Tesamorelin vs MK-677
Comprehensive side-by-side comparison of mechanisms, dosing, side effects, and research
Also: Egrifta, Egrifta WR
An FDA-approved GHRH analog used to reduce excess abdominal fat in HIV-infected patients with lipodystrophy. New F8 formulation (Egrifta WR) approved March 2025 allows weekly reconstitution vs daily.
Also: Ibutamoren, Nutrobal
An orally active growth hormone secretagogue that mimics ghrelin. Although technically not a peptide, it is frequently discussed alongside GH peptides due to similar effects.
Key Comparison Insights
- Tesamorelin is FDA approved, while MK-677 remains in research stages.
- Both peptides belong to the Growth Hormone category, suggesting similar primary applications.
- Tesamorelin has stronger research evidence (FDA Approved) compared to MK-677 (Human Trials).
Detailed Comparison
| Attribute | Tesamorelin | MK-677 |
|---|---|---|
| Category | Growth Hormone | Growth Hormone |
| FDA Status | FDA Approved | Not FDA Approved |
| Clinical Status | Pre I II III IV FDA | Pre I II III IV FDA |
| Mechanism of Action | Tesamorelin is a stabilized analog of human GHRH that stimulates the pituitary to release growth hormone. It specifically reduces visceral adipose tissue (VAT) while having minimal effect on subcutaneous fat, likely through GH-mediated lipolysis. | MK-677 binds to ghrelin receptors (GHSR) in the brain, stimulating sustained GH release and increasing IGF-1 levels. Unlike injectable GHRPs, it is orally bioavailable and has a long half-life providing 24-hour GH elevation. |
| Common Dosing | 2 mg daily (F8: 1.28 mg daily) Once daily | 10-25 mg daily Once daily, often before bed |
| Administration | Subcutaneous injection | Oral |
| Typical Duration | Indefinite for approved indication | 8-12 weeks or longer |
| Best Time to Take | Before bed (fasted) | Before bed |
Possible Side Effects May vary by individual |
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| Research Summary | FDA approved based on trials showing 15-20% reduction in visceral adipose tissue over 26 weeks. March 2025: FDA approved new F8 formulation (Egrifta WR) with weekly reconstitution, reducing patient burden. CROI 2025 data highlighted limitations of BMI for cardiovascular risk assessment in HIV patients. | Studies show increases in GH and IGF-1 levels, improved sleep quality, and increased lean body mass. However, a clinical trial was stopped early due to heart failure concerns in elderly patients. FDA lists MK-677 as having 'significant safety risks due to potential for congestive heart failure.' December 2025: FDA issued warning letters to companies selling MK-677. Never received FDA approval and remains an unapproved drug. |
Frequently Asked Questions: Tesamorelin vs MK-677
What is the difference between Tesamorelin and MK-677?
Tesamorelin is a growth hormone peptide that an fda-approved ghrh analog used to reduce excess abdominal fat in hiv-infected patients with lipodystrophy. new f8 formulation (egrifta wr) approved march 2025 allows weekly reconstitution vs daily. MK-677 is a growth hormone peptide that an orally active growth hormone secretagogue that mimics ghrelin. although technically not a peptide, it is frequently discussed alongside gh peptides due to similar effects. The main differences lie in their mechanisms of action and clinical applications.
Which is better, Tesamorelin or MK-677?
Neither is universally "better" - the choice depends on your specific goals. Tesamorelin is typically used for growth hormone purposes, while MK-677 is used for growth hormone. Always consult with a healthcare provider to determine which may be appropriate for your situation.
Can Tesamorelin and MK-677 be used together?
Some peptide protocols combine multiple compounds for synergistic effects. However, using Tesamorelin and MK-677 together should only be considered under medical supervision, as both compounds have their own side effect profiles and potential interactions. Research on their combined use may be limited.