Influence of smoking on cotinine and caffeine plasma levels in patients with alcoholic liver cirrhosis

Abstract

Background: Retention of caffeine was observed in patients with alcoholic liver cirrhosis and impaired liver function. Cotinine, the major metabolite of nicotine, is transformed by microsomal N-oxidation to secondary metabolites. The aim of this study was to investigate if impaired liver function leads to a retention of cotinine in a similar way to caffeine retention. Furthermure the influence of smoking on cotinine and caffeine plasma levels was studied.

Methods: 91 smokers and 12 nonsmokers with alcoholic liver cirrhosis were subdivided according to their smoking habits. Cotinine plasma levels and fasting caffeine concentrations were measured by a gaschromatographic method. Concentrations of conjugated bile acids were measured by RIA. 10 healthy smokers and 11 nonsmokers were used as a control group.

Results: Mean plasma cotinine concentrations found in slight smokers (200 +/- 155 ng/ml), intermediate smokers (384 +/- 223 ng/ml) and heavy smokers (430 +/- 266 ng/ml) with alcoholic liver cirrhosis were significantly higher than in healthy, smoking volunteers with slight, intermediate, and heavy smoking (101 +/- 14; 274 +/- 112; 345 +/- 85 ng/ml) (p <0.01) respectively. In nonsmokers with alcoholic liver cirrhosis plasma cotinine (44 +/- 25 ng/ml) was significantly elevated compared to healthy nonsmokers (27 +/- 19 ng/ml) (p <0.01). - Fasting caffeine plasma levels in patients with alcoholic liver cirrhosis (4.00 +/- 5. 20 microg/ml) were significantly higher than in healthy volunteers (0.91 +/- 0.42 microg/ml) (p <0.01). A decrease of plasma levels was observed in correlation to the amount of smoking in patients with alcoholic cirrhosis (slight smokers: 7.67 +/- 8.54 microg/ml, intermediate smokers: 3.35 +/- 2.91 microg/ml and heavy smokers: 2. 48 +/- 2.68 microg/ml). Conjugated bile acids were elevated in patients with alcoholic liver cirrhosis to 32,56 +/- 38,24 mmol/l.

Conclusions: Increased cotinine plasma levels in smokers and nonsmokers with alcoholic liver cirrhosis demonstrate a cotinine retention in patients with impaired liver function. The inducing effect of smoking is shown by a decrease of fasting caffeine plasma concentrations.