Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
2000-03-02
2001-10-16
Aftergut, Jeff H (Department: 1733)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S242000, C156S244110, C156S293000, C600S435000, C604S529000
Reexamination Certificate
active
06302990
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
In general, this invention relates to infusion catheters. More specifically, this invention relates to an infusion catheter for delivering fluid into an organism where the catheter has a non-reactive lining and tip, surrounded partially by a flexible silicone-type material.
2. Description of the Related Art
When chronic administration of a pharmaceutically active agent is required, internal delivery by an external infusion pump or an implantable infusion pump (“IIP”), in combination with a catheter, may be the desired delivery means. For example, IIP-catheter delivery may be preferred when, for example, the site specific delivery of the drug is critical, or the drug must be administered in tightly controlled, yet minute dosages.
In applications where the quantity of delivered drug is relatively minute and must be carefully tailored, it may be critical that the delivered drug be non-reactive with the material of the catheter. Non-reactive means that the delivered drug flows from the IIP to the delivery site without adhering to, diffusing through, or otherwise chemically reacting with, the catheter itself. Standard delivery catheters normally comprise a single tubular member and are composed of a flexible elastomeric material, typically silicone, that is biocompatible with the animal body into which the desired agent is delivered. A more recent design includes an internal lining that is more compatible with the agent desired to be delivered while maintaining the biocompatibility of the external catheter sheath.
FIG. 1
depicts a portion of a typical prior art implantable catheter
10
with a drug compatible internal lining. Catheter
10
comprises a tubular jacket or sheath
12
that is coupled at one end to the IIP (not shown) and terminates at its other end in a rounded tip
14
. One or more elution holes
16
are disposed in sheath
12
proximate the rounded tip
14
. Sheath
12
is ordinarily tubular and manufactured from a flexible biocompatible elastomeric material such as silicone. It is desirable for sheath
12
to be both flexible and biocompatible. A flexible material makes catheter
10
easier to conform to the various curved passageways in the body during placement and use. The biocompatibility of sheath
12
will enable catheter
10
to remain in the body for prolonged periods of time without prompting an immune system response. The interior of sheath
12
is lined with a tubular lining
18
which is coextensive with sheath
12
from the IIP (not shown) to a sheath/lining seal point
20
. Catheter
10
may not be manufactured solely of this material because the material may often be too rigid to make a usable catheter for actual use. Sheath/lining seal point
20
is ordinarily located a few millimeters from the elution holes
16
. The lining
18
is ordinarily fabricated from a material that will be non-reactive with the delivered agent such as polyethylene, polyurethane or polytetraflouroethylene (PTFE) or TEFLON® as it is commonly known in the trade.
If the delivered drug is sensitive to the material of sheath
12
, the delivered drug may either be adsorbed by sheath
12
, diffuse across sheath
12
or react chemically with sheath
12
or with substances diffusing through sheath
12
from outside catheter
10
. For example, if the delivered drug is adsorbed by sheath
12
, the amount of delivered drug may be significantly less than the required dosage. Similarly, if undesirable agents diffuse through sheath
12
and react with the delivered drug, the amount and efficacy of the delivered drug may be compromised. Because the seal point
20
is directly exposed to the delivered drug, there is the potential for undesirable seepage of the drug between sheath
12
and lining
18
.
Many drugs or agents exhibit some detrimental sensitivity to silicone or drugs or agents that may diffuse through a silicone sheath. Insulin presents one example. In certain circumstances, carbon dioxide may diffuse through a silicone sheath. If insulin is flowing through catheter
10
, carbon dioxide from outside catheter
10
may diffuse through sheath
12
and react with the buffer in the insulin solution, causing a pH change in the insulin solution. As a result, the insulin buffer breaks down, causing degradation and polymerization of the insulin to occur. In some applications involving the chronic dispensing of insulin, suitable buffers to counteract the pH changes brought on by CO
2
diffusion are simply not feasible.
Another example of drugs sensitive to silicone is presented by neurotrophic factors such as nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), ciliary neurotrophic factor (CNTF), or glial-derived neurotrophic factor (GDNF), currently being studied as potential therapies for amyotrophic lateral sclerosis, Parkinson's Disease, or other neurological disorders. The particular neurotrophic factor may either be adsorbed by the interior surface of the silicone sheath
12
, or alternatively react with the silicone sheath
12
and degrade into secondary components. The dosage levels for such neurotrophic factors may be so small that an appreciable loss or degradation of the delivered agent will adversely effect the agent's ability to satisfactorily treat the patient.
In the prior art catheter
10
shown in
FIG. 1
, extension of the lining
18
past the elution holes
16
has proved to be impractical, since it has been difficult, if not impossible, to adequately seal the interfaces between sheath
12
and lining
18
that are in fluid communication with the elution holes
16
. The present invention is directed to solving one or more of the above-noted problems.
SUMMARY OF THE INVENTION
In one aspect of the present invention a catheter is provided. The catheter includes an elongated inner liner that has an open first end, a distal end that has at least one opening, and a first length. An elongated jacket is disposed about the inner liner and has a second length less than the first length whereby fluid flowing in the inner liner is isolated from the jacket. The problems associated with the infused drug or agent being sensitive to the material of the jacket are eliminated by making the inner liner completely coextensive with the interior of the jacket.
In another aspect of the present invention, a catheter system for delivering agents, drugs or other fluids to a selected site within an organism is provided. The system has a catheter and a pump coupled to the catheter for delivering the fluid to the catheter. The catheter is the novel catheter described above and in more detail hereafter with the catheter additionally being in fluid communication with the pump. The jacket, disposed about the inner liner, extends from the pump to the distal end of the catheter and is isolated from fluid flowing in the inner liner.
The invention will now be described in detail with reference to the accompanying drawings where like elements, wherever referred to, are referred to with like reference numbers.
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Aftergut Jeff H
Berry Tom
Kinghorn Curtis D.
Medtronic Inc.
Waldkoetter Eric R.
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