Tirzepatide vs P21
A detailed comparison to help you understand the differences and choose the right peptide for your research goals.
Tirzepatide
Tirzepatide is a first-in-class dual GIP/GLP-1 receptor agonist. FDA-approved as Mounjaro (diabetes) and Zepbound (weight loss), it has shown superior weight loss results compared to semaglutide in clinical trials.
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 | Tirzepatide | P21 |
|---|---|---|
| Mechanism | Activates both GIP (glucose-dependent insulinotropic polypeptide) and GLP-1 receptors, providing synergistic effects on insulin secretion, appetite suppression, and metabolic regulation. The dual mechanism may explain its enhanced efficacy. | 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 | Start at 2.5mg weekly, titrate every 4 weeks through 5mg, 7.5mg, 10mg, 12.5mg, to maximum 15mg weekly. Full titration takes approximately 20 weeks. | Research protocols typically use 1-5mg administered intranasally or subcutaneously. Often used in cycles of 2-4 weeks. |
| Administration | Subcutaneous injection once weekly. Rotate injection sites. Slower titration may help reduce GI side effects. | Can be administered intranasally for direct CNS access or subcutaneously. Best used cyclically rather than continuously. |
| Side Effects | Similar to semaglutide: nausea, diarrhea, vomiting, constipation, abdominal pain, decreased appetite. Generally improve with continued use. | Limited data. Reported effects include mild headache, temporary brain fog during initial use, and fatigue. |
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