Free base

Free base (freebase, free-base) is a descriptor for the neutral form of an amine commonly used in reference to illicit drugs.

Common counterions include chloride, bromide, sulfate, phosphate, nitrate, acetate, oxalate, citrate, and tartrate.

However, since blood is buffered with carbonate at physiological pH (near 7.4), free-base amines will be rapidly converted back into their acid form.

[2] Freebasing also tends to remove water-soluble impurities and adulterants such as sugars (lactose, sucrose, glucose, mannitol, inositol), which are often added to street cocaine.

[5] In South America, coca leaves are traditionally chewed with a quantity of an alkaline lime substance ("llipta") typically derived from the ashes remaining after burning plants, shells or limestone.

[3] In a similar fashion to coca leaves, betel nuts are chewed with added limestone, turning the active ingredient arecoline into the freebase form, allowing it to be absorbed sublingually.