What percentage of nicotine is absorbed by the body through inhalation?

When nicotine is inhaled, it quickly enters the bloodstream through the lungs. The efficiency of absorption through this route is very high due to the large surface area of the lungs and the thin membranes that facilitate rapid transfer of substances into circulation. Research indicates that approximately 90% of the nicotine inhaled is absorbed by the body, making it a rapid method for delivering nicotine to the brain. This high absorption rate is one reason why smoking can lead to dependency, as the quick onset of effects reinforces the behavior. The other percentages are lower than what is typically observed with inhalation, reflecting less efficient absorption methods, such as oral or transdermal routes, where the nicotine would encounter significant metabolic barriers before reaching systemic circulation.