P21 vs Setmelanotide
A detailed comparison to help you understand the differences and choose the right peptide for your research goals.
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 →Setmelanotide
Setmelanotide (Imcivree) is an FDA-approved MC4R agonist for chronic weight management in patients with obesity due to specific genetic conditions (POMC, PCSK1, or LEPR deficiency).
Full details →Side-by-Side Comparison
| Aspect | P21 | Setmelanotide |
|---|---|---|
| Mechanism | Inhibits glycogen synthase kinase-3β (GSK-3β) and activates CREB signaling pathway. This promotes BDNF expression, neurogenesis in the hippocampus, and synaptic plasticity. | Selective agonist of melanocortin 4 receptors (MC4R) in the hypothalamus, restoring the satiety signaling pathway that is disrupted in certain genetic obesity syndromes. |
| Typical Dosage | Research protocols typically use 1-5mg administered intranasally or subcutaneously. Often used in cycles of 2-4 weeks. | Adults: Start 2mg daily, titrate based on tolerability up to 3mg daily. Pediatrics (6+): Weight-based dosing starting at 1mg daily. |
| Administration | Can be administered intranasally for direct CNS access or subcutaneously. Best used cyclically rather than continuously. | Subcutaneous injection once daily. Requires genetic testing to confirm eligible mutations before prescribing. |
| Side Effects | Limited data. Reported effects include mild headache, temporary brain fog during initial use, and fatigue. | Injection site reactions, skin hyperpigmentation, spontaneous penile erections, depression, and suicidal ideation (boxed warning). GI effects less common than GLP-1s. |
| Best For |