Disulfiram effects on responses to intravenous cocaine administration

Disulfiram for the treatment of cocaine dependence

BACKGROUND

Cocaine is a psychostimulant used by approximately 0.4% of the general population worldwide. Cocaine dependence is a chronic mental disorder characterised by the inability to control cocaine use and a host of severe medical and psychosocial complications. There is current no approved pharmacological treatment for cocaine dependence. Some researchers have proposed disulfiram, a medication approved to treat alcohol use disorder. This is an update of a Cochrane review first published in 2010.

OBJECTIVES

To evaluate the efficacy and safety of disulfiram for the treatment of cocaine dependence.

SEARCH METHODS

We updated our searches of the following databases to August 2022: the Cochrane Drugs and Alcohol Group Specialised Register, CENTRAL, MEDLINE, Embase, CINAHL, and PsycINFO. We also searched for ongoing and unpublished studies via two trials registries. We handsearched the references of topic-related systematic reviews and included studies. The searches had no language restrictions.

SELECTION CRITERIA

We included randomised controlled trials that evaluated disulfiram alone or associated with psychosocial interventions versus placebo, no intervention, other pharmacological interventions, or any psychosocial intervention for the treatment of cocaine dependence.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane.

MAIN RESULTS

Thirteen studies (1191 participants) met our inclusion criteria. Disulfiram versus placebo or no treatment Disulfiram compared to placebo may increase the number of people who are abstinent at the end of treatment (point abstinence; risk ratio (RR) 1.58, 95% confidence interval (CI) 1.05 to 2.36; 3 datasets, 142 participants; low-certainty evidence). However, compared to placebo or no pharmacological treatment, disulfiram may have little or no effect on frequency of cocaine use (standardised mean difference (SMD) -0.11 standard deviations (SDs), 95% CI -0.39 to 0.17; 13 datasets, 818 participants), amount of cocaine use (SMD -0.00 SDs, 95% CI -0.30 to 0.30; 7 datasets, 376 participants), continuous abstinence (RR 1.23, 95% CI 0.80 to 1.91; 6 datasets, 386 participants), and dropout for any reason (RR 1.20, 95% CI 0.92 to 1.55; 14 datasets, 841 participants). The certainty of the evidence was low for all these outcomes. We are unsure about the effects of disulfiram versus placebo on dropout due to adverse events (RR 12.97, 95% CI 0.77 to 218.37; 1 study, 67 participants) and on the occurrence of adverse events (RR 3.00, 95% CI 0.35 to 25.98), because the certainty of the evidence was very low for these outcomes. Disulfiram versus naltrexone Disulfiram compared with naltrexone may reduce the frequency of cocaine use (mean difference (MD) -1.90 days, 95% CI -3.37 to -0.43; 2 datasets, 123 participants; low-certainty evidence) and may have little or no effect on amount of cocaine use (SMD 0.12 SDs, 95% CI -0.27 to 0.51, 2 datasets, 123 participants; low-certainty evidence). We are unsure about the effect of disulfiram versus naltrexone on dropout for any reason (RR 0.86, 95% CI 0.56 to 1.32, 3 datasets, 131 participants) and dropout due to adverse events (RR 0.50, 95% CI 0.07 to 3.55; 1 dataset, 8 participants), because the certainty of the evidence was very low for these outcomes.

AUTHORS' CONCLUSIONS

Our results show that disulfiram compared to placebo may increase point abstinence. However, disulfiram compared to placebo or no pharmacological treatment may have little or no effect on frequency of cocaine use, amount of cocaine use, continued abstinence, and dropout for any reason. We are unsure if disulfiram has any adverse effects in this population. Caution is required when transferring our results to clinical practice.

Disulfiram: Mechanisms, Applications, and Challenges

Background: Since disulfiram’s discovery in the 1940s and its FDA approval for alcohol use disorder, other indications have been investigated. This review describes potential clinical applications, associated risks, and challenges. Methods: For this narrative review, a PubMed search was conducted for articles addressing in vivo studies of disulfiram with an emphasis on drug repurposing for the treatment of human diseases. The key search terms were “disulfiram” and “Antabuse”. Animal studies and in vitro studies highlighting important mechanisms and safety issues were also included. Results: In total, 196 sources addressing our research focus spanning 1948–2022 were selected for inclusion. In addition to alcohol use disorder, emerging data support a potential role for disulfiram in the treatment of other addictions (e.g., cocaine), infections (e.g., bacteria such as Staphylococcus aureus and Borrelia burgdorferi, viruses, parasites), inflammatory conditions, neurological diseases, and cancers. The side effects range from minor to life-threatening, with lower doses conveying less risk. Caution in human use is needed due to the considerable inter-subject variability in disulfiram pharmacokinetics. Conclusions: While disulfiram has promise as a “repurposed” agent in human disease, its risk profile is of concern. Animal studies and well-controlled clinical trials are needed to assess its safety and efficacy for non-alcohol-related indications.

A mechanistic overview of approaches for the treatment of psychostimulant dependence

Psychostimulant use disorder is a major health issue around the world with enormous individual, family-related and societal consequences, yet there are no effective pharmacological treatments available. In this review, a target-based overview of pharmacological treatments toward psychostimulant addiction will be presented. We will go through therapeutic approaches targeting different aspects of psychostimulant addiction with focus on three major areas; 1) drugs targeting signalling, and metabolism of the dopamine system, 2) drugs targeting either AMPA receptors or metabotropic glutamate receptors of the glutamate system and 3) drugs targeting the severe side-effects of quitting long-term psychostimulant use. For each of these major modes of intervention, findings from pre-clinical studies in rodents to clinical trials in humans will be listed, and future perspectives of the different treatment strategies as well as their potential side-effects will be discussed. Pharmaceuticals modulating the dopamine system, such as antipsychotics, DAT-inhibitors, and disulfiram, have shown some promising results. Cognitive enhancers have been found to increase aspects of behavioural control, and drugs targeting the glutamate system such as modulators of metabotropic glutamate receptors and AMPA receptors have provided interesting changes in relapse behaviour. Furthermore, CRF-antagonists directed toward alleviating the symptoms of the withdrawal stage have been examined with interesting resulting changes in behaviour. There are promising results investigating therapeutics for psychostimulant addiction, but further preclinical work and additional human studies with a more stratified patient selection are needed to prove sufficient evidence of efficacy and tolerability.

Pharmacogenetics of Addiction Therapy

Drug addiction is a serious relapsing disease that has high costs to society and to the individual addicts. Treatment of these addictions is still in its nascency, with only a few examples of successful therapies. Therapeutic response depends upon genetic, biological, social, and environmental components. A role for genetic makeup in the response to treatment has been shown for several addiction pharmacotherapies with response to treatment based on individual genetic makeup. In this chapter, we will discuss the role of genetics in pharmacotherapies, specifically for cocaine, alcohol, and opioid dependences. The continued elucidation of the role of genetics should aid in the development of new treatments and increase the efficacy of existing treatments.

Advantages and disadvantages of disulfiram coadministered with popular addictive substances

Disulfiram (DSF) is a well-known anti-alcohol agent that inhibits aldehyde dehydrogenase and results in extreme 'hangover' symptoms when consumed with alcohol. This drug, however, has been suggested as useful in other forms of drug addiction due to its beneficial potential in both drug abuse reduction and withdrawal. However, among other drugs used in alcohol dependence, it carries the greatest risk of pharmacological interactions. Concomitant use of DSF and central nervous system stimulants usually leads to harmful, undesirable effects. To date, there is still limited data regarding the detailed safety profile of DSF as a concomitant drug. In this review article, we outline the current state of knowledge about DSF, its broad pharmacological action, as well as therapeutic effects, with a particular emphasis on the molecular understanding of its potential pharmacodynamic interactions with common addictive substances (e.g., alcohol, cocaine, cannabinoids, opioids) supported by relevant examples.

Adverse pharmacokinetic interactions between illicit substances and clinical drugs

Adverse pharmacokinetic interactions between illicit substances and clinical drugs are of a significant health concern. Illicit substances are taken by healthy individuals as well as by patients with medical conditions such as mental illnesses, acquired immunodeficiency syndrome, diabetes mellitus and cancer. Many individuals that use illicit substances simultaneously take clinical drugs meant for targeted treatment. This concomitant usage can lead to life-threatening pharmacokinetic interactions between illicit substances and clinical drugs. Optimal levels and activity of drug-metabolizing enzymes and drug-transporters are crucial for metabolism and disposition of illicit substances as well as clinical drugs. However, both illicit substances and clinical drugs can induce changes in the expression and/or activity of drug-metabolizing enzymes and drug-transporters. Consequently, with concomitant usage, illicit substances can adversely influence the therapeutic outcome of coadministered clinical drugs. Likewise, clinical drugs can adversely affect the response of coadministered illicit substances. While the interactions between illicit substances and clinical drugs pose a tremendous health and financial burden, they lack a similar level of attention as drug-drug, food-drug, supplement-drug, herb-drug, disease-drug, or other substance-drug interactions such as alcohol-drug and tobacco-drug interactions. This review highlights the clinical pharmacokinetic interactions between clinical drugs and commonly used illicit substances such as cannabis, cocaine and 3, 4-Methylenedioxymethamphetamine (MDMA). Rigorous efforts are warranted to further understand the underlying mechanisms responsible for these clinical pharmacokinetic interactions. It is also critical to extend the awareness of the life-threatening adverse interactions to both health care professionals and patients.

Functional neural changes following behavioral therapies and disulfiram for cocaine dependence

A growing literature exists on neural correlates of treatment outcome. However, different types-or components of-treatment have distinct theorized mechanisms of action. And it is not yet known how changes in neural activity across treatment relate to engagement in different treatment components. Participants with cocaine use disorders in a randomized clinical trial received cognitive-behavioral therapy (CBT) plus, in a 2 × 2 design, contingency management (CM) or no CM, and disulfiram or placebo. Participants performed a functional MRI Stroop task, a measure of cognitive control, at the beginning of and after the 12-week treatment. Analyses assessed changes in Stroop-related neural activity within the sample overall and assessed how changes in Stroop-related activity correlated with measures of treatment process specific to each form of treatment (i.e., participation in CBT sessions, receipt of CM prizes, administration of disulfiram pills). Within the sample overall, compared with beginning of treatment, posttreatment Stroop-related neural activity was diminished in the hippocampus, thalamus, cingulate, precentral, post- and precentral gyrus, and precuneus and culmen regions (pFWE < .05). In separate whole-brain correlation analyses, greater reductions in Stroop-related activity were associated with more treatment engagement-"CBT sessions" with the precentral gyrus, inferior parietal lobule, and middle and medial frontal gyrus; "CM prizes" with the postcentral frontal gyrus. Disulfiram "medication days" were not associated with changes in Stroop-related activity. Findings suggest that key process indicators of CBT and CM may be associated with functional changes in cognitive-control-related neurocircuitry. (PsycINFO Database Record

Treatment-refractory substance use disorder: Focus on alcohol, opioids, and cocaine

Substance use disorders are common, but only a small minority of patients receive adequate treatment. Although psychosocial therapies are effective, relapse is common. This review focusses on novel pharmacological and other treatments for patients with alcohol, opioid, or cocaine use disorders who do not respond to conventional treatments. Disulfiram, acamprosate, and the opioid antagonist naltrexone have been approved for the treatment of alcoholism. A novel, "as needed" approach is the use of the mu-opioid antagonist and partial kappa agonist nalmefene to reduce alcohol consumption. Other novel pharmacological approaches include the GABA-B receptor agonist baclofen, anticonvulsants such as topiramate and gabapentin, the partial nicotine receptor agonist varenicline, and other drugs. For opioid dependence, opioid agonist therapy with methadone or buprenorphine is the first-line treatment option. Other options include oral or depot naltrexone, morphine sulfate, depot or implant formulations, and heroin (diacetylmorphine) in treatment-refractory patients. To date, no pharmacological treatment has been approved for cocaine addiction; however, 3 potential pharmacological treatments are being studied, disulfiram, methylphenidate, and modafinil. Pharmacogenetic approaches may help to optimize treatment response in otherwise treatment-refractory patients and to identify which patients are more likely to respond to treatment, and neuromodulation techniques such as repeated transcranial magnetic stimulation and deep brain stimulation also may play a role in the treatment of substance use disorders. Although no magic bullet is in sight for treatment-refractory patients, some novel medications and brain stimulation techniques have the potential to enrich treatment options at least for some patients.

Are Alcohol Anti-relapsing and Alcohol Withdrawal Drugs Useful in Cannabinoid Users?

Cannabinoids are still classified as illegal psychoactive drugs despite their broad and increasingly acknowledged therapeutic potential. These substances are most famous for their wide recreational use, particularly among young adults to either alter the state of consciousness, intensify pleasure induced by other psychoactive substances or as an alternative to the previously abused drugs. It is important to emphasize that cannabinoids are often taken together with a variety of medications intended for the treatment of alcohol use disorder (AUD) or alcohol withdrawal syndrome (AWS). These medications include disulfiram, acamprosate, and naltrexone. In this paper, we summarize recent advances in the knowledge of possible beneficial effects and interactions between cannabinoids and drugs commonly used for treatment of AUD and AWS either comorbid or existing as a separate disorder.

A randomized factorial trial of disulfiram and contingency management to enhance cognitive behavioral therapy for cocaine dependence

BACKGROUND

This study evaluated the extent to which the addition of disulfiram and contingency management for adherence and abstinence (CM), alone and in combination, might enhance the effects of cognitive behavioral therapy (CBT) for cocaine use disorders.

METHODS

Factorial randomized double blind (for medication condition) clinical trial where CBT served as the platform and was delivered in weekly individual sessions in a community-based outpatient clinic. 99 outpatients who met DSM-IV criteria for current cocaine dependence were assigned to receive either disulfiram or placebo, and either CM or no CM. Cocaine and other substance use was assessed via a daily calendar with thrice weekly urine sample testing for 12 weeks with a one-year follow-up (80% interviewed at one year).

RESULTS

The primary hypothesis that CM and disulfiram would produce the best cocaine outcomes was not confirmed, nor was there a main effect for disulfiram. For the primary outcome (percent days of abstinence, self report), there was a significant interaction, with the best cocaine outcomes were seen for the combination of CM and placebo, with the two groups assigned to disulfiram associated with intermediate outcomes, and poorest cocaine outcome among those assigned to placebo and no CM. The secondary outcome (urinalysis) indicated a significant effect favoring CM over no CM but the interaction effect was not significant. One year follow-up data indicated sustained treatment effects across conditions.

CONCLUSIONS

CM enhances outcomes for CBT treatment of cocaine dependence, but disulfiram provided no added benefit to the combination of CM and CBT.

Selective inhibition of dopamine-beta-hydroxylase enhances dopamine release from noradrenergic terminals in the medial prefrontal cortex

INTRODUCTION

Disulfiram has been claimed to be useful in cocaine addiction therapy, its efficacy being attributed to dopamine-beta-hydroxylase (DBH) inhibition. Our previous results indicate that disulfiram and the selective DBH inhibitor nepicastat increase extracellular dopamine (DA) in the rat medial prefrontal cortex (mPFC), and markedly potentiated cocaine-induced increase. Concomitantly, in rats with cocaine self-administration history, cocaine-seeking behavior induced by drug priming was prevented, probably through overstimulation of D1 receptors due to the DA increase. The present research was aimed at studying the neurochemical mechanisms originating the enhanced DA release.

METHODS

Noradrenergic system ablation was attained by intracerebroventricular (i.c.v.) administration of the neurotoxin anti-DBH-saporin (aDBH-sap). DA, noradrenaline (NA), and DOPAC were assessed by HPLC after ex vivo tissue extraction or in vivo microdialysis. Control and denervated rats were subjected to microdialysis in the mPFC and caudate nucleus to evaluate the effect of nepicastat-cocaine combination on extracellular DA levels and their regulation by α2-adrenoceptors.

RESULTS

Fifteen days after neurotoxin or its vehicle administration, tissue and extracellular NA were reduced to less than 2% the control value, while extracellular DA was increased by approximately 100%. In control rats, nepicastat given alone and in combination with cocaine increased extracellular DA by about 250% and 1100%, respectively. In denervated rats, nepicastat slightly affected extracellular DA, while in combination with cocaine increased extracellular DA by 250%. No differences were found in the caudate nucleus. Clonidine almost totally reversed the extracellular DA elevation produced by nepicastat-cocaine combination, while it was ineffective in denervated rats.

CONCLUSIONS

This research shows that the increase of extracellular DA produced by nepicastat alone or in combination with cocaine was prevented by noradrenergic denervation. The results indicate that nepicastat enhances DA release from noradrenergic terminals supposedly by removing NA from α2-autoreceptors. In addition to the inhibition of DA uptake, the latter mechanism may explain the synergistic effect of cocaine on nepicastat-induced DA release.

Serotonergic gene variation in substance use pharmacotherapy: a systematic review

Drug addiction is a serious disease with damaging effects on the brain and physical health. Despite the increase in the number of affected individuals, there are few effective pharmacological treatment options for substance use disorders. The study of the influence of an individual's genetic features on the treatment response may help to identify more efficacious treatment options. This systematic review focuses on the serotonergic system because of its relevant role in mood and impulse control disorders, and its contribution to the development and maintenance of drug use disorders. In particular, we examine the role of serotonergic genes in the response to pharmacotherapy for alcohol, cocaine and nicotine addiction. Current evidence suggests that genetic variability of the serotonergic biosynthesis enzyme tryptophan hydroxylase 2 (TPH2) and the serotonin transporter (SLC6A4) genes mediates the efficacy of several addiction treatments, such as ondansetron and disulfiram, and the antidepressants bupropion, nortriptyline and sertraline.

Evaluation of the dopamine β-hydroxylase (DβH) inhibitor nepicastat in participants who meet criteria for cocaine use disorder

In the present study, we tested the hypothesis that the potent and selective dopamine-β-hydroxylase (DβH) inhibitor nepicastat would have minimal effects on cardiovascular and pharmacokinetic parameters associated with cocaine administration and would reduce the positive subjective effects produced by cocaine. We conducted a double-blind, placebo-controlled, inpatient study of oral nepicastat (0, 80 and 160mg) concurrent with intravenous (IV) cocaine (0, 10, 20 and 40mg) in non-treatment seeking participants who metcriteria for cocaine use disorder. Safety analyses revealed that nepicastat was well-tolerated and there were no differences in adverse events observed after nepicastat plus cocaine vs. cocaine alone. In addition, the pharmacokinetic properties of cocaine administration were not altered by nepicastat treatment. Cocaine-induced cardiovascular and subjective effects were evaluated for completers in the cohort randomized to nepicastat (n=13) using a within-subjects statistical analysis strategy. Specifically, the cardiovascular and subjective effects of cocaine were assessed in the presence of placebo (0mg), 80mg of nepicastat or 160mg of nepicastat on study Days 4, 8 and 12, respectively. Analyses revealed a main effect of nepicastat to reduce several cocaine-induced positive subjective effects. Taken together, these data indicate that nepicastat is safe when co-administered with cocaine and may suppress its positive subjective effects, and may be viable as a pharmacotherapy for treatment of cocaine use disorder.

Effects of disulfiram on QTc interval in non-opioid-dependent and methadone-treated cocaine-dependent patients

OBJECTIVES

Methadone and cocaine are each known to prolong the QTc interval, a risk factor for developing potentially fatal cardiac arrhythmias. Disulfiram, often administered in the context of methadone maintenance to facilitate alcohol abstinence, has been shown to have some efficacy for cocaine dependence. Disulfiram has differential effects on cocaine and methadone metabolism, but its impact on methadone- or cocaine-induced changes in QTc interval is unclear. Thus, the effects of disulfiram on QTc interval in a subset of cocaine-dependent patients participating in a 14-week, randomized, double-blind, placebo-controlled clinical trial of disulfiram were prospectively determined.

METHODS

Opioid-dependent participants were inducted onto methadone (weeks 1-2; MT) and both MT and non-opioid-dependent (UT) participants were randomized to receive disulfiram (weeks 3-14) at one of the following doses: 0, 250, 375, or 500 mg/d. Electrocardio-grams were obtained before study entry and during weeks 2 and 4.

RESULTS

Complete QTc-interval data in 23 MT and 18 UT participants were analyzed. QTc interval tended to be higher in MT participants relative to UT participants, regardless of disulfiram dose and time point, but disulfiram did not differentially alter QTc interval. QTc interval was, however, significantly greater in participants with recent cocaine use than in those with no recent use.

CONCLUSIONS

These results suggest that cocaine use and possibly MT status, but not disulfiram, are risk factors for QTc prolongation.

Randomized clinical trial of disulfiram for cocaine dependence or abuse during buprenorphine treatment

BACKGROUND

Disulfiram may be efficacious for treating cocaine dependence or abuse, possibly through inhibiting dopamine β-hydroxylase (DβH). Consequently, this randomized, placebo-controlled clinical trial of disulfiram during buprenorphine maintenance treatment evaluated the study hypothesis that disulfiram is superior to placebo and explored whether disulfiram response is greatest for participants with a single nucleotide polymorphism coding for genetically low DβH (T-allele carriers).

METHODS

We randomized 177 buprenorphine-treated opioid dependent participants with cocaine dependence or abuse to 12 weeks of double-blind treatment with disulfiram 250mg daily (n=91) or placebo (n=86). Of 155 participants genotyped, 84 were CC-homozygous, and 71 CT or TT genotypes. Primary outcomes included days per week cocaine use, number of cocaine-negative urine tests, and maximum consecutive weeks of cocaine abstinence. We analyzed an intention-to-treat comparison between disulfiram and placebo. We also explored potential pharmacogenetic interactions and examined treatment responses of four participant groups based on medication (disulfiram or placebo) by genotype (CC-homozygous or T-allele carrier) classification.

RESULTS

Disulfiram participants reported significantly less frequent cocaine use; the differences in cocaine-negative urine tests or consecutive weeks abstinence were not significant. Frequency of cocaine use was lowest in disulfiram-treated T-allele carriers; differences in cocaine-negative urine tests or consecutive weeks abstinence were not significant among the four medication-genotype groups.

CONCLUSIONS

The findings provide limited support for the efficacy of disulfiram for reducing cocaine use and suggest that its mechanism of action may involve inhibition of DβH. Further studies of its efficacy, mechanism of action, and pharmacogenetics of response are warranted.

Pharmacogenetics of addiction therapy

Drug addiction is a serious relapsing disease that has high costs to society and to the individual addicts. Treatment of these addictions is still in its nascency, with only a few examples of successful therapies. Therapeutic response depends upon genetic, biological, social, and environmental components. A role for genetic makeup in the response to treatment has been shown for several addiction pharmacotherapies. For several addiction pharmacotherapies, response to treatment varies based on individual genetic makeup. In this chapter, we discuss the role of genetics in pharmacotherapies, specifically for cocaine, alcohol, and opioid dependences. The elucidation of the role of genetics should aid in the development of new treatments and increase the efficacy of existing treatments.

Pharmacogenetic randomized trial for cocaine abuse: disulfiram and α1A-adrenoceptor gene variation

Disulfiram is a cocaine addiction pharmacotherapy that inhibits dopamine β-hydroxylase (DβH) and reduces norepinephrine production. We examined whether a functional variant of the ADRA1A gene (Cys to Arg at codon 347 in exon 2, Cys347Arg) may enhance treatment response through decreased stimulation of this α1A-adrenoceptor, since antagonists of this receptor show promise in reducing cocaine use. Sixty-nine cocaine and opioid co-dependent (DSM-IV) subjects were stabilized on methadone for two weeks and subsequently randomized into disulfiram (250 mg/day, N=32) and placebo groups (N=37) for 10 weeks. We genotyped the ADRA1A gene polymorphism (rs1048101) and evaluated its role for increasing cocaine free urines in those subjects treated with disulfiram using repeated measures analysis of variance, corrected for population structure. The 47 patients who carried at least one T allele of rs1048101 (TT or TC genotype) reduced their cocaine positive urines from 84% to 56% on disulfiram (p=0.0001), while the 22 patients with the major allele CC genotype showed no disulfiram effect. This study indicates that a patient's ADRA1A genotype could be used to identify a subset of individuals for which disulfiram and, perhaps, other α1-adrenoceptor blockers may be an effective pharmacotherapy for cocaine dependence.

Interaction of disulfiram with antiretroviral medications: efavirenz increases while atazanavir decreases disulfiram effect on enzymes of alcohol metabolism

BACKGROUND AND OBJECTIVES

Alcohol abuse complicates treatment of HIV disease and is linked to poor outcomes. Alcohol pharmacotherapies, including disulfiram (DIS), are infrequently utilized in co-occurring HIV and alcohol use disorders possibly related to concerns about drug interactions between antiretroviral (ARV) medications and DIS.

METHOD

This pharmacokinetics study (n=40) examined the effect of DIS on efavirenz (EFV), ritonavir (RTV), or atazanavir (ATV) and the effect of these ARV medications on DIS metabolism and aldehyde dehydrogenase (ALDH) activity which mediates the DIS-alcohol reaction.

RESULTS

EFV administration was associated with decreased S-Methyl-N-N-diethylthiocarbamate (DIS carbamate), a metabolite of DIS (p=.001) and a precursor to the metabolite responsible for ALDH inhibition, S-methyl-N,N-diethylthiolcarbamate sulfoxide (DETC-MeSO). EFV was associated with increased DIS inhibition of ALDH activity relative to DIS alone administration possibly as a result of EFV-associated induction of CYP 3A4 which metabolizes the carbamate to DETC-MeSO (which inhibits ALDH). Conversely, ATV co-administration reduced the effect of DIS on ALDH activity possibly as a result of ATV inhibition of CYP 3A4. DIS administration had no significant effect on any ARV studied.

DISCUSSION/CONCLUSIONS

ATV may render DIS ineffective in treatment of alcoholism.

FUTURE DIRECTIONS

DIS is infrequently utilized in HIV-infected individuals due to concerns about adverse interactions and side effects. Findings from this study indicate that, with ongoing clinical monitoring, DIS should be reconsidered given its potential efficacy for alcohol and potentially, cocaine use disorders, that may occur in this population.

Dopamine β-hydroxylase inhibitors enhance the discriminative stimulus effects of cocaine in rats

Inhibitors of dopamine β-hydroxylase (DBH), the enzyme that converts dopamine (DA) to norepinephrine (NE) in noradrenergic cells, have shown promise for the treatment of cocaine abuse disorders. However, the mechanisms underlying the beneficial effects of these compounds have not been fully elucidated. We used the drug discrimination paradigm to determine the impact of DBH inhibitors on the interoceptive stimulus properties of cocaine. Sprague-Dawley rats were trained to discriminate cocaine (5.6 mg/kg) from saline using a multicomponent, food-reinforced discrimination procedure. On test days, subjects were pretreated with the nonselective DBH inhibitor disulfiram (0-100.0 mg/kg i.p.) or the selective DBH inhibitor nepicastat (0-56.0 mg/kg i.p.) 2 hours prior to a test session either alone or in combination with cumulatively administered cocaine (0-5.6 mg/kg i.p.). Neither disulfiram nor nepicastat substituted for the cocaine stimulus when tested up to doses that nonspecifically reduced responding. However, in combination studies, pretreatment with either disulfiram or nepicastat produced leftward shifts in the cocaine dose-response function and also conferred cocaine-like stimulus effects to the selective NE transporter inhibitor, reboxetine (0.3-5.6 mg/kg i.p.). These results indicate that pharmacological inhibition of DBH does not produce cocaine-like interoceptive stimulus effects alone, but functionally enhances the interoceptive stimulus effects of cocaine, possibly due to facilitated increases in DA released from noradrenergic terminals. These findings suggest that DBH inhibitors have low abuse liability and provide support to clinical reports that some subjective effects produced by cocaine, particularly aversive effects, are enhanced after DBH inhibition.

DBH gene as predictor of response in a cocaine vaccine clinical trial

We examined a pharmacogenetic association of the dopamine β-hydroxylase (DBH) gene with a response to an anti-cocaine vaccine that was tested in a recent clinical trial. This gene is associated with cocaine-induced paranoia, which has a slower onset than the euphoria from cocaine. The vaccine reduced euphoria by slowing the entry of cocaine into the brain, but it may not reduce aversive symptoms like paranoia. A 16-week Phase IIb randomized double-blind placebo-controlled trial of 114 cocaine and opioid dependent subjects who received five vaccinations over the first 12 weeks was examined. We genotyped 71 subjects for the rs1611115 (-1021C>T) variant of the DBH gene and compared vaccine to placebo subjects on cocaine-free urines. Using repeated measures analysis of variance, corrected for population structure, vaccine pharmacotherapy reduced cocaine positive urines significantly based on DBH genotype. Patients with the low DβH level genotype dropped from 77% to 51% on vaccine (p=0.0001), while those with the normal DβH level genotype dropped from 83% to 72%. Placebo showed no effect on cocaine use overall or by genotype. This study indicates that a patient's DBH genotype could be used to identify a subset of individuals for whom vaccine treatment may be an effective pharmacotherapy for cocaine dependence.

Pharmacogenetic randomized trial for cocaine abuse: disulfiram and dopamine β-hydroxylase

BACKGROUND

Disulfiram has been an effective cocaine addiction pharmacotherapy, and one of its possible mechanisms of efficacy is through copper chelation and inhibition of an enzyme involved in catecholamine metabolism, dopamine β-hydroxylase (DβH), which converts dopamine to norepinephrine. A variant in the gene encoding DβH leads to reduced DβH activity, and as such, disulfiram might not be an effective treatment of cocaine dependence for individuals with this variant. This study explored that potential matching.

METHODS

Seventy-four cocaine- and opioid-codependent (DSM-V) subjects were stabilized on methadone for 2 weeks and subsequently randomized into disulfiram (250 mg/day, n = 34) and placebo groups (n = 40) for 10 weeks. We genotyped the DBH gene polymorphism, -1021C/T (rs1611115), that reduces DβH enzyme levels and evaluated its role for increasing cocaine free urines with disulfiram.

RESULTS

With repeated measures analysis of variance, corrected for population structure, disulfiram pharmacotherapy reduced cocaine-positive urines from 80% to 62% (p = .0001), and this disulfiram efficacy differed by DBH genotype group. Patients with the normal DβH level genotype dropped from 84% to 56% on disulfiram (p = .0001), whereas those with the low DBH level genotype showed no disulfiram effect.

CONCLUSIONS

This study indicates that the DBH genotype of a patient could be used to identify a subset of individuals for which disulfiram treatment might be an effective pharmacotherapy for cocaine dependence.

Chronic inhibition of dopamine β-hydroxylase facilitates behavioral responses to cocaine in mice

The anti-alcoholism medication, disulfiram (Antabuse), decreases cocaine use in humans regardless of concurrent alcohol consumption and facilitates cocaine sensitization in rats, but the functional targets are unknown. Disulfiram inhibits dopamine β-hydroxylase (DBH), the enzyme that converts dopamine (DA) to norepinephrine (NE) in noradrenergic neurons. The goal of this study was to test the effects of chronic genetic or pharmacological DBH inhibition on behavioral responses to cocaine using DBH knockout (Dbh −/−) mice, disulfiram, and the selective DBH inhibitor, nepicastat. Locomotor activity was measured in control (Dbh +/−) and Dbh −/− mice during a 5 day regimen of saline+saline, disulfiram+saline, nepicastat+saline, saline+cocaine, disulfiram+cocaine, or nepicastat+cocaine. After a 10 day withdrawal period, all groups were administered cocaine, and locomotor activity and stereotypy were measured. Drug-naïve Dbh −/− mice were hypersensitive to cocaine-induced locomotion and resembled cocaine-sensitized Dbh +/− mice. Chronic disulfiram administration facilitated cocaine-induced locomotion in some mice and induced stereotypy in others during the development of sensitization, while cocaine-induced stereotypy was evident in all nepicastat-treated mice. Cocaine-induced stereotypy was profoundly increased in the disulfiram+cocaine, nepicastat+cocaine, and nepicastat+saline groups upon cocaine challenge after withdrawal in Dbh +/− mice. Disulfiram or nepicastat treatment had no effect on behavioral responses to cocaine in Dbh −/− mice. These results demonstrate that chronic DBH inhibition facilitates behavioral responses to cocaine, although different methods of inhibition (genetic vs. non-selective inhibitor vs. selective inhibitor) enhance qualitatively different cocaine-induced behaviors.

The impact of disulfiram treatment on the reinforcing effects of cocaine: a randomized clinical trial

Background

Clinical trials indicate that disulfiram (250 mg/d) reduces cocaine use, though one study found that treatment with lower doses of disulfiram (62.5 and 125 mg/d) increased cocaine use. We conducted the present study to better understand how disulfiram alters the reinforcing effects of cocaine in cocaine users.

Methods

Seventeen non-treatment seeking, cocaine-dependent volunteers participated in this double-blind, placebo-controlled, laboratory-based study. A cross-over design was utilized in which participants received placebo in one phase and disulfiram (250 mg/d) in the other. Following three days of study medication participants completed two choice sessions. In one they made 10 choices between receiving an intravenous infusion of saline or money that increased in value (US$ 0.05–16) and in the other cocaine (20 mg) or money.

Results

Participants chose cocaine more than saline under both disulfiram and placebo conditions (p<0.05). Unexpectedly, disulfiram increased both the number of cocaine and saline infusion choices (p<0.05). We next examined the relationship between disulfiram dose and cocaine choices. Disulfiram dose (mg/kg bodyweight) was negatively correlated with number of choices for cocaine (p<0.05). Disulfiram also enhanced cocaine-induced increases in cardiovascular measures (p's<0.05–0.01).

Conclusions

Disulfiram's impact on the reinforcing effects of cocaine depends on dose relative to body weight. Our results suggest that the use of weight-based medication doses would produce more reliable effects, consistent with weight-based dosing used in pediatrics and in preclinical research.

Trial Registration

Clinicaltrials.gov NCT00729300

Efficacy of disulfiram and Twelve Step Facilitation in cocaine-dependent individuals maintained on methadone: a randomized placebo-controlled trial

BACKGROUND

Cocaine use remains a major problem within methadone maintenance programs. Disulfiram's efficacy in reducing cocaine use has been demonstrated in several trials, but its relative efficacy among individuals who use versus abstain from alcohol remains unclear. Treatment approaches which seek to enhance substance users' involvement in self-help activities (Twelve Step Facilitation, TSF) have been associated with better outcomes among alcohol and cocaine users, but have rarely been evaluated among methadone-maintained cocaine-opioid users.

METHODS

We conducted a randomized, placebo-controlled, double blind (for medication condition), factorial (2×2) trial with 4 treatment conditions: Disulfiram plus TSF, disulfiram plus standard counseling only, placebo plus TSF, and placebo plus standard counseling in the context of a community-based methadone maintenance program. Participants (N=112) received either disulfiram (250 mg/d) or placebo in conjunction with daily methadone maintenance.

RESULTS

Assignment to TSF was associated with less cocaine use throughout treatment and a higher number of cocaine-negative urines. While there were no significant main effects of disulfiram versus placebo, individuals without an alcohol use disorder demonstrated greater reductions in cocaine use over time when assigned to disulfiram.

CONCLUSIONS

TSF appears feasible in this methadone maintenance program and was associated with modest reductions in cocaine use, an often intractable problem in this setting. Support for the efficacy of disulfiram was weaker, as it appeared effective only for those without a current alcohol use disorder for this sample.

BAP updated guidelines: evidence-based guidelines for the pharmacological management of substance abuse, harmful use, addiction and comorbidity: recommendations from BAP

The British Association for Psychopharmacology guidelines for the treatment of substance abuse, harmful use, addiction and comorbidity with psychiatric disorders primarily focus on their pharmacological management. They are based explicitly on the available evidence and presented as recommendations to aid clinical decision making for practitioners alongside a detailed review of the evidence. A consensus meeting, involving experts in the treatment of these disorders, reviewed key areas and considered the strength of the evidence and clinical implications. The guidelines were drawn up after feedback from participants. The guidelines primarily cover the pharmacological management of withdrawal, short- and long-term substitution, maintenance of abstinence and prevention of complications, where appropriate, for substance abuse or harmful use or addiction as well management in pregnancy, comorbidity with psychiatric disorders and in younger and older people.

Disulfiram metabolite S-methyl-N,N-diethylthiocarbamate quantitation in human plasma with reverse phase ultra performance liquid chromatography and mass spectrometry

Disulfiram has been used extensively for alcohol abuse and may have a role in treatment for cocaine addiction. Recent data suggest that disulfiram may also reactivate latent HIV in reservoirs. Disulfiram has complex pharmacokinetics with rapid metabolism to active metabolites, including S-methyl-N,N-diethylthiocarbamate (DET-Me) which is formed from cytochrome P450 (CYP450). Assessing disulfiram in HIV-infected individuals with a CYP450 inducing drug (e.g., efavirenz) or a CYP450 inhibiting drug (e.g., HIV-1 protease inhibitors) requires an assay that can measure a metabolite that is formed directly via CYP450 oxidation. Therefore, an assay to measure concentrations of DET-Me in human plasma was validated. DET-Me and the internal standard, S-ethyldipropylthiocarbamate (EPTC) were separated by isocratic ultra performance liquid chromatography using a Waters Acquity HSS T3 column (2.1 mm × 100 mm, 1.8 μm) and detection via electrospray coupled to a triple quadrupole mass spectrometer. Multiple reaction monitoring in positive mode was used with DET-Me at 148/100 and the internal standard at 190/128 with a linear range of 0.500-50.0 ng/mL with a 5 min run time. Human plasma (500 μL) was extracted using a solid phase procedure. The interassay variation ranged from 1.86 to 7.74% while the intra assay variation ranged from 3.38 to 5.94% over three days. Representative results are provided from samples collected from subjects receiving daily doses of disulfiram 62.5mg or 250 mg.

Pharmacotherapeutics directed at deficiencies associated with cocaine dependence: focus on dopamine, norepinephrine and glutamate

Much effort has been devoted to research focused on pharmacotherapies for cocaine dependence yet there are no FDA-approved medications for this brain disease. Preclinical models have been essential to defining the central and peripheral effects produced by cocaine. Recent evidence suggests that cocaine exerts its reinforcing effects by acting on multiple neurotransmitter systems within mesocorticolimibic circuitry. Imaging studies in cocaine-dependent individuals have identified deficiencies in dopaminergic signaling primarily localized to corticolimbic areas. In addition to dysregulated striatal dopamine, norepinephrine and glutamate are also altered in cocaine dependence. In this review, we present these brain abnormalities as therapeutic targets for the treatment of cocaine dependence. We then survey promising medications that exert their therapeutic effects by presumably ameliorating these brain deficiencies. Correcting neurochemical deficits in cocaine-dependent individuals improves memory and impulse control, and reduces drug craving that may decrease cocaine use. We hypothesize that using medications aimed at reversing known neurochemical imbalances is likely to be more productive than current approaches. This view is also consistent with treatment paradigms used in neuropsychiatry and general medicine.

A double-blind, placebo-controlled assessment of the safety of potential interactions between intravenous cocaine, ethanol, and oral disulfiram

BACKGROUND

A majority of cocaine addicts have a comorbid alcohol use disorder. Previous studies demonstrated efficacy of disulfiram in the treatment of cocaine dependence among patients with comorbid alcohol use disorder or opioid dependence. However, the cardiac risks of a disulfiram-ethanol reaction (DER) in individuals who drink, when coupled with the cardiac effects of cocaine, could result in significant toxicity or lethality due to the 3-way drug interaction.

AIMS

This study examined the safety of combining cocaine (30 mg i.v.) and ethanol (0.4 g/kg i.v.) in disulfiram-treated (0, 250, and 500 mg/d, p.o.) cocaine-dependent research volunteers.

RESULTS

The results showed that disulfiram did not enhance the cardiovascular effects of cocaine and may have reduced the subjective high from cocaine. In contrast, ethanol produced adverse ECG changes including QTc prolongation and a DER consisting of hypotension, tachycardia, nausea, and flushing in disulfiram-treated subjects. The severity of the DER was related to disulfiram dose and the trial with 500 mg/d was stopped prematurely due to safety concerns. The DER-related hypotension and tachycardia seen with ethanol infusion alone in disulfiram-treated subjects, was not exacerbated when combined with cocaine. In fact, cocaine tended to counteract the ethanol-related hypotension though it did exacerbate the tachycardia in two of seven subjects.

CONCLUSIONS

Though conclusions are limited by the moderate doses of cocaine, ethanol, and disulfiram tested, the data do suggest that the risks of the moderate use of cocaine and ethanol in individuals treated with moderate doses of disulfiram (≤ 250 mg/d) may not be as problematic as some may assume.

Randomized, double blind, placebo-controlled trial of disulfiram for the treatment of cocaine dependence in methadone-stabilized patients

This study examined the dose-related efficacy of disulfiram for treating cocaine dependence in methadone-stabilized cocaine dependent participants.

DESIGN

One hundred and sixty-one cocaine- and opioid-dependent volunteers were entered into a 14-week, double blind, randomized, placebo-controlled clinical trial at two sites.

METHODS

Participants were stabilized on methadone during weeks 1-2 and received disulfiram at 0, 62.5, 125 or 250 mg/day during weeks 3-14. All participants also received weekly cognitive behavioral therapy. Thrice-weekly urine samples and weekly self-reported drug use assessments were obtained.

RESULTS

Baseline subject characteristics, retention and drug use did not differ across groups. Outcome analyses were performed on those who participated beyond week 2. Opioid-positive urine samples and self-reported opioid use did not differ by treatment group. The prevalence of alcohol use was low prior to and during the trial and did not differ by treatment group. Cocaine-positive urines increased over time in the 62.5 and 125 mg disulfiram groups and decreased over time in the 250 mg disulfiram and placebo groups (p < 0.0001). Self-reported cocaine use increased in the 125 mg disulfiram group relative to the other three treatment groups (p = 0.04).

CONCLUSIONS

Disulfiram may be contraindicated for cocaine dependence at doses <250 mg/day. Whether disulfiram at higher doses is efficacious in reducing cocaine use in dually cocaine and opioid dependent individuals needs to be determined.

Disulfiram attenuates drug-primed reinstatement of cocaine seeking via inhibition of dopamine β-hydroxylase

The antialcoholism medication disulfiram (Antabuse) inhibits aldehyde dehydrogenase (ALDH), which results in the accumulation of acetaldehyde upon ethanol ingestion and produces the aversive 'Antabuse reaction' that deters alcohol consumption. Disulfiram has also been shown to deter cocaine use, even in the absence of an interaction with alcohol, indicating the existence of an ALDH-independent therapeutic mechanism. We hypothesized that disulfiram's inhibition of dopamine β-hydroxylase (DBH), the catecholamine biosynthetic enzyme that converts dopamine (DA) to norepinephrine (NE) in noradrenergic neurons, underlies the drug's ability to treat cocaine dependence. We tested the effects of disulfiram on cocaine and food self-administration behavior and drug-primed reinstatement of cocaine seeking in rats. We then compared the effects of disulfiram with those of the selective DBH inhibitor, nepicastat. Disulfiram, at a dose (100 mg/kg, i.p.) that reduced brain NE by ∼40%, did not alter the response for food or cocaine on a fixed ratio 1 schedule, whereas it completely blocked cocaine-primed (10 mg/kg, i.p.) reinstatement of drug seeking following extinction. A lower dose of disulfiram (10 mg/kg) that did not reduce NE had no effect on cocaine-primed reinstatement. Nepicastat recapitulated the behavioral effects of disulfiram (100 mg/kg) at a dose (50 mg/kg, i.p.) that produced a similar reduction in brain NE. Food-primed reinstatement of food seeking was not impaired by DBH inhibition. Our results suggest that disulfiram's efficacy in the treatment of cocaine addiction is associated with the inhibition of DBH and interference with the ability of environmental stimuli to trigger relapse.

Topiramate in the treatment of substance-related disorders: a critical review of the literature

OBJECTIVE

To critically review the literature on topiramate in the treatment of substance-related disorders.

DATA SOURCES

A PubMed search of human studies published in English through January 2009 was conducted using the following search terms: topiramate and substance abuse, topiramate and substance dependence, topiramate and withdrawal, topiramate and alcohol, topiramate and nicotine, topiramate and cocaine, topiramate and opiates, and topiramate and benzodiazepines.

STUDY SELECTION

26 articles were identified and reviewed; these studies examined topiramate in disorders related to alcohol, nicotine, cocaine, methamphetamine, opioids, Ecstasy, and benzodiazepines.

DATA EXTRACTION

Study design, sample size, topiramate dose and duration, and study outcomes were reviewed.

DATA SYNTHESIS

There is compelling evidence for the efficacy of topiramate in the treatment of alcohol dependence. Two trials show trends for topiramate's superiority over oral naltrexone in alcohol dependence, while 1 trial suggests topiramate is inferior to disulfiram. Despite suggestive animal models, evidence for topiramate in treating alcohol withdrawal in humans is slim. Studies of topiramate in nicotine dependence show mixed results. Human laboratory studies that used acute topiramate dosing show that topiramate actually enhances the pleasurable effects of both nicotine and methamphetamine. Evidence for topiramate in the treatment of cocaine dependence is promising, but limited by small sample size. The data on opioids, benzodiazepines, and Ecstasy are sparse.

CONCLUSIONS

Topiramate is efficacious for the treatment of alcohol dependence, but side effects may limit widespread use. While topiramate's unique pharmacodynamic profile offers a promising theoretical rationale for use across multiple substance-related disorders, heterogeneity both across and within these disorders limits topiramate's broad applicability in treating substance-related disorders. Recommendations for future research include exploration of genetic variants for more targeted pharmacotherapies.

Donepezil treatment and the subjective effects of intravenous cocaine in dependent individuals

Acetylcholinesterase (AChE) inhibitors increase synaptic levels of acetylcholine (ACh) by inhibiting its breakdown. Donepezil is a reversible AChE inhibitor that is clinically available and relatively selective for inhibiting AChE but not other cholinesterases. Because AChE inhibitors have been shown to decrease the reinforcing effects of cocaine in animals, our hypothesis was that pretreatment with donepezil would attenuate the perceived value and other positive subjective effects of cocaine. We conducted a within-subject, double-blind, placebo-controlled, laboratory-based evaluation of the subjective effects produced by intravenous cocaine in human subjects receiving oral donepezil. Following three days of daily treatment with 5mg of donepezil or oral placebo, participants received intravenous placebo or cocaine (0.18 and 0.36 mg/kg). After a three-day washout period, participants were crossed over to the opposite oral treatment, which was followed by identical intravenous infusions. Donepezil was well-tolerated with only two drug-related adverse events reported that were mild and self-limiting. Treatment with donepezil increased ratings of 'any' and 'good' drug effect produced by low-dose cocaine, without modifying the response to high-dose cocaine. When collapsed across intravenous dose, treatment with donepezil decreased dysphoric effects and somatic symptoms, but did not modify the value of cocaine injections as determined by the Multiple Choice Questionnaire (MCQ). In summary, pretreatment with donepezil potentiated some measures for nonspecific and positive effects of low-dose cocaine. Across all intravenous treatments, participants receiving donepezil reported fewer somatic-dysphoric effects. Neither of these actions support the value of donepezil as a treatment for cocaine dependence.

Disulfiram for the treatment of cocaine dependence

BACKGROUND

Cocaine dependence is a disorder for which no pharmacological treatment of proven efficacy exists, advances in the neurobiology could guide future medication development.

OBJECTIVES

To evaluate the efficacy and the acceptability of disulfiram for cocaine dependence.

SEARCH STRATEGY

We searched: PubMed, EMBASE, CINAHL (up to January 2008), the Cochrane Central Register of Controlled Trials (CENTRAL-The Cochrane Library, 1, 2009), reference lists of trials, main electronic sources of ongoing trials, conference proceedings.

SELECTION CRITERIA

Randomised and controlled clinical trials comparing disulfiram alone or associated with psychosocial intervention with no intervention, placebo, or other pharmacological intervention for the treatment of cocaine dependence.

DATA COLLECTION AND ANALYSIS

Three reviewers independently assessed trial quality and extracted data.

MAIN RESULTS

Seven studies, 492 participants, met the inclusion criteriaDisulfiram versus placebo: no statistically significant results for dropouts but a trend favouring disulfiram, two studies, 87 participants, RR 0.82 (95% CI 0.66 to 1.03). One more study, 107 participants, favouring disulfiram, was excluded from meta-analysis due high heterogeneity, RR 0.34 (95% CI 0.20 to 0.58). For cocaine use, it was not possible to pool together primary studies, results from single studies showed that, one, out of four comparisons, was in favour of disulfiram (number of weeks abstinence, 20 participants, WMD 4.50 (95% CI 2.93 to 6.07).Disulfiram versus naltrexone: no statistically significant results for dropouts but a trend favouring disulfiram, three studies, 131 participants, RR 0.67 (95% CI 0.45 to 1.01). No significant difference for cocaine use was seen in the only study that considered this outcome.Disulfiram versus no pharmacological treatment: for cocaine use: a statistically significant difference in favour of disulfiram, one study, two comparisons, 90 participants: maximum weeks of consecutive abstinence, WMD 2.10 (95% CI 0.69 to 3.51); number of subjects achieving 3 or more weeks of consecutive abstinence, RR 1.88 (95% CI 1.09 to 3.23).

AUTHORS' CONCLUSIONS

There is low evidence, at the present, supporting the clinical use of disulfiram for the treatment of cocaine dependence. Larger randomised investigations are needed investigating relevant outcomes and reporting data to allow comparisons of results between studies. Results from ongoing studies will be added as soon as their results will be available.

Novel pharmacological approaches to drug abuse treatment

The field of pharmacologic addiction treatment is expanding rapidly. While there are currently several FDA-approved medications for nicotine, alcohol, and opiate dependence, research into novel pharmacological approaches for these and additional substances is legion. Each drug of abuse, while sharing a common final neural pathway of increasing dopaminergic tone, has unique and individual characteristics that are important in developing improved and varied treatments. In this chapter, we discuss such research and present the neurobiological underpinnings of these explorations. In general, addiction treatment is focused on four areas: (1) reducing withdrawal discomfort, (2) diminishing cravings, (3) blocking rewarding effects of the drug, and (4) treating comorbidities, such as depression or ADHD. We present current ideas in pharmacologic research for nicotine, alcohol, cannabis, stimulants, and opiates.

Pharmacogenetic treatments for drug addiction: cocaine, amphetamine and methamphetamine

BACKGROUND

Pharmacogenetics uses genetic variation to predict individual differences in response to medications and holds much promise to improve treatment of addictive disorders.

OBJECTIVES

To review how genetic variation affects responses to cocaine, amphetamine, and methamphetamine and how this information may guide pharmacotherapy.

METHODS

We performed a cross-referenced literature search on pharmacogenetics, cocaine, amphetamine, and methamphetamine.

RESULTS

We describe functional genetic variants for enzymes dopamine-beta-hydroxylase (DbetaH), catechol-O-methyltransferase (COMT), and dopamine transporter (DAT1), dopamine D4 receptor, and brain-derived neurotrophic factor (BDNF). A single nucleotide polymorphism (SNP; C-1021T) in the DbetaH gene is relevant to paranoia associated with disulfiram pharmacotherapy for cocaine addiction. Individuals with variable number tandem repeats (VNTR) of the SLC6A3 gene 3'-untranslated region polymorphism of DAT1 have altered responses to drugs. The 10/10 repeat respond poorly to methylphenidate pharmacotherapy and the 9/9 DAT1 variant show blunted euphoria and physiological response to amphetamine. COMT, D4 receptor, and BDNF polymorphisms are linked to methamphetamine abuse and psychosis.

CONCLUSIONS

Disulfiram and methylphenidate pharmacotherapies for cocaine addiction are optimized by considering polymorphisms affecting DbetaH and DAT1 respectively. Altered subjective effects for amphetamine in DAT1 VNTR variants suggest a 'protected' phenotype.

SCIENTIFIC SIGNIFICANCE

Pharmacogenetic-based treatments for psychostimulant addiction are critical for successful treatment.

mechanisms of disulfiram-induced cocaine abstinence: antabuse and cocaine relapse

The anti-alcoholism drug disulfiram (Antabuse), which is an inhibitor of aldehyde dehydrogenase, induces an aversive reaction to alcohol consumption and thereby helps patients reduce alcohol intake. Recent clinical trials, initiated to investigate whether disulfiram could be used to treat individuals who abuse both alcohol and cocaine, have indicated that disulfiram effectively decreases cocaine consumption. Yet the ability of disulfiram to curb cocaine intake cannot be explained by the disruption of ethanol metabolism. Here, we synthesize clinical and animal data that point to dopamine beta-hydroxylase inhibition as a mechanism underlying the efficacy of disulfiram in the treatment of cocaine dependence.

Norepinephrine and stimulant addiction

No pharmacotherapies are approved for stimulant use disorders, which are an important public health problem. Stimulants increase synaptic levels of the monoamines dopamine (DA), serotonin and norepinephrine (NE). Stimulant reward is attributable mostly to increased DA in the reward circuitry, although DA stimulation alone cannot explain the rewarding effects of stimulants. The noradrenergic system, which uses NE as the main chemical messenger, serves multiple brain functions including arousal, attention, mood, learning, memory and stress response. In pre-clinical models of addiction, NE is critically involved in mediating stimulant effects including sensitization, drug discrimination and reinstatement of drug seeking. In clinical studies, adrenergic blockers have shown promise as treatments for cocaine abuse and dependence, especially in patients experiencing severe withdrawal symptoms. Disulfiram, which blocks NE synthesis, increased the number of cocaine-negative urines in five randomized clinical trials. Lofexidine, an alpha(2)-adrenergic agonist, reduces the craving induced by stress and drug cues in drug users. In addition, the NE transporter (NET) inhibitor atomoxetine attenuates some of d-amphetamine's subjective and physiological effects in humans. These findings warrant further studies evaluating noradrenergic medications as treatments for stimulant addiction.

The safety of disulfiram for the treatment of alcohol and cocaine dependence in randomized clinical trials: guidance for clinical practice

BACKGROUND

Disulfiram has demonstrated efficacy in six randomized clinical trials for the treatment of cocaine dependence, but is rarely used in clinical settings because of safety concerns.

OBJECTIVE

What are the common and serious side effects of disulfiram in cocaine-dependent individuals with and without alcohol dependence in randomized clinical trials?

METHODS

We located Phase I and II randomized trials that discussed the safety of disulfiram.

RESULTS/CONCLUSIONS

In randomized clinical trials that eliminated subjects with serious cardiovascular, hepatic, and psychiatric disorders, the most frequent side effects of disulfiram over placebo or index groups include headaches, fatigue, sleepiness, and anxiety. Disulfiram in a dose of <or= 250 mg/day led to only mild interactions with alcohol. When patients are screened for medical and psychiatric stability, and are evaluated for drug interactions, disulfiram has an acceptable side-effect profile for the treatment of cocaine dependence with or without alcohol dependence.

New treatments for cocaine dependence: a focused review

Cocaine, already a significant drug problem in North and South America, has become a more prominent part of the European drug scene. Cocaine dependence has major somatic, psychological, psychiatric, socio-economic, and legal implications. No specific effective pharmacological treatment exists for cocaine dependence. Recent advances in neurobiology have identified various neuronal mechanisms implicated in cocaine addiction and suggested several promising pharmacological approaches. Data were obtained from Medline, EMBASE, and PsycINFO searches of English-language articles published between 1985 and June 2007 using the key words: cocaine, addiction, cocaine dependence, clinical trials, pharmacotherapy(ies) singly and in combination. Large well-controlled studies with appropriate statistical methods were preferred. Pharmacological agents such as GABA agents (topiramate, tiagabine, baclofen and vigabatrin) and agonist replacement agents (modafinil, disulfiram, methylphenidate) seem to be the most promising in treatment of cocaine dependence. The results from trials of first- and second-generation neuroleptics are largely negative. Aripiprazole, a partial dopaminergic agonist that may modulate the serotonergic system, shows some promise. Preliminary results of human studies with anti-cocaine vaccine, N-acetylcysteine, and ondansetron, are promising, as are several compounds in preclinical development. While no medication has received regulatory approval for the treatment of cocaine dependence, several medications marketed for other indications have shown efficacy in clinical trials. An anti-cocaine vaccine and several compounds in preclinical development have also shown promise. Findings from early clinical trials must be confirmed in larger, less selective patient populations.

Disulfiram enhances subjective effects of dextroamphetamine in humans

Disulfiram has shown promise in several clinical trials for cocaine addiction, but its potential utility in the treatment of amphetamine addiction has not been examined. The goal of this study was to determine the effects of disulfiram on acute physiological and subjective responses to dextroamphetamine in healthy volunteers. Five male and 5 female subjects participated in an outpatient double-blind, placebo-controlled, crossover study. Subjects were randomly assigned to a sequence of disulfiram (250 mg/day) or placebo treatments each lasting for 4 days. Day four of each treatment period was the experimental session, in which subjects orally ingested a single dose of dextroamphetamine (20 mg/70 kg). Outcome measures included heart rate, blood pressure, plasma cortisol and prolactin, subjective and performance on the Sustained Attention to Response Test (SART). Disulfiram did not affect dextroamphetamine-induced increases in heart rate, blood pressure, cortisol, or prolactin. Disulfiram did enhance some of the subjective effects of dextroamphetamine including ratings of "high," "anxious," "bad drug effects," "want more drug" and "drug liking" and was also associated with decreased performance in the SART test. How these enhanced subjective amphetamine responses affect cocaine use behavior remains to be determined in future clinical trials.

Effects of disulfiram and dopamine beta-hydroxylase knockout on cocaine-induced seizures

The antialcoholism drug disulfiram has shown recent promise as a pharmacotherapy for treating cocaine dependence, probably via inhibition of dopamine beta-hydroxylase (DBH), the enzyme that catalyzes the conversion of dopamine (DA) to norepinephrine (NE). We previously showed that DBH knockout (Dbh -/-) mice, which lack NE, are susceptible to seizures and are hypersensitive to the psychomotor, rewarding, and aversive effects of cocaine, suggesting that disulfiram might exacerbate cocaine-induced seizures (CIS) by inhibiting DBH. To test this, we examined CIS in wild-type and Dbh -/- mice following administration of disulfiram or the selective DBH inhibitor nepicastat. We found that Dbh genotype had no effect on CIS probability or frequency, whereas disulfiram, but not nepicastat, increased the probability of having CIS in both wild-type and Dbh -/- mice. Both disulfiram and nepicastat increased CIS frequency in wild-type but not Dbh -/- mice. There were no genotype or treatment effects on serum cocaine levels, except for an increase in disulfiram-treated Dbh -/- mice at the highest dose of cocaine. These results suggest that disulfiram enhances CIS via two distinct mechanisms: it both increases CIS frequency by inhibiting DBH and increases CIS frequency in a DBH-independent manner.

Treatment of co-occurring alcohol and other drug use disorders

Drug use disorders (DUDs) frequently co-occur with alcohol use disorders, affecting approximately 1.1 percent of the U.S. population. Compared with alcohol use disorders or DUDs alone, co-occurring disorders are associated with a greater severity of substance dependence; co-occurring psychiatric disorders also are common in this patient population. Many effective medications and behavioral treatments are available to treat alcohol dependence and drug dependence when these occur independent of one another. There is a paucity of research, however, specifically focused on the treatment of persons with co-occurring alcohol and other DUDs (AODUDs). The evidence to date on treating this patient population suggests that combining some of the behavioral and pharmacologic treatments that are effective in treating either drug or alcohol use disorders alone may be useful in the AODUD population as well.

Update on neuropharmacological treatments for alcoholism: scientific basis and clinical findings

The past decade has seen an expansion of research and knowledge on pharmacotherapy for the treatment of alcohol dependence. The Food and Drug Administration (FDA)-approved medications naltrexone and acamprosate have shown mixed results in clinical trials. Oral naltrexone and naltrexone depot formulations have generally demonstrated efficacy at treating alcohol dependence, but their treatment effect size is small, and more research is needed to compare the effects of different doses on drinking outcome. Acamprosate has demonstrated efficacy for treating alcohol dependence in European trials, but with a small effect size. In U.S. trials, acamprosate has not proved to be efficacious. Research continues to explore which types of alcohol-dependent individual would benefit the most from treatment with naltrexone or acamprosate. The combination of the two medications demonstrated efficacy for treating alcohol dependence in one European study but not in a multi-site U.S. study. Another FDA-approved medication, disulfiram, is an aversive agent that does not diminish craving for alcohol. Disulfiram is most effective when given to those who are highly compliant or who are receiving their medication under supervision. Of the non-approved medications, topiramate is among the most promising, with a medium effect size in clinical trials. Another promising medication, baclofen, has shown efficacy in small trials. Serotonergic agents such as selective serotonin reuptake inhibitors and the serotonin-3 receptor antagonist, ondansetron, appear to be efficacious only among certain genetic subtypes of alcoholic. As neuroscientific research progresses, other promising medications, as well as medication combinations, for treating alcohol dependence continue to be explored.