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P21 vs Semax

Updated 4 sources

Key differences

  1. 1Semax is an ACTH fragment; P21 is a CNTF fragment.
  2. 2Both are used by nose, and forums often stack them.

Side by side

Facts from each record, in the same words as their own pages.
P21 and Semax side by side
P21Semax
Category
  • Cognitive
  • Cognitive
Evidence
  • Animal data only
  • Limited human data
FDA status
  • Not FDA approvedRegulatory
  • Not FDA approvedRegulatory
WADA
  • Not confirmed
  • Not confirmed
Half-lifeNot reported
  • No human data; FDA found no human pharmacokinetic studies. In rats, brain levels peak 2 minutes after a nasal dose and the peptide breaks down fast.Clinical study
Routes
  • Nasal, Subcutaneous injection
  • Nasal, Subcutaneous injection
Forms
  • Vial (powder), Nasal spray
  • Nasal spray, Vial (powder)
Reported doses
  • 1 to 4 mg (nasal)
  • 500 to 1,000 mcg (nasal)
  • 100 to 1,000 mcg (subcutaneous injection)
  • 150 to 6,000 mcg (nasal)
  • 12 to 18 mg (nasal)
  • 15 to 50 mcg/kg (nasal)
Most cited frequency
  • Once daily
  • Once daily
Vial sizes
  • 5 mg, 10 mg, 50 mg, 100 mgCompetitor guide
  • 5 mg, 10 mg, 20 mg, 30 mgCompetitor guide
Mixed vial keeps
  • Refrigerate at 2 to 8 C and use within 28 to 30 days.Competitor guide
  • Fridge at 2 to 8 C.Competitor guide
Protocols on file
  • 10
  • 30

Doses shown are what sources report, labelled by origin. Not medical advice.

Read each in full

Sources

4 sources, each checked by date. Record updated Oct 24, 2026. Numbers are restated in our own words and labelled by where they came from.