The nasal delivery of peptides is increasingly being studied as an alternative to injection. Peptides are small molecules with a high potency and a low immunogenicity and can therefore achieve quicker regulatory approval than large molecule drugs. However, the large molecular weight of peptides makes them insoluble in the aqueous vapor phase and they do not readily pass through the BBB (blood–brain barrier). Therefore, the development of formulations to enable efficient nasal delivery of peptides is an important area of research.
A number of clinical trials using nasal sprays have shown promising results, including for the treatment of autoimmune diseases and Alzheimer’s disease. One example involves a scavenger peptide that was administered via the nose and significantly reduced amyloid- accumulation in a mouse model of Alzheimer’s disease.
Another potential application of a peptide nasal spray is in the treatment of narcolepsy, which has been linked to orexinergic deficiency. This deficiency is characterized by sleepiness and cataplexies, which can be treated with the neuropeptide orexin-A when delivered via a nasal spray formulation.
Currently, most commercially approved nasal sprays are liquid-based and contain small-molecule drugs such as sumatriptan to treat migraines or large molecules like vitamin B12 and vasopressin to treat hypertension. However, a recent study by Fransen et al. demonstrated that nasal powders were more efficacious than the current commercial nasal liquid spray and sublingual tablet formulations in delivering the CNS-targeted peptide desmopressin to the brain tissue. This is attributed to the higher medication stability of the nasal dry powder and its absence of preservatives and propellants. peptide nasal sprays