thiopental

n. an ultrashort-acting barbiturate used primarily as an anesthetic that can be administered intravenously to produce almost immediate loss of consciousness. It may also be used as an antidote for an overdose of stimulants or convulsants. At one time, it was occasionally used in psychotherapy to induce a state of relaxation and suggestibility. In nonmedical circles, it gained notoriety as a truth serum. U.S. trade name: Pentothal.