The rate and extent of absorption from inhalation of cocaine is similar or greater than with intravenous injection, as inhalation provides access directly to the pulmonary capillary bed. The delay in absorption after oral ingestion may account for the popular belief that cocaine bioavailability from the stomach is lower than after insufflation. Compared with ingestion, the faster absorption of insufflated cocaine results in quicker attainment of maximum drug effects. Snorting cocaine produces maximum physiological effects within 40 minutes and maximum psychotropic effects within 20 minutes. Physiological and psychotropic effects from nasally insufflated cocaine are sustained for approximately 40–60 minutes after the peak effects are attained.Cocaine crosses the blood-brain barrier via both a proton-coupled organic cation antiporter and (to a lesser extent) via passive diffusion across cell membranes. As of September 2022, the gene or genes encoding the human proton-organic cation antiporter had not been identified.Cocaine has a short elimination half life of 0.7–1.5 hours and is extensively metabolized by plasma esterases and also by liver cholinesterases, with only about 1% excreted unchanged in the urine. The metabolism is dominated by hydrolytic ester cleavage, so the eliminated metabolites consist mostly of benzoylecgonine (BE), the major metabolite, and other metabolites in lesser amounts such as ecgonine methyl ester (EME) and ecgonine. Further minor metabolites of cocaine include norcocaine, p-hydroxycocaine, m-hydroxycocaine, p-hydroxybenzoylecgonine (pOHBE), and m-hydroxybenzoylecgonine. If consumed with alcohol, cocaine combines with alcohol in the liver to form cocaethylene.
Inhalation
The onset of cocaines euphoric effects is fastest with inhalation, beginning after 3–5 seconds. However, inhalation gives the shortest duration of euphoria (5–15 minutes). Cocaine is smoked by inhaling the vapor produced when free base cocaine is heated to the point of sublimation. In a 2000 Brookhaven National Laboratory medical department study, based on self-reports of 32 people who used cocaine who participated in the study, "peak high" was found at a mean of 1.4min +/- 0.5 minutes. Pyrolysis products of cocaine that occur only when heated/smoked have been shown to change the effect profile, i.e. anhydroecgonine methyl ester, when co-administered with cocaine, increases the dopamine in CPu and NAc brain regions, and has M1- and M3- receptor affinity.Smoking freebase cocaine is often accomplished using a pipe made from a small glass tube, often taken from "love roses", small glass tubes with a paper rose that are promoted as romantic gifts. These are sometimes called "stems", "horns", "blasters" and "straight shooters". A small piece of clean heavy copper or occasionally stainless steel scouring pad – often called a "brillo" (actual Brillo Pads contain soap, and are not used) or "chore" (named for Chore Boy brand copper scouring pads) – serves as a reduction base and flow modulator in which the "rock" can be melted and boiled to vapor. Crack is smoked by placing it at the end of the pipe; a flame held close to it produces vapor, which is then inhaled by the smoker.