Nanosized drug delivery for enhancement of oral bioavailability

Oral delivery is the most preferred way especially for chronic administration of drugs, due to patient convenience and compliance. Hence, it remains as an important and immense segment in the drug market. However, many drug molecules belong to Biopharmaceutics classification systems (BCS) class II (poorly soluble and permeable) and class IV (poorly soluble and impermeable), resulting in low bioavailability, which is the most important limitation of oral delivery. Nanosizing of drugs can lead to a dramatic increase in oral absorption and subsequent bioavailability. Possible factors affecting the transport of these nano carriers across gastrointestinal mucosa are size reduction and surface properties that modify the non-specific or targeted uptake by enterocytes and/or M cells. Benefits of nano sizing can be listed as reduction in variability of absorption, improved absorption for higher doses and rapid formulation development. Therefore, many nanosized systems have been formulated for oral delivery. This chapter presents the requirements in the field of oral delivery and describes the design, characterization and application of various nanosized formulations, such as, vesicular, micellar and particulate systems. © 2012 Springer-Verlag Berlin Heidelberg. All rights are reserved.