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Completed

NCT Number: NCT01627392

Mechanisms of the Nicotine Metabolism Effect on Tobacco Dependence

The purpose of the study is to learn more about tobacco dependence and nicotine metabolism in African-Americans and whites, by studying to see if how fast a person metabolizes nicotine (how the body breaks down nicotine into inactive compounds) affects how dependent they are on smoking cigarettes. The investigators believe that people with a faster rate of metabolism may have more severe nicotine withdrawal symptoms and also may have a harder time trying to quit smoking.

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Key information

Conditions

Cigarette Smoking Behavior Smoking Tobacco Smoking Tobacco Use

Age range

18 year–70 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

San Francisco General Hospital

San Francisco, California, 94110, United States

About this study

Our studies will use the nicotine metabolite ratio (NMR) (the ratio between the nicotine metabolites 3'hydroxycotinine and cotinine)as a simple and clinically feasible biomarker for the rate of nicotine metabolism. The investigators hypothesize that a faster rate of metabolism leads to faster elimination of nicotine from the body and a more rapid dissipation of brain tolerance to nicotine in the interval between cigarettes, leading in turn to (1) more severe nicotine withdrawal symptoms and (2) greater subjective reward from the cigarette smoked following deprivation. These effects would help to explain why smokers with faster rates of nicotine metabolism have a poorer response to smoking cessation therapy when compared to those with slower rates of metabolism.

The investigators will explore the relationship of the NMR to the endophenotypes of withdrawal, craving and reward, with the assumption that these factors are likely intermediaries for the mechanism linking nicotine metabolism to tobacco dependence and smoking cessation rates with pharmacotherapy. Our study design uses a brief (6 hour) interval of smoking abstinence followed by a "reward" cigarette to elicit the subjective responses relating to withdrawal and reward. Because smoking behavior and severity of nicotine dependence vary by race and sex the investigators will also compare the relationship between NMR and withdrawal and reward in African American vs white smokers and in men vs women.

Secondary analyses will examine whether nicotine half-life mediates the observed effects of NMR on primary response measures.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • African-American or Caucasian
  • Age 18-70 years
  • Regular smoker of 5 or more cigarettes per day
  • Saliva cotinine of 100 ng/ml or greater

Exclusion criteria

  • Obese (BMI > 38) or underweight (BMI < 17)
  • Major systemic or psychiatric condition
  • Medications that are inducers of CYP2A6
  • History of alcohol abuse
  • Positive drug urine tox test
  • Pregnancy or breast feeding

Treatment and study plan

smoking abstinence

Behavioral

6 hour smoking abstinence

Primary outcomes

  1. Nicotine withdrawal symptoms

    Time frame: 6 hours post nicotine load

    Total withdrawal score as measured by Minnesota Nicotine Withdrawal Scale

Secondary outcomes

  1. Cognitive performance

    Time frame: 6 hours post nicotine load

    Cognitive performance will be measured by n-back computerized testing

  2. Smoking behavior: number of cigarettes

    Time frame: 90 minutes post-abstinence

    Smoking behavior will be measured by number of cigarettes during a monitoring period following the 3rd (reward) cigarette of the protocol

  3. Smoking behavior: number of puffs per cigarette

    Time frame: 90 minutes post-abstinence

    Smoking behavior will be measured by number of puffs per cigarette during a monitoring period following the 3rd (reward) cigarette of the protocol

  4. Smoking behavior: time to first post-reward cigarette

    Time frame: 90 minutes post-abstinence

    Smoking behavior will be measured by time to first post-reward cigarette during a monitoring period following the 3rd (reward) cigarette of the protocol

Sponsors and collaborators

Lead sponsor

University of California, San Francisco

Other

Registry information

Acronym: NMR

Important dates

Study start
2012
Primary completion
2015
Study completion
2015
First posted
Jun 25, 2012
Registry last updated
Dec 3, 2015

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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