Surgery – Controlled release therapeutic device or system – Osmotic or diffusion pumped device or system
Reexamination Certificate
2000-02-15
2002-10-29
Jacyna, J. Casimer (Department: 3351)
Surgery
Controlled release therapeutic device or system
Osmotic or diffusion pumped device or system
C604S891100, C424S424000
Reexamination Certificate
active
06471688
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to the field of drug delivery systems. In particular, the present invention relates to osmotic pump systems, devices, kits and associated methods for shortening the time interval between implantation of the osmotic pump system and delivery of a pharmaceutical agent to the patient. The present invention also relates to osmotic implantable systems and methods for delivering multiple drugs simultaneously (and/or sequentially), implantable osmotic systems having redundant pumps, as well as systems, methods and kits for delivering mixtures of drugs and/or potentiating drugs.
2. Description of the Related Art
Since the beginning of modern medicine, drugs have been administered orally. Patients have taken pills as recommended by their physician. The pills must pass through the digestive system and then the liver before they reach their intended delivery site (e.g., the vascular system). The actions of the digestive tract and the liver often reduce the efficacy of medication; furthermore, medications delivered systemically sometimes cause undesirable side effects. Over the course of the past few decades, drug delivery technology and administration has evolved from oral delivery to site-specific delivery. In addition to the oral route of administration, drugs are also routinely administered via the vascular system (intravenous or IV). Intravenous drug delivery has the advantage of bypassing the acidic and enzymatic action of the digestive system. Unfortunately, IV administration requires the use of a percutaneous catheter or needle to deliver the drug to the vein. The percutaneous site requires extra cleanliness and maintenance to minimize the risk of infection. Infection is such a significant risk that IV administration is often limited to a number of weeks, at most. In addition, the patient must wear an external pump connected to the percutaneous catheter.
The next step in the evolution of drug delivery was the implanted pump. The implanted pump is a device that is completely implanted under the skin of a patient, thereby negating the need for a percutaneous catheter. These implanted pumps provide the patient with a drug at a constant or a programmed delivery rate. Constant rate or programmable rate pumps are based on either phase-change or peristaltic technology. When a constant, unchanging delivery rate is required, a constant-rate pump is well suited for long-term implanted drug delivery. If changes to the infusion rate are expected, a programmable pump may be used in place of the constant rate pump. Fully implanted constant rate and programmable rate infusion pumps have been sold in the United States for human use since the late 1970s and early 1980s, respectively. Two problems associated with such 1970s and 1980s vintage constant rate and programmable rate infusion pumps relate to their size and their cost. Current implantable constant rate and programmable pumps are about the size and shape of hockey pucks, and they typically are sold to the hospital for $5,000-$9,000. The current implantable pumps must be implanted in the Operating Room under general anesthesia, which further increases costs, as well as the risk, and discomfort to the patient. The size and cost of such pumps has proven to be a substantial barrier to their use, and they are rarely used to deliver medication. An added drawback of phase-change and peristaltic pumps is that they must be refilled with drug every 3-8 weeks. Refills constitute an added burden to the caregiver, and add further costs to an already overburdened healthcare system. The burden associated with such refills, therefore, further limits the use of phase-change and peristaltic pumps.
In the 1970s, a new approach toward implanted pump design was commercialized for animal use only. The driving force of the pumps based upon this new approach utilized the principle of osmosis. Osmotic pumps may be much smaller than other constant rate or programmable pumps, because their infusion rate can be very low. An example of such a pump is described listed in U.S. Pat. No. 5,728,396, the disclosure of which is hereby incorporated herein in its entirety. This patent discloses an implantable osmotic pump that achieves a sustained delivery of leuprolide. The pump includes an impermeable reservoir that is divided into a water-swellable agent chamber and a drug chamber. Fluid from the body is imbibed through a semipermeable plug into the water-swellable agent chamber and the drug is released through a diffusion outlet at a substantially constant rate.
However, osmotic pumps of this type are configured to deliver a single drug (or a single combination of drugs) at a time and at a single delivery rate. Should the patient develop a tolerance to the drug and require an increased dose to alleviate pain, for example, such a single drug/single dose pump is unable to provide the needed relief. In such a case, the physician may need to supplement the drug delivered by the implanted pump with another drug or more of the same drug, delivered via an intravenous route, for example. This, however, defeats the purpose of the implanted pump, namely to provide a self-contained drug delivery system that operates with little or no discomfort to the patient. What are needed, therefore, are novel implantable pumps and pump systems able to deliver a drug at more than a single rate.
There may be instances, moreover, when a simple increased dose of the same drug is ineffective to achieve the desired therapeutic result. In such cases, the administration of another drug may be indicated, whether in place of or in addition to the originally delivered drug. Conventional osmotic pumps, however, are single drug or single drug combination devices: they can only infuse a single drug or a single combination of drugs at a time. To administer another drug, several alternatives are available, all of which involve significant discomfort to the patient. One such alternative is to administer the other drug intravenously while the osmotic pump remains implanted. Another alternative is to surgically remove the originally implanted drug and to implant another osmotic pump configured to deliver the other drug. These alternatives are also the only ones available when the implanted osmotic pump fails to function or runs out of drug, whether at the end of its useful life or whether the pump fails unexpectedly. What are also needed, therefore, are implantable osmotic pump systems configured for the selective delivery of more than one drug or more than one drug combination, at individually selectable rates. Also needed are implantable osmotic pump systems that include a built-in backup drug delivery system, the backup system being effective to continue the delivery of the drug when the primary delivery system reaches the end of its useful life or fails unexpectedly.
SUMMARY OF THE INVENTION
It is an object of the present invention, therefore, to provide novel implantable pumps and pump systems adapted to deliver a drug at more than a single rate. It is another object of the present invention to provide implantable osmotic pump systems configured for the selective delivery of more than one drug or more than one drug combination, at individually selectable rates. A still further object of the present invention is to provide osmotic pump systems that include a built-in backup drug delivery system, the backup system being effective to continue the delivery of the drug when the primary delivery system reaches the end of its useful life or fails unexpectedly.
In accordance with the above-described objects and those that will be mentioned and will become apparent below, an implantable osmotic pump system, according to an embodiment of the present invention includes a first osmotic pump including a first semipermeable membrane; a second osmotic pump including a second semipermeable membrane, and a single catheter attached to both the first and the second osmotic pumps.
The catheter may include a first lumen and a second lumen
Harper Derek J.
Milo Charles F.
MicroSolutions, Inc.
Young Law Firm P.C.
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