An anesthetic is an agent that reduces or eliminates sensation. This effect may occur in

all tissues of the body (general anesthetic) and puts a patient asleep, or may be limited to

a particular region (local anesthetic). General anesthetics are used for surgical procedures.

They depress the activity of the central nervous system, producing loss of consciousness,

and block the perception of pain. Local anesthetics inhibit the conduction of pain impulses

in sensory nerves in the region in which they are injected or applied. An example is dental

anesthesia with a local Novocain injection. 

Specific anesthetics are listed such as ketamine (Ketalar), nitrous oxide, propofol (Diprivan), thiopental (Pentothal).