Peptipedia
Growth HormoneIn Clinical TrialsClinical Trials

MK-677

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

An orally active growth hormone secretagogue that mimics ghrelin. Provides 24-hour GH elevation due to long half-life.

Investigational - Phase II trials halted (safety concerns). FDA enforcement ongoing (2025)
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Regulatory Pathway

Preclinical
Phase I
Phase II
Phase III
Phase IV
Approved

Dosing Protocol

Typical Dose

10-25 mg daily

Frequency

Once daily, often before bed

Duration

8-12 weeks or longer

Community-reported dosing. Individual results vary. Not a medical recommendation.
Typical community protocol: 10-25 mg daily via Oral, Once daily, often before bed. Dose range: 10-50 mg daily. Duration: 8-12 weeks or longer.

Timing & Administration

Administer via Oral. Frequency: Once daily, often before bed.

Mechanism of Action

Binds to ghrelin receptors (GHSR) in the brain, stimulating sustained GH release and increasing IGF-1 levels. Orally bioavailable with long half-life providing 24-hour GH elevation.

Research Summary

Evidence level: clinical trials. Clinical status: Investigational - Phase II trials halted (safety concerns). FDA enforcement ongoing (2025).

Side Effects & Safety

Important Warnings

  • FDA lists MK-677 as having significant safety risks due to potential for congestive heart failure
  • December 2025: FDA issued warning letters.
Increased appetite and hunger
weight gain
water retention/edema
insulin resistance
elevated blood glucose
anxiety
muscle or joint pain
numbness/tingling
risk of heart failure

References

No references available.

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