Thymulin vs MK-677 (Ibutamoren)
Side-by-side comparison of key properties, dosing, and research.
Immune Support
ThymulinGrowth Hormone Peptides
MK-677 (Ibutamoren)- Summary
- Thymulin is a nonapeptide hormone produced exclusively by the thymic epithelium. It requires zinc for biological activity and plays a critical role in T-lymphocyte maturation, differentiation, and immune regulation. Thymulin levels decline dramatically with age, contributing to immunosenescence.
- MK-677 (Ibutamoren) is an orally active, non-peptide ghrelin receptor agonist that increases growth hormone and IGF-1 levels. Unlike injectable GHRPs, it can be taken orally and has a 24-hour half-life, making it convenient for sustained GH optimization.
- Half-Life
- ~30 minutes active half-life
- 24 hours
- Admin Route
- SubQ
- Oral
- Research
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- Typical Dose
- 20-30 mcg
- 10–25 mg
- Frequency
- 10 days per month (Khavinson protocol)
- Once daily
- Key Benefits
- Enhances T-cell maturation and differentiation
- Boosts NK cell cytotoxic activity
- Reduces inflammatory cytokine production (TNF-α, IL-1)
- Anti-nociceptive (pain-reducing) properties
- Restores age-related immune decline
- Anti-inflammatory via serotonin pathway modulation
- Increases lean muscle mass
- Enhances bone density
- Improves sleep quality and REM sleep
- Accelerates recovery from training
- Increases appetite
- May improve skin elasticity and appearance
- Supports fat loss while maintaining muscle
- Oral administration — no injections required
- 24-hour half-life allows once-daily dosing
- Side Effects
- Injection site reactions
- Mild fatigue initially as immune system activates
- Increased appetite (significant in some users)
- Water retention and puffiness
- Elevated blood glucose / insulin resistance (monitor in diabetics)
- Lethargy initially
- +2 more
- Stacks With
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