Retatrutide vs P21
A detailed comparison to help you understand the differences and choose the right peptide for your research goals.
Retatrutide
Retatrutide is an investigational triple agonist targeting GIP, GLP-1, and glucagon receptors. Phase 2 trials showed unprecedented weight loss of up to 24% at 48 weeks, making it potentially the most effective obesity treatment studied.
Full details →P21
P21 is a synthetic peptide derived from Cerebrolysin, specifically designed to mimic the neurotrophic effects of the parent compound. It promotes neurogenesis and has shown cognitive-enhancing properties in research.
Full details →Side-by-Side Comparison
| Aspect | Retatrutide | P21 |
|---|---|---|
| Mechanism | Triple receptor activation provides complementary metabolic effects: GLP-1 and GIP reduce appetite and improve insulin sensitivity, while glucagon receptor activation increases energy expenditure and promotes hepatic fat oxidation. | Inhibits glycogen synthase kinase-3β (GSK-3β) and activates CREB signaling pathway. This promotes BDNF expression, neurogenesis in the hippocampus, and synaptic plasticity. |
| Typical Dosage | Clinical trials used doses from 1mg to 12mg weekly. Optimal dosing still being determined in ongoing Phase 3 trials. | Research protocols typically use 1-5mg administered intranasally or subcutaneously. Often used in cycles of 2-4 weeks. |
| Administration | Subcutaneous injection once weekly. Currently only available through clinical trials - not yet FDA approved. | Can be administered intranasally for direct CNS access or subcutaneously. Best used cyclically rather than continuously. |
| Side Effects | Similar GI effects to other incretin-based therapies: nausea, diarrhea, vomiting, constipation. Dose-dependent severity. | Limited data. Reported effects include mild headache, temporary brain fog during initial use, and fatigue. |
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