Implantable, Magnetically Operated Micro Device Delivers Controlled Drug Doses

A recent paper described the development of a magnetically controlled MEMS (micro-electromechanical system) device capable of on-demand release of defined quantities of anticancer or other drugs.

The device was designed by investigators at the University of British Columbia (Vancouver, Canada) for implantation behind the eye for controlled and on-demand release of drugs to treat retinal damage caused by diabetes.

In a proof-of-concept study published in the June 23, 2011, online edition of the journal Lab on a Chip, the investigators described the assembly of a device consisting of a drug-loaded microreservoir sealed by an elastic magnetic PDMS (polydimethylsiloxane) membrane with a laser-drilled aperture. By applying a magnetic field, the magnetic PDMS membrane deformed, causing the discharge of the drug solution from the reservoir section of the device at a controllable rate.

In the current study the investigators used devices with reservoirs loaded with the antiproliferative drug, docetaxel (DTX) to conduct cytotoxicity assays on two cell lines, HUVEC (human umbilical vein endothelial cells) and PC3 (prostate cancer) cells. Results indicated that reproducible release rates were achieved and DTX within the PDMS MEMS reservoir maintained full pharmacological efficacy for more than two months.

In the absence of a magnetic field, the implantable devices maintained their integrity with negligible leakage for more than 35 days.

“We wanted to come up with a safe and effective way to help diabetic patients safeguard their sight,” said senior author Dr. Mu Chiao, associate professor of nanoscience and micro-electromechanical systems at the University of British Columbia. “Technologies available now are either battery operated and are too large for treating the eye, or they rely on diffusion, which means drug release rates cannot be stopped once the device is implanted -- a problem when patients' conditions change.”

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