Tesamorelin vs MK-677
Tesamorelin's approved evidence concerns VAT in adults with HIV and lipodystrophy; MK-677 is a nonpeptide secretagogue studied for different outcomes and is not FDA approved.
Last updated: September 29, 2026
Dossier labels summarize each dossier's research scope. They do not establish comparative treatment benefit or safety. Read the comparison below in that context.
Tesamorelin
Dossier overview
MK-677
Dossier overview
Different mechanisms and patient outcomes
Tesamorelin is a GHRH analog approved to reduce excess abdominal fat in adults with HIV and lipodystrophy. The pivotal trial assessed VAT by imaging. FDA labeling states it is not for weight-loss management and that long-term cardiovascular safety has not been established. FDA prescribing information; Falutz et al., 2007, PMID 18057338.
MK-677 (ibutamoren) is a nonpeptide ghrelin-receptor agonist. In a randomized trial of 65 healthy older adults, it increased GH, IGF-1 and fat-free mass. The study found no significant improvement in strength or function and no reduction in abdominal visceral fat; fasting glucose rose and insulin sensitivity decreased. These results cannot be transferred to tesamorelin’s indicated population or called general anti-aging benefit. Nass et al., 2008, PMID 18981485.
| Question | Tesamorelin | MK-677 |
|---|---|---|
| Evidence grade for cited endpoint | High for VAT reduction in indicated adults | Moderate for older-adult biomarker/body-composition changes; low for proven functional benefit |
| FDA status | Approved for narrow labeled indication | No FDA-approved ibutamoren product in cited FDA review |
| VAT/functional outcome | VAT reduction in indicated population | Older-adult trial did not show VAT or functional benefit |
| Long-term safety | Cardiovascular safety not established | Trial and FDA review identify unresolved safety concerns |
FDA’s 2024 review says Merck discontinued its MK-0677 program in 1999 and describes a later licensed pediatric development program under the LUM-201 name. It therefore does not support a blanket claim that development of ibutamoren has ended. The status of any individual program requires a dated registry check; a compounding assessment does not confer drug approval. FDA 2024 ibutamoren review.
No cited head-to-head trial establishes relative efficacy or safety, and no evidence here validates combining these agents.
Educational comparison only; not medical advice.
View Full Dossiers
Stay Updated on Peptide Comparisons
Get notified when we publish new comparison dossiers and evidence reviews.
No spam. Unsubscribe anytime.
Disclaimer: This comparison is for educational purposes only and does not constitute medical advice. Individual responses to medications vary. Always consult a qualified healthcare provider before making treatment decisions.