No. MK-677 is a non-peptide, orally active small molecule that mimics ghrelin. It is grouped with GH secretagogues because of its shared mechanism, not its structure.

Why does MK-677 cause water retention?

Sustained elevation of GH and IGF-1 increases sodium and fluid retention, which is one of the most commonly reported effects, especially early in use.

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Growth Hormone Secretagogues

Research Chemical

MK-677

Also known as: MK-677, Ibutamoren, MK-0677

An orally active, non-peptide ghrelin receptor agonist that raises GH and IGF-1 levels. Notable for being a daily oral compound rather than an injectable.

Mechanism of Action

MK-677 (ibutamoren) is a non-peptide growth hormone secretagogue that mimics ghrelin at the GHS-R1a receptor, stimulating sustained increases in growth hormone and IGF-1. Unlike injectable peptides, it is orally bioavailable and has a long half-life, producing prolonged elevation rather than a sharp pulse. This sustained signaling drives its characteristic appetite stimulation and effects on body composition and sleep.

Half-life: Approximately 4-6 hours (effects on IGF-1 persist longer)
Administration Routes: oral
Research Status: Research Chemical