Quick Comparison

Agmatine SulfateUridine
Half-Life2-3 hours2-5 hours
Typical DosageStandard: 500-2000 mg daily in 1-3 doses. For mood: 1000-2000 mg. For pain: 1000-2500 mg. Take on empty stomach. Agmatine sulfate is the most common supplement form. May enhance the effects of some nootropics and medications — research interactions.Standard: 150-250 mg Uridine Monophosphate sublingually or orally, twice daily. Best combined with fish oil (DHA) and a choline source for the full 'Mr. Happy Stack' protocol.
AdministrationOral (powder, capsules). Take on empty stomach for best absorption.Sublingual or oral. Uridine monophosphate is the preferred form. Triacetyluridine (TAU) is a more bioavailable prodrug.
Research Papers10 papers10 papers
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Mechanism of Action

Agmatine Sulfate

Agmatine is a polyamine neuromodulator with multiple targets: (1) NMDA receptor antagonist at the polyamine binding site (GluN1/GluN2B) — reduces excitotoxicity, pain signaling, and blocks the receptor's open channel. (2) Imidazoline I1 and I2 receptor agonist — I1 in the rostral ventrolateral medulla reduces sympathetic tone; I2 modulates monoamine oxidase and provides anxiolytic/antidepressant effects. (3) Selective nNOS (neuronal nitric oxide synthase) inhibitor — reduces peroxynitrite formation and oxidative stress while preserving eNOS (endothelial) function for vascular health. (4) Alpha-2 adrenergic receptor agonist — reduces norepinephrine release from locus coeruleus, promoting calm. (5) Modulates opioid receptors — enhances mu-opioid analgesia, potentiates delta-opioid, and may reduce tolerance via nitric oxide and NMDA mechanisms.

Uridine

Uridine (as UMP) is phosphorylated to UTP and enters the Kennedy pathway, where it combines with choline via CTP:phosphocholine cytidylyltransferase to form CDP-choline — the rate-limiting step in phosphatidylcholine synthesis. Uridine provides the nucleotide component needed for constructing phosphatidylcholine in neuronal cell membranes and synaptic vesicles. Uridine stimulates neurite outgrowth and synaptogenesis via activation of P2Y receptors and downstream PI3K/Akt signaling. It upregulates dopamine D2 receptor expression in the striatum and enhances dopaminergic neurotransmission. When combined with DHA (from fish oil) and choline, the three compounds synergistically increase synaptic membrane synthesis, dendritic spine density, and dopaminergic signaling — the 'Mr. Happy Stack' mechanism.

Risks & Safety

Agmatine Sulfate

Common

Mild gastrointestinal discomfort, diarrhea at high doses.

Serious

May potentiate opioid medications (increased sedation risk). May lower blood pressure.

Rare

Headache, nausea.

Uridine

Common

Mild gastrointestinal discomfort, diarrhea.

Serious

Very limited long-term human supplementation data.

Rare

Lethargy, vivid dreams, depressive symptoms in some users.

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