a type of drug that works by enhancing the action of the neurotransmitter gaba
gamma-Aminobutyric acid In general, GABA does not cross the blood–brain barrier,[50] although certain areas of the brain that have no effective blood–brain barrier, such as the periventricular nucleus, can be reached by drugs such as systemically injected GABA.[57] At least one study suggests that orally administered GABA increases the amount of human growth hormone (HGH).[58] GABA directly injected to the brain has been reported to have both stimulatory and inhibitory effects on the production of growth hormone, depending on the physiology of the individual.[57] Certain pro-drugs of GABA (ex. picamilon) have been developed to permeate the blood–brain barrier, then separate into GABA and the carrier molecule once inside the brain. This allows for a direct increase of GABA levels throughout all areas of the brain, in a manner following the distribution pattern of the pro-drug prior to metabolism.[citation needed]
Sodium thiopental Sodium thiopental is an ultra-short-acting barbiturate and has been used commonly in the induction phase of general anesthesia. Its use has been largely replaced with that of propofol, but retains popularity as an induction agent for rapid sequence intubation and in obstetrics.[citation needed] Following intravenous injection, the drug rapidly reaches the brain and causes unconsciousness within 30–45 seconds. At one minute, the drug attains a peak concentration of about 60% of the total dose in the brain. Thereafter, the drug distributes to the rest of the body, and in about 5–10 minutes the concentration is low enough in the brain that consciousness returns.[citation needed]