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L-Arginine: The Definitive NTRPX Integration

NTRPX Design Philosophy: We don’t optimize for cost. We optimize for outcomes. Every ingredient decision is made by asking: “What produces the best possible result for the human taking this?” Cost is a constraint we solve for, not optimize against.

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The Strategic Framework

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Three Forms, Three Purposes

The research reveals that different L-Arginine forms excel at different things. The optimal system uses the right form for the right purpose: 
┌─────────────────────────────────────────────────────────────────────────┐
│                    L-ARGININE FORM HIERARCHY                            │
├─────────────────────────────────────────────────────────────────────────┤
│                                                                         │
│  nooLVL® (1,600mg)                                                     │
│  ══════════════════                                                     │
│  • Nitrosigine® + Optimized Inositol                                   │
│  • BEST FOR: Cognitive function                                         │
│  • 3 clinical studies in cognitive/gaming populations                   │
│  • 33% improvement in executive function (TMT-B)                        │
│  • 15-minute onset, 6-hour duration                                     │
│  • Inositol enhances neurotransmitter function                          │
│                                                                         │
│  Nitrosigine® (1,500mg)                                                │
│  ══════════════════════                                                 │
│  • Inositol-Stabilized Arginine Silicate                               │
│  • BEST FOR: Sustained NO, vasodilation, physical performance           │
│  • Arginase inhibition = 6-hour arginine elevation                     │
│  • +70% higher plasma arginine vs L-Arg HCl                            │
│  • FMD improvement (+31%) matches 8g Citrulline Malate                 │
│  • -56% creatine kinase (muscle damage marker)                         │
│                                                                         │
│  L-Arginine HCl (high-dose)                                            │
│  ═════════════════════════                                             │
│  • Standard form, extensively studied                                   │
│  • BEST FOR: Growth hormone stimulation, immune function               │
│  • GH studies used 5-9g L-Arginine (dose-dependent)                    │
│  • +100-200% GH at rest (fasted state)                                 │
│  • Wound healing: +137% collagen deposition                            │
│  • Immune: Enhanced T-cell proliferation                               │
│                                                                         │
└─────────────────────────────────────────────────────────────────────────┘

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The Key Insight: Combination Is Superior

Nitrosigine® + L-Arginine HCl > Either Alone Nitrosigine® inhibits arginase—the enzyme that degrades L-Arginine. When combined with L-Arginine HCl:
  1. Nitrosigine® protects the L-Arginine from degradation
  2. L-Arginine provides additional substrate for target pathways
  3. Combined effect: Higher peak + longer duration + more total arginine
This is the same principle as L-Citrulline + L-Arginine synergy, but amplified by Nitrosigine’s superior arginase inhibition.

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Product-by-Product Optimal Formulation

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☀️ SOL (Morning Neuraldrink)

Primary Objectives:
  • Cognitive performance enhancement
  • Cerebral blood flow optimization
  • Sustained mental energy
  • Synergy with existing L-Citrulline (2g)
OPTIMAL FORMULATION:
IngredientDoseForm
nooLVL®1,600mgBonded Arginine Silicate + Inositol
Why nooLVL® (Not Standard Nitrosigine®): nooLVL® is Nitrosigine® optimized for cognitive function with additional inositol:
  • 1,500mg arginine silicate + 100mg inositol (optimized ratio)
  • 3 clinical studies specifically in cognitive/gaming populations
  • Inositol enhances neurotransmitter function involved in learning and memory
Clinical Evidence:
StudyPopulationKey Finding
Tartar 2019eGamersImproved accuracy, decision-making, reaction time during gaming
Sowinski 2021Gamers (n=26)33% improvement in TMT-B (executive function, p=0.024) at 15 min
Emerson 2022eGamers (n=9)Improved concentration, visual processing, spatial planning after single dose
Synergy with Existing Sol Ingredients: 
┌─────────────────────────────────────────────────────────────────┐
│                    SOL COMPLETE STACK                           │
├─────────────────────────────────────────────────────────────────┤
│                                                                 │
│  nooLVL® 1,600mg ─────┬───► Immediate NO boost (15 min)        │
│                       │                                         │
│  L-Citrulline 2,000mg ┴───► Sustained NO (1-6 hr)              │
│                       │                                         │
│                       ├───► COMBINED: Superadditive effect      │
│                       │     (arginase inhibition + precursor)   │
│                       │                                         │
│  Creatine 3,000mg ────┴───► Cerebral ATP regeneration          │
│                             + nooLVL blood flow = optimal       │
│                             brain energy delivery               │
│                                                                 │
│  Taurine 1,000mg ─────────► NO protection (antioxidant)        │
│                             + Osmoregulation                    │
│                                                                 │
│  OUTCOME: Maximum cognitive performance system                  │
│                                                                 │
└─────────────────────────────────────────────────────────────────┘
Citation: Sowinski R, et al. Effects of Inositol-Enhanced Bonded Arginine Silicate Ingestion on Cognitive and Executive Function in Gamers. Nutrients. 2021;13(11):3758. PMC8618773

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🌙 LUNA (Sleep/Recovery)

Primary Objectives:
  • Growth hormone stimulation at rest
  • Overnight tissue repair and recovery
  • Immune system enhancement
  • Ammonia clearance for sleep quality
OPTIMAL FORMULATION:
IngredientDoseFormPurpose
Nitrosigine®1,500mgArginine SilicateArginase inhibition, sustained arginine
L-Arginine HCl5,000mgStandardHigh substrate for GH pathway
TOTAL~6,500mg arginine equivalentCombinedMaximum GH stimulation
Why This Combination: The GH research is definitive on dose requirements:
DoseGH Response (AUC)Notes
Placebo186 min·μg/LBaseline
5g L-Arginine302 min·μg/LSignificant (p<0.05)
9g L-Arginine524 min·μg/LOptimal
13g L-Arginine198 min·μg/LGI distress, no additional benefit
The Problem: 9g L-Arginine HCl alone has poor bioavailability (~20%) and brief duration (~1 hour). The Solution: Nitrosigine® + L-Arginine HCl
  1. Nitrosigine® inhibits arginase → More L-Arginine survives to reach plasma
  2. 5g L-Arginine → Provides high substrate load for somatostatin suppression
  3. Combined effect → Higher plasma arginine sustained for 6 hours (vs 1 hour)
This is equivalent to ~9-10g L-Arginine HCl alone, but with:
  • 6× longer duration (covers entire sleep cycle)
  • Higher peak (arginase inhibition protects arginine)
  • Better GI tolerance (lower total dose needed)
GH Timing Alignment: 
┌─────────────────────────────────────────────────────────────────┐
│                    LUNA + GH TIMELINE                           │
├─────────────────────────────────────────────────────────────────┤
│                                                                 │
│  10:00 PM ─── Take Luna (Nitrosigine + L-Arg)                  │
│              │                                                  │
│  10:30 PM ─── Plasma arginine begins rising                    │
│              │                                                  │
│  11:00 PM ─── Fall asleep                                      │
│              │                                                  │
│  12:00 AM ─── Natural GH pulse #1 (Stage 3/4 sleep)            │
│              │ ▲ Arginine AMPLIFIES this pulse                  │
│              │                                                  │
│   3:00 AM ─── Natural GH pulse #2                              │
│              │ ▲ Nitrosigine STILL active (6-hour duration)    │
│              │                                                  │
│   6:00 AM ─── Natural GH pulse #3                              │
│              │ ▲ Tail-end of arginine elevation                 │
│              │                                                  │
│   7:00 AM ─── Wake refreshed, recovery maximized               │
│                                                                 │
└─────────────────────────────────────────────────────────────────┘
Additional Luna Benefits:
PathwayBenefitEvidence
Ammonia clearanceImproved sleep qualityArginine is essential for urea cycle
Immune functionT-cell support overnightBarbul studies: enhanced lymphocyte mitogenesis
Wound healingTissue repair during sleep+137% collagen deposition
IGF-1 supportAnabolic signalingKirk 1993: IGF-1 increased from 140 to 203 ng/mL
Critical Note: Arginine + Exercise ATTENUATES GH. At rest (Luna timing), it AMPLIFIES GH. This is why Luna placement is superior to Sprint for GH benefits. Citation: Collier SR, et al. Growth hormone responses to varying doses of oral arginine. Growth Horm IGF Res. 2005;15(2):136-139. PubMed 15809017

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⚡ SPRINT (Pre-Workout)

Primary Objectives:
  • Rapid vasodilation for blood flow
  • Muscle pump and nutrient delivery
  • Exercise performance enhancement
  • Reduced muscle damage markers
OPTIMAL FORMULATION:
IngredientDoseForm
Nitrosigine®1,500mgInositol-Stabilized Arginine Silicate
Why Nitrosigine® Alone (No L-Arginine HCl):
  1. Duration matches need: 6-hour coverage for entire workout + recovery
  2. Consistency: Lower variability than L-Arg HCl (more reliable response)
  3. Proven efficacy: FMD improvement equivalent to 8g Citrulline Malate
  4. No GH interference concern: Exercise already attenuates GH response (L-Arg wouldn’t help)
  5. Recovery benefits: -56% creatine kinase (muscle damage marker)
Clinical Evidence:
StudyFindingSignificance
Rogers 2020+31% FMD improvementEquivalent to 8g Citrulline Malate
Kalman 2015Plasma arginine elevated 30 min to 5 hrCovers entire workout window
Rood-Ojalvo 2015-56% creatine kinase at 24-72h post-exerciseReduced muscle damage
Rood-Ojalvo 2015Increased muscle “pump”Enhanced exercise experience
Why NOT Add L-Arginine HCl to Sprint: The GH research shows that arginine + exercise attenuates the GH response:
ConditionGH Response
Exercise alone+300-500%
L-Arginine alone (rest)+100-200%
L-Arginine + Exercise+200% (reduced!)
Adding high-dose L-Arginine to Sprint would:
  • NOT improve GH (exercise attenuates it)
  • Increase GI distress risk during workout
  • Add unnecessary cost without benefit
Nitrosigine® alone provides optimal pre-workout NO support without these downsides. Citation: Rogers JM, et al. Acute effects of Nitrosigine® and citrulline malate on vasodilation in young adults. J Int Soc Sports Nutr. 2020;17(1):12. PubMed 32093766

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💪 RECOVER (Post-Workout)

Primary Objectives:
  • Immune system support (post-exercise immunosuppression window)
  • Wound healing and tissue repair
  • Collagen synthesis for connective tissue
  • Protein synthesis activation (mTOR)
OPTIMAL FORMULATION:
IngredientDoseFormPurpose
Nitrosigine®1,500mgArginine SilicateSustained arginine for ongoing repair
L-Arginine HCl3,000mgStandardImmune and healing substrate
TOTAL~4,500mg arginine equivalentCombinedComprehensive recovery
Why This Combination: The immune and wound healing research used high doses of L-Arginine:
StudyDoseFinding
Barbul 199017-25g+137% collagen deposition, enhanced T-cell function
Kirk 1993 (elderly)17g+52% hydroxyproline, +45% IGF-1
Daly 1988 (surgical)IED with high Arg-40% infection rate
The Challenge: These are very high doses with GI tolerance issues. The Solution: Nitrosigine® + moderate L-Arginine
  • Nitrosigine® provides 6-hour sustained arginine (ongoing repair doesn’t stop at hour 1)
  • 3g L-Arginine provides meaningful substrate without GI distress
  • Arginase inhibition from Nitrosigine means more of the 3g L-Arginine is utilized
  • Combined effect approximates higher doses with better tolerability
Immune & Healing Pathways: 
┌─────────────────────────────────────────────────────────────────┐
│                    RECOVER MECHANISMS                           │
├─────────────────────────────────────────────────────────────────┤
│                                                                 │
│  Nitrosigine® + L-Arginine                                     │
│         │                                                       │
│         ├──► T-CELL PROLIFERATION                              │
│         │    • Required for T-cell cycle entry                  │
│         │    • Counters post-exercise immunosuppression         │
│         │                                                       │
│         ├──► COLLAGEN SYNTHESIS                                │
│         │    • Arginine → Proline → Collagen                    │
│         │    • +137% collagen deposition (Barbul)               │
│         │                                                       │
│         ├──► mTOR ACTIVATION                                   │
│         │    • Protein synthesis signaling                      │
│         │    • Synergy with BCAAs/EAAs                         │
│         │                                                       │
│         ├──► IGF-1 SUPPORT                                     │
│         │    • Anabolic signaling                              │
│         │    • +45% IGF-1 (Kirk 1993)                          │
│         │                                                       │
│         └──► POLYAMINE SYNTHESIS                               │
│              • Arginine → Ornithine → Putrescine               │
│              • Cell proliferation and repair                    │
│                                                                 │
└─────────────────────────────────────────────────────────────────┘
Timing Advantage: Taking Recover POST-workout avoids the GH attenuation issue (exercise-induced GH has already occurred). Citation: Barbul A, et al. Arginine enhances wound healing and lymphocyte immune responses in humans. Surgery. 1990;108(2):331-337. PubMed 2382229

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Complete NTRPX Arginine Architecture

┌─────────────────────────────────────────────────────────────────────────┐
│                    NTRPX L-ARGININE SYSTEM MAP                          │
├─────────────────────────────────────────────────────────────────────────┤
│                                                                         │
│  ☀️ SOL (Morning)                                                       │
│  ═══════════════                                                        │
│  nooLVL® 1,600mg                                                       │
│  + L-Citrulline 2,000mg (existing)                                     │
│  ─────────────────────────                                             │
│  FOCUS: Cognitive performance, cerebral blood flow                      │
│  DURATION: 6+ hours (morning through afternoon)                         │
│                                                                         │
│                              │                                          │
│                              ▼                                          │
│                                                                         │
│  ⚡ SPRINT (Pre-Workout) ─────────────────► 💪 RECOVER (Post-Workout)  │
│  ════════════════════════                   ══════════════════════════  │
│  Nitrosigine® 1,500mg                       Nitrosigine® 1,500mg       │
│                                             + L-Arginine HCl 3,000mg    │
│  ───────────────────────                    ────────────────────────    │
│  FOCUS: Vasodilation, pump                  FOCUS: Immune, healing      │
│  DURATION: 6 hours                          DURATION: 6+ hours          │
│                                                                         │
│                              │                                          │
│                              ▼                                          │
│                                                                         │
│  🌙 LUNA (Sleep)                                                        │
│  ═══════════════                                                        │
│  Nitrosigine® 1,500mg                                                  │
│  + L-Arginine HCl 5,000mg                                              │
│  ─────────────────────────                                             │
│  FOCUS: Growth hormone, overnight recovery                              │
│  DURATION: 6+ hours (entire sleep cycle)                               │
│                                                                         │
└─────────────────────────────────────────────────────────────────────────┘

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Summary: The Optimal Ingredients

ProductIngredient(s)Total DosePrimary Benefit
SolnooLVL®1,600mgCognitive performance (33% improvement)
LunaNitrosigine® + L-Arginine HCl1,500mg + 5,000mgGH stimulation (+100-200% at rest)
SprintNitrosigine®1,500mgVasodilation (+31% FMD)
RecoverNitrosigine® + L-Arginine HCl1,500mg + 3,000mgImmune/healing (+137% collagen)

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Why This Is the Best System

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1. Right Form for Right Purpose

We don’t use one form everywhere. We use:
  • nooLVL® where cognitive benefits are primary (Sol)
  • Nitrosigine® where sustained NO/vasodilation is primary (Sprint)
  • Nitrosigine® + L-Arginine HCl where high substrate load is needed (Luna, Recover)

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2. Synergistic Combinations

The Nitrosigine® + L-Arginine HCl combination is mechanistically superior to either alone:
  • Nitrosigine® inhibits arginase → protects L-Arginine from degradation
  • L-Arginine provides substrate → feeds target pathways
  • Combined = higher peak + longer duration + better utilization

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3. Timing-Optimized Placement

  • Luna (rest/sleep): Maximizes GH (arginine amplifies GH at rest)
  • Sprint (pre-workout): Nitrosigine alone (arginine + exercise = attenuated GH)
  • Recover (post-workout): Combination (GH already occurred, focus on immune/healing)

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4. Evidence-Based Dosing

Every dose is derived from clinical research:
  • nooLVL® 1,600mg: Exact dose used in cognitive studies
  • Nitrosigine® 1,500mg: Standard clinically-validated dose
  • L-Arginine 5g (Luna): Mid-range of optimal GH dose (5-9g)
  • L-Arginine 3g (Recover): Clinically-supported immune/healing dose

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5. No Compromises

We did not:
  • ❌ Use cheaper L-Arginine HCl where Nitrosigine® is superior
  • ❌ Use standard Nitrosigine® where nooLVL® (cognitive-optimized) is better
  • ❌ Skip the L-Arginine HCl where high substrate load is needed for GH/immune
  • ❌ Add arginine to Sprint where it would attenuate GH response
  • ❌ Underdose to save money

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Branded Ingredient Specifications

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nooLVL® (Sol)

  • Manufacturer: Nutrition 21, LLC
  • Composition: 1,500mg arginine silicate + 100mg inositol (optimized ratio)
  • Dose: 1,600mg per serving
  • Clinical studies: 3 (all in cognitive/gaming populations)
  • Status: GRAS, patented

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Nitrosigine® (Luna, Sprint, Recover)

  • Manufacturer: Nutrition 21, LLC
  • Composition: Inositol-stabilized arginine silicate
  • Dose: 1,500mg per serving
  • Clinical studies: 30+
  • Status: GRAS, NDI notification, patented

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L-Arginine HCl (Luna, Recover)

  • Form: L-Arginine Hydrochloride
  • Purity: ≥99%
  • Dose: 5,000mg (Luna), 3,000mg (Recover)
  • Status: GRAS

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References

  1. Sowinski R, et al. Effects of Inositol-Enhanced Bonded Arginine Silicate Ingestion on Cognitive and Executive Function in Gamers. Nutrients. 2021;13(11):3758. PMC8618773
  2. Tartar JL, Kalman D, Hewlings S. A Prospective Study Evaluating the Effects of a Nutritional Supplement Intervention on Cognition, Mood States, and Mental Performance in Video Gamers. Nutrients. 2019;11(10):2326. PMC6835425
  3. Collier SR, et al. Growth hormone responses to varying doses of oral arginine. Growth Horm IGF Res. 2005;15(2):136-139. PubMed 15809017
  4. Kanaley JA. Growth hormone, arginine and exercise. Curr Opin Clin Nutr Metab Care. 2008;11(1):50-54. PubMed 18090659
  5. Rogers JM, et al. Acute effects of Nitrosigine® and citrulline malate on vasodilation in young adults. J Int Soc Sports Nutr. 2020;17(1):12. PubMed 32093766
  6. Kalman DS, et al. A clinical evaluation to determine the safety, pharmacokinetics, and pharmacodynamics of an inositol-stabilized arginine silicate dietary supplement in healthy adult males. Clin Pharmacol. 2015;7:103-109. PMC4603712
  7. Barbul A, et al. Arginine enhances wound healing and lymphocyte immune responses in humans. Surgery. 1990;108(2):331-337. PubMed 2382229
  8. Goli P, et al. Growth hormone response to L-arginine alone and combined with GHRH: A systematic review and meta-analysis. Int J Endocrinol. 2022;2022:8739289. PMC9712012
  9. Komorowski J, Perez Ojalvo S. A pharmacokinetic evaluation of the duration of effect of inositol-stabilized arginine silicate and arginine hydrochloride in healthy adult males. FASEB J. 2016;30:lb418.
  10. Rood-Ojalvo S, et al. The benefits of inositol-stabilized arginine silicate as a workout ingredient. J Int Soc Sports Nutr. 2015;12(Suppl 1):P14.
Document Status: FINAL
Date: January 23, 2026
Philosophy: No compromises. Best ingredients. Optimal outcomes.

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Appendix: Quick Reference

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Decision Matrix

If the goal is…Use this formIn this product
Cognitive performancenooLVL® 1,600mgSol
Growth hormone (rest)Nitrosigine® + L-Arg 5gLuna
Pre-workout vasodilationNitrosigine® 1,500mgSprint
Immune/wound healingNitrosigine® + L-Arg 3gRecover

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What NOT to Do

Don’t…Because…
Use L-Arg HCl alone for sustained NODuration is only 1 hour (vs 6 for Nitrosigine)
Add high-dose L-Arg to pre-workoutAttenuates exercise-induced GH response
Use standard Nitrosigine for cognitionnooLVL® has optimized inositol for neurotransmission
Skip L-Arg HCl in Luna/RecoverHigh substrate load needed for GH/immune pathways
Underdose to save moneyThis is NTRPX. We don’t do half-measures.