What is the approximate half-life of cocaine?

• A. 30 minutes
• B. 1-2 hours
• C. 4-6 hours
• D. 12-24 hours

Answer: (B)

Half-life is the time it takes for the drug’s plasma concentration to fall to half of its current level. Cocaine is cleared quickly because it is rapidly metabolized by esterases in blood and liver into inactive metabolites such as benzoylecgonine. This rapid metabolism gives cocaine a short plasma half-life, typically around one hour, with many sources rounding it to about one to two hours. Because of this variability, 1–2 hours is a solid approximate range.

To put it into perspective, if the peak concentration were 100 ng/mL, you'd expect about 50 ng/mL after one hour, and around 25 ng/mL after two hours. The immediate psychoactive effects tend to fade sooner than the drug is fully eliminated, while metabolites can be detected longer in urine.