Source comparison
MK-677 vs Injectable Secretagogues: Practical Research Considerations
Bioavailability 60–65% oral ~100% subcutaneous Oral preferred for chronic protocols Half-Life 24 hours ~30 minutes ~2 hours Once-daily dosing vs 3–4x daily Receptor Selectivity High (GHSR1a only) Moderate (binds ACTH receptors) MK-677 isolates GH pathway clean
This comparison does not assign a generated winner or score.
- Bioavailability
- 60–65% oral
- ~100% subcutaneous
- Oral preferred for chronic protocols
- Half-Life
- 24 hours
- ~30 minutes
- ~2 hours
- Once-daily dosing vs 3–4x daily
- Receptor Selectivity
- High (GHSR1a only)
- Moderate (binds ACTH receptors)
- MK-677 isolates GH pathway cleanly
- Cortisol Elevation
- Minimal
- Moderate
- MK-677 reduces confounding HPA activation
- IGF-1 Elevation
- 60–90% at 25mg
- 40–60% at 100mcg
- 50–70% at 100mcg
- Comparable efficacy with simpler dosing
- Bottom Line
- Best for non-invasive, long-duration studies requiring daily dosing without injection compliance issues
- Preferred when rapid-onset GH pulse is needed (acute metabolic challenge studies)
- Similar to GHRP-2 but slightly higher appetite stimulation. Useful in models studying ghrelin's orexigenic effects
- Choose MK-677 when oral route, once-daily dosing, and receptor selectivity outweigh the need for injectable precision
- The choice between MK-677 and peptide secretagogues depends on study design. If the research question requires isolating growth hormone effects without cortisol or prolactin confounds, MK-677's higher selectivity is the stronger tool. If the protocol requires acute GH pulses on-demand (e.g., pre-exercise metabolic challenge), injectable GHRP-2 delivers faster onset. For chronic dosing studies lasting weeks or months. Particularly in models where injection compliance or tissue irritation would introduce variability. MK-677's oral route eliminates those constraints entirely.