Source comparison
MK-677 vs Growth Hormone vs GHRP-2: Mechanism Comparison
MK-677 (Ibutamoren) Selective ghrelin receptor agonist (GHSR-1a). Stimulates endogenous GH pulsatile release without suppressing natural production Oral capsule or liquid, once daily 10–21 days in urine Banned (S2.2. Growth Hormone Secretagogues) Experimental
This comparison does not assign a generated winner or score.
- MK-677 (Ibutamoren)
- Selective ghrelin receptor agonist (GHSR-1a). Stimulates endogenous GH pulsatile release without suppressing natural production
- Oral capsule or liquid, once daily
- 10–21 days in urine
- Banned (S2.2. Growth Hormone Secretagogues)
- Experimental use in sarcopenia, cachexia; no FDA approval
- Synthetic Growth Hormone (rhGH)
- Exogenous recombinant human GH. Directly replaces or supplements natural GH
- Subcutaneous injection, daily or multiple times per week
- 24–48 hours in blood; up to 7 days in specific biomarker assays
- Banned (S2.1. Peptide Hormones)
- FDA-approved for GH deficiency, Turner syndrome, chronic renal insufficiency
- GHRP-2 (Pralmorelin)
- Growth hormone-releasing peptide. Stimulates GH release via ghrelin receptor and GHRH pathways
- Subcutaneous or intramuscular injection, 1–3 times daily
- 24–72 hours depending on assay sensitivity
- Research-grade only; evaluated in clinical trials for GH deficiency
- Bottom Line Assessment
- MK-677 offers oral convenience and doesn't suppress natural GH, but carries metabolic side effects (insulin resistance, hunger) that exogenous GH and GHRP-2 don't. All three are banned for athletes subject to WADA testing. MK-677 is the only compound commonly available through unregulated online channels, which introduces contamination risk not present with pharmaceutical rhGH. For research purposes, GHRP-2 and injectable growth hormone secretagogues offer more predictable pharmacokinetics without the ghrelin-driven appetite surge.