Nasal drug delivery

Nasal mucosa has been considered as a potential administration route to achieve faster and higher levels of drug absorption because it is permeable to more compounds than the gastrointestinal tract. It is an attractive route of administration due to lack of pancreatic and gastric enzymatic activity, neutral pH of the nasal mucus and less dilution by gastrointestinal contents. In-situ gel forming systems have been developed to prolong the nasal residence time of a drug and improve nasal bioavailability. Fexofenadine hydrochloride is one of the most widely used drugs for allergic rhinitis. It is an anti-histaminic and is available in oral dosage forms. The present work is aimed at designing a gel formula for nasal administration. To enhance therapeutic effect of the nasal formulation of fexofenadine hydrochloride pH sensitive polymers were used. Xanthan gum and Carbopol 934 were selected as independent variables in the factorial design. Solubility of the drug in the formulation was enhanced by using Tween 80. Evaluation parameters of the formulation like pH, clarity; rheological study both formulation i.e. solution and performed gel, gelling time, drug content, in-vitro drug diffusion study, stability studies were performed. The formulations so designed shall enhance bioavailability of drug and offer better therapeutic outcomes, offer aesthetically appealing dosage form to increase patient compliance and shall overcome side effects and limitations of other dosage forms of marketed preparations.

  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.