Impact of Sweeteners on the Addictive Threshold of Nicotine

To determine if sucralose, an artificial sweetener, modulates nicotine threshold doses for discrimination, subjective-rewarding effects, and reinforcement in smokers with varying levels of dependence.

Inclusion Criteria: * 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 by level of dependence, assessed with the FTND 29 low or no dependence ≤3 and moderate or high dependence ≥ 4. * 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; and 5) seeking (or undergoing) treatment for tobacco dependence or smoking.