Determining the nicotine threshold for smokers

Addictive Threshold of Nicotine

Early Phase 1 Interventional Yale University · NCT06096714

This study is testing how different amounts of nicotine affect smokers' choices and feelings to see what levels are most rewarding for them.

Quick facts

PhaseEarly Phase 1
Study typeInterventional
Enrollment36 (estimated)
Ages21 Years to 59 Years
SexAll
SponsorYale University Academic / other
Locations1 site (West Haven, Connecticut)
Trial IDNCT06096714 on ClinicalTrials.gov

What this trial studies

This project aims to identify the nicotine threshold doses that influence discrimination, subjective-rewarding effects, and reinforcement in smokers with varying levels of dependence. Participants will undergo an Adaptation Session followed by four Test Days, where they will be exposed to different nicotine doses and saline. The study will assess their ability to distinguish between nicotine and saline, as well as their preferences for nicotine over saline. Reinforcement will be measured by the percentage of nicotine choices made during the trials, while subjective effects will be evaluated using a standardized questionnaire.

Who should consider this trial

Good fit: Ideal candidates are adults aged 21 to 59 who have been smoking for at least one year and have varying levels of nicotine dependence.

Not a fit: Patients with major medical or psychiatric disorders that could contraindicate participation may not benefit from this study.

Why it matters

Potential benefit: If successful, this study could help tailor smoking cessation strategies by understanding how different nicotine doses affect smokers' behavior and preferences.

How similar studies have performed: Other studies have explored nicotine dependence and its effects, but this specific approach to determining threshold doses is relatively novel.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

* to contact their primary care provider when necessary.
* Adults, aged 21 to 59 years. Individuals less than 21 will be excluded because the minimum age for purchasing tobacco products is 21 in our state. The upper age is set at 59 because there are no previous IV nicotine studies that enrolled smokers over the age of 59.
* Smoking at least for one year and more frequently than once a week, smoking status confirmed with a semi-quantitative urine nicotine test. Smokers will be stratified based on the level of dependence, assessed with the FTND scores (Heatherton et al. 1991) (low or no dependence 4 and moderate or high level of dependence 5.
* In good health as verified by medical history, screening examination, and screening laboratory tests.
* For women, report using acceptable birth control methods.

Exclusion Criteria:

* History of major medical or psychiatric disorders that the physician investigator deems as contraindicated for the participant to be in the study
* regular current use of certain psychotropic medications (such as mood stabilizers, antipsychotics, or anxiolytics being prescribed to treat bipolar disorder, psychosis or anxiety spectrum disorders, respectively)
* current untreated alcohol or substance use disorder for any other recreational or prescription drugs other than nicotine
* for women, pregnant as determined by pregnancy screening, or breastfeeding
* seeking (or undergoing) treatment for tobacco dependence or smoking.

Where this trial is running

West Haven, Connecticut

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions Smoking Addiction
Last reviewed 2026-06-09 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.