Head to head
MK-677 against Ghrelin
The hormone and the oral drug built to mimic it. Ghrelin itself is not a medicine, and the one approved drug on this pathway is macimorelin, an oral agonist approved as a diagnostic test rather than a treatment, which openFDA currently lists as discontinued.
Column A
MK-677Ibutamoren (oral ghrelin receptor agonist)
A non-peptide, orally active ghrelin receptor agonist that raises growth hormone and IGF-1. Completed but did not pass Phase 3 for approval.
Column B
GhrelinGhrelin (endogenous growth hormone secretagogue)
The body's own hunger hormone and the natural trigger for growth hormone release, and the template for the entire GHRP peptide class.
Side by side, on the facts we can check
| Attribute | MK-677 | Ghrelin |
|---|---|---|
| Category | Growth Hormone | Growth Hormone |
| FDA status | Not FDA-approved (failed to gain approval after Phase 3) | The hormone itself is not a medicine. No ghrelin receptor agonist is approved to stimulate appetite. The one approved drug on this pathway is macimorelin (Macrilen, NDA 205598), an oral agonist approved as a diagnostic test for growth hormone deficiency rather than as a treatment, and openFDA currently lists that product as Discontinued. |
| Half-life | ~24 hours | ~30 minutes |
| Molecular weight | 624.8 Da | 3,370.9 Da |
| Mechanism | Agonizes the ghrelin/GH secretagogue receptor (GHS-R1a), increasing GH and IGF-1 while also stimulating appetite. | Activates the GH secretagogue receptor (GHS-R1a) in the pituitary and hypothalamus, driving GH release and appetite. |
| Human studies cited | 3 | 2 |
| Legal status, US | Not approved; research use only | Not a medicine; endogenous signalling molecule |
Frequently asked questions
What is the difference between MK-677 and Ghrelin?
MK-677: A non-peptide, orally active ghrelin receptor agonist that raises growth hormone and IGF-1. Completed but did not pass Phase 3 for approval. Ghrelin: The body's own hunger hormone and the natural trigger for growth hormone release, and the template for the entire GHRP peptide class.
Which has stronger research evidence, MK-677 or Ghrelin?
This database does not grade compounds. It counts what was run in people: 3 of the 3 studies cited on the MK-677 profile were human work, against 2 of 5 for Ghrelin. Those counts are of our own citation lists and understate any larger literature, and neither is a recommendation.
Are MK-677 and Ghrelin FDA-approved?
MK-677: Not FDA-approved (failed to gain approval after Phase 3). Ghrelin: The hormone itself is not a medicine. No ghrelin receptor agonist is approved to stimulate appetite. The one approved drug on this pathway is macimorelin (Macrilen, NDA 205598), an oral agonist approved as a diagnostic test for growth hormone deficiency rather than as a treatment, and openFDA currently lists that product as Discontinued..
Related posts
Blog articles that cover MK-677 or Ghrelin, newest first.
Reviewed Sep 2026. This page sets two published records side by side. It is educational, it is not medical advice, and it contains no dosing protocols or recommendations for personal use.