4323 4-Hydroxybutyric acid 4-Hydroxybutyric acid (also known as gamma-hydroxybutyrate or GHB) is a precursor and a metabolite of gamma-aminobutyric acid (GABA). GHB acts as a central nervous system (CNS) neuromodulator, mediating its effects through GABA and GHB-specific receptors, or by affecting dopamine transmission (PMID: 16620539). GHB occurs naturally in all mammals, but its function remains unknown. GHB is labeled as an illegal drug in most countries, but it also is used as a legal drug (Xyrem) in patients with narcolepsy. It is used illegally (under the street names juice, liquid ecstasy, or G) as an intoxicant for increasing athletic performance and as a date rape drug. In high doses, GHB inhibits the CNS, inducing sleep and inhibiting the respiratory drive. In lower doses, its euphoriant effect predominates (PMID: 17658710). When present in sufficiently high levels, 4-hydroxybutyric acid can act as an acidogen, a neurotoxin, and a metabotoxin. An acidogen is an acidic compound that induces acidosis, which has multiple adverse effects on many organ systems. A neurotoxin is a compound that adversely affects neural cells and tissues. A metabotoxin is an endogenously produced metabolite that causes adverse health effects at chronically high levels. Chronically high levels of 4-hydroxybutyric acid are associated with two inborn errors of metabolism: glutaric aciduria II and succinic semialdehyde dehydrogenase deficiency (SSADH). SSADH deficiency leads to a 30-fold increase of GHB and a 2-4 fold increase of GABA in the brains of patients with SSADH deficiency as compared to normal brain concentrations of the compounds. As an acidogen, 4-hydroxybutyric acid is an organic acid, and abnormally high levels of organic acids in the blood (organic acidemia), urine (organic aciduria), the brain, and other tissues lead to general metabolic acidosis. Acidosis typically occurs when arterial pH falls below 7.35. In infants with acidosis, the initial symptoms include poor feeding, vomiting, loss of appetite, weak muscle tone (hypotonia), and lack of energy (lethargy). These can progress to heart abnormalities, kidney abnormalities, liver damage, seizures, coma, and possibly death. Many affected children with organic acidemias experience intellectual disability or delayed development. These are also the characteristic symptoms of the untreated IEMs mentioned above. Particularly for SSADH deficiency, the most common features observed include developmental delay, hypotonia, and intellectual disability. Nearly half of patients exhibit ataxia, seizures, behaviour problems, and hyporeflexia. In adults, acidosis or acidemia is characterized by headaches, confusion, feeling tired, tremors, sleepiness, and seizures. As a neurotoxin, GHB appears to affect both GABA (a neurotransmitter) signaling and glutamate signaling (another neurotransmitter). Glutamine metabolism may also play a role in the pathophysiology of excessive levels of GHB. High levels of GHB have been shown to depress both the NMDA and AMPA/kainite receptor-mediated functions and may also alter glutamatergic excitatory synaptic transmission as well. 591-81-1 3037032 C4H8O3 White powder. GHB reaches much higher concentrations in the brain and activates GABAB receptors, which are primarily responsible for its sedative effects. GHB receptors are densely expressed in many areas of the brain, including the cortex and hippocampus, and these are the receptors that GHB displays the highest affinity for. There has been somewhat limited research into the GHB receptor; however, there is evidence that activation of the GHB receptor in some brain areas results in the release of glutamate, the principal excitatory neurotransmitter. Activation of both the GHB receptor and GABA(B) is responsible for the addictive profile of GHB. GHB's effect on dopamine release is biphasic,[19] low concentrations stimulate dopamine release via the GHB receptor.[20] Higher concentrations inhibit dopamine release via GABA(B) receptors as do other GABA(B) agonists such as baclofen and phenibut.[21] After an initial phase of inhibition, dopamine release is then increased via the GHB receptor. This explains the paradoxical mix of sedative and stimulatory properties of GHB, as well as the so-called "rebound" effect, experienced by individuals using GHB as a sleeping agent, wherein they awake suddenly after several hours of GHB-induced deep sleep. That is to say that, over time, the concentration of GHB in the system decreases below the threshold for significant GABAB receptor activation and activates predominantly the GHB receptor, leading to wakefulness. Route of Elimination: Animal studies indicate that metabolism is the major elimination pathway for sodium oxybate, producing carbon dioxide and water via the tricarboxylic acid (Krebs) cycle and secondarily by beta-oxidation. Succinic acid enters the Krebs cycle where it is metabolized to carbon dioxide and water. Fecal and renal excretion is negligible. 5% renal elimination. Half Life: 30 to 60 minutes No indication of carcinogenicity to humans (not listed by IARC). Used as a general anesthetic, to treat conditions such as insomnia, clinical depression, narcolepsy, and alcoholism, and to improve athletic performance. Chronically high levels of 4-hydroxybutyric acid are associated with the inborn errors of metabolism called: 4-Hydroxybutyric Aciduria/Succinic Semialdehyde Dehydrogenase Deficiency. 2014-08-29T06:11:02Z 2018-03-21T17:46:12Z Gamma-Hydroxybutyric_acid C00989 16724 CPD-3193 DB01440 true OCCCC(O)=O C4H8O3 InChI=1S/C4H8O3/c5-3-1-2-4(6)7/h5H,1-3H2,(H,6,7) InChIKey=SJZRECIVHVDYJC-UHFFFAOYSA-N 104.1045 104.047344122 Endogenous Solid HMDB00710 CHEMBL1342 2300886 <p>Joseph Klosa, &#8220;Production of nonhygroscopic salts of 4-hydroxybutyric acid.&#8221; U.S. Patent US4393236, issued March, 1963.</p>