SYS ONLINE
SUPPLEMENT_SCHOLAR
evidence · mechanism · dose
Experimental/GH SecretagogueResearch peptide

MK-677

aka Ibutamoren

Orally active ghrelin mimetic that produces sustained GH and IGF-1 elevation.

Educational explainer of a research peptide. Profiles in this section deliberately omit clinical-trial citations, dosing protocols, and purchase links. Not FDA-approved as a supplement; not a recommendation to use.

Overview

MK-677 is a small-molecule ghrelin-receptor agonist developed by Merck. It is technically a peptidomimetic rather than a true peptide, but it shares mechanism with the GHRPs.

Source
  • Synthesized in research laboratories
Forms
  • Oral capsule or solution

Mechanism of action

Binds GHS-R1a like the GHRPs but is orally bioavailable and long-acting, producing sustained nightly GH and IGF-1 elevation.

Pathways
  • · GHS-R1a activation
  • · Somatostatin suppression
Receptors
  • · GHS-R1a
Hormones
  • · GH
  • · IGF-1
  • · Cortisol

How it acts on the body

MK-677 mimics ghrelin at GHS-R1a but is structurally a small molecule with a 24-hour half-life, so a single oral dose produces an entire night of amplified GH pulses rather than a short spike. Over weeks, IGF-1 rises substantially and stays there.

The trade-offs are the same as ghrelin itself: meaningful appetite increase, water retention, mild insulin resistance, and occasional numbness in extremities from nerve-related water shifts. Effects on cortisol and prolactin are smaller than with the injectable GHRPs but not zero.

Hormonal & endocrine impact

How this peptide is reported to shift specific hormones and signaling molecules. Directionality reflects research literature and preclinical models, not clinical prescribing data.

Projected hormonal trajectory
Illustrative curves derived from reported direction of effect. Not measured patient data.

Curves are schematic shapes (sigmoid for increases/decreases, damped oscillation for modulation/stabilization) anchored to a 100% baseline. They communicate direction and tempo of change reported in research literature — not absolute hormone concentrations.

Growth hormoneIncreases
Amplifies natural nightly GH pulses for the full dosing window.
IGF-1Increases
Sustained elevation, often 40-90% over baseline at study doses.
CortisolIncreases
Mild chronic elevation reported.
Insulin sensitivityDecreases
Fasting glucose can rise; HbA1c shifts have been documented.

Effects on the body

Increases
Nightly GH / IGF-1 exposure
Increases
Appetite
Decreases
Insulin sensitivity
Supports
Sleep depth

Organ system effects

Endocrine

Sustained pituitary GH / IGF-1 drive.

Brain & CNS

Appetite and sleep-architecture changes.

Digestive / Gut

Increased gastric motility.

Reported effects

Drawn from preclinical research, anecdote, and small-scale clinical observation. No evidence grades are assigned — most peptides on this page lack rigorous human trials.

  • Sleep-quality improvements
  • Increased recovery markers
  • Bone-density signals in trials

Potential side effects

Common
  • · Hunger
  • · Water retention
  • · Tingling
  • · Lethargy
Rare
  • · Vivid dreams
Serious
  • · Glucose dysregulation
  • · Heart-failure exacerbation in elderly trial subjects

Drug interactions

Insulin or sulfonylureas
Glucose handling shifts; monitor closely.
moderate

Pairing context

Often combined with
  • Resistance training and adequate protein
    Anabolic context for sustained IGF-1.
Avoid combining with
  • Heart failure or active cancer
    Documented worsening / theoretical risk.
Important. Research peptides described here are not FDA-approved supplements. Supplement Scholar does not endorse, recommend, or link to any source for purchase. Consult a qualified clinician before considering any peptide therapy.