Sustained cocaine abstinence in methadone maintenance patients through voucher-based reinforcement therapy

BACKGROUND

Chronic cocaine abuse remains a serious and costly public health problem. This study assessed the effectiveness of a voucher-based reinforcement contingency in producing sustained cocaine abstinence.

METHODS

A randomized controlled trial compared voucher-based reinforcement of cocaine abstinence to noncontingent voucher presentation. Patients were selected from 52 consecutively admitted injecting heroin abusers in a methadone maintenance treatment program. Patients with heavy cocaine use during baseline period (N = 37) participated. Except where otherwise indicated, the term cocaine abuse is used in this article in a generic sense and not according to the DSM-III-R definition. Patients exposed to abstinence reinforcement received a voucher for each cocaine-free urine sample (ie, negative for benzoylecgonine) provided three times per week throughout a 12-week period; the vouchers had monetary values that increased as the number of consecutive cocaine-free urine samples increased. Control patients received noncontingent vouchers that were matched in pattern and amount to the vouchers received by patients in the abstinence reinforcement group.

RESULTS

Patients receiving vouchers for cocaine-free urine samples achieved significantly more weeks of cocaine abstinence (P = .007) and significantly longer durations of sustained cocaine abstinence (P = .001) than controls. Nine patients (47%) receiving vouchers for cocaine-free urine samples achieved between 7 and 12 weeks of sustained cocaine abstinence; only one control patient (6%) achieved more than 2 weeks of sustained abstinence. Among patients receiving vouchers for cocaine-free urine samples, those who achieved sustained abstinence ( > or = 5 weeks) had significantly lower concentrations of benzoylecgonine in baseline urine samples than those who did not achieve sustained abstinence (P < or = .01). Patients receiving voucher reinforcement rated the overall treatment quality significantly higher than controls (P = .002).

CONCLUSION

Voucher-based reinforcement contingencies can produce sustained cocaine abstinence in injecting polydrug abusers.

A comparison of cocaine-dependent cigarette smokers and non-smokers on demographic, drug use and other characteristics

Cigarette smoking (n = 156) and non-smoking (n = 43) individuals seeking out-patient treatment for cocaine-dependence were compared on demographic, drug use and other variables. Smokers were younger, less educated, earned less money, began cocaine use at an earlier age, used cocaine more frequently, were more likely to inject or smoke cocaine, were more likely to report legal troubles and having harmed someone physically as consequences of their cocaine use, and had more severe employment and legal problems than non-smokers as measured by the Addiction Severity Index. Smoking remained a significant predictor of more frequent cocaine use, using more grams of cocaine per week and using cocaine via an injection or smoking route even after adjusting for demographic differences between smokers and non-smokers via regression analyses. Smoking status was not significantly related to treatment outcome. Overall, these results indicate that cocaine-dependent smokers represent a more high-risk group than non-smokers. This relationship between smoking, cocaine use, and associated problems merits further investigation.

Meconium increases surfactant secretion in isolated rat alveolar type II cells

One of the underlying causes of pathophysiology of meconium aspiration syndrome is access of meconium to the alveolar space and inhibition of activity of lung surfactant. This study examines the effects of meconium on type II cell function by following surfactant secretion. Isolated rat alveolar type II cells were labeled with [methyl-3H]choline during the initial 21-22 h of incubation. During the subsequent 150 min of incubation, phosphatidylcholine (PC) secretion in the presence of 1% meconium was increased 250 +/- 11% (mean +/- SE, n = 23) over controls. The secretagogue effect was concentration-dependent and reached a maximum at 0.5% meconium. The meconium effect was not due to cellular toxicity as evaluated by vital dye exclusion, lactate dehydrogenase release, and PC synthesis. The secretagogue effect of meconium was associated with the particulate fraction pelleted by centrifugation of the suspension for 1 h at 100,000 x g. Heat treatment of meconium decreased the effect, suggesting the active component to be a protein. The effect of meconium was additive with that of 0.1 mM terbutaline, or 1 mM ATP, suggesting different pathways of action of each agent. The effect of meconium was reduced in the presence of 0.1 mM 4,4'-diisothiocyanato-2,2'-disulfonic acid, or 100 ng/mL surfactant protein A. These agents were previously shown to inhibit surfactant secretion in a stimulus-independent manner. Our results suggest that meconium at low concentrations is not toxic to type II cells, and a component of meconium, possibly a protein, increases PC secretion.

Alcohol pretreatment increases preference for cocaine over monetary reinforcement

Non-dependent cocaine users participated in a two-phase experiment conducted under controlled laboratory conditions. During phase 1, subjects sampled intranasal cocaine (100 mg) and placebo (96 mg lactose + 4 mg cocaine) in separate sessions and under double-blind conditions. Sampling sessions were followed by a single choice session in which subjects made a maximum of ten choices between 10 mg unit doses of cocaine or placebo. Only subjects who reliably (> or = 70%) chose cocaine over placebo in phase 1 participated in phase 2. During phase 2, subjects participated in a series of nine experimental sessions conducted on different days in which they were pretreated with varying doses of alcohol (placebo, 0.5, and 1.0 g/kg) and made a maximum of ten choices between 10 mg unit doses of cocaine and an alternative reinforcer (i.e., varying amounts of money). Visual-analog ratings of drug effects and cardiac function were monitored across all experimental sessions. Cocaine was reliably chosen over placebo by the majority (9 of 11) of subjects during phase 1, demonstrating that the drug functioned as a reinforcer. During phase 2, alcohol pretreatment significantly increased choice of cocaine over the alternative reinforcer, while increasing monetary value decreased cocaine choice. Ratings on some visual-analog scales (e.g., good effects) paralleled cocaine choice, with alcohol pretreatment increasing ratings and greater monetary value decreasing them. Cardiac output increased above baseline levels across all alcohol and monetary conditions, but maximal effects were observed during sessions involving pretreatment with the active alcohol doses. Overall, these results demonstrate (a) that alcohol can increase preference for cocaine over alternative reinforcers and thereby may thwart efforts to reduce or abstain from cocaine use, (b) that availability of an alternative, non-drug reinforcer can effectively decrease preference for cocaine, and (c) that combined use of alcohol and cocaine increases cardiac risk compared to use of cocaine alone.

Preferences for clinic privileges, retail items and social activities in an outpatient buprenorphine treatment program

This study evaluated preferences for various clinic privileges, retail items, and social activities for use in an outpatient opioid dependence treatment program. Fifty-three opioid-dependent patients who received treatment with buprenorphine for at least 30 days rank ordered 11 clinic privileges, 19 retail items, and 8 social activities from the most desirable (a rank of 1) to the least desirable (a rank equal to the number of items in that category). Additional questions determined preference for counseling frequency and dosing levels. The top three mean rankings for clinic privileges were $50 cash for opioid-negative urines (2.8), take-home doses of buprenorphine (3.6), and voucher points for opioid-negative urines (4.7). The top three mean rankings for retail items were restaurant gift certificates (4.1), movie passes (4.9), and videotape movie and player rentals (6.8). The top three mean rankings for social activities were movies (2.4), barbecues (3.8), and hiking trips (4.3). There was no preference reported for increases or decreases in counseling frequency. Seventy-four percent of subjects preferred to increase their buprenorphine dose by an average of 60.84% independent of their present dose. Consistent with previous findings from methadone treatment, cash payments for opioid-negative urines and take-home medication were the highest ranked clinic privileges. These results suggest that various retail items and social activities may also be useful for reinforcing positive treatment outcomes during outpatient opioid treatment.

An experimental comparison of three different schedules of reinforcement of drug abstinence using cigarette smoking as an exemplar

The efficacy of three different schedules of reinforcement for promoting and sustaining drug abstinence was compared in this study. Cigarette smoking was studied as an exemplar of stimulant drug self-administration. Sixty cigarette smokers were assigned to one of three groups (progressive rate of reinforcement, fixed rate of reinforcement, and yoked control). Participants in all three groups were asked to refrain from smoking for 1 week. Participants in the progressive and fixed groups achieved greater mean levels of abstinence than those in the control group. Participants in the progressive group were significantly less likely to resume smoking when they became abstinent than participants in the other groups.

The behavioral economics of concurrent drug reinforcers: a review and reanalysis of drug self-administration research

In economics, goods can function as substitutes, complements, or be independent of one another. These concepts refer to increases, decreases, or no change in the consumption of one item as the price of a second item increases. This review examined whether these economic terms can be used to describe relationships between concurrently available reinforcers in drug self-administration research. Sixteen drug self-administration studies that examined the effects of concurrent reinforcers were identified through a MEDLINE search. Across these studies, the following substances were employed: caffeinated coffee, cocaine, etonitazene, ethanol, heroin, food, methadone, morphine, nicotine cigarettes, pentobarbital, phencyclidine, sucrose and water. These studies were reanalyzed and the results were shown to be consistent with these economic notions. These analyses also showed that relationships among the concurrently available reinforcers were reliable within and across studies, that concurrently available reinforcers can affect each other asymmetrically, and that the relative price may determine the magnitude of effect for substitutes. These findings suggest that these economic concepts may be useful in characterizing the type and magnitude of interactions between concurrently available reinforcers and may suggest potential mechanisms that determine these relationships.

Alcohol dependence and simultaneous cocaine and alcohol use in cocaine-dependent patients

Alcohol use and associated factors were studied in 124 consecutive cocaine-dependent admissions to an outpatient substance abuse clinic. Two analyses were conducted: First, those who did and did not meet criteria for current alcohol dependence were compared on sociodemographic and drug use characteristics. Second, patients who reported simultaneous cocaine and alcohol use on > 50% vs. < or = 50% of the occasions that they used cocaine were compared using the same dependent measures. Fifty-seven percent of patients met criteria for current alcohol dependence. Those with and without alcohol dependence did not differ on any sociodemographic characteristics, but those with dependence scored higher on the alcohol and family subscales of the Addiction Severity Index, the Michigan Alcoholism Screening Test, and measures of alcohol use, and were more likely to use cocaine and alcohol simultaneously, to use cocaine with friends and in social settings, and were more likely to report financial difficulties and unwanted sexual relations as adverse consequences of their cocaine use. Sixty-four percent of patients reported > 50% simultaneous cocaine and alcohol use. The two groups did not differ on any sociodemographic characteristics, but those reporting greater simultaneous use were more likely to be alcoholic, scored higher on most measures of alcohol use, and were more likely to report using cocaine with friends and in social settings. The only other differences observed between the two groups were fewer reports of seizures or difficulty concentrating in the group reporting greater simultaneous use. The present results confirm prior reports on the widespread prevalence of alcohol dependence among cocaine-dependent patients and extend them by providing new information on the prevalence and other characteristics of simultaneous cocaine and alcohol use.

A preliminary investigation of outcome following gradual or rapid buprenorphine detoxification

Eight opioid-dependent individuals were maintained on daily sublingual buprenorphine (8 mg) for 28 days and assigned randomly to one of two outpatient detoxification schedules under double-blind, double-dummy conditions. The two detoxification schedules were buprenorphine gradual (36 days; N = 3) or buprenorphine rapid (12 days; N = 5). Outcome variables were subject- and observer-ratings of opioid withdrawal, treatment retention and illicit-opioid use. Outcome measures were similar for the two groups during buprenorphine maintenance. Increases in subject-rated opioid withdrawal and illicit-opioid use, and a drop in treatment retention occurred during rapid detoxification. Stable subject-rated opioid withdrawal and treatment retention, and less illicit-opioid use occurred during gradual detoxification. These data suggest that gradual reduction in buprenorphine dose is likely to produce superior treatment outcomes than more rapid buprenorphine detoxification.

Nicotine withdrawal versus other drug withdrawal syndromes: similarities and dissimilarities

Many of the symptoms of nicotine withdrawal are similar to those of other drug withdrawal syndromes: anxiety, awakening during sleep, depression, difficulty concentrating, impatience, irritability/anger and restlessness. Slowing of the heart rate and weight gain are distinguishing features of tobacco withdrawal. Although nicotine withdrawal may not produce medical consequences, it lasts for several weeks and can be severe in some smokers. Like most other drug withdrawals, nicotine withdrawal is time-limited, occurs in non-humans, is influenced by instructions/expectancy and abates with replacement therapy and gradual reduction. Unlike some other drug withdrawal syndromes, protracted, neonatal or precipitated withdrawal does not occur. Whether nicotine withdrawal is associated with tolerance, acute physical dependence, greater duration and intensity of use, rapid reinstatement, symptom stages, cross-dependence with other nicotine ligands, reduction by non-pharmacological interventions and genetic influences is unclear. Whether nicotine withdrawal plays a major role in relapse to smoking has not been established but this is also true for other drug withdrawal syndromes.

Incentives improve outcome in outpatient behavioral treatment of cocaine dependence

OBJECTIVE

To assess whether incentives improved treatment outcome in ambulatory cocaine-dependent patients.

METHOD

Forty cocaine-dependent adults were randomly assigned to behavioral treatment with or without an added incentive program. The behavioral treatment was based on the Community Reinforcement Approach and was provided to both groups. Subjects in the group with incentives received vouchers exchangeable for retail items contingent on submitting cocaine-free urine specimens during weeks 1 through 12 of treatment, while the group without incentives received no vouchers during that period. The two groups were treated the same during weeks 13 through 24.

RESULTS

Seventy-five percent of patients in the group with vouchers completed 24 weeks of treatment vs 40% in the group without vouchers (P = .03). Average durations of continuous cocaine abstinence documented via urinalysis during weeks 1 through 24 of treatment were 11.7 +/- 2.0 weeks in the group with vouchers vs 6.0 +/- 1.5 weeks in the group without vouchers (P = .03). At 24 weeks after treatment entry, the voucher group evidenced significantly greater improvement than the no-voucher group on the Drug scale of the Addiction Severity Index (ASI), and only the voucher group showed significant improvement on the ASI Psychiatric scale.

CONCLUSIONS

Incentives delivered contingent on submitting cocaine-free urine specimens significantly improve treatment outcome in ambulatory cocaine-dependent patients.

Effects of diazepam and hydromorphone in triazolam-trained humans under a novel-response drug discrimination procedure

Seven healthy normal male and female volunteers (21-31 years) were trained to discriminate between the benzodiazepine triazolam (0.32 mg/70 kg, PO; e.g., drug A) and placebo (e.g., drug B) under a three-choice, instructed novel response drug discrimination procedure. Once the criterion for discrimination was met (i.e., > 85% correct responding on four consecutive sessions), dose-effect curves were determined for triazolam (0.1-0.56 mg/70 kg), the benzodiazepine diazepam (10-32 mg/70 kg) and the opioid agonist hydromorphone (1-6 mg/70 kg). Subjects met the criterion for discrimination within four to six sessions. Triazolam and diazepam produced dose-related increases in triazolam-appropriate responding and no novel-appropriate responding at any dose tested. In contrast, hydromorphone generally increased novel-appropriate responding in a dose-related manner with placebo-appropriate responding and some triazolam-appropriate responding at intermediate doses occurring also. Triazolam and diazepam produced qualitatively similar increases on several measures of sedative drug effects; hydromorphone increased ratings of "like novel" and sedative-like effects in subjects who discriminated hydromorphone as novel relative to those who did not. These results indicate that the novel response drug discrimination procedure enhances the specificity of the triazolam-placebo discrimination.

A behavioral economic analysis of concurrently available money and cigarettes

In economic terms, consumption of a reinforcer is determined by its price and the availability and price of other reinforcers. This study examined the effects of response-requirement (i.e., price) manipulations on the self-administration of two concurrently available reinforcers. Six cigarette smokers participated in 4-hr sessions in which money and puffs on a cigarette were concurrently available according to fixed-ratio schedules of reinforcement. Once stable responding was obtained with both reinforcers available at Fixed Ratio 100, the response requirement for one reinforcer was systematically varied (Fixed Ratio 1,000 and 2,500), while the other reinforcer remained scheduled at Fixed Ratio 100. Increasing the fixed-ratio size for a reinforcer decreased its consumption, with a greater decrease occurring for monetary reinforcement. This finding was quantified in economic terms as own-price elasticity, with elasticity coefficients greater for money than cigarettes. The effects of fixed-ratio size on response output also differed across the two reinforcers. Although greater responding occurred for money at Fixed Ratio 100, increases in fixed-ratio size (for money) decreased responding for money, whereas the same increase in fixed-ratio size (for puffs) increased responding for puffs. Finally, increasing the fixed-ratio size for one reinforcer had little effect on consumption of the other concurrently available reinforcer. This finding was quantified as cross-price elasticity, with elasticity coefficients near 0.0 for most subjects, indicating little or no reinforcer interaction. The results indicate that the reinforcing effects of cigarettes and money in the setting studied here differed, and that the effects produced by changing the price of one reinforcer did not interact with the consumption of the other concurrently available reinforcer.

Participation of significant others in outpatient behavioral treatment predicts greater cocaine abstinence

The present study was conducted to identify predictors of cocaine abstinence during outpatient behavioral treatment for cocaine dependence. Subjects were 52 cocaine-dependent adults. Stepwise logistic regression was used to identify predictors of abstinence during a 12-week treatment program. Demographic, drug use, and other subject characteristics were examined. The single best predictor of cocaine abstinence was whether a significant other participated in treatment. The odds of achieving a criterion level of cocaine abstinence were approximately 20 times greater for subjects who had a significant other participate in treatment. Importantly, significant others participated in a structured form of relationship counseling and behavioral contracting that is well specified and can be readily tested in a prospective, randomized trial. Considering the pressing need for the development of effective treatments for cocaine dependence, such a trial merits consideration.

Applying behavioral concepts and principles to the treatment of cocaine dependence

Cocaine dependence continues to be a widespread and serious public health problem in the US. Unfortunately, no consensus exists about how to treat cocaine dependence. Various pharmacological and psychological therapies have been investigated with mixed results. In this report we review findings from several studies conducted to assess the efficacy of an outpatient behavioral treatment for cocaine dependence. The treatment is based on the concepts and principles of behavior analysis and behavioral pharmacology. Results obtained to date indicate the treatment is acceptable to patients, retains them in treatment, engenders clinically significant levels of cocaine abstinence and can be adapted to deal with other forms of substance abuse common in this population. Overall, we believe the treatment represents an important step towards the development of empirically based and effective treatments for cocaine dependence.

Influence of an alternative reinforcer on human cocaine self-administration

Identifying factors that modulate cocaine self-administration is fundamental to the development of effective strategies to treat and prevent cocaine abuse. In the present study, the influence of an alternative reinforcer on the probability of cocaine use was examined in four adult humans under controlled laboratory conditions. During eleven test sessions, subjects chose between cocaine hydrochloride vs. placebo or between cocaine vs. varying amounts of money (0-$2.00/choice). Subjects made a maximum of 10 exclusive choices per session. Cocaine and placebo were administered intranasally in 10 mg unit doses under double-blind conditions. Subjects exclusively chose cocaine over placebo demonstrating that the drug functioned as a reinforcer. During sessions comparing cocaine vs. money, choice of cocaine decreased as the amount of money available in the monetary option increased, with all subjects exclusively choosing the monetary option in the $2.00 per choice condition. These results systematically replicate and extend to humans prior findings in laboratory animals demonstrating that the availability of alternative, nondrug reinforcers can significantly decrease cocaine use.

Alternate-day dosing during buprenorphine treatment of opioid dependence

Thirteen opioid-dependent outpatients participated in a double-blind, placebo-controlled, crossover trial. Twenty-one days of daily sublingual buprenorphine administration were compared to 21-days of alternate-day buprenorphine administration where patients received twice their daily maintenance dose every other day with placebo on the interposed day. Observer- and subject-rated measures of opioid agonist and withdrawal effects, pupillary diameter, and dose identifications were collected daily. Ten subjects (77%) completed the study (n = 6, 4 mg/70 kg; n = 4, 8 mg/70 kg); 8 subjects (62%) participated in a second crossover. Sixteen of seventeen measures of opioid agonist and withdrawal effects obtained during alternate-day administration did not differ significantly from those obtained during daily dosing in the ten subjects completing the study. The only significant difference observed was in subject-rated agonist effects, which were significantly lower during alternate-day than daily administration. No differences were observed between treatments on any measure for the eight subjects completing a second crossover. These data suggest that buprenorphine can be administered safely every 48 hours by doubling the maintenance dose. This alternate-day schedule permits patients to attend the clinic less frequently without the risk of diversion associated with take-home doses, may be cost-effective for programs, and may be useful in settings in which travel to the clinic is a barrier to treatment.

The taking of free condoms in a drug abuse treatment clinic: the effects of location and posters

Drug abuse treatment programs can help reduce high-risk sexual behavior in drug users by promoting condom use. This study examined the influence of distribution location and poster prompts on the taking of free condoms in a drug abuse treatment clinic. Over 6 months, condoms were available alternately, with and without poster prompts, in the clinic's private restroom or public waiting area. Overall, 381% more condoms were taken from the restroom. The presence of poster prompts did not affect condom taking. These results suggest that distribution location is a critical factor in promoting condom taking in public clinic.

Abuse liability of alprazolam relative to other commonly used benzodiazepines: a review

Nonhuman and human studies comparing the abuse liability of alprazolam to other commonly used benzodiazepines are reviewed. These studies are reviewed to determine to what extent prospective, controlled, experimental studies support opinions that alprazolam's abuse liability is greater than that of other commonly used benzodiazepines. Studies comparing the self-administration of alprazolam, the discriminative stimulus effects of alprazolam, self-reported effects of alprazolam, physiological dependence on alprazolam, and adverse effects of alprazolam relative to other benzodiazepines are reviewed. Overall, the experimental literature does not support the widely held belief that alprazolam's abuse liability is greater than that of other benzodiazepines, but much more research is needed. Such research should focus explicitly on alprazolam's reinforcing effects, and the nature and severity of the discontinuation syndrome associated with its long-term use. Important issues such as selection of an appropriate comparison drug, selection of an appropriate population, dosing regimen and test doses need to be considered in future studies.