CO2 Electrolyzers

CO2 electrolyzers have progressed rapidly in energy efficiency and catalyst selectivity toward valuable chemical feedstocks and fuels, such as syngas, ethylene, ethanol, and methane. However, each component within these complex systems influences the overall performance, and the further advances needed to realize commercialization will require an approach that considers the whole process, with the electrochemical cell at the center. Beyond the cell boundaries, the electrolyzer must integrate with upstream CO2 feeds and downstream separation processes in a way that minimizes overall product energy intensity and presents viable use cases. Here we begin by describing upstream CO2 sources, their energy intensities, and impurities. We then focus on the cell, the most common CO2 electrolyzer system architectures, and each component within these systems. We evaluate the energy savings and the feasibility of alternative approaches including integration with CO2 capture, direct conversion of flue gas and two-step conversion via carbon monoxide. We evaluate pathways that minimize downstream separations and produce concentrated streams compatible with existing sectors. Applying this comprehensive upstream-to-downstream approach, we highlight the most promising routes, and outlook, for electrochemical CO2 reduction.

Early Warning for the Electrolyzer: Monitoring CO2 Reduction via In-Line Electrochemical Impedance Spectroscopy

The electrochemical CO2 reduction reaction (CO2 RR) to fuels and feedstocks presents an opportunity to decarbonize the chemical industry, and current electrolyzer performance levels approach commercial viability. However, stability remains below that required, in part because of the challenge of probing these electrolyzer systems in real time and the challenge of determining the root cause of failure. Failure can result from initial conditions (e. g., the over- or under-compression of the electrolyzer), gradual degradation of components (e. g., cathode or anode catalysts), the accumulation of products or by-products, or immediate changes such as the development of a hole in the membrane or a short circuit. Identifying and mitigating these assembly-related, gradual, and immediate failure modes would increase both electrolyzer lifetime and economic viability of CO2 RR. We demonstrate the continuous monitoring of CO2 RR electrolyzers during operation via non-disruptive, real-time electrochemical impedance spectroscopy (EIS) analysis. Using this technique, we characterise common failure modes - compression, salt formation, and membrane short circuits - and identify electrochemical parameter signatures for each. We further propose a framework to identify, predict, and prevent failures in CO2 RR electrolyzers. This framework allowed for the prediction of anode degradation ~11 hours before other indicators such as selectivity or voltage.

Single-site decorated copper enables energy- and carbon-efficient CO2 methanation in acidic conditions

Renewable CH₄ produced from electrocatalytic CO₂ reduction is viewed as a sustainable and versatile energy carrier, compatible with existing infrastructure. However, conventional alkaline and neutral CO₂-to-CH₄ systems suffer CO₂ loss to carbonates, and recovering the lost CO₂ requires input energy exceeding the heating value of the produced CH₄. Here we pursue CH₄-selective electrocatalysis in acidic conditions via a coordination method, stabilizing free Cu ions by bonding Cu with multidentate donor sites. We find that hexadentate donor sites in ethylenediaminetetraacetic acid enable the chelation of Cu ions, regulating Cu cluster size and forming Cu-N/O single sites that achieve high CH₄ selectivity in acidic conditions. We report a CH₄ Faradaic efficiency of 71% (at 100 mA cm^-2) with <3% loss in total input CO₂ that results in an overall energy intensity (254 GJ/tonne CH₄), half that of existing electroproduction routes.

Concentrated Ethanol Electrosynthesis from CO2 via a Porous Hydrophobic Adlayer

Electrochemical CO₂ reduction can convert waste emissions into dense liquid fuels compatible with existing energy infrastructure. High-rate electrocatalytic conversion of CO₂ to ethanol has been achieved in membrane electrode assembly (MEA) electrolyzers; however, ethanol produced at the cathode is transported, via electroosmotic drag and diffusion, to the anode, where it is diluted and may be oxidized. The ethanol concentrations that result on both the cathodic and anodic sides are too low to justify the energetic and financial cost of downstream separation. Here, we present a porous catalyst adlayer that facilitates the evaporation of ethanol into the cathode gas stream and reduces the water transport, leading to a recoverable stream of concentrated ethanol. The adlayer is comprised of ethylcellulose-bonded carbon nanoparticles and forms a porous, electrically conductive network on the surface of the copper catalyst that slows the transport of water to the gas channel. We achieve the direct production of an ethanol stream of 12.4 wt %, competitive with the concentration of current industrial ethanol production processes.

In Situ Formation of Nano Ni-Co Oxyhydroxide Enables Water Oxidation Electrocatalysts Durable at High Current Densities

The oxygen evolution reaction (OER) limits the energy efficiency of electrocatalytic systems due to the high overpotential symptomatic of poor reaction kinetics; this problem worsens over time if the performance of the OER electrocatalyst diminishes during operation. Here, a novel synthesis of nanocrystalline Ni-Co-Se using ball milling at cryogenic temperature is reported. It is discovered that, by anodizing the Ni-Co-Se structure during OER, Se ions leach out of the original structure, allowing water molecules to hydrate Ni and Co defective sites, and the nanoparticles to evolve into an active Ni-Co oxyhydroxide. This transformation is observed using operando X-ray absorption spectroscopy, with the findings confirmed using density functional theory calculations. The resulting electrocatalyst exhibits an overpotential of 279 mV at 0.5 A cm^-2 and 329 mV at 1 A cm^-2 and sustained performance for 500 h. This is achieved using low mass loadings (0.36 mg cm^-2 ) of cobalt. Incorporating the electrocatalyst in an anion exchange membrane water electrolyzer yields a current density of 1 A cm^-2 at 1.75 V for 95 h without decay in performance. When the electrocatalyst is integrated into a CO₂ -to-ethylene electrolyzer, a record-setting full cell voltage of 3 V at current density 1 A cm^-2 is achieved.

Low coordination number copper catalysts for electrochemical CO2 methanation in a membrane electrode assembly

The electrochemical conversion of CO2 to methane provides a means to store intermittent renewable electricity in the form of a carbon-neutral hydrocarbon fuel that benefits from an established global distribution network. The stability and selectivity of reported approaches reside below technoeconomic-related requirements. Membrane electrode assembly-based reactors offer a known path to stability; however, highly alkaline conditions on the cathode favour C-C coupling and multi-carbon products. In computational studies herein, we find that copper in a low coordination number favours methane even under highly alkaline conditions. Experimentally, we develop a carbon nanoparticle moderator strategy that confines a copper-complex catalyst when employed in a membrane electrode assembly. In-situ XAS measurements confirm that increased carbon nanoparticle loadings can reduce the metallic copper coordination number. At a copper coordination number of 4.2 we demonstrate a CO2-to-methane selectivity of 62%, a methane partial current density of 136 mA cm-2, and > 110 hours of stable operation.

Dopant-tuned stabilization of intermediates promotes electrosynthesis of valuable C3 products

The upgrading of CO2/CO feedstocks to higher-value chemicals via energy-efficient electrochemical processes enables carbon utilization and renewable energy storage. Substantial progress has been made to improve performance at the cathodic side; whereas less progress has been made on improving anodic electro-oxidation reactions to generate value. Here we report the efficient electroproduction of value-added multi-carbon dimethyl carbonate (DMC) from CO and methanol via oxidative carbonylation. We find that, compared to pure palladium controls, boron-doped palladium (Pd-B) tunes the binding strength of intermediates along this reaction pathway and favors DMC formation. We implement this doping strategy and report the selective electrosynthesis of DMC experimentally. We achieve a DMC Faradaic efficiency of 83 ± 5%, fully a 3x increase in performance compared to the corresponding pure Pd electrocatalyst.

Neural correlates of adherence to extended-release naltrexone pharmacotherapy in heroin dependence

Injectable extended-release naltrexone (XRNTX) presents an effective therapeutic strategy for opioid addiction, however its utility could be hampered by poor adherence. To gain a better insight into this phenomenon, we utilized blood oxygenation level-dependent functional magnetic resonance imaging (fMRI) in conjunction with a validated cue-induced craving procedure to examine neural correlates of XRNTX adherence. We operationalized treatment adherence as the number of monthly XRNTX injections (range: 0-3) administered to a group of fully detoxified heroin-dependent subjects (n=32). Additional outcomes included urine toxicology screening and self-reported tobacco use. The presented heroin-related visual cues reliably elicited heroin craving in all tested subjects. Nine, five, three and 15 of the participants, respectively, received zero, one, two and three XRNTX injections, predicted by the individual baseline fMRI signal change in response to the cues in the medial prefrontal cortex, a brain region involved in inhibitory self-control and emotional appraisal. The incidence of opioid-positive urines during the XRNTX therapy was low and remained about half the pre-treatment rate after the XRNTX ended. During the treatment, cigarette smoking behaviors followed patterns of opioid use, while cocaine consumption was increased with reductions in opioid use. The present data support the hypothesis that medial prefrontal cortex functions are involved in adherence to opioid antagonist therapy. A potential role of concurrent non-opioid addictive substances consumption during the XRNTX pharmacotherapy warrants further investigation. Our findings set the stage for further bio-behavioral investigations of the mechanisms of relapse prevention in opioid dependence.

Case-control association analysis of polymorphisms in the δ-opioid receptor, OPRD1, with cocaine and opioid addicted populations

BACKGROUND

Addiction susceptibility and treatment responsiveness are greatly influenced by genetic factors. Sequence variation in genes involved in the mechanisms of drug action have the potential to influence addiction risk and treatment outcome. The opioid receptor system is involved in mediating the rewarding effects of cocaine and opioids. The μ-opioid receptor (MOR) has traditionally been considered the primary target for opioid addiction. The MOR, however, interacts with and is regulated by many known MOR interacting proteins (MORIPs), including the δ-opioid receptor (DOR).

METHODS

The present study evaluated the contribution of OPRD1, the gene encoding the DOR, to the risk of addiction to opioids and cocaine. The association of OPRD1 polymorphisms with both opioid addiction (OA) and cocaine addiction (CA) was analyzed in African American (OA n=336, CA n=503) and European American (OA n=1007, CA n=336) populations.

RESULTS

The primary finding of this study is an association of rs678849 with cocaine addiction in African Americans (allelic p=0.0086). For replication purposes, this SNP was analyzed in a larger independent population of cocaine addicted African Americans and controls and the association was confirmed (allelic p=4.53 × 10(-5); n=993). By performing a meta-analysis on the expanded populations, the statistical evidence for an association was substantially increased (allelic p=8.5 × 10(-7)) (p-values non-FDR corrected).

CONCLUSION

The present study suggests that polymorphisms in OPRD1 are relevant for cocaine addiction in the African American population and provides additional support for a broad role for OPRD1 variants in drug dependence.

Genetic association analyses of PDYN polymorphisms with heroin and cocaine addiction

Genetic factors are believed to account for 30-50% of the risk for cocaine and heroin addiction. Dynorphin peptides, derived from the prodynorphin (PDYN) precursor, bind to opioid receptors, preferentially the kappa-opioid receptor, and may mediate the aversive effects of drugs of abuse. Dynorphin peptides produce place aversion in animals and produce dysphoria in humans. Cocaine and heroin have both been shown to increase expression of PDYN in brain regions relevant for drug reward and use. Polymorphisms in PDYN are therefore hypothesized to increase risk for addiction to drugs of abuse. In this study, 3 polymorphisms in PDYN (rs1022563, rs910080 and rs1997794) were genotyped in opioid-addicted [248 African Americans (AAs) and 1040 European Americans (EAs)], cocaine-addicted (1248 AAs and 336 EAs) and control individuals (674 AAs and 656 EAs). Sex-specific analyses were also performed as a previous study identified PDYN polymorphisms to be more significantly associated with female opioid addicts. We found rs1022563 to be significantly associated with opioid addiction in EAs [P = 0.03, odds ratio (OR) = 1.31; false discovery rate (FDR) corrected q-value]; however, when we performed female-specific association analyses, the OR increased from 1.31 to 1.51. Increased ORs were observed for rs910080 and rs199774 in female opioid addicts also in EAs. No statistically significant associations were observed with cocaine or opioid addiction in AAs. These data show that polymorphisms in PDYN are associated with opioid addiction in EAs and provide further evidence that these risk variants may be more relevant in females.

Modeling of peptide adsorption interactions with a poly(lactic acid) surface

The biocompatibility of implanted materials and devices is governed by the conformation, orientation, and composition of the layer of proteins that adsorb to the surface of the material immediately upon implantation, so an understanding of this adsorbed protein layer is essential to the rigorous and methodical design of implant materials. In this study, novel molecular dynamics techniques were employed in order to determine the change in free energy for the adsorption of a solvated nine-residue peptide (GGGG-K-GGGG) to a crystalline polylactide surface in an effort to elucidate the fundamental mechanisms that govern protein adsorption. This system, like many others, involves two distinct types of sampling problems: a spatial sampling problem, which arises due to entropic effects creating barriers in the free energy profile, and a conformational sampling problem, which occurs due to barriers in the potential energy landscape. In a two-step process that addresses each sampling problem in turn, the technique of biased replica exchange molecular dynamics was refined and applied in order to overcome these sampling problems and, using the information available at the atomic level of detail afforded by molecular simulation, both quantify and characterize the interactions between the peptide and a relevant biomaterial surface. The results from these simulations predict a fairly strong adsorption response with an adsorption free energy of -2.5 +/- 0.6 kcal/mol (mean +/- 95% confidence interval), with adsorption primarily due to hydrophobic interactions between the nonpolar groups of the peptide and the PLA surface. As part of a larger and ongoing effort involving both simulation and experimental investigations, this work contributes to the goal of transforming the engineering of biomaterials from one dominated by trial-and-error to one which is guided by an atomic-level understanding of the interactions that occur at the tissue-biomaterial interface.

Psychotherapy for cocaine dependence

Dependence on cocaine is a new disorder for contemporary US clinicians. Until the 1980s sufficient quantities of the drug were not available to produce a true dependence. Thus far the only models for pharmacological intervention involve an interaction between medication and psychotherapy; that is, medication may be able to facilitate a drug-free interval during which time the patient can be engaged in psychotherapy. Psychotherapy programmes for cocaine dependence have generally been modelled on group-oriented treatments of the type used by Alcoholics Anonymous. Controlled studies of therapy programmes for cocaine dependence are currently being conducted and one prospective random-assignment study comparing day hospital and in-patient rehabilitation shows generally good results. Behavioural treatments aimed at reducing or extinguishing conditioned responses in cocaine addicts have also shown efficacy in a controlled study. More general relapse prevention procedures including rehearsal and role-playing are also used in the treatment of cocaine dependence. Combinations of psychotherapy and pharmacotherapy have so far shown the most promise in the treatment of this disorder.

Caffeine: behavioral effects of withdrawal and related issues

Acquired tolerance to some behavioral effects of caffeine in humans is widely assumed to occur but is poorly documented and appears, at most, to be of low magnitude. Withdrawal from regular consumption of caffeine has been reported to result in a variety of symptoms, including: irritability, sleepiness, dysphoria, delerium, nausea, vomiting, rhinorrhea, nervousness, restlessness, anxiety, muscle tension, muscle pains and flushed face. Some of these same symptoms have been reported following excess intake of caffeine. The prevalence of symptoms reported on withdrawal in different studies also covers a wide range from 11% or less to 100%. It is suggested that the evidence leads to the conclusion that non pharmacological factors related to knowledge and expectation are the prime determinants of symptoms and their reported prevalence on withdrawal of caffeine after regular consumption.

Brain activity during simulated deception: an event-related functional magnetic resonance study

TheGuilty Knowledge Test (GKT) has been used extensively to model deception. An association between the brain evoked response potentials and lying on the GKT suggests that deception may be associated with changes in other measures of brain activity such as regional blood flow that could be anatomically localized with event-related functional magnetic resonance imaging (fMRI). Blood oxygenation level-dependent fMRI contrasts between deceptive and truthful responses were measured with a 4 Tesla scanner in 18 participants performing the GKT and analyzed using statistical parametric mapping. Increased activity in the anterior cingulate cortex (ACC), the superior frontal gyrus (SFG), and the left premotor, motor, and anterior parietal cortex was specifically associated with deceptive responses. The results indicate that: (a) cognitive differences between deception and truth have neural correlates detectable by fMRI, (b) inhibition of the truthful response may be a basic component of intentional deception, and (c) ACC and SFG are components of the basic neural circuitry for deception.

Predicting treatment response to naltrexone: the influence of craving and family history

Naltrexone has repeatedly been shown to reduce drinking in alcohol-dependent patients. Previous clinical research suggests that naltrexone may be more effective at reducing drinking among patients with high levels of alcohol craving at the beginning of treatment. In addition, laboratory studies suggest that naltrexone may be more efficacious among patients with a high familial loading of alcohol problems. We explored both of these possibilities in the context of the first 12-week phase of a double blind, placebo-controlled naltrexone trial. A total of 121 patients were randomized to receive 100 mg/day naltrexone and 62 patients were randomized to receive placebo. Both naltrexone and placebo were given in conjunction with a psychosocial intervention designed to be integrated with the use of pharmacotherapy. This intervention was administered by nurse practitioners. Overall, patients randomized to naltrexone reported drinking five or more drinks on fewer days than did placebo controls (p = .04). Interactions were observed between medication group assignment and both craving level prior to randomization (p = .02) and family loading of alcohol problems (p = .05). In both cases, the interaction was in the predicted direction. These data suggest that patients with high levels of alcohol craving or a strong family history of alcoholism are more likely to benefit from naltrexone treatment.

Three decision-making tasks in cocaine-dependent patients: do they measure the same construct?

AIMS

Substance-abusing populations perform poorly on decision-making tasks related to delay and risk. These tasks include: (1) the Delay Discounting Procedure (DDP), in which choices are made between smaller-sooner and later-larger rewards, (2) the Gambling Task (GT), in which choices are made between alternatives varying in pay-off and punishment, and (3) the Rogers Decision-Making Task (RDMT) in which subjects choose between higher or lower probability gambles. We examine the interrelationship among these tasks.

DESIGN

A test battery was created which included the DDP, GT and RDMT, as well as measures of impulsivity, intellectual functioning and drug use.

SETTING

Subjects completed the test battery at an outpatient center, prior to beginning 12 weeks of treatment.

PARTICIPANTS

Thirty-two treatment-seeking cocaine dependent individuals (primarily African-American males) participated.

FINDINGS

Performance on the GT was significantly correlated with performance on the DDP (r = 0.37; p = 0.04). Reaction times on the RDMT correlated with performance on the GT (r = 0.36, p = 0.04) and DDP (r = 0.33, p = 0.07), but actual choices on the RDMT did not (p > 0.9 for both). While no significant relationships were observed between task performance and impulsivity, IQ estimate was positively correlated with both the GT (r = 0.44, p = 0.01) and RDMT (r = 0.41, p = 0.021). Split half reliability data indicated higher reliability when using only data from the latter half of the GT (r = 0.92 vs. r = 0.80).

CONCLUSIONS

These data offer preliminary evidence of overlap in the decision-making functioning tapped by these tasks. Possible implications for drug-taking behavior are discussed.

Cocaine dependence: a disease of the brain's reward centers

Cocaine addiction affects brain reward centers that have evolved to ensure survival. Cocaine euphoria is intensely pleasurable and results from mesolimbic dopamine (DA) neurotransmission. DA signal-receiving neurons in the nucleus accumbens synthesize endogenous opioids and project to numerous reward regions. Cocaine-induced neuroadaptations, including DA depletion, may underlie craving and hedonic dysregulation. Cue-induced craving is vigorously triggered by conditioned elements of the drug environment and associated with measurable limbic activation. Reduced frontal lobe metabolism in cocaine-addicted individuals could explain important clinical phenomena such as denial and the loss of control over limbic impulses. Cocaine addiction is rapidly progressive and associated with severe medical, psychiatric, and psychosocial consequences. Denial shields addicted individuals from their predicament and must be addressed in treatment. Lacking pharmacological options, clinicians must rely entirely on psychosocial approaches. Treatment principles, including engagement, motivational enhancement, abstinence strategies, and craving reduction are discussed in terms of biological rationales.

Cocaine withdrawal symptoms and initial urine toxicology results predict treatment attrition in outpatient cocaine dependence treatment

This study evaluated the ability of cocaine withdrawal symptoms, measured by the Cocaine Selective Severity Assessment (CSSA) and initial urine toxicology results, to predict treatment attrition among 128 cocaine dependent veterans participating in a 4-week day hospital treatment program. The CSSA was administered and a urine toxicology screen was obtained at intake and at the start of the day hospital (about 1 week later). The combination of a positive urine toxicology screen and a high CSSA score at intake predicted failure to complete treatment. Urine toxicology results at the start of the day hospital, but not at intake, predicted failure to complete treatment. Among participants without other psychiatric illness, high CSSA scores at intake predicted failure to complete treatment. The presence of cocaine withdrawal symptoms and a positive urine toxicology screen are clinically useful predictors of treatment attrition.

Alcoholism treatment after liver transplantation: lessons learned from a clinical trial that failed

Alcoholic liver disease is the second most common indication for liver transplantation in the United States. The lack of alcoholism treatment studies led us to study motivational enhancement therapy (MET) plus naltrexone after transplant. The authors could not complete this study. Sixty alcoholic patients were to receive MET plus naltrexone or placebo for 6 months. Fifty men and 5 women were screened. Nine died and 15 were not approached. Of 31 approached, 20 were ineligible, 11 refused, and 5 entered but dropped out before completion. Barriers to posttransplant alcoholism included infirmity, intensive medical management, and denial for alcoholism treatment. Because 30%-50% of alcoholic patients drink after transplant, the authors suggest using MET alone pretransplant.

Gender and psychiatric comorbidity: impact on clinical presentation of alcohol dependence

We examined differences in clinical presentation for outpatient alcohol treatment in: 1) males and females, considering comorbidity; and 2) three comorbid groups, considering gender. Drinking indices and emotional, physical, and sexual abuse reports were compared in 127 male and 69 female alcohol-dependent patients who have a current (36.2%) or lifetime (20.4%) psychiatric disorder or who never had a psychiatric disorder (43.4%). Females reported more emotional and physical abuse than males. Females reported drinking smaller volumes of alcohol but on more days than males. All with current comorbidity, irrespective of gender, reported more days of heavy drinking than other groups. When evaluating drinking status, gender and comorbidity should be considered.

The effect of gamma-vinyl-GABA on the consumption of concurrently available oral cocaine and ethanol in the rat

It has frequently been reported that a high percentage of individuals, identified as either alcohol- or cocaine-dependent, concurrently abuse both drugs. The experiments reported here represent a continuing effort to develop an animal model to predict the effects of a potential pharmacotherapeutic agent on concurrently available oral ethanol and cocaine. These experiments utilized drinkometer circuitry to assess the effects of gamma-vinyl-GABA (GVG), a gamma-aminobutyric acid (GABA) transaminase inhibitor, on the consumption and temporal pattern of responses for orally self-administered ethanol and cocaine. The results of these experiments showed that GVG, at doses of 100, 200 and 300 mg/kg, reduced both ethanol and cocaine consumption in a dose-related manner. When compared to vehicle, GVG at all doses significantly reduced ethanol consumption while consumption of cocaine was significantly reduced only at 300 mg/kg. This is consistent with data showing that GVG reduces consumption of these drugs when administered alone and data showing that GVG is more potent in reducing ethanol-induced compared to cocaine-induced extracellular dopamine in the nucleus accumbens. Analysis of the temporal pattern of drinking across the session suggests that GVG's effects are due to a disruption of the reinforcing properties of ethanol and cocaine rather than a more general reduction in motor behavior. These data suggest that GVG has potential for clinical use in populations that abuse either alcohol or cocaine alone or in combination.

Effect of acamprosate and naltrexone, alone or in combination, on ethanol consumption

Both acamprosate and naltrexone have demonstrated clinical utility in reducing relapse to alcohol use in recovering alcoholics. The present experiments examined the effects of acamprosate and naltrexone, either alone or in combination, on basal ethanol consumption in a limited-access model with the use of outbred Wistar rats. Naltrexone, 0.1 mg/kg, significantly reduced ethanol consumption as previously reported. Acamprosate, 50 mg/kg, did not significantly reduce ethanol consumption when administered alone and provided no evidence of additive or synergistic effects when combined with naltrexone. Acamprosate, 200 mg/kg, produced a modest reduction in ethanol consumption when administered alone but no evidence of additive or synergistic effects when combined with naltrexone. From these findings, it is suggested that a combination approach of these drugs may not be any more effective than monotherapy.

A randomized, double-blind, placebo-controlled study of ritanserin pharmacotherapy for cocaine dependence

Eighty cocaine-dependent individuals enrolled in outpatient treatment took part in a randomized, double-blind, placebo-controlled trial of ritanserin, a 5-HT(2) antagonist, as an adjunct therapy. Participants attended an outpatient day hospital therapy program each day and received tablets containing placebo or 10 mg ritanserin for a 4-week period. Primary outcome measures included retention in treatment, urine drug tests, and self-reports of craving. Secondary outcome measures were depression scores on the Beck and Hamilton inventories, negative mood as measured by the Profile of Mood States, and life functioning as measured by the Addiction Severity Index. Although participants showed improvement over the 4 weeks, there were no group differences on any of the measures. These results fail to support the use of ritanserin as a complement to outpatient psychosocial therapy for cocaine dependence.

Amantadine in the treatment of cocaine-dependent patients with severe withdrawal symptoms

OBJECTIVE

The study examined the effectiveness of amantadine in reducing cocaine withdrawal symptoms and improving treatment outcome among cocaine-dependent patients in outpatient treatment.

METHOD

Sixty-one cocaine-dependent subjects participated in a double-blind, placebo-controlled trial of amantadine.

RESULTS

Among subjects with severe cocaine withdrawal symptoms at the start of treatment, those who received amantadine used significantly less cocaine during the trial than did subjects who received placebo. Compared to subjects who received placebo, subjects who received amantadine submitted significantly more benzoylecgonine-negative urine samples and used cocaine on significantly fewer days during the trial.

CONCLUSIONS

Amantadine may be an effective treatment for cocaine-dependent patients with severe cocaine withdrawal symptoms.

Do caffeine-containing analgesics promote dependence? A review and evaluation

OBJECTIVE

Debates about the suspected association between kidney disease and use of analgesics have led to concern about whether caffeine could stimulate an undesirable overuse of phenacetin-free combined analgesics. A committee was asked to critically review the pertinent literature and to suggest guides for clinical practice and for consideration of international regulatory authorities.

PARTICIPANTS

A group of international scientists, jointly selected by the regulatory authorities of Germany, Switzerland, and Austria and the pharmaceutical industry.

EVIDENCE

All invited experts evaluated relevant literature and reports and added further information and comments.

CONCLUSIONS

Caffeine has a synergistic effectiveness with analgesics. Although caffeine has a dependence potential, the potential is low. Experimental data regarding dependence potential for caffeine alone may not correspond to the conditions in patients with pain. Withdrawal is not likely to cause stimulation or sustainment of analgesic intake. For drug-induced headache, no single or combined analgesic was consistently identified as causative, and no evidence exists for a special role of caffeine. Strong dependence behavior was observed only in patients using phenacetin-containing preparations, coformulated with antipyretics/analgesics and caffeine. This finding may have led to the impression that caffeine stimulates overuse of analgesics.

SUMMARY

Although more experimental and long-term data would be desirable to show possible mechanisms of dependence and to offer unequivocal proof of safety, the committee concluded that the available evidence does not support the claim that analgesics coformulated with caffeine, in the absence of phenacetin, stimulate or sustain overuse.

Drug dependence, a chronic medical illness: implications for treatment, insurance, and outcomes evaluation

The effects of drug dependence on social systems has helped shape the generally held view that drug dependence is primarily a social problem, not a health problem. In turn, medical approaches to prevention and treatment are lacking. We examined evidence that drug (including alcohol) dependence is a chronic medical illness. A literature review compared the diagnoses, heritability, etiology (genetic and environmental factors), pathophysiology, and response to treatments (adherence and relapse) of drug dependence vs type 2 diabetes mellitus, hypertension, and asthma. Genetic heritability, personal choice, and environmental factors are comparably involved in the etiology and course of all of these disorders. Drug dependence produces significant and lasting changes in brain chemistry and function. Effective medications are available for treating nicotine, alcohol, and opiate dependence but not stimulant or marijuana dependence. Medication adherence and relapse rates are similar across these illnesses. Drug dependence generally has been treated as if it were an acute illness. Review results suggest that long-term care strategies of medication management and continued monitoring produce lasting benefits. Drug dependence should be insured, treated, and evaluated like other chronic illnesses. JAMA. 2000;284:1689-1695.

6-beta-naltrexol reduces alcohol consumption in rats

BACKGROUND

In humans, 6-beta-naltrexol is the major metabolite of naltrexone, and its effectiveness at suppressing alcohol consumption in any species has not been previously investigated. Naltrexone is an opiate antagonist that reduces excessive drinking in many species, including humans with alcohol dependence. Whether 6-beta-naltrexol is an active metabolite that contributes to the efficacy of naltrexone remains unknown.

METHODS

Placebo and four doses of 6-beta-naltrexol were given by intraperitoneal injection to outbred Wistar rats and alcohol consumption was measured using a limited access model.

RESULTS

6-beta-Naltrexol reduced alcohol consumption in a dose-dependent manner. At doses 7.5, 12.5, and 25 mg/kg, 6-beta-naltrexol significantly decreased consumption of a 6% ethanol solution compared with saline control groups.

CONCLUSIONS

These data suggest that there may be a potential clinical use for 6-beta-naltrexol in recovering alcoholics.

Improving naltrexone response: an intervention for medical practitioners to enhance medication compliance in alcohol dependent patients

The effectiveness of naltrexone, a FDA-approved medication for alcohol dependence, can be improved if we support and help patients to consistently take their medication. We illustrate how patient noncompliance with treatment negatively affects outcome, and, we describe a new intervention to enhance medication compliance. Outcome was evaluated for 196 alcohol dependent outpatients who were treated with 50 mg/day naltrexone or placebo for 12 weeks. For patients who adhered to the prescribed treatment, relapse rates were lower with naltrexone than placebo (10% vs. 38.6%, p < 0.001). For noncompliant patients, relapse rates were high and comparable between naltrexone- and placebo-treated patients (42.9% vs. 40%). In a second study of 100 alcohol dependent outpatients, we introduced an intervention that resulted in better medication compliance rates compared to a previous naltrexone study of patients who did not receive the intervention (77.0% vs. 60.8%, p < 0.01). This provided some support for the use of an intervention that targets medication compliance when prescribing naltrexone.

Prognostic significance of antisocial personality disorder in cocaine-dependent patients entering continuing care

This study examined the relationship of antisocial personality disorder (APD) to response to continuing care treatments in a sample of cocaine-dependent patients. Patients (N = 127) were randomly assigned to 20-week standard group or individualized relapse prevention continuing care interventions after the completion of an initial treatment episode and followed up at 3, 6, and 12 months. APD and non-APD patients did not differ on retention in continuing care, substance use outcomes, social function outcomes, or experiences before or during cocaine relapse episodes. A diagnosis of APD was also not a predictor of differential response to the two continuing care interventions in the study. However, APD patients had worse medical and psychiatric problem severity than non-APD patients at entrance to continuing care and during follow-up. These results suggest that cocaine patients with APD who are in the continuing care phase of outpatient rehabilitation might benefit from additional medical and psychiatric treatment services.

Alcohol and the athlete

Alcohol and the athlete have been linked together since ancient times. It continues to be the most commonly consumed drug among the athletic population. Alcohol use carries significant potential adverse effects for both the health and welfare of the individual. It is suggested that alcohol related problems may be more prevalent in the athletic population due to their risk taking mentality and the age profile of athletes (18- to 24-year-old males). Alcohol consumption also appears to have a causative effect in sports related injury, with an injury incidence of 54.8% in drinkers compared with 23.5% in nondrinkers (p < 0.005). This may be due in part to the hangover effect of alcohol consumption, which has been shown to reduce athletic performance by 11.4%. Alcohol is a potentially lethal drug and is a banned substance for certain Olympic sports. Education is the cornerstone for appropriate social use of this drug. Athletes and coaches need to be aware of the sports related adverse effects of alcohol consumption and its role in sports injury and poor physiological performance. It is recommended that alcohol should be avoided by the serious athlete.

Mood state and recent cocaine use are not associated with levels of cocaine cue reactivity

Eighty-one cocaine-dependent outpatients were assessed for their reactions to cocaine-related cues in a laboratory setting. All subjects contributed a urine sample prior to the session. Compared with non-drug control cues, the cocaine stimuli produced increases in physiological arousal, self-reports of high, craving, and withdrawal, and self-reports of negative mood. Subjects who tested cocaine-positive on the day of testing differed only in skin resistance responding from those who tested cocaine-negative. Changes in cue-induced physiological and self-report measures were also not associated with between-subject variations in mood as measured by the Profile of Mood States (POMS) questionnaire administered prior to cue assessment. Thus, variations in baseline mood and recent cocaine use history do not introduce an additional source of variability in cue reactivity measurements. However, negative mood states at the start of a session were associated with higher levels of self-reported craving, high, and withdrawal both before and after cue exposure.

Psychosocially enhanced treatment for cocaine-dependent mothers: evidence of efficacy

Eighty-four cocaine-dependent mothers were randomly assigned either to a case management-oriented outpatient treatment program (CM), or to a psychosocially enhanced treatment program (PET). Both programs included onsite child care and both offered daily group therapy sessions. Subjects randomized to the PET condition were offered a variety of additional onsite services designed to meet their special psychosocial needs including parenting skills class, access to a psychiatrist, individual therapy sessions, and GED class. Patients in the CM program could gain access to these services only through referrals to community resources. Program retention was significantly better for patients in the PET condition. In addition, while the mean number of days of cocaine use decreased from baseline in both groups, the PET group had significantly fewer days of cocaine use at 12-month follow-up than the CM group. These results show that providing psychosocial enhancement services onsite can improve treatment outcome for cocaine-dependent mothers.

The frequency of caffeine withdrawal in a population-based survey and in a controlled, blinded pilot experiment

Reports of symptoms when regular caffeine consumption is stopped have appeared in the medical literature, but the frequency and significance of this phenomenon have remained controversial. The objective of this study was to collect information on the prevalence and severity of caffeine withdrawal in the general population and determine the incidence and type of symptoms reported on blind abrupt and gradual caffeine cessation among coffee drinkers reporting past episodes of caffeine-withdrawal symptoms. A community-based telephone survey was followed by a stratified, randomized, double-blind controlled study. Participants included 11,112 persons spontaneously calling to inquire about studies not related to caffeine and 57 regular caffeine users selected from among the callers because of self-reported caffeine-withdrawal symptoms. Gradual or abrupt withdrawal from caffeine was compared to continuation of the same caffeine level. In a survey of 11,112 persons, 61% reported daily caffeine consumption, and 11% of the caffeine consumers reported symptoms upon stopping caffeine. Among the regular caffeine users, only 0.9% of males and 5.5% of females reported symptoms significant enough to interfere with normal activities when they abruptly stopped caffeine. A group of those reporting withdrawal symptoms were randomly assigned to three subsamples. In the group subjected to abrupt withdrawal (N = 18), 6 (33.3%) reported symptoms (e.g., headaches and tiredness). Including decreases in functional ratings, a total of 7 of the 18 (38.8%) could be considered to have experienced caffeine withdrawal. The gradual withdrawal group (N = 20) reported minimal if any caffeine withdrawal symptoms. A third group (N = 18) was kept on a level dose of caffeine for comparison. When participants are unaware of the caffeine-withdrawal focus of the study, these results suggest that both the frequency and severity of caffeine-withdrawal symptoms are much lower than found in some previous reports and that clinically significant symptoms may be uncommon events among the general population.

Attenuation of the euphoric effects of cocaine by the dopamine D1/D5 antagonist ecopipam (SCH 39166)

BACKGROUND

The subjective and reinforcing effects of cocaine in humans are associated with the enhancement of endogenous dopamine function in the mesolimbic system. This study examined the role of dopamine D1-like receptors in the behavioral and mood effects of cocaine by evaluating the effects of the selective D1/D5 antagonist ecopipam (SCH 39166) on subjective responses to intravenous cocaine in 11 subjects with cocaine dependence as defined by DSM-IV.

METHODS

Subjects were pretreated in a randomized double-blind fashion with either placebo or 10 mg, 25 mg, or 100 mg of ecopipam orally on 4 separate occasions. Two hours later a single intravenous injection of 30 mg of cocaine was administered. Subjective and cardiovascular responses were measured and blood samples for pharmacokinetic evaluation were obtained prior to cocaine dosing and at various times after dosing.

RESULTS

The euphoric (P = .004) and stimulating (P = .03) effects of cocaine were attenuated in a dose-dependent manner by ecopipam, while ratings of desire to take cocaine were diminished (P = .02). Ecopipam in combination with cocaine was safe and well tolerated.

CONCLUSION

These data indicate a potentially important role for D1-like receptors in the acute mood-altering and rewarding effects of cocaine in humans.

Damage to the superior gluteal nerve after two different approaches to the hip

We have carried out a blind, prospective study of 50 consecutive patients undergoing replacement arthroplasty of the hip using two different approaches. Clinical assessment, including the Harris hip score and a modified Trendelenberg test, and electrophysiological examination of the abductor muscles of the hip were undertaken before and three months after surgery. We found that 48% of patients had preoperative evidence of chronic injury to the superior gluteal nerve. Perioperative injury to the nerve occurred commonly with both approaches to the hip. We did not find a significant correlation between injury to the superior gluteal nerve and clinical problems.

The NMDA receptor partial agonist, 1-aminocyclopropanecarboxylic acid (ACPC), reduces ethanol consumption in the rat

The present studies assessed the effects of both systemic and intraaccumbens injections of 1-aminocyclopropanecarboxylic acid (ACPC), and NMDA partial agonist, on ethanol consumption in a limited access procedure in Wistar rats. Systemically administered ACPC reduced ethanol consumption in a dose-dependent manner, while a single dose of ACPC administered bilaterally into the nucleus accumbens also reversibly reduced ethanol consumption. Indirect measures of general appetitive behavior showed no effect of ACPC on weight or water intake, which suggests that this effect of ACPC may be specific to ethanol. These data are compatible with the role of NMDA receptors in modulating ethanol consumption and provide the first data showing that ACPC can reduce ethanol consumption. ACPC has neuroprotective effects and does not show the psychotomimetic effects observed with NMDA receptor agents. Thus, ACPC may be helpful in future clinical studies designed to reduce alcohol use.

The disabling nature of comorbid depression among older DUI recipients

Alcoholism and depression are two of the most common and disabling mental illnesses in late life. This study is a descriptive report of a sample of 49 adults who had recently been convicted of Driving Under the Influence of alcohol (DUI). A lifetime history of alcohol abuse or dependence was present in 48 subjects (98%), while a depressive disorder occurred in 24 (49%) of the subjects. Concurrent alcoholism and depression, present in 12 subjects (24.5%), produced greater self-reported disability compared to those subjects with alcoholism alone. One-year longitudinal follow-up was available on 31 subjects (63.3%). Over the course of one year, there were no changes in drinking behavior, depressive symptoms, or self-reported quality of life. These data support previous studies that suggest greater disability in patients with concurrent mental illnesses.

Continuing care for cocaine dependence: comprehensive 2-year outcomes

This report presents 2-year outcome data from an outpatient continuing care study in which cocaine-dependent patients (N = 132) were randomly assigned to either standard group counseling (STND) or individualized relapse prevention (RP). Data on cocaine outcomes during the 6-month treatment phase of the study were presented in an earlier report (J. R. McKay, A. I. Alterman, J. S. Cacciola, M. R. Rutherford, & C. P. O'Brien, 1997). In the present report, a continuing care condition main effect was obtained on only 1 of 8 outcome variables examined. However, patients who endorsed a goal of absolute abstinence on entering continuing care had better cocaine use outcomes in RP than in STND, whereas the opposite was the case for those with less stringent abstinence goals. In addition, patients with current cocaine or alcohol dependence on entering continuing care who received RP had better cocaine use outcomes in Months 1-6 and better alcohol use outcomes in Months 13-24 than those in STND.

Open trials as a method of prioritizing medications for inclusion in controlled trials for cocaine dependence

This paper describes a rapid and systematic method of using open trials to identify medications that may be useful for the treatment of cocaine dependence. Results of these open trials can be used to prioritize medications for inclusion in subsequent double-blind, placebo-controlled trials. Preliminary results are presented from the evaluation of propranolol, nefazodone, and the combination of phentermine and fenfluramine (phen/fen). Each medication was evaluated in an open trial, and results were compared to results obtained from a group that received a multivitamin. Outcome measures included treatment retention, urine toxicology screens, self-reported cocaine use, and changes on the Addiction Severity Index (ASI). Treatment retention was significantly better in the propranolol group than in the multivitamin group. Concurrent alcohol abuse was associated with increased rates of attrition in the multivitamin group, and the phen/fen group, but not in the propranolol group. Neither the nefazodone nor the phen/fen groups showed any outcome advantages over the multivitamin group. We conclude that propranolol may enhance retention among cocaine-dependent patients, especially among those who also abuse alcohol. These results encourage a double-blind, placebo-controlled trial of propranolol.

The effects of naltrexone on alcohol and cocaine use in dually addicted patients

Concurrent dependence on cocaine and alcohol is common among patients seeking addiction treatment. This study was undertaken to explore the effectiveness of naltrexone (150 mg) as a potential treatment for patients who are alcohol and cocaine dependent. Of 15 subjects enrolled in the 12-week, open medication trial, 7 subjects did not complete the study. Relapse to clinically significant drinking occurred in 7 subjects (47%). There was a reduction in the average daily amount of alcohol consumed from pretreatment to treatment (p < .001) and the percentage of days engaged in drinking behavior (p < .001). Similarly, there was a reduction in the average weekly amount spent on cocaine from pretreatment to treatment (p = .001) and the percentage of days using cocaine (p < .001). This preliminary study suggests that naltrexone (150 mg) may be tolerable in patients dependent upon alcohol and cocaine and may be effective in reducing both cocaine and alcohol use. The results of this study provide a rationale for a double-blind placebo-controlled study of the efficacy of naltrexone in this difficult to treat but prevalent population.

Comparing levels of cocaine cue reactivity in male and female outpatients

Thirty-eight female and 26 male cocaine-dependent outpatients were exposed to cocaine cues in a laboratory setting. Stimuli consisted of an audiotape of patients discussing cocaine use, a videotape of simulated cocaine preparation and use, and the handling of cocaine paraphernalia. Overall, the stimuli produced significant decreases in skin temperature and skin resistance, and significant increases in heart rate, self-reported drug states (high, craving, and withdrawal), and self-reported negative moods. Females were more likely to report increased craving in response to the cues than males, but there were no other gender differences in any of the responses. Levels of reactivity in females were comparable to the results of previous studies with all male samples. These results support the use of a constant set of cues in future treatment studies employing gender-balanced patient samples.

Limbic activation during cue-induced cocaine craving

OBJECTIVE

Since signals for cocaine induce limbic brain activation in animals and cocaine craving in humans, the objective of this study was to test whether limbic activation occurs during cue-induced craving in humans.

METHOD

Using positron emission tomography, the researchers measured relative regional cerebral blood flow (CBF) in limbic and comparison brain regions of 14 detoxified male cocaine users and six cocaine-naive comparison subjects during exposure to both non-drug-related and cocaine-related videos and during resting baseline conditions.

RESULTS

During the cocaine video, the cocaine users experienced craving and showed a pattern of increases in limbic (amygdala and anterior cingulate) CBF and decreases in basal ganglia CBF relative to their responses to the non-drug video. This pattern did not occur in the cocaine-naive comparison subjects, and the two groups did not differ in their responses in the comparison regions (i.e., the dorsolateral prefrontal cortex, cerebellum, thalamus, and visual cortex).

CONCLUSIONS

These findings indicate that limbic activation is one component of cue-induced cocaine craving. Limbic activation may be similarly involved in appetitive craving for other drugs and for natural rewards.

Effects of naltrexone administered repeatedly across 30 or 60 days on ethanol consumption using a limited access procedure in the rat

The present study examined the effects of naltrexone, 1.0 mg/kg, administered repeatedly across both 30 and 60 days on the consumption of an unsweetened ethanol solution by outbred Wistar rats in a limited access procedure. Naltrexone significantly suppressed consumption of ethanol across both 30 and 60 days. These results provide no evidence for the development of tolerance based on such factors as receptor upregulation or supersensitivity due to the repeated administration of naltrexone across extended periods. Ethanol consumption during the final one-third of the naltrexone sessions, for both the 30- and 60-day groups, was significantly lower than during the initial sessions. These results suggest an associative component. That is, the rats apparently learned that ethanol consumption was no longer reinforcing across repeated exposures. After termination of naltrexone treatment, consumption of ethanol immediately increased. However, consumption in those rats who were administered naltrexone for 60 days remained significantly suppressed, compared with consumption in those rats who were administered naltrexone for 30 days. These results suggest that naltrexone reduces ethanol consumption by blocking endogenous opioid receptors that mediate, at least in part, ethanol's reinforcing properties. In addition, these data suggest that longer clinical use of naltrexone, as a pharmacological adjunct to psychosocial treatment for alcohol-dependent patients, may be beneficial in reducing the number of relapses experienced.

Clinical correlations with carbohydrate-deficient transferrin levels in women with alcoholism

Carbohydrate-deficient transferrin (CDT) has received increasing attention as a potential biological marker for heavy drinking or as an objective marker of relapse in patients who are treated for alcohol dependence. Previous studies have demonstrated the utility of CDT among men, but there are fewer and inconsistent reports on the utility of CDT among women. This study reports in a sample of 40 alcohol-dependent women, the association between CDT levels, and several different types of measures of drinking intensity including frequency of heavy drinking. Although the majority of drinking indices correlated with CDT levels in men, among women, CDT levels were significantly correlated with the percentage of days of heavy drinking when heavy drinking day was defined as drinking 6 or more drinks per drinking day. The results also support an association between current menstrual function, CDT levels, and drinking indices. These findings suggest that the pattern of drinking (combining high frequency and high intensity) may be an important determinant of CDT levels in women with alcohol dependence, compared with men.

Random versus nonrandom assignment in the evaluation of treatment for cocaine abusers

Cocaine-abusing patients randomly assigned to day-hospital or inpatient rehabilitation were compared with patients who self-selected these treatment settings to examine differences in substance use and psychosocial outcomes under experimental and nonexperimental designs. There was little evidence of setting or assignment effects or Setting x Assignment interactions over the 12-month follow-up period. However, Assignment x Time interactions were obtained with 2 measures of cocaine use and measures of family-social and psychiatric problem severity. These interactions indicated greater problem severity at intake among the randomized patients coupled with greater improvements by the 3-month follow-up relative to the nonrandomized patients. Findings suggest that randomized studies of treatment for cocaine abuse may produce somewhat larger estimates of improvement than what is observed in more typical treatment situations.