There are various genetic components that may introduce individual variation in the effect of the drug: absorption in the bloodstream, metabolism, crossing the blood-brain barrier, binding to target neurons, and the resulting effects. Δ9-THC is absorbed via inhalation or the gastrointestinal tract and is almost completely metabolized by liver enzymes. The various active and inactive components pass the bloodbrain barrier and bind to speci’c receptors in the brain to produce the psychoactivity.
Marijuana can be administered via various routes, smoking being most common. It is also orally taken. The drug Marinol comes as a pill for oral administration. Recent application of a marijuana patch also has been of interest .