Tabimorelin vs MK-677 (Ibutamoren) — Peptide Comparison

Tabimorelin vs MK-677 (Ibutamoren) — Peptide Comparison Tabimorelin vs MK-677 (Ibutamoren) — compare dosing, benefits, safety profiles, side effects, and how they stack. See which peptide is right for you. At a Glance Dose Range Tabimorelin 100–500 mg MK-677 (Ibutamoren) 10–25 mg Frequency Once daily Administration Oral (capsule or solution) Oral (capsule or liquid) Cycle Length 4-6 weeks 8-12 weeks Onset Speed Moderate (1-2 weeks) Evidence Level Moderate human trials (Phase 1-2) Efficacy Growth Hormone Stimulation Convenience & Compliance Selectivity & Safety Profile Muscle and body composition Recovery and athletic performance Sleep quality and metabolic health Technical Data 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 C27H36N4O5S 4-6 hours (IGF-1 elevation persists ~24 hours) High oral bioavailability 159634-47-6 Protocols standard 1.5 mg/kg per day (3 mg/kg first and last dose) 7-day study course Dose used in GH-deficient adults (1 week course, 3 mg/kg first and last dose) [2]; significant GH release seen at 3 mg/kg and above in single-dose healthy-volunteer studies [1]. starting 10 mg 2-4 weeks initial Lower entry dose used in practice to limit water retention and appetite surge before titrating up. 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 +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 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 Common Headache Nausea Appetite stimulation Dizziness Dry mouth Serious Drug-drug interactions via CYP3A4 inhibition 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 Glucose dysregulation and diabetes risk Research Status 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 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 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