Objectives. Cigarette smoking causes cardiovascular (CV) disease, but the relative roles of nicotine and other components of tobacco smoke remain unclear. We investigated the effect of stopping smoking, by using nicotine replacement therapy (NRT), on haemorheology parameters. Design. Open, parallel-group trial (intervention group and control smokers). Setting. Clinic within university department of pharmacology. Subjects. One hundred and ninety-seven males, aged 25-45 years, smoking >20 cigarettes per day. Interventions. One hundred and sixty-four subjects were instructed to stop smoking and received NRT for 12 weeks and 33 acted as controls. After 12 weeks, NRT was discontinued, and all subjects were followed-up at 26 weeks. At the end of the study, the NRT group was divided into abstainers (self-reported, verified by exhaled carbon monoxide <10 ppm) and relapsers, who were unable to remain abstinent. Main outcome measures. Plasma viscosity, fibrinogen, erythrocyte deformability, reactive capillary blood flow, transcutaneous partial oxygen tension (tcpO 2 ) and haematocrit, assessed at 4, 8, 12, and 26 weeks. Results. After 6 months, plasma fibrinogen (9.95 vs. 8.24 lmol L -1 at baseline; P < 0.003), reactive capillary flow (t-p max : 9.3 vs. 11.2 s at baseline; P < 0.005), and tcpO 2 (50.4 vs. 34.9 mmHg at baseline; P < 0.0001) were significantly improved in abstainers, but changes in plasma viscosity and erythrocyte deformability were inconclusive. Other CV risk factors, such as haematocrit and white blood cell count, decreased to a greater extent in abstainers than in relapsers. Expired carbon monoxide concentrations reflected the changes in smoking and decreased in abstainers from 30.4 ppm at baseline to 4.2 ppm; P < 0.0001). Conclusions. Smoking cessation improved CV parameters, and use of nicotine medications did not negate these improvements.

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This open study assessed the effects of nicotine replacement therapy (NRT) on the normalizing of exhaled carbon monoxide (CO), transcutaneous partial oxygen tension (tcpO(2)), plasma cotinine and thiocyanate levels, and cardiovascular risk markers in abstinent subjects compared with untreated smokers after 4, 8, 12, and 26 weeks. The trial enrolled 197 subjects in two parallel groups: 164 subjects who received NRT (patch plus gum) for 12 weeks and 33 untreated smokers (controls). At 26 weeks, 123/164 participants in the treatment group had completed the study; 51/123 (41.5%) sustained abstinence from smoking, whereas 72/123 (58.5%) had relapsed. Changes in cotinine (abstainers: 291.6 ng/ml at baseline vs. 27.3 ng/ml at week 26; p<.0001) and thiocyanate levels (abstainers: 10.4 ng/ml at baseline vs. 6.2 ng/ml at week 26; p<.0001) and expired CO (abstainers: 30.4 ppm at baseline vs. 4.2 ppm at week 26; p<.0001) accurately reflected the changes in smoking and/or NRT use in both abstainers and relapsers. After they stopping smoking, tcpO(2) significantly improved in abstainers (34.9 mmHg at baseline vs. 50.4 mmHg at week 26; p<0.0001). Inverse correlations between the number of daily cigarettes and plasma cotinine, thiocyanate, and exhaled CO levels were observed in both relapsers and smokers. A clinically significant increase in HDL cholesterol (39.0 vs. 44.7 mg/dl; p<.0001) occurred in the abstainers between baseline and study end. Use of combination NRT to achieve abstinence resulted in marked improvements in biochemical parameters in abstainers and partial improvements in relapsers. The safety of combination NRT was confirmed by the absence of overdose-related adverse events.