| Description |
Cotinine has an in vivo half life of approximately 20 hours, and is typically detectable for several days to up to one week after the use of tobacco. The level of cotinine in the blood is proportionate to the amount of exposure to tobacco smoke, so it is a valuable indicator of tobacco smoke exposure, including secondary (passive) smoke. People who smoke menthol cigarettes may retain cotinine in the blood for a longer period because menthol can compete with cotinine enzymatic metabolism. Genetic encoding of liver enzymes may also play a role, as African Americans routinely register higher blood cotinine levels than Caucasians. Several variable factors, such as menthol cigarette preference and puff size, suggest that the explanation for this difference may be more complex than gender or race.[citation needed]; Cotinine is a metabolite of nicotine. The word 'cotinine' is an anagram of 'nicotine'. It is used to measure the grade of tobacco smoking, but might also improve mental function.; Quantitatively, the most important metabolite of nicotine in most mammalian species is cotinine. In humans, about 70 to 80% of nicotine is converted to cotinine. This transformation involves two steps. The first is mediated by a cytochrome P450 system (mainly CYP2A6 and CYP2B6) to produce nicotine iminium ion. The second step is catalyzed by aldehyde oxidase (AOX). A number of cotinine metabolites have also been structurally characterized. Indeed, it appears that most of the reported urinary metabolites of nicotine are derived from cotinine. Cotinine is found in many foods, some of which are ceylon cinnamon, arrowhead, mountain yam, and rambutan. |
