Chapter 8 - Designing of nanocarriers for enhancing drugs absorption through gastrointestinal tract

Abstract

Oral administration of drugs is the most preferred route even though it faces some critical challenges such as off-target drug distribution causing un-desirable side effects and getting less effective delivery of the drug. The main barriers for therapeutic agents in oral drug administration are its extensive and variable pre-systemic metabolism, vulnerability to gastrointestinal (GI) tract environment, and enzymatic degradation leading to erratic and inadequate bioavailability, and low absorption. To meet these challenges, nanotechnology owes the potential to provide infinite possibilities for enhancing drug absorption through the GI tract. Numerous drug delivery systems (DDSs) have been developed that demonstrate exceptional potentials in therapeutic agents’ delivery for treating different diseases while exhibiting marginal side effects and minimizing toxicity to other tissues of the body. Formulation in nanocarriers can reduce the susceptibility of drugs in the GI tract environment, improve drug solubility and absorption, provide protection against enzymatic degradation, and offer controlled release in the GI tract. Moreover, modifications or functionalization of the nanocarriers with specific targeting ligands or molecules has demonstrated remarkable results for effective delivery and enhanced absorption through the GI tract. However, the diverse physiology of the GI tract in different sections such as variation in pH, different cell types, variation in structure and thickness of the mucus, and numerous physiological functions act as the barriers to effective drug delivery and provide an opportunity for designing and developing of novel nanocarriers. The current chapter presents a comprehensive understanding of the developments made in nanocarriers based on enhancing drug absorption through the GI tract.