Micro/nanoparticles

In recent decades, particulate drug delivery technologies have transitioned from being scientific curiosities to subjects of intense research providing several distinct benefits. One of their most advantageous characteristics is its ease of administration, either through tissue injection or intravenous delivery. They can also be readily adjusted for use in different environments, either for inhalation as a dry powder or for topical application in a suitable vehicle. However, in comparison, the oral route of drug delivery is the most favored since it is convenient, inexpensive, and patient compliance. Nevertheless, the oral absorption of several small molecules and biotherapeutics is hindered by different physiological barriers, leading to limitations such as poor solubility, limited permeability, and degradation. To this end, particulate drug delivery techniques have been utilized to develop drug delivery platforms that aim to overcome these obstacles associated with oral drug absorption. In the field of drug delivery, a common differentiation is made between micro- and nanoparticles. The terms “microparticle” and “nanoparticle” are used to define particles that have dimensions measured in micrometers and nanometers, respectively. Certain authors restrict the use of the term “nanoparticles” to refer to particles that fall under particular size limits. This is justified since larger particles tend to behave more like microparticles and hence require similar fabrication techniques. The disparity in magnitude between micro- and nanoparticles yields a multitude of consequences. It is crucial to consider that certain differences between particles of varying sizes may not apply to all types of particles. Microparticles and nanoparticles have been specifically designed with planar, asymmetric shapes to enhance uptake and enable a uniform drug release across epithelial tissue. This prolongs drug exposure and enhances drug penetration. In addition, several techniques including surface functionalization, responsive drug release, motion-based responses, and permeation enhancers have been integrated into these particulate delivery platforms to improve the absorption of drugs. Taken together in a nutshell, this chapter will discuss the utilization of microparticles and nanoparticles to precisely target the physiological barriers in oral drug delivery and showcase technologies that can be integrated into these systems to improve drug absorption.