MK-677 vs PT-141
Head-to-head comparison of MK-677 (Ibutamoren Mesylate (MK-677)) and PT-141 (Bremelanotide (Melanocortin Receptor Agonist)) — benefits, dosing, side effects, research data, and where to buy.
| Property | MK-677 | PT-141 |
|---|---|---|
| Category | Growth Hormone | Performance |
| Full Name | Ibutamoren Mesylate (MK-677) | Bremelanotide (Melanocortin Receptor Agonist) |
| Molecular Weight | 528.662 g/mol | 1,025.2 Da |
| Half-Life | ~24 hours | ~2.7 hours |
| Amino Acids | Non-peptide compound | 7 |
| Typical Dose | — | 1.75 mg |
| Route | — | SC |
| Purity | >99% | — |
| Studies Count | 120 | 178 |
| Research Status | Active Research | FDA Approved |
MK-677 Benefits
- ✓Oral GH secretagogue, 24-hour GH elevation, increases IGF-1, improves sleep quality, increases lean mass, does not suppress natural GH
PT-141 Benefits
- ✓Enhances sexual desire and arousal
- ✓Works through CNS (not vascular)
- ✓FDA-approved for HSDD
- ✓Effective for both men and women
- ✓Does not require sexual stimulation to work
MK-677 Dosing
10-25 mg orally once daily before bedtime. 25 mg is the most studied dose. Can be used long-term without cycling.
PT-141 Dosing
Standard: 1.75 mg SC, 45 min before activity|Max frequency: Once every 24 hours|Max: 8 doses per month|Men (off-label): 1-2 mg SC as needed
MK-677 Side Effects
- ⚠Increased appetite, mild water retention, drowsiness, transient numbness, mild increase in fasting blood glucose with long-term use.
PT-141 Side Effects
- ⚠Common: Nausea (40%), flushing, headache, injection site reactions
- ⚠Moderate: Elevated blood pressure (transient), fatigue
- ⚠Serious: Focal hyperpigmentation with repeated use
- ⚠Contraindications: Uncontrolled hypertension, cardiovascular disease
Research Overview
MK-677
A landmark 2-year study in elderly adults demonstrated significant increases in lean mass, GH pulsatility, and IGF-1 to youthful ranges. Selectively agonizes GHS-R1a without increasing cortisol or prolactin.
PT-141
PT-141 has robust clinical evidence including multiple Phase III trials. FDA-approved in 2019. Unique mechanism of action through melanocortin-4 receptors in the brain. Well-characterized safety and efficacy profile.
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