Head to head
MK-677 against Tesamorelin
An unapproved oral secretagogue against an FDA-approved GHRH analogue with 806 patients of phase 3 data. Both raise IGF-1; only one of them has an approved indication and a measured outcome to go with it.
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
TesamorelinTesamorelin (stabilized GHRH analogue)
An FDA-approved GHRH analogue that reduces visceral fat, now also studied for cognition in older adults at Alzheimer's risk.
Side by side, on the facts we can check
| Attribute | MK-677 | Tesamorelin |
|---|---|---|
| Category | Growth Hormone | Growth Hormone |
| FDA status | Not FDA-approved (failed to gain approval after Phase 3) | FDA-approved (Egrifta) for HIV-associated lipodystrophy |
| Half-life | ~24 hours | ~26-38 minutes |
| Molecular weight | 624.8 Da | 5,135.9 Da |
| Mechanism | Agonizes the ghrelin/GH secretagogue receptor (GHS-R1a), increasing GH and IGF-1 while also stimulating appetite. | Activates pituitary GHRH receptors to stimulate physiological, pulsatile growth hormone release, preserving hypothalamic feedback. |
| Human studies cited | 3 | 4 |
| Legal status, US | Not approved; research use only | FDA-approved for a specific indication, prescription only |
Frequently asked questions
What is the difference between MK-677 and Tesamorelin?
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. Tesamorelin: An FDA-approved GHRH analogue that reduces visceral fat, now also studied for cognition in older adults at Alzheimer's risk.
Which has stronger research evidence, MK-677 or Tesamorelin?
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 4 of 5 for Tesamorelin. Those counts are of our own citation lists and understate any larger literature, and neither is a recommendation.
Are MK-677 and Tesamorelin FDA-approved?
MK-677: Not FDA-approved (failed to gain approval after Phase 3). Tesamorelin: FDA-approved (Egrifta) for HIV-associated lipodystrophy.
Related posts
Blog articles that cover MK-677 or Tesamorelin, 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.