Source comparison
MK-677 vs HGH Injections: Mechanism Comparison
Mechanism of Action Ghrelin receptor agonist. Stimulates endogenous GH release via GHRH pathway Direct exogenous somatropin administration. Bypasses hypothalamic-pituitary axis entirely MK-677 works with your endocrine system; HGH replaces it Pulsatile Secreti
This comparison does not assign a generated winner or score.
- Mechanism of Action
- Ghrelin receptor agonist. Stimulates endogenous GH release via GHRH pathway
- Direct exogenous somatropin administration. Bypasses hypothalamic-pituitary axis entirely
- MK-677 works with your endocrine system; HGH replaces it
- Pulsatile Secretion
- Preserved. Amplifies natural 6–8 daily GH pulses without flattening circadian rhythm
- Eliminated. Creates sustained elevation, suppresses endogenous pulses within 7–10 days
- Pulsatility drives receptor sensitivity and metabolic efficiency
- IGF-1 Elevation
- 40–90% above baseline at 25mg daily; dose-dependent, peaks 4–6 hours post-dose
- 100–300% above baseline depending on dose (2–10 IU daily); sustained elevation
- HGH produces higher absolute IGF-1 but loses pulsatile signaling benefit
- Pituitary Suppression
- None. Feedback loops remain intact; no downregulation of somatotroph activity
- Severe. 60–80% reduction in endogenous GH pulse frequency after 10 days continuous use
- Suppression determines post-cycle recovery difficulty
- Half-Life
- ~24 hours (oral bioavailability; once-daily dosing sufficient)
- 2–3 hours (requires daily or twice-daily subcutaneous injection for stable levels)
- MK-677's longer half-life allows stable receptor activation without injection frequency
- Post-Cycle Recovery
- Immediate. Endogenous GH pulse returns to baseline within 48–72 hours of cessation
- 30–60 days. Pituitary hypofunction common; IGF-1 may drop below baseline temporarily
- Recovery timeline is the hidden cost of exogenous HGH