The Nasal Pathway to the Brain
While subcutaneous injection distributes peptides systemically through the bloodstream, intranasal delivery exploits a unique anatomical shortcut. The olfactory mucosa—located high up in the nasal cavity—is intrinsically linked to the central nervous system.
When a peptide spray lands on the olfactory nerve endings, it can travel directly into the brain's cerebrospinal fluid (CSF) via axonal transport, completely bypassing the restrictive Blood-Brain Barrier (BBB). For cognitive peptides, this is profoundly effective.
Candidacy: Which Peptides Survive the Nose?
Not all peptides can be absorbed nasally. The nasal mucosa acts as a filter, and the atomic weight (Daltons) of the peptide dictates its success.
• Excellent Nasal Candidates: Peptides with small molecular weights and fewer than 10-15 amino acids (e.g., Semax, Selank, Oxytocin, PT-141). Their small size allows them to easily cross the mucosal membrane.
• Poor Nasal Candidates: Large, complex proteins with heavy molecular weights (e.g., Growth Hormone, BPC-157, TB-500). If you buy nasal spray BPC-157, studies indicate a bioavailability of less than 5%; you are wasting your money.
Maximizing Nasal Bioavailability
Intranasal dosing limits the volume of liquid you can absorb. If you spray too much, it runs down your throat into your stomach acid (where it is destroyed).
For optimal absorption, use highly concentrated sprays. You should only need 1 or 2 sprays per nostril. Sniff gently to coat the upper nasal walls. Deep, aggressive sniffing merely pulls the peptide down to the throat, nullifying the effect.
