MK-677, also called ibutamoren, is described in the source as an oral non-peptide compound that acts on ghrelin-related signaling. The source connects it with increased growth hormone and IGF-1 in human research, while also noting that it did not become an approved drug and that important disease-oriented trials were not successful.

How does MK-677 work?

MK-677 activates the growth hormone secretagogue receptor GHS-R1a, a receptor associated with ghrelin signaling. That pathway can promote growth-hormone pulses and downstream IGF-1 production. The same ghrelin-like activity is also consistent with appetite effects noted in the source.

Is MK-677 FDA approved?

No. The source lists MK-677 as not FDA approved and describes it as investigational, with Phase II trials halted because of safety concerns. It also reports later FDA enforcement actions and public safety communications related to heart-failure risk.

What are the side effects of MK-677?

The source lists increased appetite or hunger, weight gain, water retention or edema, insulin resistance, elevated blood glucose, anxiety, muscle or joint pain, numbness or tingling, possible bone mineral density concerns, and a heart-failure risk concern noted in FDA-related context.

What is the typical dose of MK-677?

The source reports a community common dose of 10-25 mg daily, a community range of 10-50 mg daily, and oral once-daily use often before bed. These are source-reported dosing observations for review, not treatment instructions.

This entry is not a peptide · It is included because this compound is commonly discussed alongside peptide research.

Growth Hormone Clinical Trials - human trials under way

MK-677

Also known as: Ibutamoren, Nutrobal, L-163,191

At a glance

PeptiGuide dataset · reviewed Aug 2026

What it is

Oral ibutamoren compound studied for ghrelin-linked GH and IGF-1 signaling

Status

Clinical Trials

Evidence level: human studies

Typical dose

10–25mg

Oral

Researched for

Muscle building, sleep improvement, appetite increase

Trial progress

PrePreclinical
IPhase I
IIPhase II
IIIPhase III
IVPhase IV
FDAFDA approved

Phase II - Emerging human evidence with important limitations

Use the tools

In plain language

MK-677, also known as ibutamoren, is identified by the source as an oral non- ghrelin-receptor rather than a peptide.
The source reports human-trial evidence involving growth hormone and IGF-1 effects.
It is listed as not FDA approved, with investigational Phase II history and source-noted safety concerns.
Source-reported dosing commonly centers on 10-25 mg daily by mouth.
Research areas listed by the source include muscle building, sleep improvement, and appetite increase.

How it's thought to work

MK-677 is described as a selective GHS-R1a . By engaging this ghrelin-associated receptor in growth-hormone regulatory pathways, it can increase growth-hormone signaling and raise IGF-1. The source also links its ghrelin-like activity to appetite effects and notes possible cortisol changes.

What the research shows

Where the research stands

The source describes a mixed human-research picture. In older healthy adults, a one-year randomized study using 25 mg daily was reported to raise IGF-1 and increase fat-free mass, while strength or functional outcomes were not characterized as strong and early weight change was partly attributed to water. In an Alzheimer's disease trial with 563 participants over 12 months, IGF-1 increased but cognitive decline was not slowed. The source consistently flags appetite increase, fluid retention, and reduced insulin sensitivity as recurring tolerability concerns, and notes that the compound remains unapproved.

What it shows

✓ Human studies

Emerging human evidence with important limitations

△ Limitations

Study protocols describe research and are not dosing recommendations.

Bottom line: Investigational; Phase II trials reported halted for safety concerns, with source-noted FDA enforcement activity in 2025-2026. Not FDA Approved

Typical dosing

CommunityCommunity dataset

10–25 mg

daily

10 mgfull range seen50 mg

Community-reported dosing only. The source notes potential water retention, appetite increase, and blood-glucose concerns, and says usage patterns vary. · Oral

Research dosing

Study-specific protocolsHuman trials under way - protocols are study-specific

Doses observed in studies

10-25 mg daily

Clinical Trial Data - Investigational - Phase II trials completed

Study protocols describe research and are not dosing recommendations.

Duration: 8-12 weeks or longer
Administration: Oral

Timing & administration

Best time to take

Before bed

Once daily, consistently at the same time

Food recommendation

With or without food

Why this timing?

The source favors evening use because hunger and drowsiness may occur, and because the compound is discussed in relation to sleep-associated growth-hormone patterns.

Possible side effects

Not everyone experiences these. Individual responses vary with dose, duration, and personal factors.

Increased appetite and hunger
Weight gain
Water retention or edema
Insulin resistance
Elevated blood glucose or hyperglycemia
Anxiety
Muscle or joint pain
Numbness or tingling
Heart failure risk concern
Possible negative impact on bone mineral density
Not FDA approved with FDA warning-letter context

Not everyone experiences side effects, and severity can vary by context, purity, route, and individual health factors.

Sources

PubMed ClinicalTrials.gov FDA.gov

Frequently asked questions

One open dataset

Every fact on this page - doses, side effects, references - comes from the same PeptiGuide dataset that powers the Tracker, Compare, and the Lab.

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Educational resource, not medical advice. Talk to your clinician before acting on anything here.

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MK-677

In plain languageIn plain language

How it's thought to workHow it's thought to work

What the research showsWhat the research shows

Typical dosing

Research dosing

Timing & administrationTiming & administration

Possible side effectsPossible side effects

SourcesSources

Frequently asked questionsFrequently asked questions

What does MK-677 do?