P21vsRetatrutide
P21 vs Retatrutide — independent comparison of uses, administration, pricing across providers, and key differences. Last reviewed April 21, 2026.
Quick Verdict
Based on clinical evidence and real patient data
A 21-amino-acid peptide that mimics the action of ciliary neurotrophic factor (CNTF). Studied for neurogenesis, cognitive improvement, and neuroprotection. Shows promise in animal models for enhancing memory consolidation and protecting against neurodegenerative decline.
A next-generation triple agonist targeting GLP-1, GIP, and glucagon receptors simultaneously. Phase 3 clinical trials show weight loss exceeding tirzepatide, positioning it as the most potent anti-obesity peptide in development.
Best choice depends on your insurance, budget, and treatment history.Take the quiz to get a personalized recommendation.
P21 vs Retatrutide: At a Glance
Full comparison across all key factors.
| Factor | P21 | Retatrutide |
|---|---|---|
| Category | cognitive | weight-loss |
| Also Known As | CNTF analog, Colostrinin fragment | LY3437943 |
| Administration | Intranasal spray | Subcutaneous injection (weekly) |
| Prescription | Required | Required |
| Providers | 3 providers | 3 providers |
| Common Uses |
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Data sourced from FDA prescribing information and peer-reviewed clinical trials. Prices reflect telehealth platform costs as of April 21, 2026. See our methodology.
Pricing by Provider
2 providers offer both P21 and Retatrutide.
| Provider | P21 | Retatrutide | Consultation | Lab Testing |
|---|---|---|---|---|
 | $180/monthly | $450/monthly | Video Telehealth | Yes |
 | $230/monthly | $550/monthly | Video Telehealth | Yes |
 | $55/one-time | Not offered | Async Telehealth | No |
 | Not offered | $480/monthly | Video Telehealth | Yes |
Key Differences
P21
A 21-amino-acid peptide that mimics the action of ciliary neurotrophic factor (CNTF). Studied for neurogenesis, cognitive improvement, and neuroprotection. Shows promise in animal models for enhancing memory consolidation and protecting against neurodegenerative decline.
Retatrutide
A next-generation triple agonist targeting GLP-1, GIP, and glucagon receptors simultaneously. Phase 3 clinical trials show weight loss exceeding tirzepatide, positioning it as the most potent anti-obesity peptide in development.
Which Is Right for You?
Choose P21if…
- You want a cognitive medication
- You prefer intranasal spray administration
- 3 providers available on our platform
- Your primary goal is neurogenesis
- Your primary goal is memory consolidation
Choose Retatrutideif…
- You want a weight-loss medication
- You prefer subcutaneous injection (weekly) administration
- 3 providers available on our platform
- Your primary goal is weight loss
- Your primary goal is metabolic health
Frequently Asked Questions
What is the difference between P21 and Retatrutide?
Which is cheaper, P21 or Retatrutide?
Can I switch from P21 to Retatrutide?
Medical Disclaimer
This comparison is for informational purposes only and does not constitute medical advice. Always consult with a qualified healthcare provider before starting, stopping, or changing any medication. Individual results may vary. The information presented reflects publicly available data and may not account for your specific health situation.
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Read guide →Retatrutide Cost: What Will Eli Lilly's Triple-Agonist Cost When It Launches?
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