Pepbase

Cyclic Glycine-Proline

Also known as: cGP

Not FDA Approved
CognitiveHealthPerformanceAnti-Aging

Primary use: Cognitive enhancement and neuroprotection

ℹ️

What is Cyclic Glycine-Proline?

Cyclic glycine-proline (cGP) is a naturally occurring cyclic dipeptide derived from insulin-like growth factor-1 (IGF-1). It is found in plasma, breast milk, and cerebrospinal fluid and regulates IGF-1 bioavailability. Primarily used for its neuroprotective and cognitive enhancement properties, cGP is under research for applications in neurological conditions like Alzheimer's and Parkinson's disease. Though not FDA-approved, it shows promising safety and efficacy in preliminary studies.

Primary Benefits
  • Enhances cognitive function
  • Provides neuroprotection
  • Supports cardiovascular health
How It Works

cGP competes with IGF-1 for binding to IGFBP-3, regulating IGF-1 availability. It acts as an allosteric modulator of AMPA and GABA-A receptors and increases BDNF levels, leading to improved cognitive and neuroprotective effects.

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Safety Tips

Precautions reported in community discussions and literature. This is not a complete list. View Full Side Effects Guide →
  • 1DON'T exceed recommended doses of 20-50 μg daily.
  • 2NEVER use if you have allergies to peptide components.
  • 3AVOID inconsistent dosing times to maintain stability.
  • 4DON'T mix with substances affecting IGF-1 without medical guidance.
  • 5NEVER rely on unverified sources for purchase.

Who Should NOT Use

  • Known allergy to peptides

Dosage & Protocols

Different purposes have different protocols, dosing, and considerations

💉

Cognitive enhancement

moderate evidence

Used to enhance memory retention, attention, and overall cognitive function. Studies show benefits in healthy aging and prevention of cognitive decline.

Evidence: Research includes multiple clinical observations and animal studies indicating increased BDNF and memory improvement.

The following are ranges reported in published literature and community discussions. These are NOT recommendations or medical advice.

Range
20-50 mcg
Frequency
once daily
Cycle
4-12 weeks
Route
Subcutaneous
TimingMorning
NotesMaintaining consistent daily timing is advised.

📋Community-Reported Protocols

Not recommendations:

The following protocols are compiled from online communities and published literature. Pepbase does not endorse, recommend, or verify these protocols. They are provided for informational purposes only. Individual responses vary significantly. Consult a licensed medical professional before any use.

Reported GoalReported DoseReported FrequencyReported Route
General cognitive support20-40 μg1x dailyOral (capsule)
Neuroprotection/anti-aging40-50 μg1x dailyOral (capsule)

⏱️Pharmacokinetics

Half-Life
Not specified
Time to Peak
2-4 weeks
Clearance
Not specified

⚡Reported Side Effects

This is not a complete list. Other side effects may occur.

Common
Mild digestive upsetreported (frequency unknown)

🧊Storage

Temperature
Room temperature
Reconstituted
Not applicable
Shelf Life
18 months
Light Sensitive
No
💉

Neuroprotection in neurological conditions

limited evidence

Studied for protecting neural cells and potentially reducing symptoms in Alzheimer's and Parkinson's disease.

Evidence: Limited human data but promising animal studies showing reduction in amyloid plaques and improved cognitive symptoms in neurodegenerative models.

The following are ranges reported in published literature and community discussions. These are NOT recommendations or medical advice.

Range
20-50 mcg
Frequency
once daily
Cycle
4-12 weeks
Route
Subcutaneous
TimingMorning
NotesConsistent morning administration is preferred.

📋Community-Reported Protocols

Not recommendations:

The following protocols are compiled from online communities and published literature. Pepbase does not endorse, recommend, or verify these protocols. They are provided for informational purposes only. Individual responses vary significantly. Consult a licensed medical professional before any use.

Reported GoalReported DoseReported FrequencyReported Route
Neuroprotection40-50 μg1x dailyOral (capsule)

⏱️Pharmacokinetics

Half-Life
Not specified
Time to Peak
4-12 weeks
Clearance
Not specified

⚡Reported Side Effects

This is not a complete list. Other side effects may occur.

🧊Storage

Temperature
Room temperature
Reconstituted
Not applicable
Shelf Life
18 months
Light Sensitive
No
🛡️

Harm Reduction Information

Quality Concerns

  • Potential contamination from unregulated sources
  • Mislabeling of cGP dose per serving

Safety Tips

  • Start with the lowest effective dose to assess tolerance.
  • Only purchase from reputable sources with third-party quality testing.
  • Maintain consistent dosing schedule to ensure efficacy.
  • Ensure proper storage to prevent degradation.

Warning Signs to Stop

  • Unexpected allergic reactions
  • Severe gastrointestinal discomfort

Seek Medical Help Immediately If

  • Signs of severe allergic reactions like difficulty breathing
  • Significant changes in mood or cognitive function
❓

Frequently Asked Questions

How long until I see effects?

Cyclic Glycine-Proline typically shows cognitive benefits within 2-4 weeks of consistent use.

What time of day should I take it?

For cyclic glycine-proline, morning intake is preferred, with or without food.

How can I minimize side effects?

To minimize side effects, start with a low dose of cyclic glycine-proline and consult a healthcare provider if on IGF-1 affecting medication.

Does tolerance develop?

Generally, tolerance does not develop with cyclic glycine-proline due to its endogenous nature.

How should I store it?

Store cyclic glycine-proline supplements in a cool, dry place away from direct sunlight.

Do I need to cycle it?

Cyclic glycine-proline can be used continuously, but some users choose a 4-12 week cycle for evaluation.

🔄

Reported Combinations

Compounds reported to be used alongside Cyclic Glycine-Proline in community discussions. Not a recommendation.

investigational

IGF-1

Increases IGF-1 bioavailability and effectiveness.

investigational

BPC-157

Combines neuroprotective effects and supports IGF-1 activity.

investigational

Blackcurrant extract

Natural source of cGP, providing additional antioxidant effects.

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Reported Interactions

Interactions reported in literature and community discussions.

IGF-1 supplementsmoderate

Monitor for enhanced effects of IGF-1.

GH secretagoguesmoderate

Monitor combination closely for unintended metabolic effects.

Blood pressure medicationminor

May require adjustment due to blood pressure-lowering effects of cGP.

Reconstitution Guide

Reconstitution Calculator

mL
U100 insulin syringe01020304050607080901001mL

100 units = 1 mL

Safety Tips

  • Always consult a licensed medical professional for dosing and reconstitution instructions.
  • Always double check your units. Mixing up mg and mcg can be very dangerous.
  • Make sure to select your syringe type. U-100 and U-50 syringes have different units.
  • Ensure you're not adding more BAC than your vial can hold. Most vials have maximum capacities listed.

This calculator is for informational and educational purposes only. It does not provide medical advice, dosing recommendations, or safety determinations. Reference ranges shown are compiled from publicly available sources and are not a substitute for guidance from a licensed healthcare professional.

Explore More Research

Browse our database of peptide research information compiled from published literature and community sources.

Browse All PeptidesAbout Pepbase App
📚

Other Sources & Citations

PubMed
A Concise Review of Cyclic Glycine-Proline - PubMed Central
pmc.ncbi.nlm.nih.gov•Updated Oct 2025
PubMed
Cyclic Glycine-Proline (cGP) Normalises Insulin-Like Growth Factor ...
pmc.ncbi.nlm.nih.gov•Updated Jan 2026
PubMed
Cyclic Glycine-Proline Improves Memory and Reduces ...
pmc.ncbi.nlm.nih.gov•Updated Sep 2025
PubMed
Cyclic Glycine-Proline (cGP) Normalises Insulin-Like ...
pubmed.ncbi.nlm.nih.gov•Updated Oct 2025
PubMed
Administration of cyclic glycine-proline during infancy ...
pubmed.ncbi.nlm.nih.gov•Updated Oct 2025

Last updated: October 1, 2023

Important Disclaimer

AI-Generated Content Notice

The information on this page has been compiled using artificial intelligence (AI) and large language model (LLM) technology from multiple sources including published literature, online communities, and public databases. This content may contain errors, inaccuracies, outdated information, or omissions. We make no guarantees regarding the accuracy, completeness, or reliability of any information presented. You are solely responsible for independently verifying any information before relying on it.

Not Medical Advice

Nothing on this website constitutes medical advice, diagnosis, or treatment recommendations. The information provided is for educational and harm-reduction purposes only. We do not provide individualized dosing guidance or treatment recommendations. Protocols and dosing information shown represent reports from community discussions and published literature—they are not endorsements or recommendations. Always consult with a licensed healthcare professional before making any health-related decisions.

No Endorsement of Use

Pepbase does not endorse, encourage, or recommend the use of any peptide or substance discussed on this website. Many compounds discussed are not approved for human use by the FDA or other regulatory agencies. Some substances may be illegal to possess, sell, or use in your jurisdiction. We do not facilitate or encourage the procurement, distribution, or use of controlled or prescription-only substances. Users are solely responsible for understanding and complying with all applicable laws in their jurisdiction.

Calculators and Tools

Any calculators, estimators, or tools provided on this website are for informational purposes only and produce estimates that may be inaccurate. Errors in calculations can result in serious harm. You are solely responsible for verifying all calculations independently. These tools do not account for individual factors that may affect dosing and should never be relied upon as a substitute for professional medical guidance.

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