The half-life of nicotine is approximately how many hours?

• A. Four
• B. Six
• C. Two
• D. Eight

Answer: (C)

Understanding half-life in pharmacokinetics means looking at how long it takes for the substance in the blood to fall to half of its peak level after a dose. Nicotine is cleared from the body relatively quickly, with a typical half-life of about two hours in most adults. This rapid clearance happens because nicotine is mainly metabolized in the liver by the enzyme CYP2A6 into cotinine, which itself stays in the body longer. Because nicotine levels drop so quickly, people who use nicotine often need to replenish it every few hours, which also helps explain the pattern of craving and withdrawal. Variations in this timing can occur with differences in liver function, age, pregnancy, or certain medications or genetic factors that affect metabolism. So, the best approximate value for nicotine’s half-life is two hours.