Abstract : Historically, the majority of prescribed medications are delivered orally. Due to its many benefits, such as simplicity of administration, versatility in formulation, cost effectiveness, convenience of storage and transport, and high patient compliance, oral drug delivery systems have dominated alternative drug delivery methods for human administration.
However, the bioavailability of medications administered by oral route might differ significantly, particularly if the drugs are given in conventional dose form. This limitation was often ascribed to inter- and intra-subject heterogeneity in gastrointestinal tract (GIT) physiology, GIT transit duration, and in certain cases, a narrow absorption window of drugs in the GIT. Because of variations in pH, accessible surface area, degree of expression of different enzymes and transporters, and metabolism in distinct GIT areas, there may be non-uniformity in drug absorption across the alimentary canal or a region-specific absorption window. Age, gender, posture, and illness condition are biological characteristics that contribute to GIT region-specific absorption.
