Milestone for journey of medicine through oral route: A brief review

Oral route is the first choice for the administration of drug since it is both convenient and economical. Among the various drug delivery system, the oral route has attracted the most attention due to its unique advantages, including sustained and controllable delivery, ease of administration, and feasibility for solid formulation, patient compliance and an intensified immune response in vaccines. Around 60% of established small-molecule drug product available commercially are administered via oral route. Oral drug absorption is a process influenced by the physiochemical and biopharmaceutical properties of the drug and its inter-relationship with the gastrointestinal tract. Drug administered by oral route move through the various parts of the digestive tract: oral cavity pharynx, esophagus, small intestine, large intestine and unabsorbed compounds leave the body through anal sphincter (anus). Primary factors such as drug solubility, dissolution and Permeability across intestinal barrier are the key parameter controlling drug absorption whereas the secondary factors such as gastric emptying, intestinal motility and GI transit time plays a major role in influencing drug absorption.