Nalorphine: increased sensitivity of monkeys formerly dependent on morphine

Three rhesus monkeys Macaca mulatta, formerly dependent on morphine, had increased sensitivity to nalorphine's effect of suppressing operant responding for food, as compared with two monkeys with no history of morphine exposure. Within the dose range employed, nalorphine injections produced emesis, salivation, and hyperirritability in formerly morphine-dependent monkeys but not in controls.

The relationship between self-reported cocaine withdrawal symptoms and history of depression

This study examined the relationship between cocaine withdrawal and lifetime history of depression (major depression, dysthymia). Participants with a history of regular cocaine use (n = 146) were administered the Structured Clinical Interview for the DSM-IV (SCID) and were asked to recall whether they experienced any of the six DSM-IV cocaine withdrawal symptoms. Results of bivariate analyses demonstrated that those meeting criteria for the cocaine withdrawal syndrome (dysphoria plus two or more other symptoms), in comparison to those who did not, were significantly (P<.001) more likely to have a lifetime history of depression. Lifetime history of depression was also more common in those individuals reporting the withdrawal symptoms of "dysphoria" (P<.001), "insomnia/hypersomnia" (P<.05), "vivid unpleasant dreams" (P<.01), and "psychomotor agitation/retardation" (P<.01). These relationships remained significant after controlling for demographics, severity of addiction, and the presence of opiate, alcohol and cannabis dependence or abuse. The withdrawal symptoms of "fatigue" and "increased appetite" were not associated with mood history. Results suggest that lifetime history of depression is strongly related to whether or not a cocaine abuser self-reports withdrawal symptoms. Several competing hypotheses regarding the nature of this relationship are discussed.

Novelty seeking as a predictor of treatment retention for heroin dependent cocaine users

This study examined the relationship between novelty seeking between treatment retention and among heroin dependent cocaine users. Participants were treated with buprenorphine maintenance and contingency management. The Tridimensional Personality Questionnaire's (TPQ) Novelty Seeking scale was administered to 68 participants prior to buprenorphine induction. Demographics, mood and anxiety disorders, antisocial personality disorder, and substance use were also assessed. Variables with significant relationships with overall retention were entered into a logistic regression analysis. In addition, using a survival analysis, all variables with significant relationships with time to drop-out were entered into a multivariate proportional hazards regression with time dependent covariates. Results demonstrated that although high novelty seekers, in comparison to low novelty seekers, were more likely to drop-out by the end of treatment, they had higher retention rates during the early phases of treatment. It is suggested that buprenorphine and contingency management were viewed by participants as novel treatment components and thus facilitated high novelty seekers' success early in treatment. If replicated, results suggest that inclusion of novel treatment components might facilitate retention among this at-risk group.

Contingency management interventions for treating the substance abuse of adolescents: a feasibility study

This article reports on the feasibility of using a contingency management intervention with adolescent smokers that has proven efficacious in adult substance abuse treatment. The study used 8 adolescent participants in an A (1 week)-B (1 week)-A (1 week) reversal design. During the 2 baseline phases, no contingencies were placed on cigarette smoking, and adolescents received money noncontingently. During the experimental intervention week, adolescents received payment contingent on not smoking. The magnitude of reimbursement available during the baseline and intervention phases was equated. Results indicated that the contingency management intervention was effective in reducing smoking, both in terms of increasing the total number of abstinences and consecutive abstinences. In addition, changes in adolescents' affective states during smoking cessation were found. Anxiety, depression, anger, and fatigue were reported, and these negative states ceased once smoking resumed.

Gender differences in problem severity at assessment and treatment retention

Women in treatment for substance abuse have been reported to have more severe problems at assessment than men but not to differ in treatment retention. To examine gender differences in problems at assessment, 30-day retention, and treatment completion, data from Detroit's publicly funded substance abuse treatment system were used. Women had significantly more severe problems at assessment, lower 30-day retention, and lower treatment completion rates than men. These gender differences in retention remained significant even after controlling for problem severity, primary drug of abuse, and referred treatment setting. There was no evidence of improvements in women's problems at assessment or retention over time during this period. Women presented with more severe problems at assessment and were less likely to stay in treatment for 30 days or to complete treatment than men. Monitoring gender differences in problems at presentation and retention outcomes is recommended to assess local need for interventions.

Buprenorphine-induced changes in mu-opioid receptor availability in male heroin-dependent volunteers: a preliminary study

A principle of opioid pharmacotherapy is that high medication doses should occupy fractionally more opioid receptors that mediate heroin effects. In this preliminary study we examined in vivo mu opioid receptor (muOR) binding in three healthy opioid-dependent volunteers during maintenance on 2 and 16 mg sublingual buprenorphine (BUP) liquid, and after detoxification (0 mg) under double-blind, placebo-controlled conditions, and once in matched controls. Binding measures were obtained with the muOR-selective radioligand [11C]carfentanil (CFN) and PET 4 hrs after BUP administration. BUP induced dose-dependent reductions in muOR availability, 36-50% at 2 mg and 79-95% at 16 mg relative to placebo. Heroin abusers also had greater muOR binding potential in the inferofrontal cortex and anterior cingulate regions during placebo, compared to matched controls. Further studies are warranted to examine the relationship of muOR availability with BUP therapeutic actions, and the clinical implications of increased muOR binding during withdrawal.

Contingency management interventions for treating the substance abuse of adolescents: a feasibility study

This article reports on the feasibility of using a contingency management intervention with adolescent smokers that has proven efficacious in adult substance abuse treatment. The study used 8 adolescent participants in an A (1 week)-B (1 week)-A (1 week) reversal design. During the 2 baseline phases, no contingencies were placed on cigarette smoking, and adolescents received money noncontingently. During the experimental intervention week, adolescents received payment contingent on not smoking. The magnitude of reimbursement available during the baseline and intervention phases was equated. Results indicated that the contingency management intervention was effective in reducing smoking, both in terms of increasing the total number of abstinences and consecutive abstinences. In addition, changes in adolescents' affective states during smoking cessation were found. Anxiety, depression, anger, and fatigue were reported, and these negative states ceased once smoking resumed.

Contingency management for accurate predictions of urinalysis test results and lack of correspondence with self-reported drug use among polydrug abusers

Contingency management procedures have proven effective in the treatment of drug-dependent patients. These procedures, however, often require frequent urine testing, which is too costly for community treatment programs. To make urine-testing procedures more cost effective, the feasibility of reinforcing accurate predictions of urine drug screen (UDS) results was evaluated. Participants made extremely accurate UDS predictions, particularly when they made drug-positive predictions, regardless of whether predictions were reinforced. However, self-reports of recent drug use had poor correspondence with predictions of UDS results. Results suggested that if programs only tested samples predicted to be drug free, considerable cost savings could be incurred. Further research is needed to determine if validity would be enhanced by using a proportion of costs saved to provide nominal reinforcement when samples were verified to be drug free.

Treatment of heroin-dependent poly-drug abusers with contingency management and buprenorphine maintenance

This study targeted poly-drug (cocaine plus heroin) abstinence among buprenorphine-maintained participants with a 12-week voucher-based reinforcement therapy (VBRT) phase versus a yoked control condition. Baseline levels of cocaine and heroin use were significant predictors of treatment outcome, regardless of treatment assignment. Overall, there were no significant group differences on treatment outcome. However, among the subsample that produced one or more poly-drug-free urine results, VBRT participants had significantly increased cocaine-but not heroin and poly-drug-abstinence, although all results were in the predicted direction. Results suggest that for those who achieve poly-drug abstinence, VBRT may enhance treatment outcome. However, improved interventions, perhaps targeting single-drug abstinence, increasing reinforcement magnitude, or both, may be necessary to promote initial poly-drug abstinence in this population.

Contingency management for accurate predictions of urinalysis test results and lack of correspondence with self-reported drug use among polydrug abusers

Contingency management procedures have proven effective in the treatment of drug-dependent patients. These procedures, however, often require frequent urine testing, which is too costly for community treatment programs. To make urine-testing procedures more cost effective, the feasibility of reinforcing accurate predictions of urine drug screen (UDS) results was evaluated. Participants made extremely accurate UDS predictions, particularly when they made drug-positive predictions, regardless of whether predictions were reinforced. However, self-reports of recent drug use had poor correspondence with predictions of UDS results. Results suggested that if programs only tested samples predicted to be drug free, considerable cost savings could be incurred. Further research is needed to determine if validity would be enhanced by using a proportion of costs saved to provide nominal reinforcement when samples were verified to be drug free.

Reinforcing and subjective effects of morphine in human opioid abusers: effect of dose and alternative reinforcer

RATIONALE

Although most opioid self-administration research has been conducted with laboratory animals, such research with humans is necessary to answer questions unique to human drug-taking behavior.

OBJECTIVE

We investigated the influence of morphine dose and an alternative non-drug reinforcer on choice between morphine versus money and examined the relationship between drug-reinforced behavior and subjective euphoria.

METHODS

Five male opioid users participated in the 7-week study. During the first 5 weeks, a single dose of morphine (0, 4, 8, 16, or 32 mg/70 kg) was available each week. On Monday, subjects received an IM injection of the dose tested that week. On Tuesday, Thursday, and Friday, subjects could work for morphine or money under a second-order, progressive ratio schedule. For each primary ratio completed on the drug lever, subjects earned one-ninth of the available drug dose, and for each ratio completed on the money lever, subjects earned $1. Total amount of drug earned was administered in a single IM injection at the end of the session; money earned was credited to the subject's account.

RESULTS

As morphine dose increased, responding for drug increased in an orderly manner and responding for money decreased. During the final phase of the study, the lowest and highest doses that maintained drug responding for each subject were repeated, and the value of the alternative reinforcer was increased to $2 per ratio. This manipulation was associated with decreased drug-maintained responding at the lowest, but not the highest, reinforcing dose of morphine.

CONCLUSION

The progressive ratio, concurrent access procedure may be useful in predicting the outcome of drug abuse treatment interventions that use alternate reinforcement strategies.

Abuse liability assessment of sibutramine, a novel weight control agent

RATIONALE

Sibutramine (Meridia) is a serotonin and norepinephrine reuptake inhibitor marketed for weight control. Previous studies demonstrated low abuse potential for 20 and 30 mg sibutramine (doses near the therapeutic range); however, no data existed on supratherapeutic doses. This study, therefore, examined 25 and 75 mg sibutramine in humans compared to d-amphetamine (20 mg) as a positive control and placebo as a negative control.

OBJECTIVES

The study examined the acute subjective, reinforcing, and physiological effects of sibutramine to assess its abuse liability.

METHODS

Twelve polydrug abusers with no history of drug dependence participated in this double-blind, inpatient/outpatient study. Volunteers participated in four drug sessions, in which they completed subjective effects scales including the Profile of Mood States (POMS), Visual Analog Scales (VAS), and the Addiction Research Center Inventory (ARCI). The Multiple Choice Procedure (MCP) was used to evaluate reinforcing efficacy.

RESULTS

Sibutramine 25 mg produced subjective effects that were indistinguishable from placebo. Sibutramine 75 mg produced significant unpleasant effects, such as Anxiety, Confusion, and decreased Vigor. On the MCP, volunteers chose to give up an average of $4.04 from their study pay rather than receive the higher dose of sibutramine again. In contrast, d-amphetamine 20 mg produced positive mood changes and was well liked.

CONCLUSIONS

These data indicate sibutramine lacks amphetamine-type abuse liability when administered acutely.

Opioid reinforcement in heroin-dependent volunteers during outpatient buprenorphine maintenance

This study examined the reinforcing effects of hydromorphone (HYD) (0, 4, 8, and 16 mg/70 kg i.m.) in heroin-dependent outpatient volunteers maintained on buprenorphine (BUP) at doses of 2, 4, and 8 mg, each for 2 weeks. Following a week of maintenance at each dose, volunteers received injections of one of the four HYD doses under double-blind conditions. Eight volunteers (abstainers) were heroin-free during HYD test weeks, whereas six volunteers remained heroin-positive (nonabstainers). Among abstainers, HYD had minimal reinforcing value, whereas in nonabstainers there were marked dose-related increases in HYD reinforcing value, which were not attenuated by increasing doses of BUP. A similar pattern was found for HYD subjective agonist effects. Heroin craving among nonabstainers was significantly higher compared with abstainers, and was reduced in a dose-related manner by HYD. Although BUP and HYD produced dose-related miosis, abstinence status had no differential effect. In summary, BUP effects on opioid reinforcement were consistent from outpatient setting (heroin abstinence) to laboratory setting (decreased HYD reinforcement), supporting the validity of this laboratory model.

Improvement in naltrexone treatment compliance with contingency management

The efficacy of a voucher-based incentive program for improving adherence to outpatient, thrice weekly naltrexone maintenance was tested in a three group, randomized, 12-week clinical trial. Voucher incentives were given as follows: contingent group (n = 19) for each consecutive naltrexone dose ingested; non-contingent group (n = 19) on unpredictable schedule independently of taking naltrexone; no-voucher group (n = 20) none. Vouchers were exchangeable for goods and services. The contingent group had significantly longer treatment retention and ingested significantly more doses of naltrexone (consecutive and total) than either control group. Voucher incentives can significantly increase adherence to naltrexone maintenance in recently detoxified opioid dependent individuals.

Broad beneficial effects of cocaine abstinence reinforcement among methadone patients

Escalating reinforcement for sustained abstinence has been effective in treating cocaine abuse. Under this schedule, patients receive vouchers for cocaine-free urine samples; vouchers have monetary values that increase with the number of consecutive cocaine-free urine samples. Cocaine-abusing methadone patients were randomly assigned to receive vouchers for 12 weeks under (a) an escalating schedule (n = 20), (b) an escalating schedule with start-up bonuses (n = 20), or (c) a noncontingent schedule (n = 19). Start-up bonuses were designed to provide added reinforcement for initiating abstinence; however, they did not improve outcomes. Both contingent interventions significantly increased cocaine abstinence. In addition, the contingent interventions increased abstinence from opiates and decreased reports of cocaine craving. These results replicate the efficacy of cocaine abstinence reinforcement and show that it can have broad beneficial effects.

Cocaine use early in treatment predicts outcome in a behavioral treatment program

In this evaluation of baseline drug use as a predictor of treatment outcome, cocaine use during a 5-week baseline was compared in methadone maintenance patients who had < 5 (n = 10) versus > or = 5 (n = 9) weeks of abstinence during an experimental cocaine abstinence reinforcement treatment. Cocaine use was evaluated at the 1st and last visit and the 1st and last week of baseline and as a mean across the 5-week baseline treatment; response was calculated as a mean across 12 weeks of experimental treatment. Those who had successful outcomes (abstainers) used significantly less cocaine in the 5-week baseline than those with less successful outcomes (nonabstainers). Differences in cocaine use were not evident in the 1st baseline visit or week, but the abstainers used significantly less cocaine in the last visit and week of baseline compared with the nonabstainers. Cocaine use during baseline provided critical predictors of response to the experimental treatment.

Broad beneficial effects of cocaine abstinence reinforcement among methadone patients

Escalating reinforcement for sustained abstinence has been effective in treating cocaine abuse. Under this schedule, patients receive vouchers for cocaine-free urine samples; vouchers have monetary values that increase with the number of consecutive cocaine-free urine samples. Cocaine-abusing methadone patients were randomly assigned to receive vouchers for 12 weeks under (a) an escalating schedule (n = 20), (b) an escalating schedule with start-up bonuses (n = 20), or (c) a noncontingent schedule (n = 19). Start-up bonuses were designed to provide added reinforcement for initiating abstinence; however, they did not improve outcomes. Both contingent interventions significantly increased cocaine abstinence. In addition, the contingent interventions increased abstinence from opiates and decreased reports of cocaine craving. These results replicate the efficacy of cocaine abstinence reinforcement and show that it can have broad beneficial effects.

Cocaine use early in treatment predicts outcome in a behavioral treatment program

In this evaluation of baseline drug use as a predictor of treatment outcome, cocaine use during a 5-week baseline was compared in methadone maintenance patients who had < 5 (n = 10) versus > or = 5 (n = 9) weeks of abstinence during an experimental cocaine abstinence reinforcement treatment. Cocaine use was evaluated at the 1st and last visit and the 1st and last week of baseline and as a mean across the 5-week baseline treatment; response was calculated as a mean across 12 weeks of experimental treatment. Those who had successful outcomes (abstainers) used significantly less cocaine in the 5-week baseline than those with less successful outcomes (nonabstainers). Differences in cocaine use were not evident in the 1st baseline visit or week, but the abstainers used significantly less cocaine in the last visit and week of baseline compared with the nonabstainers. Cocaine use during baseline provided critical predictors of response to the experimental treatment.

Automated measurement of motor activity in human subjects: effects of repeated testing and d-amphetamine

Repeated exposure to a test setting decreases, and amphetamine increases, motor activity in animals. To evaluate whether these effects also occur in human subjects, we recorded motor activity levels from 12 subjects during a double-blind oral drug discrimination (placebo vs. 75 mg tripelennamine) study. Before each 4-h session, activity monitors were attached to the subject's wrist and ankle. During each session, subjects rated their drug effects hourly (task periods), and could freely choose among leisure activities during intertask intervals (recreational periods). Habituation was evaluated by comparing activity response during initial (training phase) vs. later (discrimination phase) placebo sessions. During later sessions the two training drugs, as well as diazepam (2.5, 5 mg P.O.) and d-amphetamine (5, 10 mg P.O.) were administered. Consistent with animal studies, repeated exposure to the test environment significantly decreased, and d-amphetamine significantly and selectively increased, wrist motor activity. These data indicate that human motor activity is sensitive to environmental factors (task, time), drug class, and d-amphetamine dose. Activity measures may, therefore, be useful in evaluating environment/psychostimulant interactions in humans.

Assessment of cocaine use with quantitative urinalysis and estimation of new uses

Qualitative urinalysis methods of monitoring cocaine use may over-detect frequency of use, possibly decreasing the ability of clinical trials to detect effective treatments. Quantitative urinalysis and newly developed criteria for identifying new cocaine use were evaluated as alternative measures of cocaine use. Urine specimens collected in a cocaine dosing study in non-treatment-seeking subjects (n = 5) and a cocaine treatment trial (n = 37) were analyzed for the cocaine metabolite, benzoylecgonine, with qualitative and quantitative methods. Pharmacokinetic criteria ('New Use' rules) were applied to quantitative data to identify occasions of new cocaine use. Results were compared to known cocaine administrations in the laboratory study and to self-reported drug use and qualitative urinalysis for subjects in the clinical trial. New Use criteria correctly identified cocaine administrations in the cocaine dosing study in all but a small number of specimens. In the clinical trial, quantitative urinalysis and estimated New Uses provided more information about patterns and frequency of use than qualitative urinalysis in the different treatment conditions in the clinical trial. Interpretation of quantitative urinalysis with New Use rules appears to be a useful method for monitoring treatment outcome and may be more accurate than traditional qualitative urinalysis in estimating frequency of cocaine use.

Comparison of self-reported drug use with quantitative and qualitative urinalysis for assessment of drug use in treatment studies

The effectiveness of substance abuse treatment programs can be monitored by self-reported drug use and objectively measured by qualitative and quantitative urinalysis. The advantages and disadvantages of each of these three methods of assessing drug use are reviewed. Data collected in a clinical trial of a behavioral treatment for cocaine abuse are used to evaluate the relationships among qualitative and quantitative urinalysis for cocaine metabolite and self-reported cocaine use. Qualitative and quantitative urine testing showed greater rates of drug use than that shown by self-report, though there were significant correlations between self-reported use and urine toxicology results. Benzoylecgonine concentrations in urine specimens supported the suggestions that rates of drug use as determined by qualitative urinalysis are artificially high due to carryover and were informative about subjects' patterns of use.

Increasing opiate abstinence through voucher-based reinforcement therapy

Heroin dependence remains a serious and costly public health problem, even in patients receiving methadone maintenance treatment. This study used a within-subject reversal design to assess the effectiveness of voucher-based abstinence reinforcement in reducing opiate use in patients receiving methadone maintenance treatment in an inner-city program. Throughout the study subjects received standard methadone maintenance treatment involving methadone, counseling, and urine monitoring (three times per week). Thirteen patients who continued to use opiates regularly during a 5-week baseline period were exposed to a 12-week program in which they received a voucher for each opiate-free urine sample provided: the vouchers had monetary values that increased as the number of consecutive opiate-free urines increased. Subjects continued receiving standard methadone maintenance for 8 weeks after discontinuation of the voucher program (return-to-baseline). Tukey's posthoc contrasts showed that the percentage of urine specimens that were positive for opiates decreased significantly when the voucher program was instituted. (P < or = 0.01) and then increased significantly when the voucher program was discontinued during the return-to-baseline condition (P < or = 0.01). Rates of opiate positive urines in the return-to-baseline condition remained significantly below the rates observed in the initial baseline period (P < or = 0.01). Overall, the study shows that voucher-based reinforcement contingencies can decrease opiate use in heroin dependent patients receiving methadone maintenance treatment.

Effects of phentermine and cocaine on fenfluramine-induced depletion of serotonin in mouse brain

The combined administration of phentermine and fenfluramine (PHEN/FEN) has been used as a treatment for obesity. Recent evidence suggests that this drug mixture may also be an effective medication for substance abuse disorders, including cocaine dependence. It is well-established that repeated high-dose fenfluramine causes serotonin (5-HT) terminal degeneration in laboratory animals, and no studies have addressed possible interactions between phentermine and fenfluramine. The purpose of the present work was to examine the effect of phentermine coadministration on fenfluramine-induced depletion of 5-HT in mouse forebrain. In addition, because of the potential for cocaine abuse in drug addicts taking PHEN/FEN as a medication, we examined the effects of PHEN/FEN on forebrain 5-HT levels in the presence or absence of cocaine. Fenfluramine (0, 3, 10, 30 mg/kg, s.c. twice daily for 4 days) caused a dose-dependent reduction in forebrain 5-HT without affecting dopamine or norepinephrine. Phentermine coadministration (7 mg/kg, s.c. twice daily for 4 days) did not significantly alter the 5-HT-depleting effect of fenfluramine. Likewise, cocaine (10 mg/kg, i.p.), administered 60 min prior to or 60 min after PHEN/FEN, had no effect on the PHEN/FEN-induced decrease in central 5-HT. The present results indicate that doses of phentermine far above those typically administered to humans do not potentiate the 5-HT-depleting effect of repeated high-dose fenfluramine. Moreover, exposure to cocaine does not significantly alter the long-term neurochemical actions of the PHEN/FEN mixture.

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.

Evaluation of phentermine and fenfluramine, alone and in combination, in normal, healthy volunteers

Recent clinical reports indicate that combined administration of phentermine and fenfluramine may have useful effects in the treatment of drug abuse. The present study was designed to evaluate the subjective and mood-altering effects of these drugs, alone and in combination, in normal healthy volunteers. Seven male and five female volunteers participated in an eight-session, double-blind study in which each subject received each of the following drug conditions: d-amphetamine (10 and 20 mg), phentermine (30 mg), fenfluramine (40 and 80 mg), phentermine (30 mg) with fenfluramine (40 mg), phentermine (30 mg) with fenfluramine (80 mg), and placebo. Sessions were conducted in a laboratory setting two or three days a week. Subjects completed standardized self-report questionnaires and psychomotor tests before and at regular intervals after each drug administration. Phentermine produced effects that were similar to those of d-amphetamine, whereas fenfluramine produced different and apparently aversive effects (e.g., it increased measures of anxiety and confusion). Phentermine reduced the apparently aversive effects of fenfluramine when the two drugs were given together. These results suggest that the combination of phentermine and fenfluramine would have a low potential for abuse.

Conditioned reinforcing effects of capsules associated with high versus low monetary payoff

The ability of a placebo drug capsule to serve as a conditioned reinforcer as a function of being paired with money reinforcement was evaluated. Volunteers were administered two differently colored capsules that presumably contained two different drugs. Although the volunteers were told they might contain a stimulant, sedative, or placebo, both capsules contained only a placebo. During sessions, volunteers participated in performance tasks. The tasks were programmed so that following one capsule, the amount of money obtained contingent upon responding was greater (high frequency of reinforcement) than following the other capsule (low frequency of reinforcement). During experiment 1, participants were exposed twice each to the two reinforcement conditions (sampling). During these choice sessions, 9 of 12 participants chose the capsule associated with the high frequency of reinforcement 2 or 3 times. Experiment 2 was designed to explore further whether the differential mood effects observed during sampling sessions could be conditioned. Although this could not be demonstrated, the self-administration results demonstrating the control of choice behavior even in the absence of pharmacological effects suggest that drugs may function as conditioned reinforcers. This finding has implications for broadening our understanding of the determinants of initiation and continued drug use.

Anorectic specificity as measured in a choice paradigm in rhesus monkeys

The present report describes a new procedure for assessing anorectic specificity. Two rhesus monkeys (Macaca mulatta) surgically prepared with indwelling intragastric catheters were trained in a discrete trial choice paradigm to respond for either food or visual access to a room containing other monkeys. Our hypothesis was that a specific anorectic would reduce only food-maintained responding; responding to open a window would either not be affected or would increase. Caloric preloads, d-amphetamine, (d,l)-fenfluramine, and cholecystokinin octapeptide all decreased food-maintained responding and had no effect on or increased responding maintained by window opening. These results demonstrate that choice procedures are useful for assessing anorectic specificity.

Probing the meaning of racial/ethnic group comparisons in crack cocaine smoking

OBJECTIVE

To probe the meaning of reported racial and ethnic group differences in the prevalence of crack cocaine smoking and to estimate the degree to which crack cocaine smoking is associated with personal factors specific to race/ethnicity.

DESIGN

Through reanalysis of data from the 1988 National Household Survey of Drug Abuse (NHSDA), we compared racial/ethnic group differences in crack cocaine smoking. To hold constant social and environmental risk factors that might potentially confound racial comparisons, we used an epidemiologic strategy that involves poststratification of respondents into neighborhood risk sets. A conditional logistic regression model was used to estimate the relative odds of crack use by race/ethnicity.

PATIENTS OR OTHER PARTICIPANTS

The 1988 NHSDA interviewed 8814 individuals residing within households in the United States. Subjects were selected using a multistage area probability sampling of all residents aged 12 years and older.

RESULTS

Once respondents were grouped into neighborhood clusters, the relative odds (RO) of crack use did not differ significantly for African Americans (RO, 0.85; 95% confidence interval [Cl], 0.37 to 1.93) or for Hispanic Americans (RO, 0.88; 95% Cl, 0.47 to 1.67) compared with white Americans.

CONCLUSION

Findings of race-associated differences are often presented as if a person's race has intrinsic explanatory power. This analysis provides evidence that, given similar social and environmental conditions, crack use does not strongly depend on race-specific (eg, biologic) personal factors. Although the study finding does not refute the previous analysis, it provides evidence that prevalence estimates unadjusted for social environmental risk factors may lead to misunderstanding about the role of race or ethnicity in the epidemiology of crack use. Future research should seek to identify which characteristics of the neighborhood social environment are important and potentially modifiable determinants of drug use.

Recommendations for improving drug treatment

Recognizing that drug use is both chronic and relapsing once an individual is addicted, and that treatment is effective in reducing drug use/misuse, improving drug misuse treatment is examined and research as well as practice recommendations are presented. Drug misuse treatment is now recognized in the United States to meet the expanding drug use problem and for reducing the spread of HIV. With that background, the current status of drug misuse treatment is reviewed, clinical issues are emphasized, and policy issues are noted. Recommendations include the need for uniform funding, linkage with community agencies, technology transfer, training, and expanding research and evaluation efforts.

Drug abuse research and HIV/AIDS: a national perspective from the US

The National Institute on Drug Abuse (NIDA), the lead Federal agency charged with research on reducing the demand for illicit drugs in the US, has actively pursued the associated challenge of reducing drugs-related HIV transmission. Drug abuse-related spread of the virus occurs not only through sharing contaminated needles but also sexually to partners and perinatally from infected mothers to their offspring. Through a national research and demonstration program, NIDA supports primary AIDS risk reduction activities focused on identifying effective drug abuse prevention and treatment strategies. AIDS is increasingly a disease found in women, children, minorities, and people who live in rural areas. NIDA's efforts are clearly responsive to the changing nature of this epidemic. Among the many promising initiatives currently underway are a medications development program to find new pharmacotherapies for treating drug addiction; an array of National AIDS Outreach Demonstration Projects implementing alternative control strategies for drug abusers not attracted to or successful in drug abuse treatment; establishment of several treatment research units for designing and conducting studies on treatment effectiveness; and a variety of programs aimed at identifying and potentially reducing the risks of prenatal drug use to both mother and child. Effective dissemination of our findings is particularly critical to the overall impact of our research efforts. Collaborative activities teaming NIDA with a multitude of organizations also addressing AIDS related issues are designed to provide a synergistic impact on this complex and multifaceted public health crisis.

Effects of cholecystokinin, d-amphetamine and fenfluramine in rats trained to discriminate 3 from 22 hr of food deprivation

Attempts to assess similarities between the interoceptive stimuli of anorectic drugs and food satiation have generally been limited to human verbal reports. The purpose of the present study was to develop a procedure for assessing similarities between the interoceptive stimuli of food in the gut and various drugs known to alter food intake in rats. Rats (n = 23) were trained in a two-lever, food-reinforced, discrimination paradigm to press one lever when deprived of food for 3 hr and another lever when deprived of food for 22 hr. Criteria for stimulus control over responding were achieved after a mean of 92 (range = 26-175) training sessions. In time course tests, rats were tested when 22, 12, 6 and 3 hr food-deprived. As the number of hours of food deprivation decreased, the percentage of responses that occurred on the 3-hr food deprivation lever increased. In substitution tests, rats that were 22-hr food-deprived consistently responded as if they were 3-hr food deprived after administration of sweetened condensed milk preloads or cholecystokinin, but only occasionally after administration of water preloads, LiCl, d-amphetamine or fenfluramine. These results demonstrate that the presence of food in the gut can function as a discriminative stimulus to control lever choice in rats. Furthermore, they suggest that the discriminative stimulus effects of cholecystokinin, but not d-amphetamine or fenfluramine, are similar to those of food in the gut, and support the hypothesis that cholecystokinin plays a role in the regulation of food intake.

[AIDS and intravenous drug abuse]

The importance of intravenous drug-abuse as a vehicle of HIV and AIDS is evidenced on the basis of recent epidemiological data gathered in the USA. The rate of seropositivity among intravenous drug-addicts (whose total number i is close to one million) is estimated at more than 20 percent. Besides direct contamination, risks of contamination of sexual partners and their offspring can be evaluated from these figures. The programme developed by the National Institute on Drug Abuse against AIDS, aimed at that particular target population, is presented in its various aspects, including basic research, treatment and prevention.

Effect of depletion of brain serotonin by repeated fenfluramine on neurochemical and anorectic effects of acute fenfluramine

Fenfluramine is an anorectic agent in clinical use that is believed to act by enhancing 5-hydroxytryptamine (5-HT) neurotransmission. Tolerance to the anorectic properties of fenfluramine develops rapidly and long-lasting depletions of brain 5-HT have been reported to occur after repeated administration. It is possible that tolerance to fenfluramine may be related to the 5-HT depletions. Rats (n = 96), previously allowed to drink sweetened condensed milk during daily 15-min sessions, were treated with fenfluramine (6.25 mg/kg/12 hr x 4 days) or saline. Two or 8 weeks later rats were administered fenfluramine acutely (0, 1.25, 6.25 or 12.5 mg/kg; n = 6/group), tested for milk intake and sacrificed 2 hr later. Brains were removed and regions assayed for dopamine, 5-HT and metabolites. Acute administration of fenfluramine produced a dose-dependent decrease in milk intake and 5-HT and 5-hydroxyindoleacetic acid (5-HIAA) levels in cortex, hypothalamus and hippocampus. Tolerance to the effects of acute fenfluramine on milk intake was observed in rats at 2 weeks (ED50 = 3.24 vs. 6.37 mg/kg; saline vs. fenfluramine pretreatment, respectively) and, to a lesser extent, at 8 weeks (ED50 = 2.99 vs. 4.04 mg/kg; saline vs. fenfluramine pretreatment) after the 4-day regimen of fenfluramine. Levels of 5-HT and 5-HIAA in somatosensory cortex, hypothalamus, striatum and hippocampus were depleted significantly 2 weeks after the last daily fenfluramine injection. The acute 5-HT depleting effect of fenfluramine was markedly attenuated in these regions 2 weeks after the 4-day regimen of fenfluramine.(ABSTRACT TRUNCATED AT 250 WORDS)

Sensitization to kappa opioid mechanisms associated with tolerance to the anorectic effects of cathinone

To evaluate the possibility that tolerance to the anorectic effects of cathinone (CATH), an amphetamine-like compound, involves the sensitization of endogenous kappa opioid mechanisms, the influence of chronic treatment with CATH on the effects of the selective kappa opioid agonist U50488H (U50) on food and water intake was evaluated in rats. Since kappa agonists specifically increase urine output, the interaction between CATH and U50 on this physiological function was also evaluated. Acutely, CATH produced anorexia and diuresis, whereas water intake was not affected. U50 resulted in an increase in both food and water intake as well as urine output. After 9 days of daily CATH, tolerance to its anorectic effects had developed. In addition, water intake, which was not affected acutely by CATH, was significantly enhanced with respect to controls treated daily with water. In a group treated chronically with U50, its diuretic effect was unchanged, but water intake was no longer increased after 9 days of treatment. Food intake in this group remained higher than control intake for at least 19 days, but this hyperphagic effect was not detectable on day 34. On days 10 and 20 of the chronic regimen, the administration of U50 to the chronic CATH group resulted in a doubling of the hyperphagic response to U50, and this effect was naloxone-reversible. Water intake was also increased but to a lesser extent. The diuretic effect of U50 did not appear to be influenced by chronic CATH administration.(ABSTRACT TRUNCATED AT 250 WORDS)

Relationship between the discriminative stimulus properties and subjective effects of drugs

Behavioral pharmacologists have assumed that the properties of drugs that mediate their discriminative stimulus effects are related to aspects of drug actions that result in their subjective effects in humans. The basis of this assumption is examined in this chapter. Evidence to support this assumption includes the formal properties of the learning process involved in acquiring both behaviors. Although the procedures used to train animals to learn a drug discrimination are explicit, an analysis of how humans learn to attach verbal responses to unobservable internal subjective states appears to involve a similar learning paradigm. Additional evidence of the commonality of the two effects is that the results from drug discrimination studies in animals and studies evaluating subjective effects in humans yield similar drug classifications. However, when subjective drug effects are analyzed in more detail, it is clear that the concordance between the two approaches is not always good. On the other hand, when drug discrimination and subjective effects are both measured in humans, an examination of the results generated when individuals respond differently to the same drug indicates that the hypothesis that their discrimination is based upon a profile of subjective effects is supported.

Discriminative stimulus and subjective effects of smoked marijuana in humans

The discriminative stimulus (DS) effects of smoked marijuana were studied by training marijuana smokers to discriminate between the effects of marijuana containing 2.7% delta 9-THC (M) and marijuana containing 0.0% delta 9-THC (P). In addition to measures of discrimination responding, subjective effects were assessed with standardized mood questionnaires. The post-smoking increase in expired air carbon monoxide (CO) level was used as an index of smoke inhalation. Relative to P cigarettes, M cigarettes increased heart rate and produced changes on eight mood scales. M cigarettes were rated as harsher and more potent than P cigarettes, and produced lower levels of CO than P cigarettes. The P--M discrimination was readily acquired by most subjects. The DS effects of marijuana showed a rapid onset, appearing within 90 s from the beginning of smoking. The DS effects were dose dependent, with 0.9% delta 9-THC marijuana producing primarily placebo-appropriate discrimination responding, and 1.4% delta 9-THC marijuana producing 100% drug-appropriate responding. This experimental paradigm could be used to determine whether the DS effects of smoked marijuana would generalize to those of other psychoactive drugs.

Intravenous drug use and AIDS prevention

Research programs of the National Institute on Drug Abuse take a broad approach to investigating the problems of intervention in intravenous drug use and its relation to the AIDS epidemic. Current prevention strategies are directed to reducing the rates of infection and the progression among the infected to clinical symptoms. Programs test alternative prevention models and focus on the epidemiology of the problem and on basic studies of specific high-risk behaviors. Ultimately, the problem requires community involvement to encourage behaviors which will reduce exposure on the part of drug users, their sexual partners, and their children.

Biochemical and histological evidence that methylenedioxymethylamphetamine (MDMA) is toxic to neurons in the rat brain

(+/-)-3,4-Methylenedioxymethylamphetamine (MDMA) was administered s.c. to rats (10, 20 or 40 mg/kg b. wt.) and guinea pigs (20 mg/kg) twice a day for 4 days, 2 weeks before decapitation. Norepinephrine, dopamine and serotonin (5-HT) levels were assayed in the hippocampus, hypothalamus, striatum and neocortex. In rats, MDMA produced dose-dependent reductions in 5-HT in all brain regions examined. The highest dose also reduced norepinephrine and/or dopamine in some regions. The 20-mg/kg dose of MDMA depleted 5-HT in all regions of the guinea pig brain assayed. In both species, repeated administration of 20 mg/kg of MDMA reduced the Vmax but not the Km of 5-HT uptake 2 weeks after administration. A single 40-mg/kg injection of MDMA depleted 5-HT 2 and 8 weeks after administration to rats in all regions of the brain examined except the hypothalamus. Administration of 80 mg/kg of MDMA twice a day for 2 days to rats depleted striatal 5-HT and dopamine. Brain sections from rats injected with MDMA according to this dosage regimen were stained by the Fink-Heimer method. Degenerating axon terminals and cell bodies were observed in the striatum and somatosensory cortex, respectively. These findings suggest that MDMA is toxic to serotonergic and, to a lesser extent, catecholaminergic neurons. Some neurons that do not contain these transmitters (neocortical neurons) are also affected.

The effects of ethanol on eye tracking in rhesus monkeys and humans

The effects of ethanol on eye tracking function were compared in rhesus monkeys and humans using a similar experimental procedure. In Experiment 1, 3 rhesus monkeys were trained to visually track a projected image of a disk that oscillated sinusoidally along a horizontal plane on a screen. This training was accomplished using a procedure in which responses on a lever resulted in the delivery of water when the central area of the projected disk image was dimmed for a brief period. Intragastric administrations of ethanol at doses of 0.25 to 2 g/kg were tested during one-day test sessions using a cumulative dose procedure. Pursuit eye movements were disrupted at doses of 0.5 g/kg while lever pressing behavior was not disrupted until a dose of 2 g/kg was reached. In Experiment 2, pursuit eye movements of 6 humans were not disrupted when ethanol was given orally at cumulative doses of 0.25 to 1 g/kg, while microswitch pressing behavior was disrupted in some of the subjects at a dose of 0.5 g/kg. Blood ethanol levels increased in a dose-dependent manner in both species with higher levels in humans than in monkeys. The dose dependent effects observed in both species and qualitative similarities in some of the effects such as saccadic pursuit eye movements suggest that the eye tracking method employing monkeys is useful for predicting drug effects on sensory motor function in humans.

The effects of (+/-)-methylenedioxymethamphetamine and (+/-)-methylenedioxyamphetamine in monkeys trained to discriminate (+)-amphetamine from saline

Recently, attention has been focused on (+/-)-methylenedioxymethamphetamine (MDMA), a psychotomimetic agent chemically closely related to the psychomotor stimulant methamphetamine, and also to the hallucinogen mescaline. In the present experiment, the effects of MDMA and (+/-)-3,4-methylenedioxyamphetamine (MDA) were determined in rhesus monkeys that were trained to discriminate intravenously administered (+)-amphetamine (AMPH) from saline in a two-lever, food-maintained paradigm or to discriminate intragastrically administered AMPH from saline in a signalled electric shock avoidance paradigm. MDMA produced 100% drug-appropriate responding in all six monkeys, regardless of the procedure and route of administration while MDA substituted completely for AMPH in only two of three monkeys in each paradigm. The results suggest that MDMA has subjective effects that are similar to those of AMPH while MDA is somewhat less like AMPH.