In vitro and ex vivo experimental models for evaluation of intranasal systemic drug delivery as well as direct nose-to-brain drug delivery.

The intranasal route of administration provides a non-invasive method to deliver drugs into the systemic circulation and/or directly into the brain. Direct nose-to-brain drug delivery offers the possibility to treat central nervous system diseases more effectively, as it can evade the blood-brain barrier. In vitro and ex vivo intranasal models provide a means to investigate physiological and pharmaceutical factors that could play a role in drug delivery across the nasal epithelium as well as to determine the mechanisms involved in drug absorption from the nose. The development and implementation of cost-effective pharmacokinetic models for intranasal drug delivery with good in vitro-in vivo correlation can accelerate pharmaceutical drug product development and improve economic and ecological aspects by reducing the time and costs spent on animal studies. Special considerations should be made with regard to the purpose of the in vitro/ex vivo study, namely whether it is intended to predict systemic or brain delivery, source and site of tissue or cell sampling, viability window of selected model, and the experimental set up of diffusion chambers. The type of model implemented should suit the relevant needs and requirements of the project, researcher and laboratory. This review aims to provide an overview of in vitro and ex vivo models that have been developed to study intranasal and direct nose-to-brain drug delivery. This article is protected by copyright. All rights reserved.