MK-677 Oral (Ibutamoren) (25mg capsule)
MK-677 (Ibutamoren) is an orally active, non-peptidic ghrelin receptor (GHS-R1a) agonist that increases growth hormone (GH) and IGF-1 levels without affecting cortisol levels. Multiple clinical trials confirm oral efficacy at doses of 10–25 mg daily.
Reviewed by the AllPeptides.eu Editorial Team·Last reviewed: 2026-06-16
Educational information. Not medical advice, and no efficacy claim is implied. Regulatory approval is not a use recommendation by AllPeptides.eu.
⚠️ For informational/educational purposes only. Not medical advice. We do not sell any products. Self-treatment carries serious risks — consult a healthcare professional. Disclaimer
Research monograph
See the full MK-677 encyclopedia page with mechanism, evidence tier, related variants and research context.
How It Works
MK-677 binds to the ghrelin receptor (GHS-R1a) in the hypothalamus and pituitary gland, causing: (1) increased pulsatile GH secretion, (2) a 40–60% increase in IGF-1, (3) improved REM sleep, (4) increased lean body mass. It does not suppress the HPA axis (cortisol remains stable).
Quick Start
- Form: 25mg capsule — no reconstitution required.
- Typical dose: 10–25 mg daily, once, in the evening.
- Timing: Before bedtime (enhances natural GH pulse).
- Cycle duration: 8–16 weeks (long-term study: 2 years).
Typical Research Dosing — MK-677 Per Os
Route: Oral (per os) | Frequency: Once daily (in the evening)
| Week | Dose | Amount |
|---|---|---|
| Weeks 1–2 | 10 mg (10,000 mcg) | ½ capsule or 1 10mg capsule |
| Weeks 3–8 | 25 mg (25,000 mcg) | 1 25mg capsule |
| Weeks 9–16 (optional) | 25 mg (25,000 mcg) | 1 25mg capsule |
Take once daily before bedtime. The half-life (~24 hours) allows for once-daily dosing. Evening administration synchronizes with the physiological nocturnal GH peak.
Related compounds
Protocol Overview
- MK-677 (Ibutamoren Mesylate) is a non-peptidic small molecule that mimics ghrelin at the GHS-R1a receptor. It is not a SARM or a steroid.
- Clinical trials in healthy older adults (Nass et al., 2008) showed an increase in IGF-1 to young adult levels without serious side effects over 2 years.
- Oral bioavailability is high (~60%) due to its non-peptidic structure.
Dosing Protocol
- Start with 10mg daily for the first 2 weeks.
- Increase to 25mg daily (full dose).
- Take before bedtime — can be taken with or without food.
- An 8–16 week cycle is followed by a 4-week break.
- Break between cycles: A 4-week break between cycles is recommended to prevent GHS-R1a desensitization.
Washout & Cycle Restart
When can I restart?
A 4-week break between cycles is recommended to prevent GHS-R1a desensitization.
Minimum wait period: 4 weeks
Storage Instructions
- Store at room temperature (15–25 °C).
- Keep away from moisture and light.
Important Notes
- ⚠️ Significantly increases appetite (ghrelin mimetic) — use caution if the goal is weight loss.
- May increase fasting glucose and insulin resistance.
- Possible fluid retention and swelling, especially in the first few weeks.
- Not an approved drug — research substance.
Potential Benefits & Side Effects
Potential Benefits:
- Increased GH and IGF-1 without injection
- Improved sleep quality
- Increased lean body mass
- Improved bone density (long-term)
- High oral bioavailability (~60%)
Potential Side Effects:
- Increased appetite
- Fluid retention / swelling
- Increased fasting glucose
- Muscle pain (rarely)
- Lethargy / drowsiness
⚠️ Serious Warnings & Long-Term Risks
The following warnings are based on published literature, FDA labels, and post-marketing surveillance. They do not constitute medical advice. Consult a healthcare professional.
Chronic IGF-1 elevation
As an oral GHS, significantly increases IGF-1 on a 24-hour basis. A 2-year study in elderly showed no increase in neoplasms, but concern remains theoretical.
📄 Ann Intern Med 2008Insulin resistance
MK-677 significantly increases fasting glucose levels and may worsen type 2 diabetes. The study in diabetic patients was terminated early.
📄 J Clin Endocrinol Metab 2001References
- Nass R. et al. — Effects of an oral ghrelin mimetic on body composition and clinical outcomes in healthy older adults (2008) — 2-year clinical trial of oral MK-677 in older adults — increased GH/IGF-1, body composition.
View Source - Murphy MG. et al. — MK-677, an orally active growth hormone secretagogue — Pharmacokinetics and dose-dependent response of oral MK-677.
View Source - Copinschi G. et al. — Effects of MK-677 on GH pulsatility and sleep — Improvement in stage IV sleep and increased GH pulsatility with MK-677.
View Source
External Sources & Regulatory Status
Regulatory Approvals
GH deficiency / Sarcopenia
Phase II (Merck — development discontinued)
Educational information. Not medical advice, and no efficacy claim is implied. Regulatory approval is not a use recommendation by AllPeptides.eu.
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