Amphetamine. Computer model of a molecule of the drug amphetamine. It is also known as speed, and is sold under the brand name Benzedrine. It is a stimulant and banned drug, used medically to treat narcolepsy and attention-deficit hyperactivity disorder. The molecule's chemical formula is C9.H13.N. Atoms (spheres) are colour-coded: carbon (grey), hydrogen (light blue), nitrogen (dark blue).