Microchips and controlled‐release drug reservoirs

Abstract

This review summarizes and updates the development of implantable microchip-containing devices that control dosing from drug reservoirs integrated with the devices. As the expense and risk of new drug development continues to increase, technologies that make the best use of existing therapeutics may add significant value. Trends of future medical care that may require advanced drug delivery systems include individualized therapy and the capability to automate drug delivery. Implantable drug delivery devices that promise to address these anticipated needs have been constructed in a variety of ways using micro- and nanoelectromechanical systems (MEMS or NEMS)-based technology. These devices expand treatment options for addressing unmet medical needs related to dosing. Within the last few years, advances in several technologies (MEMS or NEMS fabrication, materials science, polymer chemistry, and data management) have converged to enable the construction of miniaturized implantable devices for controlled delivery of therapeutic agents from one or more reservoirs. Suboptimal performance of conventional dosing methods in terms of safety, efficacy, pain, or convenience can be improved with advanced delivery devices. Microchip-based implantable drug delivery devices allow localized delivery by direct placement of the device at the treatment site, delivery on demand (emergency administration, pulsatile, or adjustable continuous dosing), programmable dosing cycles, automated delivery of multiple drugs, and dosing in response to physiological and diagnostic feedback. In addition, innovative drug-medical device combinations may protect labile active ingredients within hermetically sealed reservoirs.

Implantable microchip: the futuristic controlled drug delivery system

“…To overcome these precincts, one of the most sophisticated methods, microfabrication technology for MEMS has been implemented for drug delivery systems (Polla et al, 2000;Webb, 2004;Sharma et al, 2006) which is the same processing techniques used to make microprocessors for computer microchips (Santini et al, 2000b). MEMS technology has been used to create reservoirs on silicon chips that can be filled with drug, reservoir seals can be added to protect and contain the drug, and device circuitry can be designed and programmed to open seals on individual reservoirs and release drug on command (Staples, 2010). A highly programmable drug release at the site of action is one of the most important benefits of these microfabricated drug delivery systems which improve drug bioavailability (Hilt & Peppas, 2005).…”

“…These micro implants offer a great deal of promise in addressing current unmet medical needs and have resulted in some of the most pioneering and elegant drug delivery concepts (Stevenson et al, 2012). Microchip technology has the potential to change the way clinicians practice drug delivery (Staples, 2010). These devices offer a range of advantages.…”

“…(Tao & Desai, 2003). Alternative materials for microfabrication processing schemes for microchips will be modified to optimize mass production (decreases cost) and to produce defect-free membranes (prevents drug leakage) (Santini et al, 2000b;Staples, 2010). In 2003, MicroCHIPS developed reservoir arrays where the metal membranes coating the reservoirs were opened by electrothermal mechanism that behaves similarly to an electrical fuse (Maloney et al, 2005) instead of electrochemically (Smith et al, 2007;Stevenson et al, 2012).…”

“…Furthermore, the structure of microchip presented by Santini, has been modified by Chung and his colleagues (Chung et al, 2008). Their depicted device contain the silicon layer containing the drug well(s) and the upper set of electrodes, while the polydimethylsiloxane (PDMS; Staples, 2010) layer served to seal the well and hold the lower electrode (Chung et al, 2008). In a recent mechanistic study, it was suggested that polypyrrol (PPy) is suitable and attractive candidates for accommodating drugs for polypyrrole-based controlled release microchip due to unique redox properties (Ge et al, 2009;Staples, 2010).…”

“…MEMS based devices have the potential to store the drugs in their most stable form, and release multiple medications at the appropriate time at which to dose each drug by opening various reservoirs on command (Maloney, 2003;Grayson et al, 2004a;Bramstedt, 2005). Such as, implantable microchips, a MEMS based drug delivery system, can be used for long-term treatment, complex dosing schedule, and/or an individualized or emergency-based dosing regimen (Staples et al, 2006;Staples, 2010). At this age of rapid advances in computer technology, it may not be long before microchips find their way from the desktop to the pharmacy (Langer, 1990).…”