MK-677 (Ibutamoren) vs Tesamorelin
A neutral, side-by-side comparison of two performance & growth hormone peptides — their mechanisms, dosing ranges, administration routes, side effects, and research evidence. For research and educational purposes only.
MK-677 (Ibutamoren)
Oral non-peptide growth hormone secretagogue that mimics ghrelin to stimulate GH and IGF-1 release without injection. Long half-life (~24 hours) enables once-daily oral dosing. Widely researched for body composition, sleep quality, and IGF-1 elevation.
Full profileTesamorelin
Tesamorelin is an FDA-approved synthetic analog of growth hormone-releasing hormone (GHRH). Approved in 2010 as Egrifta, it is the only GHRH peptide with an approved clinical indication — reduction of excess visceral abdominal fat in people with HIV-associated lipodystrophy. It has the most robust human trial evidence of any growth hormone secretagogue, including dedicated studies on visceral fat and liver fat.
Full profile| MK-677 (Ibutamoren) | Tesamorelin | |
|---|---|---|
| Category | Performance & Growth Hormone | Performance & Growth Hormone |
| Also known as | Ibutamoren, Nutrobal, MK677, L-163,191 | Egrifta, Egrifta SV, TH9507, GHRH analog |
| Evidence | Research-stage | FDA-approved |
| Dosing range | 10mg–50mg mg, once daily oral | 1.28mg–2mg mg, once daily (subcutaneous) |
| Administration | Oral (capsule/liquid) | Subcutaneous injection (abdomen, with site rotation) |
| Key side effects | Water retention, Increased appetite, Elevated fasting glucose (long-term), Fatigue (initial, transient) | Injection site reactions (erythema, pruritus), Peripheral edema, Arthralgia (joint pain), Myalgia |
| Cited sources | 2 references | 5 references |
Key differences
- Evidence level differs: MK-677 (Ibutamoren) is research-stage, while Tesamorelin is fda-approved.
- Administration: MK-677 (Ibutamoren) — Oral (capsule/liquid); Tesamorelin — Subcutaneous injection (abdomen, with site rotation).
- Frequency: MK-677 (Ibutamoren) is typically once daily oral; Tesamorelin is once daily (subcutaneous).
- Research depth: this profile cites 2 sources for MK-677 (Ibutamoren) vs 5 for Tesamorelin.
How each works
MK-677 (Ibutamoren)
MK-677 binds the ghrelin receptor (GHS-R1a) to stimulate pulsatile GH release and increase circulating IGF-1. Unlike peptide GHRPs it survives oral administration. Clinical trials demonstrate significant increases in GH pulsatility and IGF-1 without suppression of the endogenous GH axis, though long-term use raises glucose metabolism concerns.
Tesamorelin
Tesamorelin stimulates pulsatile growth hormone (GH) release from the pituitary, raising serum IGF-1 and preferentially reducing visceral adipose tissue (VAT). FDA-registration trials (Falutz et al., NEJM 2007; JAIDS 2010) showed ~15% VAT reduction versus placebo over 26 weeks. Later randomized trials (Stanley et al., JAMA 2014; Lancet HIV 2019) extended the evidence to liver fat, showing meaningful reductions in hepatic fat fraction and attenuated fibrosis progression in HIV-associated NAFLD.
This comparison aggregates public research and structured profile data for informational purposes only. It is not medical advice and does not recommend either compound for human use. Consult a qualified healthcare provider before considering any peptide.