MK-677 is a non-peptide ghrelin receptor agonist taken orally.
Mechanism: Mimics ghrelin's action on the pituitary GHS-R1a receptor, producing sustained elevation of GH and IGF-1. Half-life ~24 hours, once-daily oral dosing.
Use case: Convenient GH-axis support without injections. Modest gains in lean mass, sleep architecture (deeper slow-wave sleep), and recovery. Often used during off-cycles from injectable peptides.
Caveats: Not a peptide; categorized here by mechanism. Well-known appetite increase via ghrelin receptor activation. Insulin resistance can rise with sustained use. Water retention and lethargy are common in the first weeks.