Educational reference only. Not medical advice. Consult a healthcare provider before starting any protocol.
MK-677 (Ibutamoren)
Ibutamoren Mesylate (MK-0677, L-163,191)
What it is
A non-peptide, orally active small molecule that acts as a potent agonist of the growth hormone secretagogue receptor (GHS-R1a), mimicking endogenous ghrelin to stimulate pulsatile GH and IGF-1 release. MK-677 has been studied in multiple human randomized controlled trials across indications including sarcopenia, diet-induced catabolism, Alzheimer's disease, hip fracture recovery, and sleep quality, but has not received FDA approval for any indication. It is discussed in biohacking communities in the context of GH optimization, body composition, sleep improvement, and recovery, and is notable for its oral bioavailability and ~24-hour effective half-life.
Community-reported ranges
Ranges sourced from published clinical trial protocols, community forums, and peptide education sites. Not dosing guidance.
Reported dose range
10000–25000 mcg
Estimated half-life
~24 hours (effective/biological)
Source: clinical trial dosing protocols (Nass et al. 2008; Copinschi et al. 1997)
Reported cycle length
8–16 weeks on
4-8 weeks off
Route
oral
Common vial sizes
10mg capsules, 25mg capsules, 25mg/mL liquid
Reported timing
Before bedtime (to align with nocturnal GH pulses and mitigate daytime appetite increase)
Reported frequency
1x daily (oral)
Frequently discussed alongside
Based on community forum discussions. Not a recommendation to combine compounds.
Ipamorelin
Both are GHS-R1a agonists; compared as injectable peptide vs oral non-peptide options
CJC-1295
Discussed together as complementary GH-axis stimulators via different receptor pathways
Tesamorelin
MK-677 sometimes discussed as an oral bridge during off-cycles from injectable GHRH
Sermorelin
Contrasted as oral vs injectable GH secretagogue approaches
Published research
MK-677 has been evaluated in multiple human RCTs: a 2-year sarcopenia trial in healthy older adults (Nass et al. 2008, PMID 18981485, n=65), diet-induced catabolism reversal (Murphy et al. 1998, PMID 9467534), a large Alzheimer's trial (Sevigny et al. 2008, PMID 19015485, n=563), hip fracture recovery (Adunsky et al. 2011, PMID 21067829, terminated early), and sleep quality improvement (Copinschi et al. 1997, PMID 9349662). Key findings include sustained GH/IGF-1 elevation with oral once-daily dosing, increased lean mass, but also insulin resistance and glucose intolerance concerns with extended use. Lumos Pharma's Phase 2 OraGrowtH trials for pediatric GHD have met primary endpoints. Community dosing ranges are derived from clinical trial protocols.
Nass R et al. Effects of an oral ghrelin mimetic on body composition and clinical outcomes in healthy older adults: a randomized trial.
Annals of Internal Medicine
Adunsky A et al. MK-0677 (ibutamoren mesylate) for the treatment of patients recovering from hip fracture: a multicenter, randomized, placebo-controlled phase IIb study.
Archives of Gerontology and Geriatrics
Sevigny JJ et al. Growth hormone secretagogue MK-677: no clinical effect on AD progression in a randomized trial.
Neurology
Reported side effects
From community self-reports. Not from controlled studies.
From clinical trial data (Nass et al. 2008, 2-year RCT): increased appetite (most common, subsiding over months), transient lower-extremity edema, muscle pain, elevated fasting blood glucose (~0.3 mmol/L increase), decreased insulin sensitivity, weight gain (2.7 kg vs 0.8 kg placebo at 12 months), increased cortisol. A congestive heart failure safety signal led to early termination of the hip fracture trial (Adunsky et al. 2011). A case report documented hepatotoxicity (transaminitis) after 2 months of use. Community users have reported intense hunger, water retention/bloating, lethargy, numbness/tingling in extremities, vivid dreams, and joint pain.
Regulatory status
FDA (United States)
Not approved for any indication. Investigational New Drug. Received FDA Orphan Drug Designation for GH deficiency (June 2017). A hip fracture trial was terminated early due to a congestive heart failure safety signal (Adunsky et al. 2011). FDA has issued warning letters to companies marketing MK-677 products. Not eligible for pharmacy compounding — reviewed at October 29, 2024 PCAC meeting; FDA recommended exclusion from 503A bulk substances.
Health Canada
Not authorized as a therapeutic product. No DIN assigned.
WADA (Competitive Athletes)
Prohibited at all times under S2.2.4 — Growth Hormone Releasing Factors. Specifically named: 'growth hormone secretagogues (GHS) and their mimetics [e.g. anamorelin, capromorelin, ibutamoren (MK-677), ipamorelin…].' Classified as Specified Substance. Confirmed on 2025 and 2026 WADA Prohibited Lists.