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Growth Hormone

MK-677

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

Clinical Trials
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Key Facts: MK-677

Category
Growth Hormone
FDA Status
Not FDA Approved
Clinical Status
Investigational - Phase II trials halted (safety concerns). FDA enforcement escalated 2025-2026: product recalls, warning letters, and public safety alerts about congestive heart failure risk.
Administration
Oral
Typical Dose
10-25 mg daily
Frequency
Once daily, often before bed
Duration
8-12 weeks or longer
Also Known As
Ibutamoren, Nutrobal, L-163,191

Mechanism of Action

MK-677 binds to ghrelin receptors (GHSR) in the brain, stimulating sustained GH release and increasing IGF-1 levels. Unlike injectable GHRPs, it is orally bioavailable and has a long half-life providing 24-hour GH elevation.

Research Summary

Studies show increases in GH and IGF-1 levels, improved sleep quality, and increased lean body mass. However, a clinical trial was stopped early due to heart failure concerns in elderly patients. FDA lists MK-677 as having 'significant safety risks due to potential for congestive heart failure.' December 2025: FDA issued warning letters to companies selling MK-677. Never received FDA approval and remains an unapproved drug.

Trial Progress:Phase II
Pre
I
II
III
IV
FDA

Dosing Information

Human Trials·Human studies conducted, not FDA approved

Typical Dosingⓘ

Community experience

Common Dose

10-25 mg daily

Range

10-50 mg daily

Frequency

Once daily, often before bed

Oral GH secretagogue. Can cause water retention, increased appetite, and blood sugar issues. Some cycle it, others run year-round.

Research Dosingⓘ

Scientific studies

Doses from research studies

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?

MK-677 can cause drowsiness and hunger. Evening dosing minimizes daytime appetite increase and supports sleep-related GH release.

Possible Side Effects

Not everyone experiences these effects. Individual responses vary based on dosage, duration, and personal factors.

  • ●Increased appetite and hunger
  • ●Weight gain
  • ●Water retention/edema
  • ●Insulin resistance
  • ●Elevated blood glucose/hyperglycemia
  • ●Anxiety
  • ●Muscle or joint pain
  • ●Numbness/tingling
  • ●Risk of heart failure (FDA concern - clinical trial halted)
  • ●May negatively impact bone mineral density
  • ●NOT FDA approved - FDA issuing warning letters (2025)

References

Research This Peptide Further

PubMedClinicalTrials.govFDA.gov

Frequently Asked Questions

What does MK-677 do?

An orally active growth hormone secretagogue that mimics ghrelin. Although technically not a peptide, it is frequently discussed alongside GH peptides due to similar effects.

How does MK-677 work?

MK-677 binds to ghrelin receptors (GHSR) in the brain, stimulating sustained GH release and increasing IGF-1 levels. Unlike injectable GHRPs, it is orally bioavailable and has a long half-life providing 24-hour GH elevation.

Is MK-677 FDA approved?

No, MK-677 is not currently FDA approved. Current status: Investigational - Phase II trials halted (safety concerns). FDA enforcement escalated 2025-2026: product recalls, warning letters, and public safety alerts about congestive heart failure risk.

What are the side effects of MK-677?

Reported side effects include: Increased appetite and hunger, Weight gain, Water retention/edema, Insulin resistance, Elevated blood glucose/hyperglycemia. Individual responses vary based on dosage, duration, and personal health factors.

What is the typical dose of MK-677?

Community-reported common dose: 10-25 mg daily (Once daily, often before bed). Range: 10-50 mg daily. Administration: Oral. Community-reported doses. Not medical advice. Consult healthcare provider.

Related Peptides

Peptides commonly compared with MK-677 or used in similar applications.

Ipamorelin

Clinical Trials

A selective growth hormone secretagogue that stimulates GH release without significantly affecting cortisol or prolactin. Considered one of the safest GHRPs.

Growth Hormone

CJC-1295 (No DAC)

Clinical Trials

A synthetic analog of growth hormone-releasing hormone (GHRH) that stimulates GH release from the pituitary. Often combined with a GHRP like Ipamorelin for synergistic effects.

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Tesamorelin

FDA

An FDA-approved GHRH analog used to reduce excess abdominal fat in HIV-infected patients with lipodystrophy. New F8 formulation (Egrifta WR) approved March 2025 allows weekly reconstitution vs daily.

Growth Hormone

GHRP-6

Clinical Trials

One of the first synthetic GH secretagogues developed. Strongly stimulates GH release and significantly increases appetite through ghrelin receptor activation.

Growth Hormone

GHRP-2

Clinical Trials

A synthetic hexapeptide that potently stimulates GH release. More potent than GHRP-6 with less appetite stimulation, but still elevates cortisol and prolactin.

Growth Hormone

Sermorelin

Preclinical

A truncated analog of natural GHRH containing the first 29 amino acids. Previously FDA-approved for pediatric GH deficiency, now used off-label for adult hormone optimization.

Growth Hormone
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