Apelin-13 vs Thymosin Beta-4
A natural heart hormone that helps your cardiovascular system work better and supports healthy blood flow throughout your body.
The body's natural healing peptide that accelerates tissue repair and reduces inflammation
Written by Michael Carroll — Owner, Director of Research · Reviewed by the Peptide Initiative Research Team · Editorial standards
Quick comparison
Dose range
Apelin-13
100–100 nmol/min
Thymosin Beta-4
2–5 mg
Frequency
Apelin-13
Once daily
Thymosin Beta-4
Twice weekly
Administration
Apelin-13
Intravenous (IV)
Thymosin Beta-4
Subcutaneous injection
Cycle length
Apelin-13
Ongoing/indefinite
Thymosin Beta-4
8-12 weeks
Onset speed
Apelin-13
Moderate (1-2 weeks)
Thymosin Beta-4
Moderate (1-2 weeks)
Evidence level
Apelin-13
Moderate human trials (Phase 1-2)
Thymosin Beta-4
Moderate human trials (Phase 1-2)
Benefit ratings
Cardiovascular Support
Heart Function & Strength
Blood Flow & Circulation
Wound Healing
Inflammation Reduction
Tissue Regeneration
Compound specifications
Apelin-13
Molecular formula
C69H111N23O16S
Molecular weight
1550.8 Da
Half-life
Minutes in plasma; varies by route of administration
Bioavailability
~90-95% (subcutaneous injection)
CAS number
Not yet assigned (research compound)
Thymosin Beta-4
Molecular formula
C212H350N56O78S
Molecular weight
4963
Half-life
Dose-dependent (increases with higher doses)
Bioavailability
100% (subcutaneous and intravenous)
CAS number
77591-33-4
Dosing compared
Apelin-13
Intravenous
30 nmol/min
Continuous infusion · 5 minutes per dose step (research setting)
Apelin-13 is a research peptide given as a short drip into a vein in studies, not by self-injection. This low rate was the first step tested in a human heart study. [4]
100 nmol/min
Continuous infusion · 5 minutes per dose step (research setting)
Middle infusion rate used in the human heart study. It increased the heart's output and relaxed blood vessels. [4]
300 nmol/min
Continuous infusion · 5 minutes per dose step (research setting)
Highest infusion rate tested in the same human study, producing the strongest effect on heart output and blood pressure. [4]
Thymosin Beta-4
Subcutaneous injection
2-5 mg (community injectable practice for 'TB-500')
Once or twice weekly · 4-6 week loading phase, then weekly maintenance
Documented community/research-practice injectable dosing for tissue repair; thymosin beta-4 has ~100% bioavailability by the subcutaneous route [1]. Not an FDA-approved use.
Topical ophthalmic (eye drops)
0.1% (1 mg/mL) RGN-259 solution, 1 drop
Several times daily (e.g. up to 5x/day) · 4 weeks
0.1% RGN-259 ophthalmic solution used in phase III neurotrophic keratopathy and dry-eye trials, applied as eye drops several times daily for ~4 weeks [5].
Intravenous injection
450-1200 mg
IV push daily for the first 3 days, then weekly · Total of 7 doses over ~5 weeks
Doses studied in the RGN-352 acute myocardial infarction clinical program, given IV after PCI [6].
Best suited for
Apelin-13
Research into cardiovascular health and heart function
Apelin-13 is particularly well-suited for individuals focused on research into cardiovascular health and heart function. Research and clinical experience suggest meaningful benefits in this area when used as part of a comprehensive treatment approach [4][7].
Understanding how the body naturally protects the heart
Apelin-13 is particularly well-suited for individuals focused on understanding how the body naturally protects the heart. Research and clinical experience suggest meaningful benefits in this area when used as part of a comprehensive treatment approach [3].
Exploring potential treatments for heart failure
Apelin-13 is particularly well-suited for individuals focused on exploring potential treatments for heart failure. Research and clinical experience suggest meaningful benefits in this area when used as part of a comprehensive treatment approach [4][7].
Studying mechanisms of heart muscle strength
Apelin-13 is particularly well-suited for individuals focused on studying mechanisms of heart muscle strength. Research and clinical experience suggest meaningful benefits in this area when used as part of a comprehensive treatment approach [4].
Thymosin Beta-4
Post-Surgery Recovery
Accelerates healing of surgical wounds and reduces post-operative inflammation and scarring
Chronic Wound Management
Helps pressure ulcers, venous stasis ulcers, and other slow-healing wounds progress faster
Tissue Regeneration
Supports repair of damaged tissues from injury, burns, or degenerative conditions
Side effects
Apelin-13
Common
- Mild changes in blood pressure
- Minimal systemic effects in animal studies
- Headache (theoretical, based on blood pressure effects)
- Flushing or warmth at injection site
- Mild inflammation at injection site
- Dizziness if blood pressure drops too quickly
- Allergic reactions to the peptide
- Heart rhythm changes (requires monitoring)
- Blood pressure, heart rate, cardiac function
Serious
- Severe allergic reaction
Thymosin Beta-4
Common
- Injection site redness
- Injection site swelling
Uncommon
- Temporary mild headache
- Mild bruising at injection site
- Transient fatigue
Serious
- Allergic reaction
Safety & evidence
Apelin-13
Evidence level
Moderate human trials (Phase 1-2)
FDA status
Research compound
Safety overview
Apelin-13 is a research compound with no human clinical trials or FDA approval. All safety data comes from animal studies and in vitro mechanistic work showing beneficial effects on vascular function and cardiac remodeling. However, animal models do not predict human safety, and the peptide's effects on immune regulation in humans remain untested. No dose-ranging studies, pharmacokinetics, or organ accumulation data exist in humans. The APJ receptor is expressed in multiple tissues including brain, raising concerns about off-target neurological effects at high doses.
Contraindications
- Currently under investigation - not for human clinical use
- May interact with blood pressure medications (in theory)
- Should not be used if allergic to peptides or component amino acids
- Pregnant or breastfeeding individuals should avoid
Thymosin Beta-4
Evidence level
Moderate human trials (Phase 1-2)
FDA status
Research compound
Safety overview
Thymosin Beta-4 is a naturally occurring peptide found in all cells and body fluids in the human body. Clinical trials have demonstrated excellent safety even at very high doses. IV studies showed doses up to 1260 mg were well tolerated with no serious adverse events.
Contraindications
- Active systemic infections
- Severe immunosuppression
- Hypersensitivity to thymosin or any component
- Pregnancy (insufficient safety data)
Which is right for you?
Choose Apelin-13 if...
- Research into cardiovascular health and heart function
- Understanding how the body naturally protects the heart
- Exploring potential treatments for heart failure
- Studying mechanisms of heart muscle strength
Choose Thymosin Beta-4 if...
- Recovering from injuries or surgery
- Improving wound healing speed
- Reducing inflammation
- Minimizing scar formation