Picamilon

Soviet-era (1969) prodrug — GABA covalently bonded to niacin so the conjugate can cross the blood-brain barrier, where it hydrolyzes to free GABA + free niacin. B-tier Russian evidence for anxiety, migraine prophylaxis, and chronic cerebral ischemia; thin Western data; FDA stripped it from the dietary-supplement market in November 2015 because it doesn't fit any DSHEA dietary-ingredient category. Non-sedating, non-addictive, mild anxiolytic + cognitive-lift profile. For Dylan: OPTIONAL-ADD as a PRN tool for stress days — niche tianeptine-alternative without the dependence trap.

Picamilon is N-nicotinoyl-γ-aminobutyric acid: GABA's amino group is amide-bonded to the carboxylic acid of nicotinic acid (niacin). The two pieces alone — GABA and niacin taken separately — do not reproduce the effect, because oral GABA crosses the BBB extremely poorly. The point of the conjugate is the lipophilicity boost: the nicotinoyl moiety raises log P enough that picamilon penetrates the BBB intact, then once inside the CNS, brain esterases hydrolyze the amide bond, liberating free GABA and free niacin in situ. This is the canonical "Trojan-horse prodrug" architecture.

The metabolites do the work, not the parent molecule. In 2023, Santillo & Sprando (FDA) screened picamilon against 50 safety-related biological targets — receptors, ion channels, enzymes, transporters — using both in silico prediction and in vitro binding at 10 μM. Picamilon itself was inactive at every target tested, including GABA-A, GABA-B, and calcium channels. This is mechanistically important: unlike phenibut (which is itself a GABA-B agonist) or gabapentin (which itself binds α2δ calcium channels), picamilon's clinical effects are entirely contingent on hydrolysis to its two active components inside the brain.

Once cleaved, the GABA half:

• Activates GABA-A receptors at chloride-influx ionotropic sites (the same family that benzodiazepines positively modulate, but at the agonist site rather than the allosteric site). Effect: tonic and phasic inhibition in cortical, limbic, and thalamic circuits → anxiolysis without the strong sedation/amnesia that benzo allosteric modulation produces.
• May contribute via GABA-B at higher concentrations, but the primary anxiolytic signal looks GABA-A driven (which is also why it's milder than phenibut, a GABA-B-dominant agonist).

Once cleaved, the niacin half:

• Acts as a cerebral vasodilator through GPR109A (HCAR2) activation on vascular smooth muscle and via prostaglandin D2 release. This is the same mechanism behind the well-known niacin "flush" — peripheral vasodilation. Centrally, it increases cerebral blood flow and oxygen delivery in poorly perfused brain regions (the basis of the cerebrovascular indication).
• This is why picamilon is described as non-sedating GABAergic — the niacin component adds a small "lift" component that offsets the GABA-driven slow-down. Net: calm without drowsiness.

Pharmacokinetics:

• Bioavailability: 50–88% oral (high — comparable to phenibut, far better than oral GABA which is essentially zero).
• Plasma t½: 1–2 hours (one source reports 0.5 h elimination half-life). Short — clears quickly.
• Plasma concentration after 50–200 mg single oral dose: 500–3000 μg/L during first few hours.
• Excretion: Renal. Up to 79% of a single dose is recovered in urine as parent + metabolites (which is why chronic renal failure is a contraindication in the Russian product label).
• Linear pharmacokinetics: No nonlinear accumulation at therapeutic doses.

The short half-life is why Russian dosing is 2-3× daily rather than once-daily — clinical effect requires repeated dosing to maintain CNS levels.