ABSTRACT
This chapter provides a brief review of the impact of the route of administration and transport on the distribution of drug products and discuss tissue- and cell-specific challenges in drug delivery. Different routes of administration significantly alter the bioavailability as well as biodistribution of drugs and nanoparticles. The barrier function of the mucosal layer protects the gastrointestinal tract, urinary bladder, reproductive tracts, lung airways, nose, eyes, and other mucosal surfaces. Oral delivery is the most common method of drug administration with greater convenience, efficacy, safety, no pain, high patient compliance, a reduction in the risk of infection from needle stick injuries, and cost-effectiveness. Hepatic stellate cells are located in the space of Disse, an anatomical space between hepatocytes and the sinusoid, and maintain close interactions with liver sinusoidal endothelial cells and hepatocytes. The permeable nasal epithelium allows rapid drug absorption to the brain due to high blood flow, porous endothelial membrane, reasonable surface area, and avoidance of first-pass metabolism.
