(93b) Drug Delivery from a Biodegradable Polymeric Microchip Device

The biodegradability of component materials is critical when designing a drug delivery device. The primary motivation for creating a biodegradable polymeric drug-delivery device is the long term ability to treat conditions requiring pulsatile drug release. Current polymeric microchip device fabrication presents new challenges for future implementation of the technology. Biodegradable polymeric microchips are fabricated from poly (L-lactic acid) (PLLA) by means of two compression-moulding steps. After loading the drug, the back of the microchip is sealed with a pressure sensitive adhesive. It is the only part of the device that is not biodegradable, which means surgery is required to implant the device and a second surgery is required to remove the adhesive. The focus of this project was to develop a biodegradable sealing mechanism to prevent the need for a second surgery. This was accomplished in two separate phases. First, the sealing technique was constructed by investigating lamination of several biodegradable thin films. Biodegradable polymeric microchips 1.2 cm in diameter, 370-420µm thick with 36 reservoirs were fabricated for the study. Sealing of the microchip was done by lamination of a 56µm poly(lactic acid) film on a 370-420µm thick PLLA backing-chip at 40˚C under 12500psi for 10 minutes. PLLA was chosen for the laminate because of its long biodegradation time and its well-characterized biocompatibility and biodegradation. Finally, reservoirs were sealed by micro-injection of poly(lactic-co-glycolic acid) (PLGA) membranes to control the time at which radiolabelled Dextran was released from the device. The long biodegradation time enables the Dextran to be completely released from the device before the backing-chip and the microchip degrades. Comparing the results of the PLLA sealing technique with the pressure sensitive adhesive, this technique offers some unique properties for fabricating a completely biodegradable and biocompatible drug delivery device.