Cotinine

Cotinine2DACS

Cotinine is an alkaloid found in tobacco and is also the predominant metabolite of nicotine. Cotinine is used as a biomarker for exposure to tobacco smoke. Similar to nicotine, cotinine is absorbed into the body through the lungs, skin, and mucous membranes. However, cotinine has a longer half-life than nicotine, typically staying in the body for 16-20 hours, making it a more reliable marker of tobacco exposure.

Chemistry

Cotinine is a derivative of nicotine, with its chemical name being 1-methyl-5-(3-pyridyl)pyrrolidin-2-one. Its molecular formula is C₁₀H₁₂N₂O, and it has a molecular weight of 176.215 g/mol. Cotinine is more stable than nicotine, which contributes to its utility in measuring nicotine exposure.

Metabolism

After the intake of nicotine, it is metabolized in the liver by the enzyme cytochrome P450 2A6 (CYP2A6) into cotinine. The rate of conversion and the eventual elimination of cotinine from the body can be influenced by various factors, including genetic variations in the CYP2A6 enzyme, age, diet, and the presence of certain diseases.

Health Implications

Cotinine itself is thought to have less pharmacological effect compared to nicotine. However, its presence in the body is indicative of nicotine exposure, which is associated with numerous health risks, including heart disease, respiratory problems, and cancer. Measuring cotinine levels in blood, saliva, or urine is a common method for assessing an individual's exposure to tobacco smoke, including secondhand smoke.

Uses in Research and Medicine

Cotinine levels are widely used in medical and epidemiological studies as a reliable biomarker of tobacco exposure. This has applications in research into the health effects of tobacco, in assessing the effectiveness of smoking cessation programs, and in evaluating exposure to secondhand smoke. In some cases, cotinine testing is used in clinical settings to verify a patient's smoking status.

Legal and Social Implications

The measurement of cotinine levels can have legal and social implications, particularly in contexts where smoking behaviors have consequences, such as in custody disputes, health insurance, and employment. Some employers and insurance companies test for cotinine as part of their health and wellness programs to identify smokers and potentially adjust premiums or benefits accordingly.