MK-677 vs Orexin-A
Head-to-head comparison of MK-677 (Ibutamoren Mesylate (MK-677)) and Orexin-A (Hypocretin-1 (Orexin-A)) — benefits, dosing, side effects, research data, and where to buy.
| Property | MK-677 | Orexin-A |
|---|---|---|
| Category | Growth Hormone | Cognitive Enhancement |
| Full Name | Ibutamoren Mesylate (MK-677) | Hypocretin-1 (Orexin-A) |
| Molecular Weight | 528.662 g/mol | 3562 Da |
| Half-Life | ~24 hours | Minutes to <1 hour |
| Amino Acids | Non-peptide compound | 33 |
| Typical Dose | — | Research-only; no validated human dose |
| Route | — | Intracerebroventricular/Intranasal |
| Purity | >99% | ≥98% |
| Studies Count | 120 | 42 |
| Research Status | Active Research | Pre-clinical |
MK-677 Benefits
- ✓Oral GH secretagogue, 24-hour GH elevation, increases IGF-1, improves sleep quality, increases lean mass, does not suppress natural GH
Orexin-A Benefits
- ✓wakefulness
- ✓attention
- ✓memory consolidation
- ✓fatigue resistance
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.
Orexin-A Dosing
Research-only i.c.v. microgram/nanomolar studies|intranasal experimental use|no established human protocol
MK-677 Side Effects
- ⚠Increased appetite, mild water retention, drowsiness, transient numbness, mild increase in fasting blood glucose with long-term use.
Orexin-A Side Effects
- ⚠insomnia
- ⚠headache
- ⚠blood pressure changes
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.
Orexin-A
Preclinical studies link orexin signaling to arousal, learning, and memory consolidation, making orexin-A a candidate for cognition-related research. It is not an approved cognitive enhancer and remains an experimental peptide.
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