Emerging microtechnologies for the development of oral drug delivery devices

Abstract

The development of oral drug delivery platforms for administering therapeutics in a safe and effective manner across the gastrointestinal epithelium is of much importance. A variety of delivery systems such as enterically coated tablets, capsules, particles, and liposomes have been developed to improve oral bioavailability of drugs. However, orally administered drugs suffer from poor localization and therapeutic efficacy due to various physiological conditions such as low pH, and high shear intestinal fluid flow. Novel platforms combining controlled release, improved adhesion, tissue penetration, and selective intestinal targeting may overcome these issues and potentially diminish the toxicity and high frequency of administration associated with conventional oral delivery. Microfabrication along with appropriate surface chemistry, provide a means to fabricate these platforms en masse with flexibility in tailoring the shape, size, reservoir volume, and surface characteristics of microdevices. Moreover, the same technology can be used to include integrated circuit technology and sensors for designing sophisticated autonomous drug delivery devices that promise to significantly improve point of care diagnostic and therapeutic medical applications. This review sheds light on some of the fabrication techniques and addresses a few of the microfabricated devices that can be effectively used for controlled oral drug delivery applications.

Planar Bioadhesive Microdevices: A New Technology for Oral Drug Delivery

“…A flat shape increases the surface area in contact with the GI wall, improving adhesive properties of the device [26]. In addition, a flat microdevice shape decreases the shear force per mass on the devices as shown in Figure 1B, preventing detachment of the device from the intestinal epithelium and further increasing residence time [27].…”

“…To overcome a second major barrier to oral drug uptake - issues with drug permeability, microdevices are designed with reservoirs on only one side of the device, allowing drug to be released in only one direction. In addition to asymmetric shape, devices can be asymmetrically modified with targeting moieties, mucoadhesive materials, and micro- and nanotopography, providing selective binding of the device side from which drug will be selectively released [26]. Thus, microdevices are designed to adhere to the mucosal or GI epithelial layer and release drug to enterocytes in a proximal, unidirectional manner as shown in Figure 1B.…”

Synthesis and Evaluation of Mesoporous Carbon/Lipid Bilayer Nanocomposites for Improved Oral Delivery of the Poorly Water-Soluble Drug, Nimodipine

“…Over recent decades, various nanonization strategies have been proposed to increase the aqueous solubility and regulate the dissolution rate of poorly water-soluble drugs. These strategies include reducing the particle size to increase the surface area [3,7], using cyclodextrin inclusion complexes or solid lipid nanoparticles [8,9], solubilization in surfactant systems and developing novel nano-drug delivery systems for sustained release [10][11][12][13].…”

Current Trends in MEMS Drug Delivery Techniques

“…The main reason behind improper therapeutic benefits from oral drug delivery is the presence of enzymes in the gastrointestinal track and limited permeability of the epithelial barrier. These obstacles can be abolished by using appropriate knowledge of surface chemistry with the microfabrication technology [19], [20].…”