Substance use after participation in laboratory studies involving smoked cocaine self-administration

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Abstract

Objective

Laboratory studies in which drugs of abuse are self- or experimenter-administered to non-treatment-seeking research volunteers provide valuable data about new pharmacotherapies for substance use disorders, as well as behavioral and performance data for understanding the neurobiology of drug abuse. This paper analyzed follow-up data from six smoked cocaine self-administration laboratory studies, in order to determine whether changes in substance use occurred 1 and 3 months after study participation compared to pre-study baseline.

Methods

Ninety-eight healthy, non-treatment-seeking cocaine users were admitted to inpatient and combined inpatient/outpatient studies lasting from 12 to 105 days. The studies allowed participants to self-administer repeated doses of smoked cocaine (0, 6, 12, 25, and/or 50 mg per dose) on multiple occasions. Participants returned for follow-up at 1 and 3 months, at which time self-reported consumption of cocaine, alcohol, marijuana, and nicotine was assessed.

Results

Compared to baseline ($374.04/week, S.D. $350.09), cocaine use significantly decreased at 1 month ($165.13/week, S.D. $165.56) and 3 months ($118.59/week, S.D. $110.48) after study participation (p < 0.001; results based on the 39 participants who completed all 3 time points). This decrease was not accompanied by a change in other drug use, e.g., a compensatory increase in alcohol, marijuana or nicotine use.

Conclusion

Study participation was not associated with increased post-study cocaine, alcohol, marijuana, or nicotine use. Thus, human laboratory models of cocaine self-administration, conducted in non-treatment-seeking research volunteers, are relatively safe, and study participation does not exacerbate ongoing drug use.

Introduction

Laboratory studies in which drugs of abuse are self- or experimenter-administered to non-treatment-seeking research volunteers provide valuable drug interaction data about new pharmacotherapies for substance use disorders. In addition, these studies provide valuable behavioral and performance data for understanding the neurobiology of drug abuse (Comer et al., 2008, Fischman et al., 1990, Foltin and Fischman, 1994, Haney and Spealman, 2008). Such studies characterize the subjective, reinforcing and physiological effects of a drug of abuse over a range of doses, often in the presence and absence (placebo) of potential pharmacotherapies. In this way, the effects of a candidate pharmacotherapy on the direct effects of the abused drug can be assessed. Such studies also characterize the behavioral, performance and cognitive effects of a drug of abuse, which can be useful in the development and assessment of effective treatment interventions. Finally, these laboratory studies can yield important insights into neurobiological, behavioral, and social factors underlying initiation and maintenance of problematic drug use (Childs and de Wit, 2010, Hamidovic et al., 2010).

Studies involving the administration of drugs of abuse have been extensively used and are typically accepted as relatively safe and ethically sound (Fischman and Johanson, 1998, Modell et al., 1993). However, there are limited data to address concerns about how drug administration during a laboratory study may influence subsequent drug use patterns. Some studies have shown no significant change from pre-admission to post-study follow-up (Bigelow et al., 1994, Kaufman et al., 2000, Vadhan et al., 2006). Other studies have shown a significant decrease in substance use from pre-admission to post-study follow-up (Drobes and Anton, 2000, Elman et al., 2001, Pratt and Davidson, 2005, Sinha et al., 1999). Overall, participation in drug administration studies has not appeared to increase subsequent drug use.

This paper adds to the literature by presenting an analysis of follow-up data from six laboratory studies carried out by the Substance Use Research Center at Columbia University in which participants self-administered smoked cocaine. The primary aim was to determine whether changes in substance use occurred 1 and 3 months after study participation compared to pre-study baseline. Based on the existing literature, we hypothesized that substance use would significantly decrease following study participation. Other analyses investigated whether those who completed the study differed in baseline demographics, psychiatric diagnoses or drug use from those who did not, and determined whether features of cocaine use at baseline predicted changes in cocaine use at post-study follow-up.

Section snippets

Screening procedures and measures

After providing informed consent, volunteers for study participation underwent comprehensive screening to ensure that they were physically and psychiatrically healthy. Screening procedures are described in detail elsewhere (Evans and Foltin, 2006, Haney et al., 2011, Reed et al., 2011, Vosburg et al., 2010a, Vosburg et al., 2010b, Vosburg et al., 2005). Only non-treatment-seeking candidates were recruited. All potential candidates underwent an initial telephone-screening interview, followed by

Baseline features and substance use

Table 1 presents baseline demographics and SCID diagnoses. Table 2 presents substance use at baseline, 1-month and 3-month follow-up. Table 3 presents urine toxicology results at baseline, 1-month and 3-month follow-up.

Based on the 39 individuals for whom there were data at all three time points, Fig. 1(top panel) shows that there was a significant effect of time on mean dollars of cocaine used/week [baseline ($374.04/week, S.D. $350.09), 1-month ($165.13/week, S.D. $165.56), 3-month

Discussion

We found that compared to pre-study baseline, non-treatment-seeking cocaine users decreased their self-reported cocaine use at 1-month and 3-month follow-up after participation in a smoked cocaine self-administration laboratory study. This decrease was not accompanied by a compensatory increase in alcohol, marijuana or nicotine use.

There are a range of possible explanations for the robust decrease in self-reported cocaine use observed during follow-up for these studies. For instance, due to the

Conclusion

These analyses indicate that participation in laboratory studies involving self-administration of smoked cocaine does not increase, and may be associated with reductions in cocaine use among non-treatment-seeking cocaine users, as compared to pre-study baseline. Cocaine use decreased at 1- and 3-month follow-up after participation, regardless of whether participants completed the study in which they enrolled. Moreover, this decrease was not accompanied by a compensatory increase in use of

Role of funding source

The National Institute on Drug Abuse (NIDA) had no role in the study's design, data collection, analysis, interpretation, manuscript preparation, or decision to submit the manuscript for publication. The studies in this manuscript were funded by the following NIDA grants: DA06234, DA10755, DA08105, and DA021319.

Contributors

MH, SME, RWF and ER wrote the protocols and designed the studies in this manuscript. RKK completed the background literature search. RKK and GB completed the statistical analyses. RKK wrote the first draft of the manuscript. All authors contributed to and have approved the final manuscript.

Conflict of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the manuscript.

References (31)

  • Community Epidemiology Work Group (CEWG)
  • Community Epidemiology Work Group (CEWG)
  • E. Childs et al.

    Effects of acute psychosocial stress on cigarette craving and smoking

    Nicotine Tob. Res.

    (2010)
  • D.J. Drobes et al.

    Drinking in alcoholics following an alcohol challenge research protocol

    J. Stud. Alcohol

    (2000)
  • R.N. Ehrman et al.

    Comparing self-reported cocaine use with repeated urine tests in outpatient cocaine abusers

    Exp. Clin. Psychopharmacol.

    (1997)
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