Pyridoxine

Category: vitamin

Aliases: Vitamin B6, Pyridoxine HCl

Pharmacological Mechanism

Converted in liver (see vitamin b6 metabolism) to pyridoxal-5'-phosphate (P5P), the coenzyme for ~150 enzymes — transaminases (AST/ALT), decarboxylases (gaba, dopamine, serotonin synthesis), glycogen phosphorylase, δ-ALA synthase (heme biosynthesis), cystathionine β-synthase (homocysteine clearance). Pyridoxine HCl is cheap but requires PLP kinase / pyridoxamine phosphate oxidase for activation — impaired in some PNPO polymorphisms.

Half-Life (t½)

PO: 15h

Dosing Guidelines

PO: Typical 1.43 mg (Range: 1.3–1.7 mg)

Target Organ Systems

nervous
digestive

Interactions

Magnesium (synergistic): P5P improves intracellular Mg²⁺ uptake; classic 'P5P + Mg glycinate' stack for premenstrual/anxious symptoms.
Levodopa (caution): B6 is the PLP cofactor for peripheral AADC; high-dose pyridoxine without carbidopa accelerates peripheral decarboxylation of L-DOPA and blunts antiparkinsonian response. Safe when L-DOPA is given as a fixed-dose carbidopa combination (Sinemet). [Mars 1975]
5-HTP (synergistic): AADC cofactor.
Pyridoxal-5'-Phosphate (synergistic): Same family — P5P is the activated form. Pick one.

Pathways It Modulates

Folate / one-carbon metabolism (cofactor) — SHMT (serine ↔ glycine + 5,10-methylene-THF)
Kynurenine pathway (cofactor) — PLP cofactor for KAT enzymes (KYNA branch) + kynureninase

Chemical Identifiers

PubChem CID: 1054
Formula: C8H11NO3
Molecular weight: 169.18 g/mol
InChIKey: LXNHXLLTXMVWPM-UHFFFAOYSA-N
SMILES: CC1=NC=C(C(=C1O)CO)CO