Nasal route

  Many therapeutic drugs are difficult to reach the central nervous system (CNS) from the systemic blood circulation because the blood-brain barrier (BBB) and the blood-cerebrospinal fluid barrier (BCSFB) form a very effective barrier which prevents most molecules from passing through. BBB allows a selective entry of nutrients and minerals across it and limits the entry of foreign substances like drugs as well as neuropharmaceutical agents. To bypass BBB, drugs can be delivered through olfactory region for nose-to-brain targeting. . Intranasal administration of therapeutic agents (i.e., drug delivery via the nose) offers several advantages over oral, intravenous, and other routes of administration. Drugs can be rapidly absorbed through the large surface area of the nasal mucosa. Intranasal delivery is also non-invasive and essentially painless.  This review provides an overview of strategies to improve the drug delivery to the brain via the nasal mucosa and recent advances in the field.