To define the pharmacological properties of a newly developed transdermal nicotine system (TNS) designed to facilitate abstention from smoking, three human pharmacology studies were performed in healthy, nicotine-dependent smokers. The first study, in which cigarette smoking served as the standard mode of nicotine intake, was carried out to evaluate the most suitable non-invasive methods for detecting the pharmacodynamic effects of nicotine and to provide a baseline for comparisons with the results of the subsequent studies to assess the effects of single and repeated applications of the TNS. The pharmacodynamic changes induced by smoking were generally most pronounced after the first cigarette following 10 hours' abstinence. The most sensitive parameters were heart rate, which increased, stroke volume measured by impedance cardiography, which decreased, cutaneous blood flow measured by Laser Doppler flowmetry and skin temperature, which diminished to a statistically significant extent after each cigarette. Increases in blood pressure were not very pronounced. Plasma catecholamines were consistently elevated after each cigarette, but the changes were not statistically significant. Compared with those induced by cigarette smoking, the cardiovascular effect seen after either a single application of the TNS (10, 20 and 40 mg/24 h) or repeated application of a TNS delivering 14 mg nicotine/24 h were minor. A slight increase in blood pressure was detectable only on the first day of application and had disappeared after 10 days' repetitive application, suggesting the development of partial tolerance. Heart rate was slightly increased by 3-7% and stroke volume decreased by 5-12% on the tenth day of TNS application.(ABSTRACT TRUNCATED AT 250 WORDS)