GHB
GHB. γ-hydroxybutyrate, an endogenous GABA metabolite; an agonist at GABA-B and at specific high-affinity GHB receptors, producing CNS… Oral half-life 0.5 h.
γ-hydroxybutyrate, an endogenous GABA metabolite; an agonist at GABA-B and at specific high-affinity GHB receptors, producing CNS depression, euphoria, and (marketed) anabolic/sleep effects. Very narrow margin between recreational sedation and coma/respiratory depression. Medical form is sodium oxybate (Xyrem) for narcolepsy/cataplexy.
PubChem CID 10413. PK: Brenneisen 2004 (PMID:15538955) verbatim "The terminal plasma elimination half-life was 30.4 +/- 2.45 min" after a single oral 25 mg/kg dose in 8 healthy volunteers (=0.51 h). GABA-B occupancy deferred. Same paper states "the distribution volume 52.7 +/- 15.0 L" (V added 2026-09-06). Brailsford 2012 (PMID:22337777), 12 volunteers, 25 mg/kg PO: Tmax 24.6 min whole blood; no t½, V or F in the abstract. PK: A MERGED RECORD THAT IS COHERENT EVERYWHERE IT SPEAKS AND SILENT WHERE IT MATTERS MOST. Everything cited is verbatim and correctly converted, the clearance the stored pair implies lands within three percent of its own source, and THE MERGE GENUINELY FIXED a maximal-effect value that the pre-merge record contradicted in its own note. BUT THE ORAL ROW DECLARED NEITHER BIOAVAILABILITY NOR AN ABSORPTION RATE, so the solver substituted both — and at the citation own dose the model predicted a peak roughly four-fold below that same abstract observed "GHB plasma peaks of 39.4 +/- 25.2 microg/mL". THAT GAP IS UNREACHABLE AT ANY ABSORPTION RATE: the ceiling is the dose times bioavailability over the volume, which sits BELOW the observed peak even at complete absorption, so pinning bioavailability at unity is the most the model can offer and the residual is structural. THE MECHANISM IS KNOWN AND DELIBERATELY NOT AUTHORED: capacity-limited absorption and elimination are confirmed verbatim in humans, but NO HUMAN SATURATION CONSTANTS ARE PUBLISHED — the only ones are rat, sitting in this record own effect-compartment citation — and storing rat constants as human pharmacokinetics is exactly the error this audit exists to prevent.
Pharmacokinetics
- Oral — t½ 31 min · F 100% · Vd 52.7 L
Sources: PMID:15538955, PMID:22337777, PMID:11804399, PMID:10587082