Cerebrolysin vs P21

Cerebrolysin

Cerebrolysin is not a single peptide. It is a standardised enzymatic hydrolysate of purified porcine brain protein containing low-molecular-weight neuropeptides and free amino acids, so no single half-life or molecular weight applies. DOSING CONVENTION: it is supplied as a ready-made sterile solution at 215.2 mg of peptide concentrate per mL, in sealed ampoules of 1, 2, 5, 10 and 20 mL, and it is prescribed in mL, never in mcg. The figures in this entry are the mg equivalents of that solution converted to mcg for consistency with the rest of the dataset: 215,200 mcg = 1 mL, 430,400 mcg = 2 mL, 1,076,000 mcg = 5 mL. It is NOT reconstituted, so the vial sizes above are ampoule contents and the bacteriostatic water field does not apply. Route matters: 5 mL is the practical ceiling for a single intramuscular injection, and the larger doses used in trials (10-50 mL/day) are given as slow intravenous infusions in a clinical setting, not IM. It is approved in a number of European, Asian and CIS countries but is NOT FDA approved. Human evidence is more substantial than for the other compounds in this class - randomized trials and Cochrane reviews in acute ischaemic stroke, vascular dementia, Alzheimer disease and traumatic brain injury - but the results are mixed, the stroke reviews found no convincing benefit on death or dependency, and much of the trial base is manufacturer-sponsored. Courses are conventionally given 5 days a week for about 4 weeks rather than continuously.

P21

THERE IS ESSENTIALLY NO HUMAN DATA ON P21. It is a small adamantylated tetrapeptide derivative (Ac-DGGL-amide) of an 11-residue active region of ciliary neurotrophic factor, designed to be orally available and blood-brain-barrier permeable. The entire evidence base is preclinical: transgenic and aged rodent models of Alzheimer disease and Down syndrome, reporting increased neurogenesis and BDNF signaling and reduced tau hyperphosphorylation, from the group that developed it at the New York State Institute for Basic Research. No human trial has been published, no human pharmacokinetic or toxicology data exists, and no approved product exists anywhere. Rodent work dosed it orally or subcutaneously; the subcutaneous and intranasal routes listed here reflect how unregulated users actually take it. The range given is deliberately narrow and conservative and is extrapolated from that practice, NOT from any dose-finding study - treat it as a description, not a recommendation. It is frequently confused with the unrelated cell-cycle protein p21 (CDKN1A); they are not the same thing.