CROSS-REFERENCE TO REPLATED APPLICATIONS
This application is a continuation of U.S. patent application Ser. No. 12/168,468 entitled “Complementary Drug Delivery Sheath for an Implantable Medical Device”, filed on Jul. 7, 2008, now issued as U.S. Pat. No. 8,160,714 on Apr. 17, 2012, which claims the benefit of U.S. Provisional Patent Application 60/948,411 entitled “Complimentary Drug Delivery Sheath for an Implantable Medical Device”, filed on Jul. 6, 2007. The content of each of these applications is incorporated herein by reference in their entirety.
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1. Field of the Invention
The present invention relates generally to implantable medical devices, and more particularly, to a complementary drug delivery sheath for an implantable medical device.
2. Related Art
Implantable medical devices are capable of providing a wide range of benefits to a patient. For example, implantable prosthetic hearing devices process ambient sound to supplement or provide hearing ability to hearing impaired patients (sometimes referred to herein as “recipients”).
Implantable prosthetic hearing devices include a category of implantable devices known as Cochlear™ implants (also referred to as Cochlear™ devices, Cochlear™ implant devices, and the like; “cochlear implants” herein). (COCHLEAR is a trademark of Cochlear Limited, Lane Cove, NSW, Australia.) In cochlear implants, an array of stimulation electrodes is implanted in a recipient's cochlea. This array is controlled by an electronic system encased in a hermetically sealed, biocompatible housing typically implanted in the mastoid. The electronic system essentially contains decoder and driver circuits for the stimulation electrodes. Acoustic sound reception and conversion of acoustic signals into electrical signals typically occurs externally in a sound processor worn by the recipient. The sound processor superimposes the preprocessed signals, properly coded, on a high frequency carrier signal which is transmitted transcutaneously to the implanted components through the closed skin. A microphone is located outside of the recipient's body, typically in a behind-the-ear housing worn on the auricle.
Traditionally, there has been interest in delivering bioactive substances or chemicals (generally and collectively referred to herein as “drugs”) in conjunction with a cochlear implant and other implantable medical devices for a variety of purposes. For example, in one conventional approach the implantable medical device is coated with a bioactive substance. In another conventional approach a bioactive substance is integrated into the polymeric coating of the implantable medical device. In other conventional approaches various techniques for delivering drugs in liquid form to a target location in a patient from an external or implanted reservoir.
These and other conventional approaches typically require the incorporation of the drug into the implantable medical device during the manufacturing process of the device. This introduces a number of difficult problems and challenges for the manufacturing and sterilization processes, particularly for complex implantable medical devices. On the other hand, the use of reservoirs provides significant limitations to many aspects of the administration of the drug therapy.
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In accordance with one aspect of the present invention, a kit of implantable components for implantation in a recipient is disclosed. Embodiments of the kit comprise an implantable medical device and a drug delivery sheath physically separate from the device and configured to be implanted in the recipient proximate to the device, comprising: at least one pannicular substrate configured to be operably positioned adjacent to one or more surfaces of the device subsequent to the device's manufacture, and at least one drug carried on the at least one substrate so as to be released into the recipient.
In accordance with a second aspect of the present invention, a complementary drug-delivery sheath for implantation into a recipient of an implantable medical device is disclosed. Embodiments of the complementary drug-delivery sheath comprise: a pannicular substrate having dimensions which enable the sheath to be implanted proximate to one or more surfaces of the device; and at least one drug carried in the substrate for release into the body of the recipient.
BRIEF DESCRIPTION OF THE DRAWINGS
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Illustrative embodiments of the present invention are described herein with reference to the accompanying drawings, in which:
FIG. 1A is an embodiment of a cochlear implant device which may be advantageously complemented with an embodiment of a drug-delivery sheath of the present invention;
FIG. 1B is a perspective view of a region or portion of a drug-delivery sheet of the present invention showing a pannicular substrate on which components of a drug are releasably secured, in accordance with embodiments of the present invention;
FIG. 2A is a top view of an embodiment the present invention comprising a single drug-delivery sheath configured to be disposed on top of an implantable medical device such as the stimulator unit illustrated in FIG. 1A when the stimulator unit is implanted in a recipient;
FIG. 2B is a side view of the embodiment the present invention illustrated in FIG. 2A;
FIG. 3A is a side view of an embodiment the drug-delivery sheath of the present invention in the form of a conformal pouch or pocket configured to receive an implantable medical device such as the stimulator unit illustrated in FIG. 1A;
FIG. 3B is a side view of the embodiment the present invention illustrated in FIG. 3A;
FIG. 4 is a top view of an embodiment the present invention having a drug-loaded component sheath configured to be partially disposed on the stimulator unit illustrated in FIG. 1A;
FIG. 5 is a top view of an alternative embodiment a drug-delivery sheath configured to be secured at the implant site for the implantable medical device; and
FIG. 6 is a side view of an alternative embodiment a drug-delivery sheath of the present invention.
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The present invention is generally directed to a complementary drug-delivery sheath for implantable medical devices. Embodiments of the complementary drug-delivery sheath are covered, impregnated or otherwise carry one or more drugs and, as such, are at times referred to herein as drug-delivery sheaths.
Embodiments of the complementary drug-delivery sheaths physically separate from the implantable medical device and, as such, may be manufactured separately from to the implantable medical device. The complementary drug-delivery sheath is operationally combined with the implantable medical device subsequent to the device\'s manufacture and/or sterilization. For example, embodiments of the complementary drug-delivery sheath may be configured, for example, to attain an implanted position adjacent to one or more surfaces of an implantable medical device. In certain embodiments, the sheath is configured in the form of a glove, pocket, pouch, or the like (collectively and generally referred to as a “pouch” herein), to receive and to partially or completely wrap around or envelop (“envelop” herein) all or a portion of an implantable medical device. Embodiments of the complementary drug delivery sheath may be implanted into the recipient prior to, concurrently with, or subsequent to the implantation of the implantable medical device.
Providing an independently-manufactured and physically distinct, complementary drug delivery sheath to an implantable medical device increases flexibility in the applied therapy while reducing the undesirable aspects associated with manufacturing an implantable medical device with a drug integrated therein. For example, this enables manufacturing efforts to be focused solely on the successful manufacture of the implantable medical device rather than on manufacturing an integrated assembly of the device and drug-delivery mechanism. Additionally, the implantable medical device may be manufactured as a universal device which may be complemented with different embodiments of the drug-delivery sheath. This advantageously enables a single implantable component to be manufactured and inventoried for a length of time not determined by a drug. This is particularly advantageous in those circumstances in which the drug to be delivered via the sheath has a limited shelf life.
As used herein, the term ‘drug” refers to any bioactive substance now or later developed, including, but not limited to, pharmaceuticals and other chemical compounds such as those intended to provide therapeutic benefits to, or other reactions in, an implant recipient, whether localized or distributed throughout the recipient. Such bioactive substances may include, for example, steroids or other anti-inflammatory drug to reduce inflammation at the implantation site. Another class of bioactive substances that may be included in the drug-delivery sheath are antibiotics to mitigate bacterial growth related to the implantation of the medical device.
FIG. 1A is a perspective view of an exemplary cochlear implant with which a complementary drug-delivery sheath of the present invention may be implemented. In fully functional human hearing anatomy, outer ear 101 comprises an auricle 105 and an ear canal 106. A sound wave or acoustic pressure 107 is collected by auricle 105 and channeled into and through ear canal 106. Disposed across the distal end of ear canal 106 is a tympanic membrane 104 which vibrates in response to acoustic wave 107. This vibration is coupled to oval window or fenestra ovalis 110 through three bones of middle ear 102, collectively referred to as the ossicles 111 and comprising the malleus 112, the incus 113 and the stapes 114. Bones 112, 113 and 114 of middle ear 102 serve to filter and amplify acoustic wave 107, causing oval window 110 to articulate, or vibrate. Such vibration sets up waves of fluid motion within cochlea 115. Such fluid motion, in turn, activates tiny hair cells (not shown) that line the inside of cochlea 115. Activation of the hair cells causes appropriate nerve impulses to be transferred through the spiral ganglion cells and auditory nerve 116 to the brain (not shown), where they are perceived as sound. In deaf persons, there is an absence or destruction of the hair cells. A cochlear implant 120 is utilized to directly stimulate the ganglion cells to provide a hearing sensation to the recipient.