MK-677 (Ibutamoren) vs Thymosin Alpha-1
A detailed comparison to help you understand the differences and choose the right peptide for your research goals.
MK-677 (Ibutamoren)
MK-677, also known as Ibutamoren, is an orally active growth hormone secretagogue. Unlike peptides, it can be taken orally and has a long half-life, providing 24-hour GH elevation.
Full details →Thymosin Alpha-1
Thymosin Alpha-1 is a peptide naturally produced by the thymus gland that plays a crucial role in immune system modulation. It is approved in over 35 countries for various conditions including hepatitis B and C.
Full details →Side-by-Side Comparison
| Aspect | MK-677 (Ibutamoren) | Thymosin Alpha-1 |
|---|---|---|
| Dose Range | 10 mg–25 mg | 1.6 mg–3.2 mg |
| Frequency | 1x daily | Less than daily |
| Cycle Length | 8–24 weeks | 4–12 weeks |
| Route | oral | subcutaneous |
| Mechanism | Acts as a potent, selective agonist of the ghrelin receptor (GHS-R1a). Increases GH and IGF-1 levels without affecting cortisol. Mimics ghrelin's GH-releasing effects. | Enhances T-cell function and maturation, stimulates dendritic cell activity, and modulates cytokine production. Promotes the differentiation of stem cells into mature T lymphocytes. |
| Typical Dosage | Typical dosing: 10-25mg taken orally once daily. Often taken at night due to sleep benefits and appetite increase. | Clinical dosing typically ranges from 1.6mg to 6.4mg administered subcutaneously 2-3 times weekly. Research protocols may vary. |
| Administration | Oral administration (capsule or liquid). Can be taken with or without food. Long half-life allows once-daily dosing. | Subcutaneous injection. Often used in cycles or as part of comprehensive immune support protocols. |
| Side Effects | Increased appetite and water retention are most common. May cause lethargy, vivid dreams, and mild numbness. Can affect blood glucose and insulin sensitivity. | Generally well-tolerated. Rare side effects include injection site reactions, mild flu-like symptoms, and temporary fatigue. |
| Best For |
What They Have in Common
MK-677 (Ibutamoren), Thymosin Alpha-1 are both commonly used for:
Key Differences
Unique to MK-677 (Ibutamoren):
Which Has Stronger Evidence?
- Recovery & Healing: Thymosin Alpha-1 has stronger research support.
| Goal | MK-677 (Ibutamoren) | Thymosin Alpha-1 |
|---|---|---|
| Recovery & Healing | medium | high |
Key Studies
MK-677 (Ibutamoren)
- Knowing the minimal detectable dose can facilitate the interpretation of a hair test result: II. Case example with ibutamoren (MK-677), a growth hormone secretagogue.
Clinica chimica acta; international journal of clinical chemistry, 2026
- Hepatotoxicity induced by MK-677.
BMJ case reports, 2025
- Investigating the P53-dependent anti-cancer effect of ibutamoren in human cancer cell lines.
Basic & clinical pharmacology & toxicology, 2025
Thymosin Alpha-1
- Aging and Thymosin Alpha-1.
International journal of molecular sciences, 2025
- Phenotypic drug discovery: a case for thymosin alpha-1.
Frontiers in medicine, 2024
- The efficacy of thymosin alpha-1 therapy in moderate to critical COVID-19 patients: a systematic review, meta-analysis, and meta-regression.
Inflammopharmacology, 2023
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