Author + information
- Received November 13, 1992
- Revision received March 4, 1993
- Accepted March 18, 1993
- Published online October 1, 1993.
- Neal L. Benowitz, MD∗,a,b,
- Garret A. Fitzgerald, MDa,b,∗,
- Margaret Wilson, MSa,b and
- Qi Zhang, MDa,b
- ↵∗Address for correspondence: Neal L. Benowitz, MD, San Francisco General Hospital Medical Center, Building 30, 5th Floor, 1001 Potrero Avenue, San Francisco, California 94210.
Objectives. The purpose of this study was to examine the possible role of nicotine in enhancing coagulation and to assess the potential cardiovascular toxicity of transdermal nicotine therapy for smoking cessation.
Background. Cigarette smoking increases the risks of acute coronary events. A likely contributing mechanism is activation of coagulation. The role of nicotine in enhancing coagulability has not been resolved.
Methods. We compared in a crossover study the effects of cigarette smoking, transdermal nicotine and placebo transdermal nicotine, each for 5 days, in 12 healthy smokers.
Results. Cigarette smoking increased the urinary excretion of 11-dehydro-thromboxane B2(reflecting thromboxane A2generation) and increased plasma concentration of the platelet alphagranule constituents, platelet factor 4 and beta-thromboglobulin, compared with placebo treatment, indicating in vivo platelet activation. Cigarette smoking was also associated with higher levels of fibrinogen in plasma. Transdermal nicotine produced plasma levels of nicotine in the same range as those during smoking but had no effect on thromboxane A2metabolite excretion, platelet alpha-granule release or plasma fibrinogen, compared with placebo. Excretion of 2,3-dinor-6-keto-PGF1α(reflecting prostacyclin generation) was not significantly influenced by any treatment. These results suggest that nicotine as such is not responsible for the platelet activation or elevation of plasma fibrinogen seen in smokers. However, we cannot exclude the possibility that intermittent bolus-like dosing of nicotine from cigarettes could have different effects from those produced by continually released transdermal nicotine. Other findings were that cigarette smoking and transdermal nicotine treatment were both associated with a higher white blood cell count compared with the placebo patch condition, suggesting a direct effect of nicotine to increase circulating white cells. Factor VII coagulant activity (VIIc) was significantly lower during cigarette smoking, than during either nicotine or placebo patch conditions.
Conclusions. Transdermal nicotine has less effect on platelet activation and catecholamine release than does cigarette smoking, and its use in smoking cessation treatment of patients with coronary heart disease is likely to be safer than cigarette smoking.
↵∗ Present address: Center for Cardiovascular Science, University College Dublin, Mater Hospital, Dublin, Ireland.
☆ This study was supported by Alza Corporation, Palo Alto, California; Marion Merrell Dow, Inc., Kansas City, Missouri; and Grants DA-02277, DA-01696 and GM-13541, from the U.S. Public Health Service, Bethesda, Maryland. It was carried out in part in the General Clinical Research Center at San Francisco General Hospital Medical Center with support from the Division of Research Resources, National Institutes of Health (Grant RR-00083), Bethesda, Maryland.
☆☆ All editorial decisions for this article, including selection of referees, were made by a Guest Editor. This policy applies to all articles with authors from the University of California, San Francisco.
- Received November 13, 1992.
- Revision received March 4, 1993.
- Accepted March 18, 1993.