Quick Comparison
| Alpha-GPC | Coluracetam | |
|---|---|---|
| Half-Life | 4-6 hours | 2-3 hours |
| Typical Dosage | Standard: 300-600 mg daily in 1-2 doses. For racetam stacking: 300 mg per racetam dose. Clinical (Alzheimer's): 1200 mg daily in 3 divided doses. | Standard: 20-80 mg sublingually, 2-3 times daily. Start at 20 mg to assess sensitivity. Sublingual is strongly preferred for bioavailability. |
| Administration | Oral (capsules, powder). High oral bioavailability. | Sublingual (strongly preferred) or oral. Oral bioavailability is limited. |
| Research Papers | 10 papers | 1 papers |
| Categories |
Mechanism of Action
Alpha-GPC
Alpha-GPC (L-alpha-glycerylphosphorylcholine) is hydrolyzed by phospholipases in the gut and brain to release free choline, which is transported across the blood-brain barrier via the choline transporter (CHT1) and taken up by neurons for acetylcholine synthesis via choline acetyltransferase (ChAT). It is the most efficient oral choline source for raising brain acetylcholine levels due to high bioavailability and direct utilization. Alpha-GPC also provides glycerophosphate (glycerol-3-phosphate), which enters the Kennedy pathway and supports phosphatidylcholine and cell membrane phospholipid synthesis. It may stimulate growth hormone release through cholinergic activation of the pituitary. Alpha-GPC enhances high-affinity choline uptake and supports muscarinic (M1, M2) and nicotinic receptor function.
Coluracetam
Coluracetam's primary mechanism is enhancement of high-affinity choline uptake (HACU) in hippocampal neurons — the rate-limiting step in acetylcholine synthesis. HACU is mediated by the high-affinity choline transporter (CHT1/SLC5A7), which coluracetam upregulates or potentiates, increasing the Vmax of choline transport into presynaptic terminals. By making this process more efficient, coluracetam increases acetylcholine production and vesicular packaging via the vesicular acetylcholine transporter (VAChT) even when choline levels are normal. This enhances cholinergic transmission in the hippocampus, cortex, and retina — explaining reports of enhanced color vision and visual acuity. Coluracetam also has minor AMPA receptor positive allosteric modulation. The compound was studied for treatment-resistant depression, possibly through cholinergic modulation of mood circuits.
Risks & Safety
Alpha-GPC
Common
Headache, heartburn, dizziness, skin rash.
Serious
High chronic doses may be associated with increased stroke risk (epidemiological data, not confirmed causally).
Rare
Fishy body odor from trimethylamine production, depression.
Coluracetam
Common
Headache, fatigue, brain fog at high doses.
Serious
Very limited human safety data — studied only in small trials.
Rare
Anxiety, irritability, suicidal ideation was reported in one clinical trial participant.
Full Profiles
Alpha-GPC →
The most bioavailable choline source for the brain. Alpha-GPC crosses the blood-brain barrier efficiently and directly provides choline for acetylcholine synthesis. Used clinically in Europe for Alzheimer's disease and cognitive decline. The go-to choline supplement for stacking with racetams and preventing the headaches that come from increased acetylcholine demand.
Coluracetam →
A racetam that enhances high-affinity choline uptake (HACU) — the rate-limiting step in acetylcholine synthesis. This makes it uniquely effective at boosting acetylcholine levels, which is why users commonly report enhanced color vision, sharper visual perception, and improved memory. It was briefly studied for treatment-resistant depression.