Semaglutide vs P21
A detailed comparison to help you understand the differences and choose the right peptide for your research goals.
Semaglutide
Semaglutide is a GLP-1 receptor agonist that has revolutionized weight management and diabetes treatment. FDA-approved as Ozempic (diabetes), Wegovy (weight loss), and Rybelsus (oral form), it has become one of the most prescribed peptides worldwide.
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 | Semaglutide | P21 |
|---|---|---|
| Mechanism | Mimics glucagon-like peptide-1 (GLP-1) to stimulate insulin secretion, suppress glucagon release, slow gastric emptying, and reduce appetite through hypothalamic signaling. The result is significant reduction in food intake and improved glycemic control. | 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 | Wegovy (weight loss): Start at 0.25mg weekly, titrate up to 2.4mg weekly over 16-20 weeks. Ozempic (diabetes): 0.25mg to 1mg weekly. Research protocols vary. | Research protocols typically use 1-5mg administered intranasally or subcutaneously. Often used in cycles of 2-4 weeks. |
| Administration | Subcutaneous injection once weekly, typically in abdomen, thigh, or upper arm. Rybelsus is taken orally on empty stomach. Dose titration is essential to minimize GI side effects. | Can be administered intranasally for direct CNS access or subcutaneously. Best used cyclically rather than continuously. |
| Side Effects | Common: nausea, vomiting, diarrhea, constipation, abdominal pain. These typically decrease over time. May cause injection site reactions. | Limited data. Reported effects include mild headache, temporary brain fog during initial use, and fatigue. |
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