Peptide Comparison
TabimorelinvsMK-677 (Ibutamoren)
An investigational oral growth hormone secretagogue that stimulates GH release through ghrelin receptor activation, though development was discontinued due to drug interaction concerns.
The oral growth hormone secretagogue that tricks your body into producing more GH — no needles required.
At a Glance
Quick
comparison
Dose Range
Tabimorelin
100–500 mg
MK-677 (Ibutamoren)
10–25 mg
Frequency
Tabimorelin
Once daily
MK-677 (Ibutamoren)
Once daily
Administration
Tabimorelin
Oral (capsule or solution)
MK-677 (Ibutamoren)
Oral (capsule or liquid)
Cycle Length
Tabimorelin
4-6 weeks
MK-677 (Ibutamoren)
8-12 weeks
Onset Speed
Tabimorelin
Moderate (1-2 weeks)
MK-677 (Ibutamoren)
Moderate (1-2 weeks)
Evidence Level
Tabimorelin
Moderate human trials (Phase 1-2)
MK-677 (Ibutamoren)
Moderate human trials (Phase 1-2)
Efficacy
Benefit
ratings
Growth Hormone Stimulation
Convenience & Compliance
Selectivity & Safety Profile
Muscle and body composition
Recovery and athletic performance
Sleep quality and metabolic health
Technical Data
Compound
specifications
Tabimorelin
Molecular Formula
C32H40N4O3
Molecular Weight
528.7 g/mol
Half-Life
Several hours (exact human half-life not published; dose-dependent pharmacokinetics)
Bioavailability
Orally active with dose-dependent bioavailability (increases at higher doses)
CAS Number
193079-69-5
MK-677 (Ibutamoren)
Molecular Formula
C27H36N4O5S
Molecular Weight
528.7 g/mol
Half-Life
4-6 hours (IGF-1 elevation persists ~24 hours)
Bioavailability
High oral bioavailability
CAS Number
159634-47-6
Applications
Best
suited for
Tabimorelin
+Stimulates growth hormone release from the pituitary gland through ghrelin receptor activation
+Orally active—no injections required, making it convenient for daily use
+Dose-dependent growth hormone and IGF-1 elevation at therapeutic doses
+Does not significantly raise ACTH, cortisol, or prolactin at most doses, showing better selectivity than some competing GH-releasing peptides
+Well-tolerated in short-term human studies with generally mild adverse effects
MK-677 (Ibutamoren)
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
Side
effects
Tabimorelin
Common
- Headache
- Nausea
- Appetite stimulation
- Dizziness
- Dry mouth
Serious
- Drug-drug interactions via CYP3A4 inhibition
MK-677 (Ibutamoren)
Common
- Increased appetite
- Mild water retention or edema
- Elevated fasting glucose
Uncommon
- Joint or muscle pain
- Carpal tunnel syndrome or nerve compression symptoms
- Mild nausea or digestive upset
Serious
- Glucose dysregulation and diabetes risk
Research Status
Safety
& evidence
Tabimorelin
Evidence Level
Moderate human trials (Phase 1-2)
FDA Status
Research compound
Safety Overview
Tabimorelin is an oral GHS-R agonist with preclinical and early clinical data indicating dose-dependent appetite stimulation (potentially problematic for weight-conscious users) and transient blood glucose elevation due to GH's insulin-antagonistic effects. No human safety database exists beyond Phase 1/2 studies—efficacy and long-term safety profile in humans remain incompletely characterized. Potential risks include carpal tunnel syndrome (documented with chronic GH therapy), arthralgias, and theoretical tumor growth acceleration, though these are extrapolated from GH physiology rather than directly observed in limited human exposure.
Contraindications
- xActive or history of carcinomas (ghrelin receptor agonists may stimulate growth of certain tumors)
- xConcurrent use of potent CYP3A4 substrates due to risk of dangerous drug-drug interactions
- xUntreated thyroid dysfunction
- xUncontrolled diabetes
MK-677 (Ibutamoren)
Evidence Level
Moderate human trials (Phase 1-2)
FDA Status
Research compound
Safety Overview
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.
Contraindications
- xUncontrolled diabetes or severe glucose dysregulation
- xActive cancer or high cancer risk requiring caution with IGF-1 elevation
- xPregnancy or breastfeeding
Decision Guide
Which is
right for you?
Choose Tabimorelin if...
- Stimulating growth hormone production in healthy individuals
- Exploring GH secretagogue mechanisms in research settings
- Patients preferring oral administration over injections
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