At a Glance
Quickcomparison
Dose Range
SM-130686
5–20 mg
MK-677 (Ibutamoren)
10–25 mg
Frequency
Multiple times daily
Once daily
Administration
Oral capsule or powder
Oral (capsule or liquid)
Cycle Length
8-12 weeks
Onset Speed
Moderate (1-2 weeks)
Evidence Level
Moderate human trials (Phase 1-2)
Efficacy
Benefitratings
Muscle and Strength
Recovery and Performance
Metabolic Health
Muscle and body composition
Recovery and athletic performance
Sleep quality and metabolic health
Technical Data
Compoundspecifications
Molecular Formula
C22H24Cl2F3N3O3
Molecular Weight
506.3 g/mol (as HCl salt)
Half-Life
Not published in humans (preclinical only)
Bioavailability
28% in rats (oral administration)
CAS Number
259667-25-9
C27H36N4O5S
528.7 g/mol
4-6 hours (IGF-1 elevation persists ~24 hours)
High oral bioavailability
159634-47-6
Protocols
Dosingtiers
starting
10 mg
2-4 weeks initial
Lower entry dose used in practice to limit water retention and appetite surge before titrating up.
standard
25 mg
Studied up to 1-2 years
25 mg once-daily oral is the dose used in the randomized trial in healthy older adults; increased GH/IGF-1 and fat-free mass [1]. Most-studied dose [2].
Applications
Bestsuited for
Lean Mass Building in Trained Athletes
SM-130686 targets GHS-R to stimulate GH release, which supports anabolic processes. Preclinical studies in rats showed significant increases in fat-free mass and body weight when combined with resistance training principles.
Age-Related GH Decline
As a GHS-R agonist, SM-130686 may help restore physiological GH secretion in adults experiencing age-related decline. The oral route is convenient for long-term administration.
GH supports tissue repair, collagen synthesis, and recovery. May benefit individuals engaged in intensive resistance training or athletic performance work.
Older Adults (60+) Seeking Body Composition Improvements
MK-677 was designed for aging populations. It restores GH and IGF-1 to youthful levels, increases lean mass, and improves physical function in people over 60. A 2-year clinical trial showed a 1.1 kg gain in fat-free mass with only modest fat gain—ideal for maintaining strength in older age.
Athletes and Fitness Enthusiasts Wanting Recovery Support
Oral dosing makes MK-677 convenient for athletes. It enhances muscle protein synthesis, speeds recovery after intense training, and supports lean mass building without the hassle of injections.
People with Chronic Wasting or Protein Deficiency
Clinical trials show MK-677 helps treat protein-energy wasting in kidney disease and other conditions. It stimulates appetite (a feature in these populations) and preserves muscle tissue—making it useful for those losing mass despite good nutrition.
Safety Profile
Sideeffects
Common
Appetite stimulation
Transient water retention
Uncommon
Joint or muscle aches
Transient changes in blood glucose
Serious
Potential carpal tunnel syndrome
Unknown effects on tumor growth
Increased appetite
Mild water retention or edema
Elevated fasting glucose
Joint or muscle pain
Carpal tunnel syndrome or nerve compression symptoms
Mild nausea or digestive upset
Glucose dysregulation and diabetes risk
Research Status
Safety& evidence
FDA Status
Research compound
Safety Overview
SM-130686 is a research compound that has never been tested in humans. All safety and efficacy data come from animal studies (primarily rats). No human clinical trials have been conducted. Use carries unknown risks. Potential side effects based on GH physiology and limited preclinical work.
Contraindications
xPregnancy or breastfeeding (no safety data)
xActive cancer (GH stimulation may be contraindicated)
xUncontrolled diabetes (may affect glucose metabolism)
xSevere cardiovascular disease (GH effects on heart not fully characterized)
MK-677 has been studied in hundreds of humans over 2+ years and is generally well tolerated. Most side effects are mild and manageable, especially with lower starting doses. The lack of injection requirement makes it safer than injectable GH in terms of infection risk and sterility concerns. However, it is not FDA approved and should be viewed as a research compound.
xUncontrolled diabetes or severe glucose dysregulation
xActive cancer or high cancer risk requiring caution with IGF-1 elevation
xPregnancy or breastfeeding
Decision Guide
Which isright for you?
Choose SM-130686 if...
Lean mass building (theoretical)
Strength development (preclinical evidence)
Body composition improvement (animal studies)
Choose MK-677 (Ibutamoren) if...
Building lean muscle mass and strength
Improving overall body composition in aging adults
Enhancing athletic recovery and performance
Supporting metabolic health and fat loss