GHRP-6 vs MK-677

Endpoint-specific evidence

GHRP-6 is a peptide growth hormone secretagogue; MK-677 (ibutamoren) is an oral nonpeptide secretagogue. GHRP-6 has been studied as a GH stimulation test, including adults with GH deficiency. A hormone response in that setting is not proof of muscle, weight-loss or recovery benefit. GHRP-6 GH-testing study, PMID 11980622; FDA ibutamoren review.

In 65 healthy older adults, randomized MK-677 increased GH, IGF-1 and fat-free mass. It did not show significant improvement in strength, function or abdominal visceral fat. The authors said study size and duration were insufficient to assess functional endpoints definitively. Fasting glucose rose and insulin sensitivity fell. None of these findings establish relative efficacy or safety versus GHRP-6. Nass et al., PMID 18981485.

FDA’s ibutamoren review reports no approved product and explains that the earlier Merck MK-0677 program ended while later LUM-201 pediatric development proceeded. Official Phase 3 NCT06948214 was recruiting in the September 29, 2026 registry archive. Registration does not establish clinical benefit or approval. FDA review.

No cited clinical study supports a source-count ranking, “compatible” label, combination synergy or regimen. This page makes no use recommendation.