Implantable Pressure-Actuated Drug Delivery Systems and Methods of Manufacture and Use
Coronary stents are commonly used to treat heart attacks. Stents, however, have been known to abruptly clot. Conventional stent clot treatment includes emergency angioplasty, which is expensive, difficult to coordinate, and accompanied by relatively high mortality rates. Conventional intracoronary drug-delivery systems are passive. Drugs are released with predetermined kinetics, and these systems cannot sense nor respond to new, abrupt environmental changes such as clotting. Active drug-delivery systems deliver drugs in response to an external stimulus, but conventional systems require a bulky or externalized power source and a separate sensor and are unsuitable for intracoronary application.
A team of researchers consisting of materials researchers at The Johns Hopkins Applied Physics Laboratory and physicians at The Johns Hopkins Medical Institute has developed a small-scale (100-ým diameter), implantable, minimally invasive, and mechanically actuated drug-delivery system that overcomes the limitations of conventional implantable devices described above. The JHU drug-delivery system is shown below in FIG. 1. Specifically, the implantable pressure-actuated system (labeled 100) delivers a drug (labeled 106) in response to a pressure difference between a system cavity (labeled 108) and an exterior environment, such as an interior of a blood vessel. A pressure-rupturable membrane or diaphragm (labeled 104) may be tuned to rupture at a desired rupture pressure (e.g., at a predetermined range of blood pressure). The diaphragm-protective layer (labeled 114) may be provided to prevent premature diaphragm rupture at atmospheric pressure before implantation, and the layer is designed to dissipate (e.g., dissolve) within an implant environment, such as in a vein. Under normal conditions, the integrity of the diaphragm is maintained by the counteracting pressure of the implant environment. When the counteracting pressure of the implant environment falls, such as when there is a loss of blood pressure due to an occlusive blood clot (heart attack condition), and the pressure difference across the diaphragm protective layer falls, the diaphragm ruptures and the drug is released or delivered into the implant environment (e.g., intravenously).
The drug and/or other substance used in the system may include, for example, a thrombolytic, plasminogen, plasmin, heparin, and/or other antithrombotic agent, antiplatelet agent, anti-inflammatory agent, immunomodulator, and/or other medication.
The JHU drug-delivery system may be implemented alone and/or in combination with one or more other implant platforms, such as a stent (for example, a coronary, noncoronary, or peripheral stent). It does not require an external power source nor a separate sensor, which is a significant improvement over conventional implantable devices.
Patent Status: U.S. and international patents pending.CONTACT:
Mr. J. E. Dietz
Phone: (443) 778-2782