The human brain, a highly sensitive organ, functions as the body's central control unit and is naturally protected to preserve neurological health. The Blood-Brain Barrier (BBB) presents a significant challenge to the delivery of drugs into the brain. Oral medications face low bioavailability and restricted brain exposure, compounded by rapid metabolism, elimination, unwanted side effects, and the necessity for high doses. These factors lead to inconvenience for patients and substantial costs for patients, their families, and society. The primary obstacle to effective brain penetration of these compounds is the BBB, which safeguards the brain from xenobiotics. Consequently, treating brain diseases such as Alzheimer's, Parkinson's, dementia, mood disorders, and bacterial infections is more complex. The intranasal route of administration offers a promising alternative for bypassing the BBB in brain drug delivery, facilitating drug transport from the nasal cavity to the brain via the olfactory and trigeminal nerves.