Background: Smoking increases plasma fibrinogen and cardiovascular risk whereas transdermal nicotine may not. Fibrinogen is an acute phase protein and may reflect disease activity in ulcerative colitis.

Objective: To examine the effect of topical nicotine on plasma fibrinogen and any relationship between fibrinogen and ulcerative colitis disease activity.

Methods: Forty-eight non-smokers with moderately active ulcerative colitis. Methods: Patients were randomised to 6 mg nicotine enema or placebo for 6 weeks, followed by open nicotine therapy for 4 weeks. Plasma fibrinogen was measured at baseline and after 6 and 10 weeks; at each assessment sigmoidoscopy with a rectal biopsy was performed. RESULTS.: At 6 weeks median plasma fibrinogen was 3.30 g/l on nicotine compared to 3.05 g/l on placebo, P = 0.90 when adjusted for baseline values. There was a correlation between fibrinogen and the UC disease activity index (UCDAI) at weeks 0 and 10, P = 0.036 and 0.033, respectively, and between fibrinogen and sigmoidoscopic grade at each assessment, P = 0.014, 0.021 and 0.034. Changes in fibrinogen did not correlate with changes in disease severity.

Conclusions: There was no significant effect of nicotine enemas, in either direction, on plasma fibrinogen-this was raised in moderately active UC and correlated with the sigmoidoscopic grade of colitis and the UCDAI; however, fibrinogen was not sufficiently sensitive to be of practical clinical value.