Side-by-side comparison of mechanisms, dosing, interactions, and stacking potential.
| Epitalon (Epithalon) | P21 (Cerebrolysin Analog) | |
|---|---|---|
| Category | Peptides | Peptides |
| Standard Dose | Research indicates 5-10 mg daily via subcutaneous injection for 10-20 day cycles. | Research indicates 750 mcg-1 mg daily via intranasal administration or subcutaneous injection. |
| Timing | Evening administration preferred (aligns with pineal/melatonin function). Some protocols split doses AM/PM. | Morning dosing preferred for cognitive effects. |
| Cycle Duration | 10-20 day intensive cycles repeated every 4-6 months. Not used continuously. | 4-8 week cycles with 4-week rest periods. |
| Evidence Level | animal_plus_anecdotal | animal_plus_anecdotal |
Epitalon (Ala-Glu-Asp-Gly / AEDG) is a synthetic tetrapeptide based on the natural pineal gland peptide epithalamin. It activates telomerase by inducing expression of the catalytic subunit hTERT, resulting in telomere elongation averaging 33.3% in human somatic cells. Epitalon restores pineal melatonin synthesis and circadian gene expression in aged organisms, increases BDNF, and upregulates CREB1. It also modulates the neuroendocrine system through its effects on the hypothalamic-pituitary axis and antioxidant enzyme regulation.
Research indicates 5-10 mg daily via subcutaneous injection for 10-20 day cycles.
Evening administration preferred (aligns with pineal/melatonin function). Some protocols split doses AM/PM.
10-20 day intensive cycles repeated every 4-6 months. Not used continuously.
P21 is a tetrapeptide (DGGL — Asp-Gly-Gly-Leu) derived from the most active region of ciliary neurotrophic factor (CNTF, residues 148-151), identified through reverse engineering of Cerebrolysin. An adamantylated glycine enhances BBB permeability and metabolic stability. P21 works through LIF/STAT3 pathway inhibition, BDNF/TrkB/CREB signaling enhancement, and restoration of synaptic proteins (synaptophysin, synapsin I) and glutamate receptors. It promotes neurogenesis and maturation of newborn neurons in the dentate gyrus.
Research indicates 750 mcg-1 mg daily via intranasal administration or subcutaneous injection.
Morning dosing preferred for cognitive effects.
4-8 week cycles with 4-week rest periods.
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