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MK-677 (Ibutamoren)

Growth Factors & Muscle Building

MK-677 (Ibutamoren) is a long-acting, orally active ghrelin mimetic that stimulates the secretion of growth hormone (GH) and insulin-like growth factor 1 (IGF-1) by binding to the GHS-R1a receptor. It has been studied in preclinical and clinical research for its potential to support GH/IGF-1 axis signaling, muscle mass retention, and metabolic regulation in aging and disease models.

Administration
Oral
mg capsule/tablet
Daily Range
10–30 mg Oral
Once daily, typically in the evening
Standard Dose
20 mg
Cycle
4–8 weeks
then reassess
MK-677Ibutamorengrowth hormoneghrelin agonistIGF-1

Dosing Guide

In research studies, MK-677 has been administered orally at 10–25 mg per day over periods ranging from 2 to 12 weeks. These dosing protocols are used in tightly controlled clinical trials and are not approved for general use..

Standard / Gradual Approach

standard
PhaseDose
Week 1-210 mg daily at bedtime
Week 3-415-20 mg daily at bedtime
Week 5+25 mg daily at bedtime

Protocol Summary

Oral: Once daily, typically in the evening · Dose range 10–30 mg with gradual titration
Cycle Length: 4–8 weeks typical; reassess before extending

Frequency & Cycling

Oral

Take once daily for 8–12 weeks. Breaks of 2–4 weeks recommended to monitor insulin sensitivity. Best taken pre-sleep or fasted in AM.

💊 Quick Start

Starting Dose
10 mg daily (oral)
Maintenance Dose
25 mg daily (oral)

Potential Benefits & Use Cases

MK-677 (Ibutamoren) is a research-use-only compound. It is not approved for human or veterinary use. This content is intended for scientific and educational reference only.
Increases endogenous GH and IGF-1 secretion (without increasing prolactin)
Studied for muscle preservation and lean body mass in aging models
Investigated for potential improvements in sleep architecture (e.g., REM sleep increase)
Explored for bone mineral density support in preclinical and human research
Evaluated for effects on appetite and metabolism via ghrelin pathway activation
Clinical data Strong preclinical Limited data

Mechanism of Action

→Acts as a ghrelin receptor (GHS-R1a) agonist
→Stimulates pulsatile growth hormone release
→Increases circulating IGF-1 without elevating cortisol or prolactin significantly
→Promotes sleep-related GH secretion and deep wave sleep

Lifestyle & Optimization

timing

Bedtime dosing recommended to align with natural GH pulse and reduce appetite/water retention during waking hours.

diet

May increase appetite significantly. Monitor caloric intake if weight management is a goal.

exercise

Resistance training enhances growth hormone-mediated effects.

sleep

Improves deep sleep quality through GH elevation.

Peptide Research & Preclinical Studies

Evidence-Based Research Findings

Study TitleType
Effects of MK-677 on GH Secretion and Body Composition in Older AdultsReference
Ibutamoren as an Oral GH SecretagogueReview
Sleep-Promoting and GH-Stimulating Effects of MK-677Reference

Side Effects & Safety

Common Side Effects

• Water retention
• Increased appetite
• Mild lethargy or fatigue

Contraindications & Warnings

• Can exacerbate insulin resistance and cause transient blood sugar elevation
• Use caution in diabetics or those with metabolic syndrome

Long-Term Safety Data

• Long-term use may affect insulin sensitivity; monitoring is advised
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Bioavailability & Absorption

SubQ Injection
Not used via injection; oral administration is highly bioavailable
Oral Administration
Excellent oral bioavailability; long half-life supports once-daily dosing
Half-Life
24 hours
Degradation
Metabolized in liver; maintains stable GH elevation throughout day
Tissue Specificity
Acts on pituitary GH axis, hypothalamus, and metabolic tissues
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Peptide Details

Molecular Weight
528.7
Formula
C27H36N4O5S
Sequence
Non-peptide mimetic (ghrelin receptor agonist)
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Legal Status & Regulatory

RegionStatus
FDANot Approved
EUNot Approved
AustraliaPrescription Only
CanadaNot Approved

Storage Instructions

Lyophilized (Powder)
Store capsules or powder at room temperature in a cool, dry place. Protect from moisture and light. Oral administration is the standard route. No reconstitution needed for capsule form.
Reconstituted (Mixed)
If using liquid form, refrigerate at 2-8°C. Use within 4-6 weeks.