MK-677vsP21
MK-677 vs P21 — 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
An oral growth hormone secretagogue that mimics the action of ghrelin, stimulating growth hormone release from the pituitary gland. Unlike injectable peptides, MK-677 is taken orally and has a long half-life.
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.
Best choice depends on your insurance, budget, and treatment history.Take the quiz to get a personalized recommendation.
MK-677 vs P21: At a Glance
Full comparison across all key factors.
| Factor | MK-677ALLY PICK | P21 |
|---|---|---|
| Category | growth-hormone | cognitive |
| Also Known As | Ibutamoren | CNTF analog, Colostrinin fragment |
| Administration | Oral capsule | Intranasal spray |
| Prescription | Required | Required |
| Providers | 6 providers✓ Better | 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
3 providers offer both MK-677 and P21.
| Provider | MK-677 | P21 | Consultation | Lab Testing |
|---|---|---|---|---|
 | $50/one-time | $55/one-time | Async Telehealth | No |
 | $120/monthly | $180/monthly | Video Telehealth | Yes |
 | $180/monthly | $230/monthly | Video Telehealth | Yes |
 | $150/monthly | Not offered | Video Telehealth | Yes |
 | $149/monthly | Not offered | Async Telehealth | Yes |
 | $149/monthly | Not offered | Video Telehealth | Yes |
Key Differences
MK-677
More ProvidersAn oral growth hormone secretagogue that mimics the action of ghrelin, stimulating growth hormone release from the pituitary gland. Unlike injectable peptides, MK-677 is taken orally and has a long half-life.
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.
Which Is Right for You?
Choose MK-677if…
- You want a growth-hormone medication
- You prefer oral capsule administration
- You want more provider options (6 available)
- Your primary goal is growth hormone elevation
- Your primary goal is improved sleep quality
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
Frequently Asked Questions
What is the difference between MK-677 and P21?
Which is cheaper, MK-677 or P21?
Can I switch from MK-677 to P21?
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.