposure blocks cocaine-induced behavioral and neural adaptations.

Opiate and cocaine addiction: from bench to clinic and back to the bench

This review primarily focuses on our recent findings in bidirectional translational research on opiate and cocaine addictions. First, we present neurobiological and molecular studies on endogenous opioid systems (e.g. proopiomelanocortin, mu opioid receptor, dynorphin, and kappa opioid receptor), brain stress-responsive systems (e.g. orexin, arginine vasopressin, V1b receptor, and corticotropin-releasing factor), hypothalamic-pituitary-adrenal axis, and neurotransmitters (especially dopamine), in response to both chronic cocaine or opiate exposure and to drug withdrawal, using several newly developed animal models and molecular approaches. The second aspect is human molecular genetic association investigations including hypothesis-driven studies and genome-wide array studies, to define particular systems involved in vulnerability to develop specific addictions, and response to pharmacotherapy.

Cocaine-Related Torsade de Pointes in a Methadone Maintenance Patient

A patient maintained on methadone for opioid-dependency developed recurrent syncope. Episodes occurred within hours after using cocaine, and were initially presumed secondary to seizure disorder. However, the patient subsequently suffered a cardiac arrest, and polymorphic ventricular tachycardia (torsade de pointes) was documented. Other than cocaine and methadone the patient was receiving no additional agents known to prolong the QT interval. Low serum methadone concentrations and marked reversible left ventricular systolic dysfunction were noted during the hospitalization. These findings, in conjunction with a history of torsade de pointes temporally related to cocaine abuse, suggest that cocaine was a major precipitant of arrhythmia. Recent experimental studies have shown that cocaine and methadone prolong the QT interval through the same mechanism. We examine the effects of cocaine and methadone on cardiac conduction in the context of the opioid-dependent population.

Office-based maintenance treatment of opioid dependence: how does it compare with traditional approaches?

The increasing global public health burden of heroin dependence and prescription opioid dependence warrants further expansion of treatment models. The most effective intervention for opioid dependence remains maintenance with methadone, a full mu-opioid receptor agonist, or buprenorphine, a partial mu-opioid receptor agonist.A growing body of evidence supports the use of opioid receptor agonist maintenance in office-based settings. Office-based opioid treatment (OBOT) can expand treatment access in a less stigmatized environment, which enables integrated care of co-morbid conditions. The current review primarily examines OBOT in the US, although a comparison with the British and French models is provided, given that the public health impact and implementation of OBOT will likely vary between countries because of policy and logistical differences. The comparative effectiveness of maintenance treatment in office-based and traditional programme-based models of care requires further study. Clinical and practical considerations when providing treatment for opioid dependence in traditional versus office-based settings include patient selection and monitoring, health economics, management of co-morbid conditions, and access to ancillary psychosocial treatment. OBOT is not a replacement for more structured, traditional models of care, but provides an additional opportunity to help address the tremendous public health impact of opioid dependence.

Opioids, dopamine, stress, and the addictions

The articulated goals of Dialogues in Clinical Neuroscience are to serve as "an interface between clinical neuropsychiatry and the neurosciences by providing state-of-the-art information and original insights into relevant clinical, biological, and therapeutic aspects." My laboratory the Laboratory of the Biology of Addictive Diseases at The Rockefeller University, has for years been focused on "bidirectional translational research," that is, learning by careful observations and study in patient populations with the disorders under study, in this case primarily specific addictive diseases, and then using that knowledge to create improved animal models or other laboratory-based research paradigms, while, at the same time, taking research findings made at the bench into the clinic as promptly as that is appropriate and feasible. In this invited review, therefore, the focus will be on perspectives of our Laboratory of the Biology of Addictive Diseases and related National Institutes of Health/National Institute on Drug Abuse research Center, including laboratory-based molecular neurobiological research, research using several animal models designed to mimic human patterns of drug abuse and addiction, as well as basic clinical research, intertwined with treatment-related research.

A profile of the substance abuse treatment industry: organization, costs, and treatment completion

Nationally representative data from the Alcohol and Drug Services Study, conducted between 1996 and 1999, are used to explore the structure and operation of the substance user treatment industry in the United States. The empirical relationship among client (N=4945) retention and completion, types and use of counseling and medical personnel, diagnostic mix, client demographics, the level of services used, and the cost of treatment in different treatment settings is discussed using tabular presentation and tests of significance. Limitations of the analysis are outlined. This information and analysis are expected to help the research community understand the potential of the ADSS data in addressing many important questions about substance user treatment.

High-dose methadone maintenance in rats: effects on cocaine self-administration and behavioral side effects

It has been demonstrated that high-dose methadone maintenance is efficacious in reducing cocaine abuse in opioid-dependent individuals, but it is not clear whether this is caused by an action of methadone on the direct reinforcing properties of cocaine or on cocaine seeking. Also, it is not clear whether high-dose methadone maintenance may induce behavioral side effects, which could limit its clinical use. Here, we report that high-dose methadone maintenance (20-40 mg/kg/day) does not reduce, and even enhances cocaine (10-30 mg/kg, i.p.)-induced elevation in dopamine concentration in the ventral striatum measured by in vivo microdialysis. In parallel, however, rats maintained on high-dose methadone (30 mg/kg/day) seek and consume significantly less cocaine than controls when tested for intravenous cocaine (0.5 mg/kg/infusion) self-administration on a progressive ratio schedule of reinforcement. This reduction in cocaine self-administration does not result from impaired sensory-motor functioning as rats maintained on high-dose methadone show normal locomotor activity. Furthermore, the reduction in responding for cocaine does not seem to result from general behavioral deficits as male rats maintained on high methadone doses respond normally to palatable food and thermal pain, although their sexual responses to receptive females are greatly suppressed. Taken together, these results from studies in rats support the usefulness of larger doses of methadone to reduce severe cocaine abuse in opioid-dependent individuals and possibly in the management of pure-cocaine addiction.

Adolescent and young adult heroin patients: drug use and success in methadone maintenance treatment

This study examined the impact of methadone maintenance treatment on an inclusive group of adolescent and young adult opiate-dependent patients, ages 15-23, admitted over a 6-year period, during their first year in the program. Retention in treatment was the primary outcome variable, and at 12 months, 48% were still in treatment. The findings were: (a) a stepwise discriminant function analysis revealed that patients who consistently used heroin were at a greater risk of leaving treatment within the first 12 months; (b) the use of cocaine was an indicator of higher levels of heroin use in those who reached the one-year mark; (c) among patients who stayed in treatment for one year, there was a significant reduction in heroin use, a trend toward a reduction in cocaine use, and no significant impact on benzodiazepine use; and (d) the group that stayed in treatment was slightly younger than the group that left before the first year ended. There were no gender or ethnic differences between the two groups. Suggestions for interventions that might improve treatment outcome are presented.

An exploratory analysis of treatment completion and client and organizational factors using hierarchical linear modeling

Data from the Alcohol and Drug Services Study (ADSS) are used to analyze the structure and operation of the substance abuse treatment industry in the United States. Published literature contains little systematic empirical analysis of the interaction between organizational characteristics and treatment outcomes. This paper addresses that deficit. It develops and tests a hierarchical linear model (HLM) to address questions about the empirical relationship between treatment inputs (industry costs, types and use of counseling and medical personnel, diagnosis mix, patient demographics, and the nature and level of services used in substance abuse treatment), and patient outcomes (retention and treatment completion rates). The paper adds to the literature by demonstrating a direct and statistically significant link between treatment completion and the organizational and staffing structure of the treatment setting. Related reimbursement issues, questions for future analysis, and limitations of the ADSS for this analysis are discussed.

High methadone dose significantly reduces cocaine use in methadone maintenance treatment (MMT) patients

AIM

To evaluate whether effective methadone treatment affects cocaine use.

METHODS

421 consecutive patients admitted to a methadone maintenance clinic in Israel (1993-2002) were prospectively studied. Patients' urine samples were analyzed for cocaine during months 1 and 13.

RESULTS

On admission 55(13.1%) of 421 patients had urine positive for cocaine and 366 had negative. Of the 55 cocaine-positive patients, 45(81.8%) stayed in treatment at least one year, as did 267(73%) of cocaine-negative. After one year (n=312) 31 of 45 cocaine users stopped and 25 of 267 started. Methadone dose was highest in 31 patients who stopped cocaine (176.1+/-42.1 mg/ day), followed by 14 who did not stop (161.4+/-37.5 mg/day), and 25 who started during treatment (122.9+/-48.7 mg/day), or 242 who never used cocaine (119.5+/-48.4 mg/day) (ANOVA, F=15.6, p<0.0005).

CONCLUSIONS

High methadone dose may reduce cocaine use in patients addicted to both heroin and cocaine.

Effects of high-dose methadone maintenance on cocaine place conditioning, cocaine self-administration, and mu-opioid receptor mRNA expression in the rat brain

Methadone maintenance at appropriate doses can effectively reduce cocaine abuse in heroin-dependent individuals. In the present studies, we investigated the effect of high-dose methadone maintenance cocaine conditioned place preference (CPP) and cocaine intravenous self-administration. Rats implanted with methadone-filled osmotic mini-pumps (20 and 55 mg/kg/day, SC) and conditioned with cocaine (1, 5, and 20 mg/kg, i.p.) did not express cocaine CPP. Similarly, rats implanted with methadone pumps (55 mg/kg/day) after cocaine conditioning (20 mg/kg) displayed neither spontaneous nor cocaine-precipitated (20 mg/kg, i.p.) CPP. In contrast, methadone maintenance (30 and 55 mg/kg/day, SC) did not alter the intravenous self-administration (continuous schedule of reinforcement) of various doses of cocaine (0.1, 0.5, and 2.0 mg/kg/inf). To explore neuropharmacological interactions between methadone maintenance and cocaine conditioning, we quantitatively measured mRNA levels of mu-opioid receptor (MOR) and proopiomelanocortin genes 10 days after methadone maintenance. MOR mRNA levels in both the nucleus accumbens core and frontal cortex were significantly elevated in rats exposed to cocaine during CPP conditioning. However, upregulation of MOR mRNA levels in the nucleus accumbens core were reduced by methadone maintenance in a dose-dependent manner. In conclusion, our results suggest that high-dose methadone maintenance does not alter the direct reinforcing effect of cocaine, but blocks spontaneous and cocaine-precipitated cocaine-seeking, possibly by preventing MOR alterations in the nucleus accumbens core induced by cocaine conditioning.

Randomized trial of drug abuse treatment-linkage strategies

A clinical trial contrasted 2 interventions designed to link opioid-dependent hospital patients to drug abuse treatment. The 126 out-of-treatment participants were randomly assigned to (a) case management, (b) voucher for free methadone maintenance treatment (MMT), (c) case management plus voucher, or (d) usual care. Services were provided for 6 months. MMT enrollment at 3 months was 47% (case management), 89% (voucher), 93% (case management plus voucher), and 11% (usual care); at 6 months enrollment was 48%, 68%, 79%, and 21%, respectively. Case management and vouchers can be valuable in health settings to link substance abusers with medical problems to drug abuse treatment.

Co-Consumption of Benzodiazepines in Heroin Users, Methadone-Substituted and Codeine-Substituted Patients

Concomitant consumption of benzodiazepines (BZDs) and opioids is a major problem in patients with opioid dependence. It may have substantial impact on morbidity, mortality and clinical course. The current retrospective study aims to determine whether there are differences in the additional use of BZDs among addicts regularly taking methadone or codeine medications in treatment and untreated addicts injecting heroin. The records of 1,685 patients admitted for detoxification were analyzed using bivariate analysis and multiple logistic regression analysis. Demographic and drug related variables were considered, both as possible confounders and predictors of concomitant BZD use. Daily intake of BZDs was reported in 44.4% of the patients. Patients treated with methadone or codeine medications report daily intake of BZDs significantly more often than the heroin-dependent patients (p < 0.01). Using multiple regression analyses, the results were confirmed as independent from the assessed possible confounders. Further we found that daily use of alcohol or barbiturates, early onset of opioid use (p < 0.01), unemployment, having a substance dependent family member with, and a history of imprisonment (for all p < 0.05) were associated with concomitant daily consumption of BZDs in opioid dependent subjects. These finding underline the need to further explore the causes, interactions and consequences of concomitant BZD and opiate use.

Factors associated with methadone maintenance therapy use among a cohort of polysubstance using injection drug users in Vancouver

We identified methadone maintenance therapy (MMT) use during follow-up interviews and examined associations between MMT use and socio-demographic and drug-related variables using generalized estimating equations (GEE). Of the 1587 participants recruited into this cohort, 170 (11%) were enrolled in MMT at baseline and additional 498 (31%) initiated MMT during follow-up. Of those ever enrolled in MMT, 406 (61%) ceased MMT and re-initiated MMT on more than one occasion. The median treatment duration was 14.4 months. Factors that were negatively and significantly associated with MMT use in multivariate analyses included: Aboriginal ethnicity (adjusted odds ratio [AOR] = 0.40); recent incarceration (AOR = 0.79); sex trade involvement (AOR = 0.87); syringe lending (AOR = 0.72); heroin injection (AOR = 0.64), whereas female gender (AOR = 2.47), HIV positivity (AOR = 1.57), and crack cocaine smoking (AOR = 1.23) were positively and significantly associated with being on MMT. Unstable housing, syringe borrowing, non-fatal overdose, cocaine injection, and residence in Vancouver's Downtown Eastside were not associated with MMT use in multivariate analyses. Our study demonstrates high rates of initiation of and retention in MMT among local IDUs. While the use of MMT was associated with reductions in heroin use and HIV risk behavior, barriers to Aboriginal IDUs were evident, and the association with increased crack cocaine use deserves further study.

Patterns of heroin, cocaine, and alcohol abuse during long-term methadone maintenance treatment

Individuals' use of heroin, cocaine, and alcohol during long-term methadone maintenance treatment (MMT) was studied. Prospectively collected data from 103 heroin-addicted individuals who were consecutively admitted for MMT and remained 2 years in treatment were evaluated. The patients were assessed every 6 months with a standardized interview. Three longitudinal patterns of drug abuse were identified. A proportion of patients abstained fully from their particular drug use (26% from heroin, 39% from cocaine, and 19% from alcohol); a proportion (39%, 32%, and 47%, respectively) switched between periods of abuse and nonuse of these drugs; and chronic drug users (34%, 28%, and 33%, respectively) continued use, including periods of daily abuse throughout MMT. Different therapeutic interventions may be needed in patients with different longitudinal patterns of additional substance use during MMT.

Patterns of opioid and cocaine co-use: a descriptive study in a Canadian sample of untreated opioid-dependent individuals

This study examined prevalence and patterns of co-use of opioids and cocaine in regular users of illicit opioids (N = 729) recruited from 5 Canadian cities. Fifty-seven percent (n = 417) reported having used both opioids and cocaine in the month and week preceding the interview; of these, 73% (n = 304) were able to identify a typical pattern of daily co-use. In a typical day, injectors of opioids and cocaine (n = 119) and injectors of opioids who inhaled cocaine (n = 111) showed stable opioid use but variable cocaine use, which peaked at 21 hr. Overall, 30% of the individuals used both drugs exclusively in a sequential fashion, 35% reported taking opioids and cocaine within the same hour, and 35% reported taking them together at the same time or mixing them. These findings indicate that different individuals display different patterns of opioids and cocaine co-use.

Prediction of relapse to frequent heroin use and the role of methadone prescription: an analysis of the Amsterdam Cohort Study among drug users

The risk of relapse into frequent heroin use was studied among 732 participants of the Amsterdam Cohort Study (ACS) on HIV/AIDS among drug users, who experienced an episode of abstinence from or occasional use of heroin. Participants of the ACS were recruited primarily from easy access ("low-threshold") methadone programs. The duration of abstinence/occasional use and relative risks (RR) of relapse were estimated by analyzing 1577 episodes by means of survival analysis using characteristics of patients and methadone treatment as covariates. The majority of episodes (85.8%) were followed by relapse within 5 years. Less education, intense use of heroin prior to the episode of abstinence or well-controlled use, occasional use of heroin and intense use of cocaine during the episode, and having a drug-using partner or having no partner were significantly associated with a higher risk of relapse. Among frequent attendees of a "low-threshold" methadone program, relapse was associated with the daily dose of methadone: RR for dosages <40 and 40-60 mg, compared with doses of >100mg, were 1.45 (P<0.01) and 1.59 (P<0.01), respectively. No beneficial influence was revealed of methadone dosage or program attendance in itself on the risk of relapse into cocaine. High doses of methadone in a harm-reduction setting extend the duration of an episode of no or occasional use of heroin. Other factors, such as no occasional use of heroin during the episode, no use of cocaine, and having a non-using partner, seem to be equally important.

Methadone maintenance reduces heroin- and cocaine-induced relapse without affecting stress-induced relapse in a rodent model of poly-drug use

Although it is well established that methadone can be an effective treatment for opiate addiction, it is not clear how methadone maintenance affects cocaine use and cravings in individuals who self-administer both opiates and cocaine. In our attempt to explore the effect of methadone maintenance on the effects of cocaine, we first assessed the locomotor stimulatory effects of cocaine in rats maintained on methadone (0, 10, 20, or 30 mg/kg/day, via osmotic minipumps). Chronic methadone elevated baseline locomotion in a dose-dependent manner and did not reduce the direct stimulatory effects of cocaine (5 mg/kg). We then investigated the effects of the highest methadone maintenance dose (30 mg/kg/day) on heroin and cocaine seeking in extinction, and when it was precipitated by exposure to heroin, cocaine, or foot-shock stress in rats trained to self-administer both drugs in the same experimental context (heroin 0.05 mg/kg/inf; cocaine 0.5 mg/kg/inf, eight 3-h sessions each). In tests of reinstatement, rats responded selectively on the appropriate drug-associated lever after priming injections of heroin (0.25 mg/kg) or cocaine (20 mg/kg). Methadone maintenance blocked both cocaine- and heroin-induced reinstatement, but not stress-induced reinstatement, which was not lever selective. These results suggest that although methadone maintenance may not reduce the direct stimulatory effects of cocaine, it has the potential to reduce both spontaneous and cocaine-primed cocaine-seeking behavior.

Effects of chronic methadone treatment on cocaine- and food-maintained responding under second-order, progressive-ratio and concurrent-choice schedules in rhesus monkeys

The effects of chronic infusion with saline or methadone (0.032-1.0 mg/kg/h) were examined on cocaine- and food-maintained responding in rhesus monkeys using three procedures. In one procedure, cocaine injections (0.0032-0.032 mg/kg per injection) and food pellets were available under a second-order schedule during alternating daily sessions. During saline treatment, cocaine maintained a dose-dependent increase in the number of cocaine injections per day, and monkeys usually responded for the maximum number of pellets. Methadone dose-dependently decreased cocaine self-administration, and methadone doses that decreased cocaine self-administration had variable effects on food-maintained responding. In the second procedure, 0.032 mg/kg per injection cocaine or food pellets were available under a progressive-ratio schedule. During saline treatment, cocaine and food maintained similar break points. Methadone produced a dose-dependent and non-selective decrease in break points maintained by both cocaine and food. In the third procedure, cocaine injections (0-0.1 mg/kg per injection) and food pellets were available under a concurrent-choice schedule. During saline treatment, increasing unit doses of cocaine produced a dose-dependent increase in cocaine choice. Methadone had little effect on the cocaine choice dose-effect curve up to doses that eliminated responding. These results provide little evidence to suggest that chronic methadone altered the reinforcing effects of cocaine; rather methadone appeared to non-selectively decrease rates of operant responding.

Pharmacological treatments for heroin and cocaine addiction

AIMS

To provide an overview of the pharmacological options for the treatment of heroin- and cocaine-dependent patients based on known biochemical pathways to addiction and the chronic disease model as a starting point for treatment planning.

RESULTS

Recent pre-clinical and clinical studies indicate that different brain structures and different neurotransmitters are involved in different stages of the addiction process. In addition, clinical experience shows that heroin and cocaine addiction can best be conceptualised and treated as a chronic, relapsing disorder with the following treatment goals: crisis intervention, cure or recovery (detoxification, relapse prevention) and care or partial remission (stabilization and harm reduction). The various high-quality studies, systematic literature reviews and formal meta-analyses clearly demonstrate that today many proven effective interventions are available for crisis intervention, detoxification, stabilization and harm reduction for heroin-dependent patients. Interventions directed at relapse prevention are still problematic and only effective in a minority of motivated patients in stable living conditions and adequate social support. In contrast, no proven effective pharmacological interventions are available for the treatment of cocaine-dependent patients, maybe with the exception of some patient groups that seem to benefit from treatment with disulfiram or amantadine. Treatment innovations are primarily based on experimental animal studies. Newly developed cannabinoid receptor antagonists and cortisol synthesis inhibitors show great promise.

CONCLUSION

Heroin addiction is a chronic relapsing disease that is difficult to cure, but stabilization and harm reduction can greatly increase the life time expectancy and the quality of life of the patient, his direct environment and society as a whole. Currently, no proven effective pharmacological interventions are available for cocaine addiction, and treatment has to rely on existing cognitive behaviour therapies combined with contingency management strategies.

Interindividual variability of the clinical pharmacokinetics of methadone: implications for the treatment of opioid dependence

Methadone is widely used for the treatment of opioid dependence. Although in most countries the drug is administered as a racemic mixture of (R)- and (S)- methadone, (R)-methadone accounts for most, if not all, of the opioid effects. Methadone can be detected in the blood 15-45 minutes after oral administration, with peak plasma concentration at 2.5-4 hours. Methadone has a mean bioavailability of around 75% (range 36-100%). Methadone is highly bound to plasma proteins, in particular to alpha(1)-acid glycoprotein. Its mean free fraction is around 13%, with a 4-fold interindividual variation. Its volume of distribution is about 4 L/kg (range 2-13 L/kg). The elimination of methadone is mediated by biotransformation, followed by renal and faecal excretion. Total body clearance is about 0.095 L/min, with wide interindividual variation (range 0.02-2 L/min). Plasma concentrations of methadone decrease in a biexponential manner, with a mean value of around 22 hours (range 5-130 hours) for elimination half-life. For the active (R)-enantiomer, mean values of around 40 hours have been determined. Cytochrome P450 (CYP) 3A4 and to a lesser extent 2D6 are probably the main isoforms involved in methadone metabolism. Rifampicin (rifampin), phenobarbital, phenytoin, carbamazepine, nevirapine, and efavirenz decrease methadone blood concentrations, probably by induction of CYP3A4 activity, which can result in severe withdrawal symptoms. Inhibitors of CYP3A4, such as fluconazole, and of CYP2D6, such as paroxetine, increase methadone blood concentrations. There is an up to 17-fold interindividual variation of methadone blood concentration for a given dosage, and interindividual variability of CYP enzymes accounts for a large part of this variation. Since methadone probably also displays large interindividual variability in its pharmacodynamics, methadone treatment must be individually adapted to each patient. Because of the high morbidity and mortality associated with opioid dependence, it is of major importance that methadone is used at an effective dosage in maintenance treatment: at least 60 mg/day, but typically 80-100 mg/day. Recent studies also show that a subset of patients might benefit from methadone dosages larger than 100 mg/day, many of them because of high clearance. In clinical management, medical evaluation of objective signs and subjective symptoms is sufficient for dosage titration in most patients. However, therapeutic drug monitoring can be useful in particular situations. In the case of non-response trough plasma concentrations of 400 microg/L for (R,S)-methadone or 250 microg/L for (R)-methadone might be used as target values.

Understanding polydrug use: review of heroin and cocaine co-use

The use of cocaine by heroin-dependent individuals, or by patients in methadone or buprenorphine maintenance treatment, is substantial and has negative consequences on health, social adjustment and outcome of opioid-addiction treatment. The pharmacological reasons for cocaine use in opioid-dependent individuals, however, are poorly understood and little is known about the patterns of heroin and cocaine co-use. We reviewed anecdotal evidence suggesting that cocaine is co-used with opioid drugs in a variety of different patterns, to achieve different goals. Clinical and preclinical experimental evidence indicates that the simultaneous administration of cocaine and heroin (i.e. 'speedball') does not induce a novel set of subjective effects, nor is it more reinforcing than either drug alone, especially when the doses of heroin and cocaine are high. There is mixed evidence that the subjective effects of cocaine are enhanced in individuals dependent on opioids, although it is clear that cocaine can alleviate the severity of symptoms of withdrawal from opioids. We also reviewed preclinical studies investigating possible neurobiological interactions between opioids and cocaine, but the results of these studies have been difficult to interpret mainly because the neurochemical mechanisms mediating the motivational effects of cocaine are modified by dependence on, and withdrawal from, opioid drugs. Our analysis encourages further systematic investigation of cocaine use patterns among opioid-dependent individuals and in laboratory animals. Once clearly identified, pharmacological and neuroanatomical methods can be employed in self-administering laboratory animals to uncover the neurobiological correlates of specific patterns of co-use.

Methadone maintenance at different dosages for opioid dependence

BACKGROUND

Methadone maintenance treatment (MMT) is a long term opioid replacement therapy, recognised as effective in the management of opioid dependence. Even if MMT at high dosage is recommended as therapy for reducing illicit opioid use and promoting longer retention in treatment, at present day "the organisation and regulation of the methadone maintenance treatment varies widely".

OBJECTIVES

To evaluate the efficacy of different dosages of MMT for opioid dependence in modifying health and social outcomes and in promoting patients' familial, occupational and relational functioning.

SEARCH STRATEGY

The following sources were scanned: - MEDLINE (OVID 1966-2001)- EMBASE (1988-2001)- ERIC (1988-2001)- Psychinfo (1947-2001)- Cochrane Controlled Trials Register (CCTR) (1947-2001)- Register of the Cochrane Drug and Alcohol Group (CDAG) (1947-2001)The CDAG search strategy was applied together with a specific MESH strategy. Further studies were searched through: letters to the authors of selected trials or to experts in order to obtain unpublished data. check of references of relevant reviews.

SELECTION CRITERIA

Randomised Controlled Trials (RCT) and Controlled Prospective Studies (CPS) evaluating methadone maintenance at different dosages in the management of opioid dependence were included in the review. Non-randomised trials were included when proper adjustment for confounding factors was performed at the analysis stage.

DATA COLLECTION AND ANALYSIS

Extraction of data was performed separately by two reviewers. Discrepancies were resolved by a third reviewer. RevMan software was used for analysis. Quality assessments of the methodology of studies were carried out using CDAG checklist.

MAIN RESULTS

22 studies were excluded from the review. 21 studies were included; of them, 11 were RCTs with 2279 people randomised and 10 were CPSs with 3715 people followed-up.

OUTCOMES

Retention rate - RCTs: High vs low doses at shorter follow-ups: RR=1.36 [1.13,1.63], and at longer ones: RR=1.62 [0.95,2.77]. Opioid use (self reported), times/w - RCTs: high vs low doses WMD= -2.00 [-4.77,0.77] high vs middle doses WMD= -1.89[-3.43, -0.35] Opioid abstinence, (urine based) at >3-4 w - RCTs: high vs low ones: RR=1.59 [1.16,2.18] high vs middle doses RR=1.51[0.63,3.61] Cocaine abstinence (urine based) at >3-4 w - RCTs: high vs low doses RR=1.81 [1.15,2.85]Overdose mortality - CPSs: high dose vs low dose at 6 years follow up: RR=0.29 [0.02-5.34] high dose vs middle dose at 6 years follow up: RR=0.38 [0.02-9.34] middle dose vs low dose at 6 years follow up: RR=0.57 [0.06-5.06]

REVIEWER'S CONCLUSIONS

Methadone dosages ranging from 60 to 100 mg/day are more effective than lower dosages in retaining patients and in reducing use of heroin and cocaine during treatment. To find the optimal dose is a clinical ability, but clinician must consider these conclusions in treatment strategies.

Pharmacotherapy of addictions

Addiction to drugs, such as heroin, cocaine and alcohol, exacts great human and financial costs on society, but the development of pharmacotherapies for addiction has been largely neglected by the pharmaceutical industry. With advances in our understanding of the underlying biology of addictions now opening the door for the development of novel pharmacotherapies, it could be time for a reassessment of involvement in this increasingly important therapeutic area. Here, we summarize the current approved and implemented pharmacotherapeutic approaches to the treatment of addiction, and then highlight the most promising areas for future drug development from the perspective of our laboratory and our National Institutes of Health (NIH) National Institute on Drug Abuse (NIDA) Research Center.

History and current status of opioid maintenance treatments: blending conference session

Opiate addiction is a chronic, relapsing disorder. Left untreated, high morbidity and mortality rates are seen. Pharmacotherapies for this disorder using mu opiate agonists (methadone and levomethadyl acetate) and partial agonists have been developed in the last 40 years. Agonist pharmacotherapy with oral methadone for the treatment of opiate dependence was developed in clinical pharmacology studies at Rockefeller University by Dole, Nyswander, and Kreek. Further studies by this laboratory and others established that moderate to high dose treatment with methadone (80-120 mg) reduced or eliminated opiate use in outpatient settings with consequent reductions in morbidity and up to 4-fold reductions in mortality. Levomethadyl acetate (LAAM), a congener of methadone, is biotransformed to active metabolites responsible for its longer duration of action. The Federal Regulations regarding the dispensation of methadone and LAAM have recently been revised to facilitate the treatment of patients under a "medical maintenance" model. Future regulatory reform will likely involve the establishment of rules for "office based opioid treatment."

Effects of mu-opioid agonists on cocaine- and food-maintained responding and cocaine discrimination in rhesus monkeys: role of mu-agonist efficacy

Mu-opioid agonists decrease cocaine self-administration in laboratory studies and cocaine use by many cocaine- and opioid-dependent polydrug abusers. To assess the role of mu-agonist efficacy as a determinant of these effects, this study evaluated cocaine- and food-maintained responding by rhesus monkeys (Macaca mulatta) during chronic treatment with saline or the high-efficacy mu-agonist fentanyl (0.001-0.01 mg/kg/h), the intermediate-efficacy mu-agonist morphine (0.032-0.32 mg/kg/h), or the low-efficacy mu-agonists nalbuphine (0.1-1.0 mg/kg/h) and butorphanol (0.0032-0.032 mg/kg/h). Responding was maintained by cocaine and food under a second order schedule of reinforcement during multiple daily sessions of cocaine and food availability. Saline and each opioid dose were administered continuously for 7 consecutive days during availability of each cocaine dose. All four mu-agonists produced dose-dependent and sustained decreases in cocaine self-administration across a range of cocaine doses (0.0032-0.1 mg/kg/injection). Nalbuphine and butorphanol produced the greatest decreases in cocaine self-administration and the smallest effects on food-maintained responding. Morphine and fentanyl produced smaller decreases in cocaine self-administration, and undesirable effects precluded evaluation of higher fentanyl and morphine doses. Decreases in cocaine self-administration produced by nalbuphine and butorphanol probably did not reflect a general blockade of cocaine's abuse-related effects, because nalbuphine and butorphanol did not block the discriminative stimulus effects of cocaine in monkeys trained to discriminate 0.4 mg/kg cocaine from saline in a food-reinforced drug discrimination procedure. These results suggest that low-efficacy mu-agonists may decrease cocaine self-administration to a greater degree and with fewer undesirable effects than high-efficacy mu-agonists.

Treating cocaine-using methadone patients: predictors of outcomes in a psychosocial clinical trial

Cocaine-using methadone patients in two clinics were assigned to 8 months of enhanced methadone treatment-primarily cognitive-behavioral therapy (CBT) for cocaine use-while similar patients in two "sibling" clinics were assigned to standard methadone treatment during 1995-1998. Cocaine use declined significantly from baseline to 4- and 12-month follow-ups. Patients receiving CBT rated the quality of their counseling relationship higher and obtained more supportive services than those receiving standard treatment. However, study treatment condition itself was not associated with outcome. Baseline measures associated with poorer outcomes across both treatment conditions were: currently enrolled in methadone treatment (in contrast to being newly enrolled), higher cocaine use frequency, greater cocaine use associated problem recognition, and an ambivalent attitude toward methadone. The results are consistent with some previous clinical trials showing that psychosocial treatments of different intensities result in similar declines in cocaine use. The findings indicate that methadone maintenance treatment can help dually-addicted patients reduce their cocaine use.