Among the many ways of administering therapeutic peptides, peptide nasal sprays are perhaps the most user-friendly. They allow for quick delivery to the brain, bypassing the blood-brain barrier (BBB) and minimizing systemic exposure. The use of these dosage forms can especially increase the bioavailability and safety of peptides compared to other administration methods such as oral tablets, injections or intravenous infusion.
Peptide n-to-B delivery has been shown to be effective in a number of conditions including neurodegenerative diseases such as Alzheimer’s. In particular, a nasal formulation of BPC-157 has been shown to decrease the accumulation of beta amyloid scavenging peptide in mice with Alzheimer’s disease.
However, to reach the brain through a nose-to-brain route, drugs must first pass the olfactory nasal epithelium and then enter the cerebrospinal fluid (CSF) or brain tissues. This process is facilitated by pathways involving the olfactory and trigeminal nerves, vasculature, and lymphatic system. Intranasal drug bioavailability depends on factors such as molecular weight, osmolality, lipophilic and ionic properties, cellular membrane permeability, and cellular deposition.
To overcome this obstacle, scientists have developed nasal devices that can increase peptides’ olfactory availability and delivery time. In addition, peptides have been formulated into liquid formulations and nasal dry powder inhalers (DPIs) that allow for rapid delivery to the CNS. These devices can be used to treat a number of conditions, such as narcolepsy and cataplexies in narcoleptic patients, which are believed to result from orexinergic deficiency or dysfunction of the olfactory receptor system.