MK-677
Ibutamoren · MK677 · Nutrobal
MK-677 (ibutamoren mesylate) is a non-peptide, orally active growth hormone secretagogue that mimics the action of ghrelin by binding to the growth hormone secretagogue receptor (GHS-R1a). Unlike growth hormone releasing peptides (GHRPs), MK-677 is not a peptide and has excellent oral bioavailability. It stimulates the pituitary gland to release growth hormone (GH) in a pulsatile, physiological pattern, and significantly increases circulating levels of both GH and IGF-1 without suppressing the hypothalamic-pituitary axis.
Oral: Bedtime dosing preferred (GH pulse during sleep, reduces daytime hunger). Take with or without food. Continuous or 5-on-2-off.
Start here. Every protocol below is ordered lowest-first. Begin at the smallest effective dose, hold about a week to assess tolerance, and step up only if needed.
How it works
Binds to the ghrelin/growth hormone secretagogue receptor (GHS-R1a) in the hypothalamus and pituitary, mimicking endogenous ghrelin. This stimulates growth hormone-releasing hormone (GHRH) neurons and directly activates pituitary somatotrophs, producing pulsatile GH release that mirrors the natural secretory pattern.
Amplifies GH pulse amplitude without altering pulse frequency, preserving the physiological GH secretion pattern. Also reduces somatostatin (GH-inhibiting hormone) tone, further facilitating GH release. The result is sustained elevation of both GH and IGF-1 levels without the tachyphylaxis seen with continuous GH administration.
As a ghrelin mimetic, MK-677 activates hypothalamic appetite centers (NPY/AgRP neurons), increasing hunger and food intake. It also modulates glucose metabolism through GHS-R1a-mediated effects on pancreatic islets and hepatic glucose output, which can worsen insulin sensitivity.
What to expect
Days 1-7: Increased appetite and improved sleep quality are the first noticeable effects. Mild water retention begins. GH/IGF-1 elevation starts within 2-3 days.
Evidence
Claims we could not support
No abstract we checked supports these for this molecule at this route. That is not the same as saying they are false — it marks where the evidence is missing.
Dose/route: 10-25mg; Oral; daily, preferably before bed. No checked live PubMed abstract verified this exact displayed dose, route, and frequency for the same molecule/formulation and relevant population.
Mechanism: Binds to the ghrelin/growth hormone secretagogue receptor (GHS-R1a) in the hypothalamus and pituitary, mimicking endogenous ghrelin. This stimulates growth hormone-releasing hormone (GHRH) neurons and directly activates pituitary somatotrophs, producing pulsatile GH release that mirrors the natural secretory pattern.. No checked live PubMed abstract provided an exact-molecule/formulation sentence supporting this source-JSON mechanism claim.
Primary safety claim: Increased appetite and food cravings (very common, 40-60% of users). No checked live PubMed abstract directly verified this source-JSON safety claim at the displayed formulation, route, and regimen.
Interactions & stacking
Two different questions: what is documented about running these together, and what is documented about drawing them into the same syringe. A good pharmacological partner can still have to be pinned separately.
Documented together
Keep separate
Check any specific pair in the Stack & Interaction Checker, which answers both questions separately. Absence of a documented conflict is not evidence of safety.
Pharmacokinetics
Effective duration ~24 hours due to sustained IGF-1 elevation
Oral
(parent compound). IGF-1 elevation persists ~24 hours.
High oral bioavailability (exact % not published, but effective at standard oral doses)
GH pulsatility and IGF-1 elevation sustained with daily dosing
Hepatic (CYP3A4-mediated metabolism); renal excretion of metabolites
Storage. Store at room temperature in a cool, dry place. Protect from moisture and light. Oral compound - no reconstitution needed.
Regulatory status
Investigational compound - never FDA-approved. Clinical development discontinued by Merck. Not a dietary supplement. Listed as a prohibited substance by WADA. Classified as a research chemical.
Put it to work
Calculate, log & track
Open MK-677 straight into OnePin with your vial and dose pre-filled, then let it handle the syringe math and remind you before the vial runs out.
Open MK-677 in the app →Go deeper
The guide & community
The complete MK-677 walkthrough, real protocol discussion and coaching live inside the BlessUp community on Skool.
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