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Biomedical subjects

N M Petry

Publications and source records attributed to N M Petry.

At least 37 records · Page 2Linked to original sources
PubMed2000

Give them prizes, and they will come: contingency management for treatment of alcohol dependence.

This study evaluated the efficacy of a contingency management (CM) procedure that provided opportunities to win prizes as reinforcers. At intake to outpatient treatment, 42 alcohol-dependent veterans were randomly assigned to receive standard treatment or standard treatment plus CM, in which they earned the chance to win prizes for submitting negative Breathalyzer samples and completing steps toward treatment goals. Eighty-four percent of the CM participants were retained in treatment for an 8-week period compared with 22% of the standard treatment participants (p < .001). By the end of the treatment period, 69% of those receiving CM were still abstinent, but 61% of those receiving standard treatment had used alcohol (p < .05). These results support the efficacy of this CM procedure. Participants earned an average of $200 in prizes. This CM procedure may be suitable for use in standard treatment settings because prizes can be solicited from the community.

Alcoholism↗
PubMed2000

Effects of increasing income on polydrug use: a comparison of heroin, cocaine and alcohol abusers.

AIMS: To assess how income affects hypothetical drug and non-drug purchasing decisions. PARTICIPANTS AND SETTING: Ninety-four subjects (26 heroin abusers, 28 cocaine abusers, 15 alcohol abusers and 25 non-drug using controls) were recruited from advertisements. INTERVENTION: Subjects were exposed to six conditions in which they "purchased" drugs as well as food, housing, and entertainment as income rose from $30 to $560 per day. FINDINGS: Heroin abusers selected significantly more hypothetical heroin and cocaine as income rose and demand for these two drugs was income elastic, with purchases rising in greater proportion than income. Cocaine abusers significantly increased purchases of, and showed income elastic demand for, cocaine and alcohol. Among alcohol abusers, significant increases in purchases and income elastic demand were found for alcohol and cigarettes, but not for other drugs. Across all four groups, demand for rent and food were income inelastic, such that purchases did not rise in proportion to the changes in income, while demand for entertainment was income elastic. Hypothetical choices were reliable between and within subjects, and drug choices were correlated with urinalysis results and life-time years of drug use. CONCLUSIONS: Income is an important variable in understanding choices for drug and non-drug commodities across a variety of substance-abusing populations.

Adult↗
PubMed2000

A comparison of four buprenorphine dosing regimens using open-dosing procedures: is twice-weekly dosing possible?

AIMS: To compare opioid withdrawal symptoms during 24-, 48-, 72- and 96-hour buprenorphine dosing regimens and to evaluate subjects' preferences for these different dosing schedules. SUBJECTS: Fourteen opioid-dependent subjects participated in this study. They received daily sublingual maintenance doses of 4 mg/70 kg (n = 4) or 8 mg/70 kg (n = 10) of buprenorphine. INTERVENTION: In the first study subjects received, in a random order, four dosing regimens for five repetitions of each: daily maintenance doses every 24 hours (4 or 8 mg/70 kg), double the daily maintenance dose every 48 hours (8 or 16 mg/70 kg), triple the daily maintenance dose every 72 hours (12 or 24 mg/70 kg), and quadruple the daily maintenance dose every 96 hours (16 or 32 mg/70 kg). Measures of subjective and observer opioid withdrawal symptoms were assessed prior to receipt of each dose. In a second study, subjects chose between the different dosing regimens. FINDINGS: Some withdrawal ratings increased during the less frequent dosing schedules in the first study. In the second study, 46% of subjects preferred the quadruple-every-fourth-day dosing regimen over every other option, and only 14% preferred to be dosed daily. CONCLUSIONS: These results suggest that some opioid-dependent outpatients are willing and able to endure the withdrawal symptoms associated with less than daily dosing, and a twice-weekly dosing regimen may be possible.

Adult↗
PubMed2000

Gambling problems in substance abusers are associated with increased sexual risk behaviors.

OBJECTIVES: This study evaluated the association between gambling problems and HIV risk behaviors in substance abusers. PARTICIPANTS AND SETTING: One hundred and thirty-four substance abusers were recruited from advertisements placed in newspapers and at social service agencies. INTERVENTION: Gambling problems were assessed using the South Oaks Gambling Screen (SOGS). The Addiction Severity Index evaluated drug and psychosocial problems, and the HIV Risk Behavior Scale assessed risk behaviors. FINDINGS: Based on SOGS scores, 24% (n = 31) of substance abusers evidenced probable pathological gambling. Problem gambling substance abusers were more likely to be male than non-problem gamblers, but no other differences in demographic characteristics or drug use variables were noted. Compared to non-problem gamblers, problem gamblers reported more sex partners and less frequent use of condoms with casual and paid sex partners. Stepwise logistic regression confirmed the association between severity of gambling problems and more risky sexual behaviors; higher SOGS scores predicted having more than 50 sex partners, exchanging sex for drugs/money, and engaging in anal intercourse (p < 0.05). Participants with gambling problems were also less knowledgeable about HIV transmission. CONCLUSIONS: These data suggest that gambling problems may be a risk factor for contracting HIV. Increased efforts are needed to screen for and treat gambling problems among substance abusers.

Adult↗
PubMed2000

Elevated liver enzyme levels in opioid-dependent patients with hepatitis treated with buprenorphine.

The purpose of this study was to assess changes in liver enzyme levels among opioid-dependent patients treated with buprenorphine. Liver enzyme levels were evaluated among 120 individuals before treatment and following a minimum of 40 days of buprenorphine treatment (2, 4, or 8 mg/70 kg/day). Among patients with a history of hepatitis, AST and ALT levels significantly increased (p < .05) with buprenorphine treatment. The odds of observing an increase in AST were determined to be dependent upon buprenorphine dose (p < .05; odds ratio = 1.23 per 1 mg increase in dose). These results suggest that liver enzyme levels should be monitored carefully when patients with hepatitis are treated with buprenorphine.

Adult↗
PubMed2000

Psychiatric symptoms in problem gambling and non-problem gambling substance abusers.

This study compared demographic characteristics, Addiction Severity Index (ASI) ratings, and psychiatric symptoms in 103 substance abusers with and without gambling problems. Thirty-one of the substance abusers were identified as probable pathological gamblers on the South Oaks Gambling Screen. Although no differences in demographic characteristics or ASI ratings were noted between the groups, subjects with a gambling problem consistently reported more psychiatric distress than substance abusers without a gambling problem. Specifically, they had increased ratings on somatization, obsessive-compulsive, interpersonal sensitivity, hostility, and paranoia scales. These results are discussed in terms of the need to identify and treat gambling problems among substance abusers.

Adult↗
PubMed1999

Excessive discounting of delayed rewards in substance abusers with gambling problems.

This study evaluated delay discounting functions of substance abusing problem gamblers, substance abusing non-problem gamblers, and non-problem gambling/non-substance abusing controls. Subjects chose between hypothetical monetary amounts available after various delays or immediately. In one condition, a USUS$1000 reward was delayed at intervals ranging from 6 h to 25 years. At each delay interval, the immediately available rewards varied from USUS$1 to USUS$999 until choices reflected indifference between the smaller immediate and larger delayed rewards. In a second condition, the delayed reward was USUS$100, and immediate rewards varied from USUS$0.10 to USUS$99.90. In all three groups, hyperbolic discounting functions provided a good fit of the data, and the smaller reward was discounted at a higher rate than the larger reward. Substance abusers discounted delayed rewards at significantly higher rates than non-substance abusing controls, and problem gambling substance abusers discounted delayed rewards at higher rates than their non-problem gambling substance abusing counterparts. Discounting rates were not associated with types or recency of drug use. These results provide further evidence of more rapid discounting of delayed rewards in substance abusers, and especially among substance abusers with a comorbid gambling problem. Rapid discounting of delayed rewards may be a feature central to impulse control and addictive disorders.

Adult↗
PubMed1999

A comparison of four buprenorphine dosing regimens in the treatment of opioid dependence.

OBJECTIVES: This study compared 24-, 48-, 72-, and 96-hour buprenorphine dosing regimens in opioid-dependent outpatients. METHODS: Fourteen subjects received buprenorphine in a double-blind, placebo-controlled crossover trial. Daily sublingual maintenance doses were 4 mg/70 kg (n = 5) and 8 mg/70 kg (n = 9). After a stabilization period of maintenance administration, subjects received, in a random order, four dosing regimens for five repetitions of each regimen: a maintenance dose every 24 hours, a doubled maintenance dose every 48 hours, a tripled maintenance dose every 72 hours, and a quadrupled maintenance dose every 96 hours. In the latter three dosing regimens, subjects received placebo on the interposed day(s). Study participation was contingent on opioid abstinence and daily clinic attendance. Measures of subjective opioid agonist and withdrawal effects were assessed daily. RESULTS: Relative to standard maintenance dosing, none of the higher doses induced agonist effects. Changes in indices of subjective withdrawal effects were noted as the time since the last active dose increased during intermittent dosing regimens, but the magnitude of these effects was relatively low and was comparable to those found in other alternate-day dosing studies. CONCLUSIONS: These results support the feasibility and safety of twice weekly buprenorphine dosing regimens.

Adult↗
PubMed1999

Heroin addicts have higher discount rates for delayed rewards than non-drug-using controls.

Fifty-six heroin addicts and 60 age-matched controls were offered choices between monetary rewards ($11-$80) available immediately and larger rewards ($25-$85) available after delays ranging from 1 week to 6 months. Participants had a 1-in-6 chance of winning a reward that they chose on one randomly selected trial. Delay-discounting rates were estimated from the pattern of participants' choices. The discounting model of impulsiveness (Ainslie, 1975) implies that delay-discounting rates are positively correlated with impulsiveness. On average, heroin addicts' discount rates were twice those of controls (p = .004), and discount rates were positively correlated with impulsivity as measured by self-report questionnaires (p < .05). The results lend external validity to the delay-discounting rate as a measure of impulsiveness, a characteristic associated with substance abuse.

Adult↗
PubMed1999

Buprenorphine dose self-selection: effects of an alternative reinforcer, behavioral economic analysis of demand, and examination of subjective drug effects.

Buprenorphine (BUP)-maintained patients were first exposed to various BUP doses and then chose between BUP doses and money. In the choice phase, they had 10 units exchangeable for units of BUP (constant at 3 mg/unit) or money (varied from $0.30 to $20/unit). They chose BUP exclusively (30 mg) when the money alternative was low. As available money increased, they selected lower daily BUP doses (down to 3 mg). An economic analysis indicated demand for BUP was inelastic; changes in drug intake were proportionally lower than changes in price. Subjective reports of agonist and withdrawal effects increased > 200% when high and low BUP doses, respectively, were given during the exposure phase. In the choice phase, subjective drug effects were constant regardless of the BUP dose selected. Thus, BUP dose selection varies with the magnitude of alternative reinforcers, and subjective drug effects depend on whether doses are self- or experimenter-selected.

Adult↗
PubMed1999

Therapeutic alliance and psychiatric severity as predictors of completion of treatment for opioid dependence.

OBJECTIVE: The role of patient characteristics and the strength of the therapeutic alliance in predicting completion of treatment by opioid-dependent patients was examined. METHODS: Information about patient characteristics and scores on subscales of the Addiction Severity Index (ASI) were obtained for 114 patients at intake to a buprenorphine treatment program lasting three to four months. The strength of the therapeutic alliance was assessed by the Helping Alliance Questionnaire (HAQ). Patients were classified as treatment completers or noncompleters, and logistical regression examined predictors of treatment completion. RESULTS: Only two variables significantly predicted treatment completion: severity of psychiatric symptoms and interaction between HAQ scores and psychiatric severity. Patients with fewer psychiatric symptoms were more likely to complete treatment. The strength of the therapeutic alliance was not related to treatment completion among patients with few psychiatric symptoms, and 62 percent of these patients completed treatment. In contrast, among patients with moderate to severe psychiatric problems, less than 25 percent with weak therapeutic alliances completed treatment, while more than 75 percent with strong therapeutic alliances completed treatment. CONCLUSIONS: The results underscore the importance of early identification of opioid-dependent patients with moderate to severe levels of psychopathology. In this patient subgroup, a strong therapeutic alliance may be an essential condition for successful treatment.

Adult↗
PubMed1999

Prevalence, assessment, and treatment of pathological gambling: a review.

OBJECTIVE: Although pathological gambling is an increasing problem, many mental health providers are unfamiliar with its diagnosis and treatment. To improve recognition and treatment of pathological gambling, the authors reviewed the literature on its prevalence, assessment, and treatment. METHODS: Entries in PsycLIT and MEDLINE were examined for the years 1984 to 1998. RESULTS AND DISCUSSION: The prevalence of pathological gambling seems to be increasing with the spread of legalized gambling; casinos are now operating in 27 states. Point and lifetime prevalence rates of pathological gambling are reported to be as high as 1.4 percent and 5.1 percent, respectively. The most commonly used assessment instrument is the DSM-based, 20-item South Oaks Gambling Screen. There is no standard treatment for pathological gambling. Gamblers Anonymous (GA) is the most popular intervention, and about 1,000 chapters exist in the U.S. Studies suggest that only 8 percent of GA attendees achieve a year of abstinence. Combining professional therapy and GA participation may improve retention and abstinence. Marital and family treatments, including participation in Gam-Anon, the spousal component of GA, have not been sufficiently evaluated. The few studies of cognitive-behavioral treatments suggest that this approach, which may include cognitive restructuring, problem solving, social skills training, and relapse prevention, is promising. Carbamazepine, naltrexone, clomipramine, fluvoxamine, and lithium have been used with some effect. Therapists' manuals and self-help manuals are available. Although research evaluating their efficacy is necessary, manuals can provide a start for therapists who encounter patients with gambling problems. Brief motivational interviewing may be a useful strategy for decreasing gambling among heavy gamblers who are ambivalent about entering treatment or who do not desire abstinence.

Cognitive Behavioral Therapy↗
PubMed1999

Alcohol use in HIV patients: what we don't know may hurt us.

Our objectives are to evaluate the prevalence of and problems associated with alcohol use disorders among HIV patients. We review the literature on alcohol use and HIV. Rates of alcohol use disorders are high among HIV patients. The co-occurrence of alcohol use disorders and HIV may lead to medical and psychiatric complications, difficulties with HIV medication compliance, and poorer treatment outcomes. Additionally, alcohol use is associated with risky sexual behaviours and intravenous drug use, the 2 major modes of HIV transmission. Recommendations for screening and treating alcohol problems in HIV patients are provided.

Alcohol-Related Disorders↗
PubMed1999

Contingency management. Incentives for sobriety.

Contingency management (CM), the systematic reinforcement of desired behaviors and the withholding of reinforcement or punishment of undesired behaviors, is an effective strategy in the treatment of alcohol and other drug (AOD) use disorders. Animal research provides the conceptual basis for using CM in AOD abuse treatment, and human studies have demonstrated the effectiveness of CM interventions in reducing AOD use; improving treatment attendance; and reinforcing other treatment goals, such as complying with a medication regimen or obtaining employment.

Alcoholism↗
PubMed1998

A comparison of subjective, psychomotor and physiological effects of a novel muscarinic analgesic, LY297802 tartrate, and oral morphine in occasional drug users.

This study compared the subjective, physiological and psychomotor effects of a novel muscarinic analgesic (LY297802) and oral morphine in healthy volunteers. Nine, non-dependent, occasional drug users participated in nine experimental sessions in which they received the following conditions: placebo, 0.1, 0.3, 0.56 and 1 mg of oral LY297802 and 10, 30, 56 and 100 mg of oral morphine. Subjective drug effects were assessed using the Visual Analog Scale (VAS), the Addiction Research Center Inventory (ARCI) and subjective and objective agonist and antagonist scales of the Adjective Rating Scale (ARS). These measures were collected 30 min before and every 30 min post drug administration for a 4-h period. Psychomotor performance was evaluated using the Digit Symbol Substitution Test (DSST) at these same time intervals. Physiological measures were collected continuously throughout the sessions. Oral morphine produced significant increases in some subjective effects scales, including elevations on the VAS, ARCI and ARS. In contrast, LY297802 did not engender changes different from placebo on any of these indices. Morphine produced significant dose-dependent effects in DSST performance, heart rate, blood oxygen saturation and pupil diameter. LY297802 significantly and dose dependently increased heart rate, mean arterial pressure and diastolic blood pressure. These results suggest that LY297802 does not induce subjective effects similar to morphine, but that it has some significant physiological effects.

Adult↗
PubMed1998

Ethanol's effects on operant responding: differentiating reinforcement efficacy and motor performance.

The purpose of this study was to examine the effects of ethanol on operant responding in rats. Drugs may affect response rates by several mechanisms, including altering motor performance or sensitivity to reinforcement. These two processes can be dissociated by applying a quantitative model of reinforced responding the response-strength equation, to response rates obtained during multiple variable-interval (VI) schedules of reinforcement. This equation has two fitted parameters. One (k) is thought to measure changes in motor performance, and the other (Re) is thought to measure changes in reinforcement efficacy. In experimental sessions, rats earned sucrose reinforcement on a seven-component multiple VI operant schedule. The average intervals varied from 108 to 3 s and provided reinforcement rates from 30 to 1200/h. Following stable baseline performance, rats were injected intraperitoneally prior to sessions with different doses of ethanol: 0.0, 0.3, 0.6. and 0.9 g/kg. Low to moderate doses of ethanol (0.3 and 0.6 g/kg) significantly decreased response rates on several of the VI schedules but did not alter either of the fitted parameters, suggesting that these doses of ethanol did not affect motor performance or sensitivity to reinforcement. The 0.9 g/kg dose decreased responding maintained by many of the VI schedules and significantly increased the Re parameter, suggesting that the sucrose became relatively less efficacious in ethanol compared to vehicle sessions. This relatively high dose of ethanol, however, did not alter responding maintained by the richest reinforcement schedule, and it did not affect motor performance as defined by the k parameter. These results suggest that, within this paradigm, ethanol affects motivation to respond rather than ability to respond.

Analysis of Variance↗
PubMed1998

Polydrug abuse in heroin addicts: a behavioral economic analysis.

AIM: To assess how price and income affect hypothetical drug-purchasing decisions of polydrug abusers undergoing treatment for heroin addiction. PARTICIPANTS, DESIGN AND SETTING: Forty subjects participated in experiments in which they hypothetically "purchased" drugs as price or income varied. INTERVENTION: Experiment 1 examined effects of heroin price on purchases of heroin, valium, cocaine, marijuana and alcohol. Experiment 2 examined the effects of both heroin and valium prices on purchases of these drugs. In both these experiments, income remained constant. Experiment 3 examined the effects of increasing income on drug choices, with drug prices constant. FINDINGS: As price of heroin rose in Experiment 1, heroin purchases decreased. Reductions in heroin purchases were proportionally less than price increases, demonstrating inelastic demand for heroin. Valium and cocaine purchases increased as heroin price rose, and cross-price elasticity coefficients indicated that these drugs substituted for heroin. In Experiment 2, demand for both heroin and valium was inelastic. Valium substituted for heroin, but heroin purchases were independent of valium prices, suggesting an asymmetrical substitution effect. Marijuana and alcohol purchases were independent of valium price, but both these drugs substituted for heroin. In Experiment 3 demand for heroin and cocaine was income elastic, with purchases rising in greater proportion than income. Marijuana, alcohol and valium purchases did not vary with income, demonstrating that demand for these drugs was income inelastic. Hypothetical choices were reliable both between and within subjects. Moreover, drug choices in this hypothetical situation were correlated with urinalysis results, demonstrating initial validity of this methodology. CONCLUSIONS: This methodology may be useful for understanding the phenomenon of polydrug abuse.

Adult↗