GHRP-6 vs MK-677 (Ibutamoren)
A detailed comparison to help you understand the differences and choose the right peptide for your research goals.
GHRP-6
Growth Hormone Releasing Peptide 6 (GHRP-6) is one of the first synthetic growth hormone secretagogues discovered. It stimulates significant GH release but is known for causing intense hunger.
Full details →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 →Side-by-Side Comparison
| Aspect | GHRP-6 | MK-677 (Ibutamoren) |
|---|---|---|
| Dose Range | 100 mcg–300 mcg | 10 mg–25 mg |
| Frequency | 3x daily | 1x daily |
| Cycle Length | 8–12 weeks | 8–24 weeks |
| Route | subcutaneous | oral |
| Mechanism | Acts as a ghrelin mimetic, binding to the GHS-R receptor in the pituitary and hypothalamus. Stimulates GH release and also significantly increases appetite by mimicking ghrelin's hunger-signaling effects. | 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. |
| Typical Dosage | Typical dosing: 100-300mcg administered 2-3 times daily. Often combined with GHRH peptides like CJC-1295 for synergistic effects. | Typical dosing: 10-25mg taken orally once daily. Often taken at night due to sleep benefits and appetite increase. |
| Administration | Subcutaneous injection. Best administered on an empty stomach. The strong hunger response can be beneficial for those trying to gain weight but challenging for cutting. | Oral administration (capsule or liquid). Can be taken with or without food. Long half-life allows once-daily dosing. |
| Side Effects | Intense hunger (most notable effect), water retention, increased cortisol and prolactin, tingling/numbness, and potential blood pressure changes. | Increased appetite and water retention are most common. May cause lethargy, vivid dreams, and mild numbness. Can affect blood glucose and insulin sensitivity. |
| Best For |
What They Have in Common
GHRP-6, MK-677 (Ibutamoren) are both commonly used for:
Key Differences
Unique to MK-677 (Ibutamoren):
Which Has Stronger Evidence?
| Goal | GHRP-6 | MK-677 (Ibutamoren) |
|---|---|---|
| Muscle Growth | high | high |
| Recovery & Healing | medium | medium |
Key Studies
GHRP-6
- Growth hormone-releasing peptide 6 (GHRP-6) hydrogel for acute kidney injury therapy via metabolic regulation.
Journal of nanobiotechnology, 2025
- Growth hormone releasing peptide-6 (GHRP-6) prevents doxorubicin-induced myocardial and extra-myocardial damages by activating prosurvival mechanisms.
Frontiers in pharmacology, 2024
- [D-Lys3]-GHRP-6 exhibits pro-autophagic effects on skeletal muscle.
Molecular and cellular endocrinology, 2015
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
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