Clinical pharmacology of buprenorphine: ceiling effects at high doses

OBJECTIVE

The purpose of this study was to characterize the acute effects of buprenorphine, an opioid partial mu-agonist, across a wide range of doses in comparison to methadone.

METHOD

Healthy adult male volunteers, who had experience with but were not physically dependent on opioids, participated while residing on a closed research unit. Four subjects received buprenorphine (0, 1, 2, 4, 8, 16, and 32 mg sublingually and five subjects received methadone (0, 15, 30, 45, and 60 mg orally) in ascending order at 1-week intervals. Physiologic, subjective, and behavioral measures were monitored for 96 hours after drug administration.

RESULTS

Both drugs produced typical opioid agonist effects (positive mood, sedation, respiratory depression, and miosis), some of which persisted for 24 to 48 hours. A plateau was observed for the dose effects of buprenorphine on subjective measures and respiratory depression. Pharmacokinetic data revealed that plasma concentrations of buprenorphine were linearly related to dose, indicating no limits on sublingual absorption in this dose range.

CONCLUSIONS

This study shows a plateau on buprenorphine effects, consistent with its partial agonist classification, and that single doses of buprenorphine up to 70 times the recommended analgesic dose are well tolerated by nondependent humans.

Toward a model of drug relapse: an assessment of the validity of the reinstatement procedure

BACKGROUND AND RATIONALE

The reinstatement model is widely used to study relapse to drug addiction. However, the model's validity is open to question.

OBJECTIVE

We assess the reinstatement model in terms of criterion and construct validity.

RESEARCH HIGHLIGHTS AND CONCLUSIONS

We find that the reinstatement model has adequate criterion validity in the broad sense of the term, as evidenced by the fact that reinstatement in laboratory animals is induced by conditions reported to provoke relapse in humans. The model's criterion validity in the narrower sense, as a medication screen, seems promising for relapse to heroin, nicotine, and alcohol. For relapse to cocaine, criterion validity has not yet been established primarily because clinical studies have examined medication's effects on reductions in cocaine intake rather than relapse during abstinence. The model's construct validity faces more substantial challenges and is yet to be established, but we argue that some of the criticisms of the model in this regard may have been overstated.

Blockade of effects of smoked marijuana by the CB1-selective cannabinoid receptor antagonist SR141716

BACKGROUND

SR141716, a recently developed CB1 cannabinoid receptor antagonist, blocks acute effects of Delta-9-tetrahydrocannabinol (THC) and other CB1 cannabinoid agonists in vitro and in animals. These findings suggest that CB1 receptors mediate many of the effects of marijuana, but this has not been evaluated in humans.

METHODS

Sixty-three healthy men with a history of marijuana use were randomly assigned to receive oral SR141716 or a placebo in an escalating dose (1, 3, 10, 30, and 90 mg) design. Each subject smoked an active (2.64% THC) or placebo marijuana cigarette 2 hours later. Psychological effects associated with marijuana intoxication and heart rate were measured before and after antagonist and marijuana administration.

RESULTS

Single oral doses of SR141716 produced a significant dose-dependent blockade of marijuana-induced subjective intoxication and tachycardia. The 90-mg dose produced 38% to 43% reductions in visual analog scale ratings of "How high do you feel now?" "How stoned on marijuana are you now?" and "How strong is the drug effect you feel now?" and produced a 59% reduction in heart rate. SR141716 alone produced no significant physiological or psychological effects and did not affect peak THC plasma concentration or the area under the time x concentration curve. SR141716 was well tolerated by all subjects.

CONCLUSIONS

SR141716 blocked acute psychological and physiological effects of smoked marijuana without altering THC pharmacokinetics. These findings confirm, for the first time in humans, the central role of CB1 receptors in mediating the effects of marijuana.

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.

Assessment of visual acuity in infants and children: the acuity card procedure

The 'acuity card' procedure described here is a simplified method of testing visual acuity of infants and young children, and has been developed to allow preferential looking to be assessed in a laboratory or clinic. A higher proportion of children can be tested successfully than has been reported for more traditional procedures. Initial studies indicate that the acuity card procedure is a fast, accurate method for assessing the acuity of normal infants and children, and those with visual or neurological impairments, across a wide age-range and in both clinical and laboratory settings.

Real-time electronic diary reports of cue exposure and mood in the hours before cocaine and heroin craving and use

CONTEXT

In ecological momentary assessment (EMA), participants electronically report their activities and moods in their daily environments in real time, enabling a truly prospective approach to the study of acute precipitants of behavioral events. Ecological momentary assessment has greatly enhanced the study of tobacco addiction, but its use has rarely been attempted in individuals with cocaine or heroin addiction.

OBJECTIVE

To prospectively monitor the acute daily life precipitants of craving for and use of cocaine and heroin.

DESIGN

Cohort study.

PARTICIPANTS

A volunteer sample of 114 cocaine- and heroin-abusing outpatients who were being treated with methadone provided EMA data on handheld electronic devices for 14 918 person-days (mean, 130.9; range, 6-189 days per participant). Of these outpatients, a total of 102 (63 men, 39 women) provided acute precraving and/or preuse data and were thus included in the present analyses.

MAIN OUTCOME MEASURES

Changes in reports of mood and exposure to 12 putative drug-use triggers at random intervals during the 5 hours preceding each self-reported episode of drug craving or use, analyzed via repeated-measures logistic regression (generalized linear mixed models).

RESULTS

During the 5 hours preceding cocaine use or heroin craving, most of the 12 putative triggers showed linear increases. Cocaine use was most robustly associated with increases in participants reporting that they "saw [the] drug" (P < .001), were "tempted to use out of the blue" (P < .001), "wanted to see what would happen if I used" (P < .001), and were in a good mood (P < .001). Heroin craving was most robustly associated with increases in reports of feeling sad (P < .001) or angry (P = .01). Cocaine craving and heroin use showed few reliable associations with any of the putative triggers assessed.

CONCLUSIONS

These findings confirm that polydrug-abusing individuals can provide behavioral data in their daily environments using handheld electronic devices and that those data can reveal orderly patterns, including prospectively detectable harbingers of craving and use, which may differ across drugs.

Abuse potential and pharmacological comparison of tramadol and morphine

The purpose of the study was to assess the abuse potential of the opioid analgesic tramadol. Tramadol (75, 150 and 300 mg), morphine (15 and 30 mg) and placebo were tested intramuscularly in volunteer non-dependent opiate abusers. Subjective, behavioral and miotic changes were assessed prior to dosing and intermittently for 12 h after drug administration. Morphine produced typical subjective effects, opiate identifications and miosis. Tramadol 75 and 150 mg were not different from placebo. Although tramadol 300 mg was identified as an opiate, it produced no other morphine-like effects. These findings suggest that tramadol has a low abuse potential by the parenteral route.

The role of inducible transcription factors in apoptotic nerve cell death

Recent studies have shown that certain types of nerve cell death in the brain occur by an apoptotic mechanism. Researchers have demonstrated that moderate hypoxic-ischemic (HI) episodes and status epilepticus (SE) can cause DNA fragmentation as well as other morphological features of apoptosis in neurons destined to die, whereas more severe HI episodes lead to neuronal necrosis and infarction. Although somewhat controversial, some studies have demonstrated that protein synthesis inhibition prevents HI-and SE-induced nerve cell death in the brain, suggesting that apoptotic nerve cell death in the adult brain is de novo protein synthesis-dependent (i.e., programmed). The identity of the proteins involved in HI-and SE-induced apoptosis in the adult brain is unclear, although based upon studies in cell culture, a number of potential cell death and anti-apoptosis genes have been identified. In addition, a number of studies have demonstrated that inducible transcription factors (ITFs) are expressed for prolonged periods in neurons undergoing apoptotic death following HI and SE. These results suggest that prolonged expression of ITFs (in particular c-jun) may form part of the biological cascade that induces apoptosis in adult neurons. These various studies are critically discussed and in particular the role of inducible transcription factors in neuronal apoptosis is evaluated.

Primary outcome indices in illicit drug dependence treatment research: systematic approach to selection and measurement of drug use end-points in clinical trials

AIMS

Clinical trials test the safety and efficacy of behavioral and pharmacological interventions in drug-dependent individuals. However, there is no consensus about the most appropriate outcome(s) to consider in determining treatment efficacy or on the most appropriate methods for assessing selected outcome(s). We summarize the discussion and recommendations of treatment and research experts, convened by the US National Institute on Drug Abuse, to select appropriate primary outcomes for drug dependence treatment clinical trials, and in particular the feasibility of selecting a common outcome to be included in all or most trials.

METHODS

A brief history of outcomes employed in prior drug dependence treatment research, incorporating perspectives from tobacco and alcohol research, is included. The relative merits and limitations of focusing on drug-taking behavior, as measured by self-report and qualitative or quantitative biological markers, are evaluated.

RESULTS

Drug-taking behavior, measured ideally by a combination of self-report and biological indicators, is seen as the most appropriate proximal primary outcome in drug dependence treatment clinical trials.

CONCLUSIONS

We conclude that the most appropriate outcome will vary as a function of salient variables inherent in the clinical trial, such as the type of intervention, its target, treatment goals (e.g. abstinence or reduction of use) and the perspective being taken (e.g. researcher, clinical program, patient, society). It is recommended that a decision process, based on such trial variables, be developed to guide the selection of primary and secondary outcomes as well as the methods to assess them.

Stress in the daily lives of cocaine and heroin users: relationship to mood, craving, relapse triggers, and cocaine use

RATIONALE

Quantitative real-time data on the stress experienced by drug misusers in their daily lives may provide additional insight into stress's role in drug use.

OBJECTIVE

The purpose of this study is to evaluate stress in relation to craving, mood, relapse-trigger exposure, and cocaine use in cocaine-dependent outpatients.

METHODS

Methadone-maintained cocaine- and heroin-abusing outpatients (N = 114) provided ecological momentary assessment data on handheld computers. Ratings of stress were compared to those of craving and mood and past-hour exposure to putative drug-use triggers in randomly prompted entries and in the 5 h prior to participant-initiated cocaine use reports.

RESULTS

Stress had significant positive relationships with current ratings of craving for cocaine, heroin, and tobacco and with ratings of tiredness, boredom, and irritation, and had significant negative relationships with ratings of happiness and relaxation. Stress was significantly greater in entries in which participants also reported past-hour exposure to negative-mood triggers, most of the drug-exposure triggers, or any trigger involving thoughts about drugs (e.g., tempted out of the blue). The linear increase in stress during the 5-h preceding individual episodes of cocaine use was not significant (p = 0.12), though there was a trend for such an increase before the use episodes that participants attributed to stressful states when they occurred (p = 0.87).

CONCLUSIONS

The findings suggest a complex role of stress in addiction. Stress reported in real time in the natural environment showed strong cross-sectional momentary relationships with craving, mood, and exposure to drug-use trigger. However, the prospective association between stress ratings and cocaine-use episodes was, at best, weak.

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.

Single and multiple doses of rimonabant antagonize acute effects of smoked cannabis in male cannabis users

RATIONALE

A single 90-mg dose of the cannabinoid CB1 receptor antagonist rimonabant attenuates effects of smoked cannabis in humans.

OBJECTIVES

The objective of this study is to evaluate whether repeated daily 40-mg doses of rimonabant can attenuate effects of smoked cannabis to the same extent as a single higher (90 mg) dose.

MATERIALS AND METHODS

Forty-two male volunteers received one of three oral drug regimens in a randomized, double blind, parallel group design: (1) 40 mg rimonabant daily for 15 days, (2) placebo for 14 days, then 90 mg rimonabant on day 15, or (3) placebo for 15 days. All participants smoked an active or placebo cannabis cigarette 2 h after medication on days 8 and 15. Subjective effects were measured with visual analog scales and the marijuana-scale of the Addiction Research Center Inventory.

RESULTS

Cannabis-induced tachycardia was significantly lower for the 40-mg group on day 8 and for the 40 and 90 mg rimonabant groups on day 15 as compared to placebo. The 40-mg dose significantly decreased peak subjective effects on day 8. Neither the 90-mg nor 40-mg doses significantly decreased peak subjective effects on day 15. Rimonabant treatment did not significantly affect Delta(9)-tetrahydrocannabinnol pharmacokinetics.

CONCLUSIONS

Repeated lower daily rimonabant doses (40 mg) attenuated the acute physiological effects of smoked cannabis to a similar degree as a single 90-mg dose; repeated 40-mg doses attenuated subjective effects after 8 but not 15 days.

The reinstatement model and relapse prevention: a clinical perspective

OBJECTIVES

This commentary assesses the degree to which the reinstatement model is homologous to the human experience of relapse.

RESULTS

A review of the literature suggests that the relationship is less clear than is often assumed, largely due to a lack of prospective data on the precipitants and process of relapse (especially relapse to heroin or cocaine abuse). However, reinstatement does not need to resemble relapse to have immediate clinical value; predictive validity as a medication screen would be sufficient. Whether the model has predictive validity is unknown, because, to date, very few clinical trials have tested medications that are effective in the reinstatement model, and even fewer have used designs comparable to those of reinstatement experiments. A clinical trial comparable to a reinstatement experiment would enroll participants who are already abstinent, and its main outcome measure would be propensity to undergo a specific type of relapse (e.g., relapse induced by stress or cues).

CONCLUSIONS

Until clinical and preclinical work are more comparable, criticisms of the reinstatement model's presumed shortcomings are premature.

Cognitive-behavioral therapy plus contingency management for cocaine use: findings during treatment and across 12-month follow-up

Contingency management (CM) rapidly reduces cocaine use, but its effects subside after treatment. Cognitive-behavioral therapy (CBT) produces reductions months after treatment. Combined, the 2 might be complementary. One hundred ninety-three cocaine-using methadone-maintained outpatients were randomly assigned to 12 weeks of group therapy (CBT or a control condition) and voucher availability (CM contingent on cocaine-negative urine or noncontingent). Follow-ups occurred 3, 6, and 12 months posttreatment. Primary outcome was cocaine-negative urine (urinalysis 3 times/week during treatment and once at each follow-up). During treatment, initial effects of CM were dampened by CBT. Posttreatment, there were signs of additive benefits, significant in 3- versus 12-month contrasts. Former CBT participants were also more likely to acknowledge cocaine use and its effects and to report employment.

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.

Comparison of autofocus methods for automated microscopy

Traditional autofocus methods were designed for microscopes driven by single processor computers. As computers are developed that exploit massive parallelism when acquiring and analyzing images, parallel cellular logic techniques became available to focus automatically. This paper introduces the reader to both cellular logic techniques for autofocus and a new spectral moment autofocus measure. It then compares these methods with more traditional autofocus methods. It is shown that traditional methods based on measurements of image power-give the best results when tested on one set of real images and two sets of synthetic images. The next best methods are the cellular logic and spectral moment techniques, while the worst are those based on the image probability density function or histogram.

Abuse liability, behavioral pharmacology, and physical-dependence potential of opioids in humans and laboratory animals: lessons from tramadol

Assessment of abuse potential of opioid analgesics has a long history in both laboratory animals and humans. This article reviews the methods used in animals and in humans and then presents the data collected in the evaluation of tramadol, an atypical centrally acting opioid analgesic approved for marketing in the United States in 1998. Finally, data on the abuse of tramadol from postmarketing surveillance and case reports are presented. The consistency between animal and human study results and the predictive value of both are discussed. Overall, there was substantial agreement between animal and human data, with each having predictive value. Nonetheless, it is suggested that abuse-potential screening of new medications would benefit from an organized, integrated cross-species program.

Randomized trial of buprenorphine for treatment of concurrent opiate and cocaine dependence

BACKGROUND

Buprenorphine is a partial mu-opiate agonist and kappa-opiate antagonist with established efficacy in the treatment of opiate dependence. Its efficacy for cocaine dependence is uncertain. This study evaluated buprenorphine for the treatment of concomitant cocaine and opiate dependence.

METHODS

Two hundred outpatients currently dependent on both cocaine and opiates were randomly assigned to double-blind groups receiving a sublingual solution of buprenorphine (2, 8, or 16 mg daily, or 16 mg on alternate days, or placebo), plus weekly individual drug abuse counseling, for 13 weeks. The chief outcome measures were urine concentrations of opiate and cocaine metabolites (quantitative) and proportion of urine samples positive for opiates or cocaine (qualitative). Group differences were assessed by use of mixed regression modeling.

RESULTS

The target dose of buprenorphine was achieved in 179 subjects. Subjects receiving 8 or 16 mg buprenorphine daily showed statistically significant decreases in urine morphine levels (P =.0135 for 8 mg and P <.001 for 16 mg) or benzoylecgonine concentrations (P =.0277 for 8 mg and P =.006 for 16 mg) during the maintenance phase of the study. For the 16-mg group, mean benzoylecgonine concentrations fell from 3715 ng/mL during baseline to 186 ng/mL during the withdrawal phase; mean morphine concentrations fell from 3311 ng/mL during baseline to 263 ng/mL during withdrawal. For the 8-mg group, mean benzoylecgonine concentrations fell from 6761 ng/mL during baseline to 676 ng/mL during withdrawal; mean morphine concentrations fell from 3890 ng/mL during baseline to 661 ng/mL during withdrawal. Qualitative urinalysis showed a similar pattern of results. Subjects receiving the highest dose showed concomitant decreases in both urine morphine and benzoylecgonine concentrations. There were no significant group differences in treatment retention or adverse events.

CONCLUSIONS

A sublingual buprenorphine solution at 16 mg daily is well tolerated and effective in reducing concomitant opiate and cocaine use. The therapeutic effect on cocaine use appears independent of that on opiate use.

Methadone dose increase and abstinence reinforcement for treatment of continued heroin use during methadone maintenance

BACKGROUND

Although methadone maintenance is an effective therapy for heroin dependence, some patients continue to use heroin and may benefit from therapeutic modifications. This study evaluated a behavioral intervention, a pharmacological intervention, and a combination of both interventions.

METHODS

Throughout the study all patients received daily methadone hydrochloride maintenance (initially 50 mg/d orally) and weekly counseling. Following baseline treatment patients who continued to use heroin were randomly assigned to 1 of 4 interventions: (1) contingent vouchers for opiate-negative urine specimens (n = 29 patients); (2) methadone hydrochloride dose increase to 70 mg/d (n = 31 patients); (3) combined contingent vouchers and methadone dose increase (n = 32 patients); and (4) neither intervention (comparison standard; n = 28 patients). Methadone dose increases were double blind. Vouchers had monetary value and were exchangeable for goods and services. Groups not receiving contingent vouchers received matching vouchers independent of urine test results. Primary outcome measure was opiate-negative urine specimens (thrice weekly urinalysis).

RESULTS

Contingent vouchers and a methadone dose increase each significantly increased the percentage of opiate-negative urine specimens during intervention. Contingent vouchers, with or without a methadone dose increase, increased the duration of sustained abstinence as assessed by urine screenings. Methadone dose increase, with or without contingent vouchers, reduced self-reported frequency of use and self-reported craving.

CONCLUSIONS

In patients enrolled in a methadone-maintainence program who continued to use heroin, abstinence reinforcement and a methadone dose increase were each effective in reducing use. When combined, they did not dramatically enhance each other's effects on any 1 outcome measure, but they did seem to have complementary benefits.

Cocaine craving and use during daily life

RATIONALE

Craving is often assumed to cause ongoing drug use and relapse and is a major focus of addiction research. However, its relationship to drug use has not been adequately documented.

OBJECTIVES

The aim of this study was to investigate the relationship between craving and drug use in real time and in the daily living environments of drug users.

METHODS

In a prospective, longitudinal, cohort design (ecological momentary assessment), 112 cocaine-abusing individuals in methadone maintenance treatment rated their craving and mood at random times (two to five times daily, prompted by electronic diaries) as they went about their everyday activities. They also initiated an electronic diary entry each time they used cocaine. Drug use was monitored by thrice-weekly urine testing.

RESULTS

During periods of urine-verified cocaine use, ratings of cocaine craving increased across the day and were higher than during periods of urine-verified abstinence. During the 5 h prior to cocaine use, ratings of craving significantly increased. These patterns were not seen in ratings of heroin craving or mood (e.g., feeling happy or bored).

CONCLUSIONS

Cocaine craving is tightly coupled to cocaine use in users' normal environments. Our findings provide previously unavailable support for a relationship that has been seriously questioned in some theoretical accounts. We discuss what steps will be needed to determine whether craving causes use.

Effects of buprenorphine and methadone in methadone-maintained subjects

Buprenorphine, a partial mu opioid agonist, is an experimental medication under development for the treatment of opioid dependence as an alternative to methadone maintenance. The present study examined the relationship between level of opioid physical dependence and response to buprenorphine administration as part of a program to develop procedures for transferring patients from methadone to buprenorphine treatment. This laboratory study characterized the agonist and antagonist effects of acute doses of buprenorphine and methadone in subjects maintained on either 30 (n = 7) or 60 (n = 6) mg/day oral methadone. Test doses of placebo [sl. and PO), methadone (15, 30, and 60 mg PO) and buprenorphine (2, 4, and 8 mg sl.) were administered to volunteers residing on a closed residential unit. Subjective, physiological, observer-rated, and cognitive/psychomotor measures were collected for 6.5 h after test doses. Test doses of methadone, but not buprenorphine, constricted pupils and produced dose-related increases on subjective report measures reflecting opioid agonist drug effects. Agonist effects of methadone were more prominent in the 30 mg than in the 60 mg methadone maintenance condition. Buprenorphine, but not methadone, precipitated opioid withdrawal signs and symptoms that were more prominent in the 60 mg than in the 30 mg methadone maintenance condition. These findings suggest that abrupt transition from methadone to buprenorphine may produce patient discomfort that is positively related to both methadone maintenance dose and buprenorphine transition dose.

Tobacco, cocaine, and heroin: Craving and use during daily life

BACKGROUND

Relationships among tobacco smoking, tobacco craving, and other drug use and craving may have treatment implications in polydrug-dependent individuals.

METHODS

We conducted the first ecological momentary assessment (EMA) study to investigate how smoking is related to other drug use and craving during daily life. For up to 20 weeks, 106 methadone-maintained outpatients carried PalmPilots (PDAs). They reported their craving, mood, behaviors, environment, and cigarette-smoking status in 2 to 5 random-prompt entries/day and initiated PDA entries when they used cocaine or heroin or had a discrete episode of craving for cocaine or heroin.

RESULTS

Smoking frequency increased linearly with random-prompt ratings of tobacco craving, cocaine craving, and craving for both cocaine and heroin. Smoking frequency was greater during discrete episodes of cocaine use and craving than during random-prompt reports of low craving for cocaine. This pattern was also significant for dual cocaine and heroin use and craving. Smoking and tobacco craving were each considerably reduced during periods of urine-verified abstinence from cocaine, and there was a (nonsignificant) tendency for morning smoking to be especially reduced during those periods.

CONCLUSIONS

This EMA study confirms that smoking and tobacco craving are strongly associated with the use of and craving for cocaine and heroin. Together with prior findings, our data suggest that tobacco and cocaine may each increase craving for (and likelihood of continued use of) themselves and each other. Treatment for tobacco dependence should probably be offered concurrently with (rather than only after) initiation of treatment for other substance-use disorders.

Pathological gambling among cocaine-dependent outpatients

OBJECTIVE

The authors investigated the occurrence of pathological gambling among cocaine-dependent outpatients, its influence on short-term outcome of treatment, and comparative characteristics of patients with and without pathological gambling.

METHOD

The subjects were 313 cocaine-dependent (200 also opiate-dependent) outpatients in clinical trials of medication for cocaine dependence. Pathological gambling (DSM-III-R criteria) was assessed with the Diagnostic Interview Schedule, and sociodemographic and socioeconomic characteristics were determined with the Addiction Severity Index. Outcome was defined as time in treatment (proportion of maximum scheduled time) and proportion of cocaine-positive urine samples during treatment.

RESULTS

Pathological gambling had a lifetime occurrence rate of 8.0% and a current (past month) occurrence of 3.8%. Onset preceded the onset of cocaine dependence in 72.0% of the patients (and preceded onset of opiate dependence in 44.4%). Patients with pathological gambling (lifetime or current) did not differ significantly from other patients in length of treatment or proportion of cocaine-positive urine samples. Those with lifetime pathological gambling were significantly more likely to have tobacco dependence (84.0% versus 61.1%) and antisocial personality disorder (56.0% versus 19.8%), to be unemployed (84.0% versus 49.3%), to have recently engaged in illegal activity for profit (64.0% versus 38.5%), and to have been incarcerated (62.5% versus 33.9%).

CONCLUSIONS

Pathological gambling is substantially more prevalent among cocaine-dependent outpatients than in the general population. Patients with pathological gambling differ from other cocaine-dependent outpatients in some sociodemographic characteristics but not in short-term outcome of treatment for cocaine dependence.

Discriminative stimulus and subjective effects of theobromine and caffeine in humans

Theobromine versus placebo discrimination and caffeine versus placebo discrimination were studied in two consecutive experiments in seven volunteers who abstained from methylxanthines. Daily sessions involved PO double-blind ingestion of two sets of capsules sequentially, one of which contained drug and the other placebo. Subjects attempted to identify, and were later informed, which set of capsules contained the drug. In each experiment subjects were exposed to progressively lower doses. Five subjects acquired the theobromine discrimination; the lowest dose discriminated ranged from 100 to 560 mg. All seven subjects acquired the caffeine discrimination; the lowest dose discriminated ranged from 1.8 to 178 mg. A final experiment evaluated subjective effect ratings following 560 mg theobromine, 178 mg caffeine and placebo, which were administered double-blind in capsules once daily, five times each in mixed sequence. Caffeine produced changes in both group and individual ratings (e.g. increased well-being, energy, social disposition and alert). Theobromine did not produce changes in group ratings but changed ratings in some subjects. Across subjects, sensitivity to caffeine discriminative effects in the discrimination experiment correlated significantly with the number and magnitude of caffeine subjective effects in the final experiment. This study documents modest discriminative effects of theobromine in humans, but the basis of the discrimination is unclear. This study suggests that commonly consumed cocoa products contain behaviorally active doses of caffeine and possibly theobromine.