MK-677
also known as Ibutamoren, MK0677, MK 677
Non-peptide, orally bioavailable ghrelin receptor agonist. Distinct from injectable GHRPs because it is a small molecule (not technically a peptide, but listed for class completeness) with a long ~24 hour half-life. The Nass et al. 2008 trial showed sustained GH/IGF-1 elevation and lean mass preservation in elderly adults over 2 years — but with a measurable glucose-tolerance signal (HbA1c +0.3-0.5%).
At a glance
Oral capsule · 1×/day
Mechanism
Primary target — Ghrelin receptor (GHS-R1a) [murphy-2001-mk677].
Pathway — GHS-R1a → Gαq → Ca²⁺ → sustained GH pulses across 24 hr [nass-2008-mk677].
Downstream effect — Sustained GH + IGF-1 elevation; appetite stimulation; lean mass preservation [nass-2008-mk677].
Origin — Non-peptide spiroindane-piperidine small molecule designed at Merck [murphy-2001-mk677].
Feedback intact — Pulsatile pattern preserved despite long half-life [murphy-2001-mk677].
Dosage
Protocols described in the cited literature; not medical advice.
| Parameter | Value |
|---|---|
| Standard dose | 10–25 mg / day oral [nass-2008-mk677]25 mg used in Nass 2008 elderly trial; 10–15 mg common community dose. |
| Frequency | Once daily, oral |
| Lower / starter dose | 5 mg / day |
| Evidence basis | Phase 2 trials (Nass 2008, Murphy 1998) [nass-2008-mk677][murphy-2001-mk677] |
| Duration | 8–16 weeks per cycle (off-cycle to reset receptor sensitivity) |
| Reconstitution | Oral, no reconstitution |
| Timing | Pre-sleep preferred for natural GH pulse alignment |
| Half-life | ~24 hr [nass-2008-mk677]Once-daily dosing covers 24 hours. |
Reconstitution
A pure mass-to-volume utility. Enter what you have in the vial; the atlas computes the volume per dose. No prescription information.
Adverse events
Severities follow the FDA / CTCAE convention.
- — Active malignancy
- — Pregnancy / breastfeeding
- — Disrupted hypothalamic-pituitary axis
- — Congestive heart failure (caution)
- — Untreated diabetes
- — Pre-diabetes
- — Severe insulin resistance
Administration
- 01Form
Capsule or oral solution. No injection.
- 02Site
Oral. Take with or without food.
- 03Timing
Pre-sleep preferred — aligns with natural GH pulse.
- 04Storage
Capsule: room temp ≤25 °C, dry place.
- 05Caveat
Monitor HbA1c every 8–12 weeks during chronic use.
Sources
of 45 rendered claims carry a resolvable citation.
- [murphy-2001-mk677]Murphy 1998 — MK-677, an orally active growth hormone secretagogue, reverses diet-induced catabolism
JCEM, 1998 - [nass-2008-mk677]Nass 2008 — Effects of an oral ghrelin mimetic on body composition and clinical outcomes in healthy older adults
Ann Intern Med, 2008