The purpose of this study is to investigate the effects of labetalol in response to intravenous nicotine

The purpose of this study is to determine whether labetalol, an alpha and beta adrenergic blocker, will block the subjective and physiological effects of intravenously administered nicotine in humans. A total of 12 subjects will participate in the double blind placebo controlled, outpatient study. Subjects will have 3 separate experimental sessions 3-9 days apart. On each of the experimental sessions, a single oral dose of low (100mg) or high dose of labetalol (200mg ), or placebo will be administered. Two hours after labetalol or placebo treatment, subjects will receive 15 variance grams nicotine base/kg intravenously. Several physiological endocrine and subjective measures will be obtained during the sessions. We propose that blockage of adrenergic receptors by labetalol will significantly block the physological and subjective effects of nicotine.

Inclusion Criteria:

Male/Female, aged 21-55 years with a smoking history of at least 1 pack of cigarettes daily for at least 1 year. In good health as verified by medical history, screening examination, and screening laboratory tests.

Exclusion Criteria:

History of heart disease, peripheral vascular disease, COPD, any other medical condition which physician investigator deems inappropriate for subject participation. Pregnant or lactating or not using adequate birth control methods. Use of regular psychotropic medication (antidepressants, antipsychotics, or anxiolytics and recent psychiatric history). Chronic use of systemic steroids or antihistamines. Abuse of alcohol or any other recreational or prescription drug. Regular use of any other tobacco products, including smokeless tobacco and nicotine products.