Retatrutide vs Semax
A detailed comparison to help you understand the differences and choose the right peptide for your research goals.
Retatrutide
Retatrutide (LY3437943) is a first-in-class triple agonist peptide targeting GIP, GLP-1, and glucagon receptors simultaneously. Developed by Eli Lilly, it is currently in Phase 3 clinical trials and has demonstrated the highest weight loss of any obesity medication to date — up to 28.7% body weight reduction at 48 weeks. The triple-receptor mechanism represents the next evolution beyond dual agonists like tirzepatide.
Full details →Semax
Semax is a synthetic peptide derived from ACTH (adrenocorticotropic hormone). Developed in Russia as a nootropic and neuroprotective agent.
Full details →Side-by-Side Comparison
| Aspect | Retatrutide | Semax |
|---|---|---|
| Mechanism | Retatrutide is a synthetic peptide that activates three incretin/metabolic hormone receptors: (1) GLP-1 receptor — appetite suppression, insulin secretion, delayed gastric emptying, (2) GIP receptor — enhanced insulin sensitivity, improved fat metabolism, (3) Glucagon receptor — increased energy expenditure, hepatic fat mobilization, thermogenesis. The glucagon receptor component is the key differentiator, adding an energy-expenditure mechanism absent from GLP-1 and dual GIP/GLP-1 agonists. The molecule uses a C20 fatty diacid for albumin binding, enabling once-weekly dosing. | Enhances BDNF expression, modulates dopamine and serotonin systems, and provides neuroprotective effects. Increases attention, memory formation, and learning. |
| Typical Dosage | Phase 2 trial doses: 0.5 mg, 4 mg, 8 mg, and 12 mg weekly. The 12 mg dose produced maximum weight loss (28.7%). Phase 3 trials are evaluating doses up to 12 mg. Dose escalation schedule similar to other GLP-1s (start low, increase every 4 weeks). Final approved dosing not yet established — Phase 3 trials ongoing. | Intranasal: 200-600mcg 2-3 times daily. Higher doses (up to 1mg) used in clinical settings for stroke recovery. |
| Administration | Subcutaneous injection, once weekly. Phase 3 trials use pre-filled single-dose pens. Not yet commercially available — estimated FDA approval ~2027-2028. | Primarily administered intranasally. N-Acetyl Semax Amidate (NASA) is a modified version with enhanced stability and potency. |
| Side Effects | Phase 2 data: nausea (up to 25%), diarrhea (up to 22%), vomiting (up to 15%), constipation, decreased appetite. GI side effects were dose-dependent and generally mild-to-moderate. Lower rates of nausea compared to semaglutide, potentially due to GIP component. Increased heart rate observed at higher doses. | Generally well-tolerated. May cause mild irritability or hair shedding in some users. |
| Best For |
Key Differences
Unique to Retatrutide:
Unique to Semax:
Detailed Analysis
Commonalities
Retatrutide and Semax are used for different purposes and have limited overlap in their applications.
Which Should You Choose?
Choose Retatrutide for Fat Loss. Choose Semax for Cognitive Performance.
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