Current prospects and future challenges for nasal vaccine delivery

Abstract

Nasal delivery offers many benefits over traditional approaches to vaccine administration. These include ease of administration without needles that reduces issues associated with needlestick injuries and disposal. Additionally, this route offers easy access to a key part of the immune system that can stimulate other mucosal sites throughout the body. Increased acceptance of nasal vaccine products in both adults and children has led to a burgeoning pipeline of nasal delivery technology. Key challenges and opportunities for the future will include translating in vivo data to clinical outcomes. Particular focus should be brought to designing delivery strategies that take into account the broad range of diseases, populations and healthcare delivery settings that stand to benefit from this unique mucosal route. In this review the current state of the art in nasal vaccine delivery will be described along with future prospects. A brief introduction to the anatomy and physiology of the nasal cavity will highlight the advantages and disadvantages of the route. Encapsulation and presentation methods along with particular formulation considerations for the nasal route will also be discussed.There are many mucosal routes which have been regarded as potential sites for vaccine delivery such as oral, nasal, pulmonary, conjunctival, rectal and vaginal mucosa. However, for practical and cultural reasons researchers have tended to focus only on oral, nasal, and pulmonary administration. 1 Needlefree vaccines offer many advantages over traditional vaccination approaches including convenience, cost, ease of administration and disposal.There are several needle free methods of vaccination such as transdermal delivery and mucosal delivery. 2,3 Mucosal immunization has been successfully used in human vaccination. The human mucosal immune system is large and specialized in performing inspection for foreign antigens to protect the surfaces themselves and of course human body interior. Since most infections affect or start from mucosal surfaces, using a mucosal route of vaccination is of great interest and provides a rational reason to induce a protective immune response. 3 Nasal delivery of vaccine offers an easily accessible route to the immune system.The nose has the function of olfactory detection (sense of smell) and also filtration, humidification and temperature control of air as it enters the respiratory system. Moving from front to back the areas of the nasal cavity are the nasal vestibule, the respiratory region, and the olfactory region. The nasal cavity is divided by the septum to form the left and right nares, which lead into the left and right choana before opening onto the nasopharynx at the top of the throat. The turbinates bound the nasal walls and are responsible for air conditioning and the large mucosal surface area of the nasal cavity. The nose is also the main port of entry for many pathogens. The first barrier to foreign bodies is hair at the entrance to the nares, the nostrils, which successfully keeps ou...

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