Human Cotinine is alkaloid present in tobacco. Human cotinine is a metabolite which is predominantly found in nicotine. Cotinine is an anagram of nicotine. Cotinine is formed once nicotine gets inside the body.  This alkaloid is used as a treatment used for schizophrenia, depression, Parkinson’s disease and Alzheimer’s disease currently. Cotinine is used as biomarker for exposure to tobacco smoke. Cotinine levels in saliva, blood and urine correlates to the exposure to tobacco smoke. Also it is a preferred method for measuring tobacco exposures as cotinine stays in the body for longer periods of time in comparison to nicotine. This feature makes cotinine an important indicator to tobacco active and passive smoke exposures. The cotinine levels are related to variations in the activity of CYP2A6. The formation and removal of cotinine is mediated by CYPA26 enzyme. The CYP2A6 activity varies according to the race and sex. The individuals showing low activity of CYP2A6 show accumulation of cotinine.

Individuals with less than 10ng/ml cotinine are considered as non-active smoking, individuals showing cotinine levels of 10ng/ml to 100ng/ml are considered to have moderate smoke exposures while more than 300ng/ml are considered as heavy smokers. Cotinine assays provide complete history and reliable measures of cigarette smoking. Passive smoking can also be measured with cotinine assays. Low range of cotinine concentrations can be detected in saliva. And the saliva concentrations of cotinine correlate to that of the blood concentrations. Thus, detection of drug use, smoking and exposures to tobacco smoke can be easily detected by knowing the cotinine concentration of the individual. Cotinine is also used as an alternative for people who are willing to quit tobacco.  Various gums, patches, lozenge, inhalers are used for this purpose. Under these conditions too, the cotinine test would show a positive result. It is advised to have a history check before coming to conclusions for the test.