Onset: 15-30 min on empty stomach. Duration: 3-4 hours per dose (matches 2-hr plasma half-life with some BBB lag).

Characteristic effects:

• Mild calm without sedation. Most users describe a "smooth" baseline shift, not a "lift." Often imperceptible at 250-500 mg, more noticeable at 1 g+.
• Pre-workout vascular response — visible pump, vascularity, warmth in extremities. Real and reproducible at 500-1000 mg pre-training. Comparable to citrulline malate but slightly faster-onset.
• Modest pain modulation — reports range from "nothing" to "noticeable taking the edge off neuropathic-flavored pain (radicular, post-injury nerve)". Acute nociceptive pain (e.g., bruise, cut) is unaffected.
• Stim-tolerance attenuation (anecdotal) — some users on chronic caffeine/modafinil/Vyvanse report that adding agmatine makes the stimulant feel "less worn out" by week 4-6. No controlled data; mechanism overlap with memantine angle.
• No cognitive sharpening — not a focus tool; do not expect modafinil-like wakefulness or racetam-like clarity.

Variability: High. ~30% of users report no detectable subjective effect. The 4-in-1 framing (calm + pump + pain + tolerance) is the steel-man case; in practice, most users notice 1-2 effects and not all four.

• Tolerance buildup: Minimal. Single 5-year continuous-use case report shows no tolerance development and no AEs.
• Recommended cycle: None required. Daily-safe.
• Reset protocol if needed: N/A. If subjective effect plateaus, more likely the effect was modest to begin with rather than tolerance.

Synergistic with

• memantine: Theoretical NMDA-antagonist synergy for opioid/stimulant tolerance prevention. Mechanism overlap (GluN2B preferential for both) suggests potentiation. Caveat: combined NMDA blockade is unstudied in humans. Use medical supervision if combining.
• magnesium (especially L-threonate): Mg is the physiological NMDA gatekeeper (voltage-dependent block); agmatine adds GluN2B-preferential channel block. Excellent safety overlap. Already in Dylan's V4 (Magtein 3 caps + Mg glycinate 4 tabs). Stack is clean.
• taurine: Both are inhibitory/calming neuromodulators with no mechanistic conflict. Taurine has GABAergic and glycinergic effects; agmatine is imidazoline/NMDA. Combined: smooth, daily-safe baseline calm. Already planned in Dylan's V5.
• alcar (acetyl-l-carnitine): No direct interaction; complementary. ALCAR feeds mitochondrial fatty acid oxidation, agmatine modulates polyamine flux. Both planned in Dylan's V5.
• l-tyrosine: Neutral. Tyrosine boosts dopamine/norepinephrine synthesis pre-stress; agmatine modulates downstream. Planned co-use is fine.
• citrulline malate (pre-workout): Synergistic for pump — citrulline raises arginine substrate, agmatine downregulates iNOS/nNOS while raising eNOS. Standard pre-workout combo.
• opioids (clinically interesting): Animal-strong, human-thin. Plausible: lower opioid dose for same analgesia + reduced tolerance accumulation. Off-label / not for self-treatment without prescriber.

Avoid stacking with

• Strong antihypertensives (clonidine, prazosin): Additive hypotension via alpha-2/imidazoline overlap. Not relevant for Dylan.
• High-dose memantine without medical supervision: Compounded NMDA block — not dangerous at agmatine's modest contribution but uncharacterized. If using both, start each one alone first.
• MAOIs (high-theoretical caution): Agmatine is itself oxidized by diamine oxidase, not classical MAO, so the interaction is theoretical rather than serotonin-syndrome-mechanistic. Still worth flagging because agmatine's polyamine intermediates could shift monoamine flux unpredictably. Dylan is not on MAOIs (selegiline at 1-2.5 mg is MAO-B selective and the risk is minimal, but flag if dose increases).

Neutral / safe co-administration

Modafinil, bromantane, semax, selank, NAC, citicoline, fish oil, phosphatidylserine, curcumin, rhodiola, theanine, glycine/tryptophan, D3+K2, beta-alanine, vitamin C, creatine (separate by 2-3 hours per encyclopedia note — the mechanism is unproven but compliance is cheap).

• Opioids: Agmatine potentiates morphine analgesia (animal data) via alpha-2 mechanism (yohimbine blocks the potentiation). Chronic agmatine prevents tolerance development at doses (0.1 mg/kg in rats) that don't acutely alter analgesia. Clinically interesting for opioid-naive patients on chronic pain regimens — not a self-administered intervention. Real human data is lacking.

• SSRIs: Theoretical caution rather than mechanistic contraindication. Agmatine animal data shows potentiation of imipramine (TCA) and bupropion (NDRI) by ~10×. SSRI-specific potentiation data is sparse. The serotonin-syndrome mechanism (SERT inhibition + MAO inhibition) doesn't apply directly to agmatine. Practical: if on SSRI, start agmatine low (250 mg) and monitor for serotonergic over-shoot; no documented cases of agmatine-induced serotonin syndrome.

• MAOIs: Theoretical caution (see above). Avoid combining without prescriber awareness.

• NMDA antagonists (memantine, ketamine, dextromethorphan): Compounded NMDA blockade. At agmatine's modest affinity this is not a hard contraindication, but the combination is uncharacterized. Memantine + agmatine for stim-tolerance has anecdotal use; ketamine + agmatine has no human safety data.

• Antihypertensives: Additive hypotension via alpha-2/I1 mechanism. Monitor BP if combining.

• Metformin / sulfonylureas: Theoretical additive hypoglycemia. Animal data shows mild fasting glucose reduction with agmatine. Monitor if diabetic.

• CYP enzymes: Agmatine is not metabolized by CYPs (renal clearance + diamine oxidase + agmatinase). No CYP-driven drug interactions.

• Contraceptives: No documented interaction.

Minimal data. The relevant enzymes are arginine decarboxylase (encoded by AZIN2 / ADC, with disputed activity in humans — debate over how much endogenous agmatine humans actually make), agmatinase (AGMAT), diamine oxidase (AOC1), and the polyamine-pathway enzymes (ODC1, SAT1).

Plausible polymorphism angles (speculative, no clinical data):

• AOC1 (diamine oxidase) variants affect histamine metabolism and may alter agmatine clearance. The rs10156191 variant is associated with reduced DAO activity and histamine intolerance. Carriers might have slower agmatine clearance and higher peak exposure.
• AGMAT (agmatinase) expression variability affects polyamine-pathway flux. No clinical correlation studied.
• ADC1/AZIN2 variants affect endogenous agmatine production. May matter for baseline pool but not for supplemental response.

For Dylan (23andMe results pending): No actionable pharmacogenomic flags. If raw data shows AOC1 reduced-function variants, consider lower starting dose (250 mg) due to potentially extended half-life. Otherwise, dose normally.

Cost reality check: $10-15/month at 1 g/day from Bulk or Primaforce. $25-30/month at 2.67 g/day (pain protocol). Among the cheapest compounds in any V5 stack.

Recommendation for Dylan: Powder from BulkSupplements (cheapest) or capsules from Nootropics Depot (already a vendor in Dylan's stack). 1 g/day = ~$8-12/month.

• Baseline (before starting): Blood pressure (BP, especially if hypotension-prone). Fasting glucose. Creatinine + BUN (renal handling). LH/FSH only if HPG concern.
• During use: BP weekly × 4 weeks at 2.67 g/day dose. Fasting glucose at month 1 and month 3 if metabolic concern. Subjective tracking: pain VAS, mood/anxiety scale, pump quality (training journal).
• Post-cycle (if cycled): N/A — not cycled. If discontinuing, no rebound expected.