Effects of Commonly Used Medications on Mood and Choice

Volunteers will participate in a double-blind study conducted over a period of about 14-17 weeks including sessions for screening, food and beverage diary review (Phase 1), drug exposure and choice sessions (Phase 2), and no-choice exposure sessions (Phase 3). During Phases 2 and 3, participants will orally ingest capsules containing varying doses of commonly prescribed over-the-counter medications and/or placebo. During screening, participants will be asked questions about participants' general characteristics including demographic information, mood, and personality. Participants will also be examined to determine medical eligibility. Eligible participants will proceed to Phase 1 in which participants will report to the laboratory to review their food and beverage intake up to three times per week and will provide saliva samples to be analyzed for caffeine content (3 sessions). During Phases 2 and 3, participants will be administered placebo or drug-containing capsules under double-blind conditions. To facilitate blindness to the study drugs being administered, caffeine, nicotine, and methylphenidate are disclosed to participants during consent among a longer list of potential drugs they may receive including other prescription and over-the-counter stimulant, sedative, and antihistamine medications. During Phase 2 (choice phase), participants will choose between caffeine (200 mg/70 kg) and placebo across 10 choice sequences. Each choice sequence consists of two exposure sessions (i.e., one session each of caffeine or placebo, order counterbalanced) and one choice session (i.e., choice between caffeine or placebo) for a total of 30 sessions in Phase 2. Following the choice phase, participants will complete the dose-effect phase (Phase 3) to measure the subjective reinforcing effects of methylphenidate (10, 20, and 40 mg/70 kg) and nicotine (1, 2, 3 and 4 mg/70 kg) under double-blind conditions. Phase 3 will consist of 13 total sessions including one session per drug/dose condition plus placebo (8 sessions), a replication of the four nicotine doses (4 sessions), and a final multiple-choice reinforcement session (1 session). During the multiple-choice reinforcement session, we will reinforce a randomly selected choice (i.e., drug vs. money) made by the participant after previous sessions as a surrogate measure of drug reinforcement. The identification of behavioral and pharmacological markers of vulnerability to the effects of drugs of abuse is important in order to inform future substance use disorder prevention and regulatory efforts.

Inclusion criteria

• Age 18-65
• Fluent in written and spoken English and is capable of understanding and complying with the protocol
• Medically healthy
• Non-smoker
• Appropriate dietary/over-the-counter/prescription/illicit drug use history
• Body Mass Index between 18.5 and 35
• Appropriate use of birth control in females e.g., barrier methods, hormonal contraceptives, Intra Uterine Devices (IUDs)

Exclusion criteria

• Known hypersensitivity to administered drugs
• Current neurological, hepatic, renal, endocrine, cardiovascular, gastrointestinal, pulmonary or metabolic disease for which administration of the study drugs would be contraindicated
• Current psychiatric or substance use condition that would interfere with study participation
• Diastolic blood pressure >90 mmHg or a systolic pressure of >140 mmHg
• Use of medications that would interfere with study participation
• Past prescriptions that may affect study participation
• Unwilling or unable to comply with the protocol
• Any other serious disease or condition that might affect life expectancy or make it difficult to successfully manage the subjects according to the protocol
• Females: Pregnancy, breastfeeding, or plans to become pregnant