Biomedical subjects

K L Preston

Publications and source records attributed to K L Preston.

At least 19 recordsLinked to original sources

PubMed2004

Cyclazocine: comparison to hydromorphone and interaction with cocaine.

Kappa-opioid agonists produce neurobiological and behavioral effects opposite to those of cocaine and may be useful for the treatment of cocaine dependence. To evaluate the kappa- and mu-agonist effects of cyclazocine and to test whether cyclazocine pretreatment would attenuate the effects of cocaine, healthy, male and female, experienced opiate and cocaine users (n = 13) were enrolled in a two-phase study. In Phase 1, placebo, cyclazocine (0.2, 0.4 and 0.8 mg) and the mu-agonist hydromorphone (5 and 15 mg) were administered orally in six 4.5-hour sessions separated by at least 72 h. In Phase 2, cocaine (100 mg intranasal) was given 2 h after oral pretreatment with cyclazocine (0, 0.1, 0.2, 0.4, 0.8 and 0 mg, in that order) in each of six sessions conducted daily Monday to Friday and the following Monday. Physiological, subjective and behavioral measures were collected in each session. Nine participants completed Phase 1; eight completed Phase 2. Hydromorphone (15 mg) produced prototypic mu-agonist effects. Cyclazocine exhibited only modest kappa-like effects. Cyclazocine also had only modest, non-dose-related effects on response to cocaine. However, cocaine effects were consistently lower on the last administration (cyclazocine 0 mg pretreatment) following 4 days of cyclazocine pretreatment, compared to the first administration (0 mg pretreatment). This finding is unlikely to be fully attributable to cocaine tolerance and is not accounted for by pharmacokinetic changes; plasma concentrations of cocaine were not altered by cyclazocine. This study is suggestive but not strongly supportive for the use of kappa-opiate drugs to diminish acute effects of cocaine administration or for the use of these kappa agonists in drug abuse treatment applications.

Administration, Intranasal↗

PubMed2003

Does cannabis use predict poor outcome for heroin-dependent patients on maintenance treatment? Past findings and more evidence against.

AIMS: To determine whether cannabinoid-positive urine specimens in heroin-dependent out-patients predict other drug use or impairments in psychosocial functioning, and whether such outcomes are better predicted by cannabis-use disorders than by cannabis use itself. DESIGN: Retrospective analyses of three clinical trials; each included a behavioral intervention (contingency management) for cocaine or heroin use during methadone maintenance. Trials lasted 25-29 weeks; follow-up evaluations occurred 3, 6 and 12 months post-treatment. For the present analyses, data were pooled across trials where appropriate. SETTING: Urban out-patient methadone clinic. PARTICIPANTS: Four hundred and eight polydrug abusers meeting methadone-maintenance criteria. MEASUREMENTS: Participants were categorized as non-users, occasional users or frequent users of cannabis based on thrice-weekly qualitative urinalyses. Cannabis-use disorders were assessed with the Diagnostic Interview Schedule III-R. Outcome measures included proportion of cocaine- and opiate-positive urines and the Addiction Severity Index (at intake and follow-ups). FINDINGS: Cannabis use was not associated with retention, use of cocaine or heroin, or any other outcome measure during or after treatment. Our analyses had a power of 0.95 to detect an r2 of 0.11 between cannabis use and heroin or cocaine use; the r2 we detected was less than 0.03 and non-significant. A previous finding, that cannabis use predicted lapse to heroin use in heroin-abstinent patients, did not replicate in our sample. However, cannabis-use disorders were associated weakly with psychosocial problems at post-treatment follow-up. CONCLUSIONS: Cannabinoid-positive urines need not be a major focus of clinical attention during treatment for opiate dependence, unless patients report symptoms of cannabis-use disorders.

Adult↗

PubMed2001

Family history influence on drug abuse severity and treatment outcome.

Influence of parental alcohol/substance abuse on methadone maintenance therapy (MMT) outcome was examined in 164 DSM-III-R opioid dependent adults with no other current DSM Axis I disorder. Family history positive patients had more DSM-III-R opioid dependence symptoms and were more likely to be classified as severely dependent. However, when placed on identical daily doses of methadone (50 mg), they had lower rates of illicit opioid use but higher rates of cocaine use than family history negative patients. Both effects remained significant after adjusting for gender and race. These results suggest that common genetic factors may underlie both susceptibility to heroin dependence and response to therapeutic methadone treatment.

Adult↗

PubMed2001

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.

Administration, Oral↗

PubMed2001

Shaping cocaine abstinence by successive approximation.

Cocaine-using methadone-maintenance patients were randomized to standard contingency management (abstinence group, n = 49) or to a contingency designed to increase contact with reinforcers (shaping group, n = 46). For 8 weeks, both groups earned escalating-value vouchers based on thrice-weekly urinalyses: The abstinence group earned vouchers for cocaine-negative urines only; the shaping group earned vouchers for each urine specimen with a 25% or more decrease in cocaine metabolite (first 3 weeks) and then for negative urines only (last 5 weeks). Cocaine use was lower in the shaping group, but only in the last 5 weeks, when the response requirement was identical. Thus, the shaping contingency appeared to better prepare patients for abstinence. A 2nd phase of the study showed that abstinence induced by escalating-value vouchers can be maintained by a nonescalating schedule, suggesting that contingency management can be practical as a maintenance treatment.

Adult↗

PubMed2001

Detection of opiate use in a methadone maintenance treatment population with the CEDIA 6-acetylmorphine and CEDIA DAU opiate assays.

Heroin, with a plasma half-life of approximately 5 min, is rapidly metabolized to 6-acetylmorphine (6-AM). 6-AM, a specific marker for heroin use, which also has a short half-life of only 0.6 h, is detected in urine for only a few hours after heroin exposure. Ingestion of poppy seeds and/or licit opiate analgesics can produce positive urine opiate tests. This has complicated the interpretation of positive opiate results and contributed to the decision to raise opiate cutoff concentrations and to require 6-AM confirmation in federally mandated workplace drug-testing programs. Microgenics Corp. has developed the CEDIA 6-AM assay, a homogeneous enzyme immunoassay for semiquantitative determination of 6-AM in human urine, in addition to its CEDIA DAU opiate assay. Urine specimens were collected 3 times per week from 27 participants enrolled in a clinical research trial evaluating a contingency management treatment program for heroin and cocaine abuse. Of the 1377 urine specimens screened, 261 (18.9%) were positive for opiates at > or = 300 ng/mL, 153 (11.1%) were positive for opiates at > or = 2000 ng/mL, and 55 (4.0%) were positive for 6-AM at > or = 10 ng/mL. For opiate-positive screens > or = 300 and > or = 2000 ng/mL, 91.3% and 80.8% confirmed positive for morphine or codeine at the respective gas chromatography-mass spectrometry (GC-MS) cutoffs. All specimens screening positive for 6-AM also confirmed positive by GC-MS at > or = 10 ng/mL. Increasing the opiate screening and confirmation cutoffs for the federal workplace drug-testing program resulted in 8% fewer opiate-positive tests; however, recent heroin use was not affected by this change.

Adolescent↗

PubMed2000

The brief abstinence test: voucher-based reinforcement of cocaine abstinence.

This study assessed the effectiveness of a brief abstinence reinforcement procedure for initiating cocaine abstinence in methadone maintenance patients. On Monday of the test week, 72 cocaine-abusing methadone patients were offered a $100 voucher if urine samples collected on Wednesday indicated that they had abstained from cocaine across that 2-day period. A patient was considered abstinent and the voucher delivered if the urine benzoylecgonine concentration decreased by 50% from Monday to Wednesday (quantitative criterion) or if the concentration of Wednesday's urine sample was < or = 300 ng/ml. Overall, 79% of study patients showed urinalysis evidence of abstention from cocaine between Monday and Wednesday of the test week. In a subsample with complete data (n = 50), significantly more patients abstained from cocaine from Monday to Wednesday of the test week (84%) than from Monday to Wednesday of the week before (36%) or after (32%) the test week. Furthermore, while almost all patients (94%) decreased their benzoylecgonine concentration from Monday to Wednesday of the test week, significantly fewer patients' benzoylecgonine concentrations decreased from Monday to Wednesday of the week before (56%) or after (48%) the test week. This highly efficacious procedure may have clinical application where reliable abstinence initiation is desired, either on a temporary basis (e.g. sobriety sampling) or at the start of longer-term interventions. It may also be possible to use the brief abstinence test as an experimental model to assess the effects of other therapeutic interventions on abstinence initiation in treatment settings.

Adult↗

PubMed2000

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.

Adult↗

PubMed2000

Cocaine and metabolite elimination patterns in chronic cocaine users during cessation: plasma and saliva analysis.

Several reports suggest a prolonged elimination of cocaine and metabolites after chronic use compared with single or occasional use. This study was designed to measure the half-lives of cocaine in plasma and saliva of individuals who consumed cocaine on a frequent basis. The disposition and elimination patterns of cocaine and metabolites in the body fluids of chronic high-dose cocaine users during acute cessation of use were investigated. Plasma and saliva specimens were collected over a 12-h period during cessation and analyzed by gas chromatography-mass spectrometry. Pharmacokinetic parameters were derived by noncompartmental analysis of plasma and saliva data. Results indicated a cocaine terminal T(1/2) of 3.8 h in plasma and 7.9 h in saliva. The terminal T(1/2) of benzoylecgonine was 6.6 h in plasma and 9.2 h in saliva. Compared with prior studies of acute low-dose cocaine administration, these findings suggest that cocaine's half-life is longer in active street users than in occasional users though the half-life of its main metabolite benzoylecgonine remains similar (as do cocaine saliva-to-plasma ratios). Thus, regular use of cocaine appears to alter the disposition and elimination of cocaine when compared to single or occasional use.

Adolescent↗

PubMed2000

Monitoring opiate use in substance abuse treatment patients with sweat and urine drug testing.

Although urine testing remains the standard for drug use monitoring, sweat testing for drugs of abuse is increasing, especially in criminal justice programs. One reason for this increase is sweat testing may widen the detection window compared to urine testing. Drug metabolites are rapidly excreted in urine limiting the window of detection of a single use to a few days. In contrast, sweat collection devices can be worn for longer periods of time. This study was designed to compare the efficacy of sweat testing versus urine testing for detecting drug use. Paired sweat patches that were applied and removed weekly on Tuesdays were compared to 3-5 consecutive urine specimens collected Mondays, Wednesdays, and Fridays (355 matched sweat and urine specimen sets) from 44 patients in a methadone-maintenance outpatient treatment program. All patches (N = 925) were extracted in 2.5 mL of solvent and analyzed by ELISA immunoassay for opiates (cutoff concentration 10 ng/mL). A subset (N = 389) of patches was analyzed by gas chromatography-mass spectrometry (GC-MS). Urine specimens (N = 1886) were subjected to qualitative analysis by EMIT (cutoff 300 ng/mL). Results were evaluated to (1) determine the identity and relative amounts of opiates in sweat; (2) assess replicability in duplicate patches; (3) compare ELISA and GC-MS results for opiates in sweat; and (4) compare the detection of opiate use by sweat and urine testing. Opiates were detected in 38.5% of the sweat patches with the ELISA screen. GC-MS analysis confirmed 83.4% of the screen-positive sweat patches for heroin, 6-acetylmorphine, morphine, and/or codeine (cutoff concentration 5 ng/mL) and 90.2% of the screen-negative patches. The sensitivity, specificity, and efficiency of ELISA opiate results as compared to GC-MS results in sweat were 96.7%, 72.2%, and 89.5%, respectively. Heroin and/or 6-acetylmorphine were detected in 78.1% of the GC-MS-positive sweat patches. Median concentrations of heroin, 6-acetylmorphine, morphine, and codeine in the positive sweat samples were 10.5, 13.6, 15.9, and 13.0 ng/mL, respectively. Agreement in paired sweat patch test results was 90.6% by ELISA analysis. For the purposes of this comparison of ELISA sweat patch to EMIT urine screening for opiates, the more commonly used urine test was considered to be the reference method. The sensitivity, specificity, and efficiency of sweat patch results to urine results for opiates were 68.6%, 86.1%, and 78.6%, respectively. There were 13.5% false-negative and 7.9% false-positive sweat results as compared to urine tests. Analysis of sweat patches provides an alternate method for objectively monitoring drug use and provides an advantage over urine drug testing by extending drug detection times to one week or longer. In addition, identification of heroin and/or 6-acetylmorphine in sweat patches confirmed the use of heroin in 78.1% of the positive cases and differentiated illicit heroin use from possible ingestion of codeine or opiate-containing foods. However, the percentage of false-negative results, at least in this treatment population, indicates that weekly sweat testing may be less sensitive than thrice weekly urine testing in detecting opiate use.

Adolescent↗

PubMed2000

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.

Adolescent↗

PubMed2000

Effects of agonist-antagonist opioids in humans trained in a hydromorphone/not hydromorphone discrimination.

The purpose of this study was to examine the discrimination of agonist-antagonist opioids in humans trained in a two-choice hydromorphone/not hydromorphone discrimination. Eight adult male volunteers with histories of opioid abuse who were not currently physically dependent were trained to discriminate the mu receptor agonist hydromorphone (3 mg/70 kg, i.m.) ("Drug A") from a "Not Drug A" training condition (saline placebo). Volunteers received financial reinforcement for correct responses. After training, generalization dose-effect curves for hydromorphone, butorphanol, pentazocine, nalbuphine, and buprenorphine were determined. Other subjective, behavioral, and physiological measures were concurrently collected in all sessions. In generalization testing hydromorphone and buprenorphine produced dose-related increases in hydromorphone-appropriate responses. Pentazocine produced an inverted U-shaped dose-response curve with complete substitution at 32 mg/70 kg but not at 64 mg/70 kg. Butorphanol and nalbuphine did not completely substitute for hydromorphone at any dose tested. These results differ from an earlier two-choice, Drug A versus Drug B (hydromorphone/saline) discrimination study. After Drug/Not Drug instructions the behavioral discriminations of agonist-antagonist opioids were more consistent with their putative agonist activities at the mu opioid receptor and with their subjective effects profiles than was the case after Drug A versus Drug B instructions. These results suggest that instructions are an important factor in the outcome of human drug discrimination studies.

Adult↗

PubMed1999

Naltrexone shortened opioid detoxification with buprenorphine.

This double-blind, randomized, placebo-controlled clinical trial evaluated the impact on withdrawal symptoms of (i) combining naltrexone with a 4-day buprenorphine taper for short opioid detoxification (NB Group), compared to (ii) using a 4-day buprenorphine taper alone, followed by naltrexone on day 8 (PB Group). Sublingual buprenorphine was administered on days 1-4 (26 mg total). For the NB Group (n = 32) escalating doses of oral naltrexone were given on days 2-8 (placebo day 1). For the PB Group (n = 28) placebo was given on days 1-7 and naltrexone on day 8. Main outcome measures were Observed Opioid Withdrawal scores (OOW, 0-30) and use of medications to treat opioid withdrawal. Of 32 patients in the NB group, 59% experienced clinically relevant withdrawal (defined as OOW > or = 5) on day 2, but, after day 5, none experienced withdrawal. In the PB group, the number of patients experiencing withdrawal increased over time. The first naltrexone dose induced comparable withdrawal in both groups: peak OOW scores were (mean +/- SD) 5.2 +/- 3.3 on day 2 for the NB group, and 4.0 +/- 3.9 on day 8 for the PB group (NS), though, on day 2, 7 patients dropped out in the NB group and none in the PB group, while only one patient dropped out in the PB group on day 8. Throughout the 8-day study, patients in both groups received similar amount of adjunct medication: 0.64 +/- 0.07 mg (NB group) of clonidine vs 0.73 +/- 0.15 mg (PB group; NS). Only 25% of patients required use of sedatives (up to 20 mg diazepam). Starting naltrexone on day 2 appeared to abolish withdrawal symptoms after day 5 and, thus, to shorten the duration of withdrawal symptoms. Peak withdrawal symptoms after naltrexone were of moderate intensity, suggesting that naltrexone combined with buprenorphine is an acceptable and safe treatment for shortened opioid detoxification and induction of naltrexone maintenance.

Adult↗

PubMed1999

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.

Adult↗

PubMed1999

Monitoring cocaine use in substance-abuse-treatment patients by sweat and urine testing.

Sweat and urine specimens were collected from 44 methadone-maintenance patients to evaluate the use of sweat testing to monitor cocaine use. Paired sweat patches that were applied and removed weekly (on Tuesdays) were compared with 3-5 consecutive urine specimens collected Mondays, Wednesdays, and Fridays. All patches (N = 930) were extracted in 2.5 mL of solvent and analyzed by ELISA immunoassay (cutoff concentration 10 ng/mL); a subset of patches (N = 591) was also analyzed by gas chromatography-mass spectrometry (GC-MS) for cocaine, benzoylecgonine (BZE), and ecgonine methyl ester (EME) (cutoff concentration 5 ng/mL). Urine specimens were subjected to qualitative analysis by EMIT (cutoff 300 ng/mL) and subsets were analyzed by TDx (semiquantitative, LOD 30 ng/mL) and by GC-MS for cocaine (LOD 5 ng/mL). Results were evaluated to (1) determine the relative amounts of cocaine and its metabolites in sweat; (2) assess replicability in duplicate patches; (3) compare ELISA and GC-MS results for cocaine in sweat; and (4) compare the detection of cocaine use by sweat and urine testing. Cocaine was detected by GC-MS in 99% of ELISA-positive sweat patches; median concentrations of cocaine, BZE, and EME were 378, 78.7, and 74 ng/mL, respectively. Agreement in duplicate patches was approximately 90% by ELISA analysis. The sensitivity, specificity, and efficiency of sweat ELISA cocaine results as compared with sweat GC-MS results were 93.6%, 91.3%, and 93.2%, respectively. The sensitivity, specificity, and efficiency between ELISA sweat patch and EMIT urine results were 97.6%, 60.5%, and 77.7%, respectively. These results support the use of sweat patches for monitoring cocaine use, though further evaluation is needed.

Adolescent↗

PubMed1999

Low-dose oral cocaine in humans: acquisition of discrimination and time-course of effects.

Seven cocaine-abusing volunteers were trained to discriminate 50 mg oral cocaine vs placebo across 50 2-h sessions. Discriminative, subjective and autonomic effects were assessed with a procedure developed for precise characterization of their acute time-course. Subjective effects of oral cocaine began 10-15 min post-drug, peaked at 40-50 min and took up to 100 min post-drug to return nearly to baseline. Autonomic effects also began 10-15 min post-drug, peaked at 40-50 min and typically returned to baseline by 120 min post-drug; for most participants, peak heart rate and blood pressure remained within the range seen with placebo. Six out of seven participants acquired the discrimination (although this typically required 15-30 sessions, and there were some intriguing dissociations between the ability to discriminate oral cocaine from placebo and the ability to identify it as a stimulant). In most participants, oral cocaine produced increases in ratings of 'liking', 'alertness' and 'good effects', and in motor performance. Overall, the results support the sensitivity of the behavioral-testing procedure used, and show that 50 mg oral cocaine can serve as a discriminative stimulus in adult humans.

Administration, Oral↗

PubMed1999

Assessment of opioid partial agonist activity with a three-choice hydromorphone dose-discrimination procedure.

The discriminative stimulus and subjective effects of opioid mixed agonist-antagonists were assessed in volunteer nondependent heroin users trained in a three-choice drug discrimination procedure to discriminate among the effects of i.m. administration of 2 ml of saline, 1 mg of hydromorphone, and 4 mg of hydromorphone (a morphine-like mu agonist). Other subjective, behavioral, and physiological measures were concurrently collected. The discrimination was readily learned by six of the eight subjects. After training, generalization curves were determined for the following i.m. drug conditions: hydromorphone (0.375-4.0 mg), pentazocine (7.5-60 mg), butorphanol (0.75-6 mg), nalbuphine (3-24 mg), and buprenorphine (0.075-0.6 mg). All five of the test drugs were discriminated significantly or showed trends toward being discriminated as hydromorphone 1 mg-like at one or more dose levels. Hydromorphone showed an inverted U-shaped dose-effect function on the hydromorphone 1 mg-like discrimination. Subjective effect measures produced clearer differentiation among the test drugs than did drug discrimination performance. The present results differ from those of a previous study that observed a close relationship between the results of the discrimination measure and subjective effect measures. The previous study used similar methods and test drugs but different training drugs (e.g., 3 mg of hydromorphone versus 6 mg of butorphanol versus saline). It appears that both the sensitivity of drug discrimination performance to between-drug differences and the relationship between discriminative and subjective effects depends upon the specific discrimination that is trained (e.g., two-choice or three-choice). The present high dose-low dose-saline discrimination procedure appears useful for assessing partial agonist activity. The present data are consistent with partial agonist activity for pentazocine, butorphanol, nalbuphine, and buprenorphine.

Adult↗

PubMed1998

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.

Adult↗