Mitragynine

alkaloid · nervous · digestive · Oral

Mitragynine, an alkaloid. The principal indole alkaloid of kratom (Mitragyna speciosa); a G-protein-biased partial agonist at the µ-opioid… Oral half-life 23 h.

The principal indole alkaloid of kratom (Mitragyna speciosa); a G-protein-biased partial agonist at the µ-opioid receptor, producing stimulant-like effects at low doses and opioid-like analgesia/sedation at higher doses. Its CYP3A-derived metabolite 7-hydroxymitragynine is a far more potent MOR agonist and contributes substantially to the in-vivo opioid effect. Reported G-protein bias is hypothesized to limit respiratory depression, though dependence and withdrawal still occur.

PubChem CID 3034396. Parent alkaloid of the registry's 7-hydroxymitragynine metabolite. PK: Trakulsrichai 2015 (PMID:25995615), first human PK study, verbatim "terminal half-life (23.24±16.07 hours)". Opioid Ki/EC50 SKIP — real but table/figure-only in every abstract (see AUTHORING_GAPS). PK: THE VOLUME WAS IN THE FULL TEXT OF THIS RECORD OWN CITATION — the first human pharmacokinetic study of this compound, nine subjects. Verbatim: "the pharmacokinetic parameters established were time to reach the maximum plasma concentration (0.83±0.35 hour), terminal half-life (23.24±16.07 hours), and the apparent volume of distribution (38.04±24.32 L/kg)". THE STORED HALF-LIFE ALREADY MATCHES THAT SENTENCE EXACTLY, so the volume beside it was simply never taken; at the seventy-kilogram reference it is 2,663 L. It is an APPARENT volume, so bioavailability is pinned at unity rather than left at the 0.9 default, which would otherwise divide by absorption twice. TWO CAVEATS ARE RECORDED RATHER THAN BURIED: the paper fits a TWO-COMPARTMENT model and this is its apparent volume paired with a terminal half-life, the class-12 shape; and the spread is enormous, plus or minus 64 percent on the volume and 69 percent on the half-life, in nine subjects.

Pharmacokinetics

Sources: PMID:25995615