4hydroxybutanoic

4-hydroxybutanoic acid, commonly known as gamma-hydroxybutyric acid (GHB), is a four-carbon, water-soluble short-chain fatty acid that occurs naturally in low amounts in mammalian tissue. It serves as a neurotransmitter and neuromodulator in the central nervous system and can function as a precursor to the inhibitory neurotransmitter GABA. The compound is typically encountered as the free acid or as its salts, notably the sodium salt (sodium oxybate).

Chemically, 4-hydroxybutanoic acid has the molecular formula C4H8O3. It contains a carboxyl group on one end of a linear chain and a hydroxyl group on the gamma carbon relative to that carboxyl group. The molecule is highly polar and readily dissolves in water. In solution, it can exist in protonated and deprotonated forms, with the carboxylate form predominating at physiological pH. It is generally used and studied in its salt forms for pharmaceutical and research applications.

Biological context and occurrence: GHB is produced endogenously in small amounts in the brain and other tissues, though its precise physiological role remains under investigation. It can be formed from the metabolism of GABA and is related to the gamma-aminobutyric acid system, engaging GABA-B receptors and, at higher concentrations, a distinct GHB receptor pathway described in some studies.

Regulatory status and uses: The free acid is a substance subject to regulation in many jurisdictions due to its abuse potential. The sodium salt, sodium oxybate, is approved in several countries as a prescription medication for narcolepsy with cataplexy under specialist control. Illicit use is associated with sedation, amnesia, and risks of unconsciousness or respiratory depression, particularly when combined with alcohol. The legal status of GHB and its salts varies by country and is strictly controlled in many places.