MK-677 vs Neuropeptide S
Head-to-head comparison of MK-677 (Ibutamoren Mesylate (MK-677)) and Neuropeptide S (Neuropeptide S) — benefits, dosing, side effects, research data, and where to buy.
Research Score
| Property | MK-677 | Neuropeptide S |
|---|---|---|
| Category | Growth Hormone | Cognitive Enhancement |
| Full Name | Ibutamoren Mesylate (MK-677) | Neuropeptide S |
| Molecular Weight | 528.662 g/mol | 2203 Da |
| Half-Life | ~24 hours | Minutes to <1 hour |
| Amino Acids | Non-peptide compound | 20 |
| Typical Dose | — | Research-only; no validated human dose |
| Route | — | Intracerebroventricular/Intranasal |
| Purity | >99% | ≥98% |
| Studies Count | 120 | 28 |
| 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
Neuropeptide S Benefits
- ✓anxiolysis
- ✓stress resilience
- ✓attention support
- ✓arousal modulation
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.
Neuropeptide S Dosing
0.1-1 nmol i.c.v. in animal studies|intranasal research-only exploration|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.
Neuropeptide S Side Effects
- ⚠sleep disruption
- ⚠headache
- ⚠jitteriness
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.
Neuropeptide S
Animal studies suggest NPS can reduce anxiety-like behavior while altering wakefulness and alertness through the NPS receptor system. Human cognitive data are very limited, and it has no approved clinical indication.
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