How does cocaine have an anaesthetic numbing effect on the body?
Cocaine works as a chemical block on the nerves. It chemically binds and blocks the sodium channels in the nerves. Thus causing the nerve transmission to be stopped. When the nerve loses the ability to transmit information via the chemical pathway, numbness is felt in the region governed by that bundle of nerves or by that single nerve.
Cocaine also affects the Central Nervous System by blocking the reuptake of dopamine in the central region of the brain. This action produces the euphoria often associated with cocaine use as a recreational drug. When the cocaine wears off, the craving begins...many users state that they are always chasing the first one. This is true because the first use of cocaine causes the dopamine pump to clog, and the available dopamine is always less on the second and third use of cocaine.
Cocaine is also the only local anesthetic with vasoconstrictive properties. (It constricts the blood vessels) It blocks the reuptake of norepinephrine in the sympathetic portion of the autonomic nervous systemre resulting in the racing heart, rise in blood pressure, tremors, and faster breathing rate. Because of these properties, it is an excellent anesthetic for the oral/nasal cavity and is used extensively in these types of surgeries as a local anesthetic. Because of the vasoconstricitve properties, cocaine is able to reduce swelling of the oral or nasal mucosa to the point that pain associated with that swelling is diminished or a constricted airway may be opened slightly through the action of this drug.