Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
1995-06-07
2003-02-25
Sykes, Angela D. (Department: 3762)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C604S265000, C604S021000, C604S509000, C604S103010, C604S103020, C606S194000, C600S435000, C427S002250
Reexamination Certificate
active
06524274
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to delivery of drugs to a desired location within the body.
BACKGROUND OF THE INVENTION
Systemic administration of drugs treats the organism as a whole, even though the disease may be localized, such as occlusion of a duct or vessel. When administered to a patient systemically, many drugs, e.g., chemotherapeutic drugs such as those used to treat cancer and benign prostate hyperplasia, cause undesirable side effects. Localization of a drug poses special problems in cases involving the walls of ducts and vessels, since, by nature, these organs serve as transport systems.
Artherosclerotic disease, for example, causes localized occlusion of the blood vessels resulting from the build-up of plaque. As the deposits increase in size, they reduce the diameter of the arteries and impede blood circulation. Angioplasty, which involves the insertion of catheters, such as balloon catheters, through the occluded region of the blood vessel in order to expand it, has been used to treat artherosclerosis.
The aftermath of angioplasty in many cases is problematic, due to restenosis, or closing of the vessel, that can occur from causes including mechanical abrasion and the proliferation of smooth muscle cells stimulated by the angioplasty treatment. Restenosis may also occur as a result of clot formation following angioplasty, due to injury to the vessel wall which triggers the natural clot-forming reactions of the blood.
SUMMARY OF THE INVENTION
The invention features a method for delivering a drug to tissue at a desired location within the body comprising the following steps: providing a catheter constructed for insertion in the body, a portion of which carries a hydrogel having the capacity to incorporate a predetermined substantial amount of a drug which is substantially immobilized in the hydrogel until released by a triggering agent or condition that differs from ambient physiological conditions; introducing the catheter to the body to the point of desired drug application; and exposing the hydrogel to the triggering agent or condition. Exposure of the hydrogel to the triggering agent or condition triggers release of the drug from the hydrogel for delivery to the desired location within the body.
The invention also features a method for triggering release of a drug from a hydrogel to a tissue at a desired location of the body using a balloon catheter such as a non-vascular or vascular catheter, e.g., an angioplasty catheter. The balloon portion of the catheter is coated on its outer surface with a hydrogel having the capacity to incorporate a predetermined substantial amount of drug which is substantially immobilized in the hydrogel until released by a triggering agent or condition which is different from ambient physiological conditions. Preferably, the catheter has a porous balloon portion, e.g, a balloon with channels or pores through which a solution containing a triggering agent can pass and come in contact with the hydrogel. The invention also includes a kit for triggering release of a drug from a hydrogel-coated drug delivery catheter and a catheter for triggered drug delivery.
The method of triggered drug delivery includes the following steps: providing a catheter constructed for insertion in the body with a catheter shaft having an expandable hydrogel-coated porous balloon portion mounted on the catheter shaft which is expandable to engage the tissue at a controlled pressure to fill a cross-section of the body lumen and press against the body lumen wall; introducing the catheter to the body lumen wherein the balloon portion is positioned at the point of desired drug application; expanding the balloon portion to engage the tissue; and infusing the triggering agent into the hydrogel. Upon contact of the triggering agent with the hydrogel, the drug is released at the desired location of the wall of a body lumen.
Following release of the drug from the hydrogel coating, the hydrogel coating may be replenished with an additional dose of drug delivered to the hydrogel from the catheter through pores or channels in the porous balloon portion. The drug contacts the hydrogel and becomes immobilized in the hydrogel until a subsequent delivery of triggering agent to the hydrogel, which in turn, triggers release of the additional dose of drug. This process of replenishment of hydrogel with drug and triggered release may be repeated as many times as desired.
The drug to be delivered is associated with the hydrogel by covalent, ionic or hydrogen bonding. Preferably, the associations are ionic interactions, and the triggering agent increases local ionic strength causing release of the drug from the hydrogel. A change in ionic strength may also affect the hydrogel itself, causing a volume phase transition, e.g., an expansion or contraction, of the hydrogel, thus triggering release of the drug. The drug may also be associated with the hydrogel by hydrogen-bonding, and the drug released by a change in pH.
The drug may be cationic and the hydrogel anionic. Alternatively, the drug may be anionic and the hydrogel cationic. In either situation, release of the drug is induced by contacting the hydrogel with a physiologically-acceptable saline solution, the ionic strength of which differs from that of ambient physiological conditions. The saline solution alters the ionic strength in the microenvironment of the hydrogel, thus triggering drug release. Preferably, the solution consists essentially of 0.2M to 5 M NaCl, more preferably 0.2M to 3.5 M NaCl, and most preferably 0.1 to 0.2M NaCl. In addition to a physiologically-acceptable saline solution, any salt solution may be used to trigger drug release, e.g., sodium phosphate, sodium bicarbonate, sodium citrate, potassium chloride, sodium sulfate, or sodium acetate. The solution may also contain inactive ingredients, e.g., buffering agents or preservatives.
A variety of drugs may be delivered using the claimed methods. The drug may be an anti-thrombogenic drug, such as heparin; low molecular weight heparin, e.g., ENOXAPRIN; aspirin; phe-L-pro-L-arginyl chloromethyl ketone (PPACK); hirudin, HIRULOG®; Warfarin; Argatroban; or tissue factor pathway inhibitor (TPFI). The drug may also be a thrombolytic drug, such as urokinase; pro-urokinase; streptokinase; tissue plasminogen activator; anisolated plasminogen streptokinase activator complex (APSAC), e.g., EMINASE®; an inhibitor of PAI-1, TA plasminogen; or cathepepsin D. Anti-platelet agents, such as chimeric 7E3 antibody (Reopro); Ticolpidine; Integrilin; TP9201; nitric oxide (NO) and derivatives thereof, e.g., protein-linked NO; Iloprost, or MK383, may be similarly delivered and triggered. Other drugs suitable for delivery in this manner include protein and polypeptide drugs, e.g., angiogenesis factors including but not limited to fibroblast growth factor (FGF), vascular endothelial growth factor (VEGF), transforming growth factor-beta, (TGF&bgr;), platelet-derived growth factor (PDGF), epidermal growth factor (EGF), and urokinase. Other drugs to be delivered according to the invention include those to treat benign hyperplasia, e.g., PROSCAR®, and HYTRIN®. Other drugs include antiproliferative drugs, such monoclonal antibodies capable of blocking smooth muscle cell proliferation, e.g., anti-PDGF and anti-FGF; tyrosine kinase inhibitors, e.g., tyrophosphins, antisense oligonucletides to c-myc, c-myb; NO; gene encoding thymidine kinase (TK); fusion toxins, e.g, DAB
389
-EGF; immunotoxins, angiopeptin; antioxidant drugs, e.g., probudol, lovastatin, vitamin C and vitamin E; calcium channel blockers, e.g., nificitine, veratimil, ACE inhibitors, fofinopril and cilazapril. Chemotherapeutic drugs to treat various forms of cancer, e.g., HLB-7; granulocyte macrophage colony stimulating factor (GM-CSF); interferon&ggr;; immunotoxins, e.g., BMS-18224801, and BR-96-DOX; ONCOLYSIN®; fusion toxins, e.g., DAB
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-IL-2, and DAB
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-EGF; 5-Fluorouracil; methotrexate; and TAXOL®. The drugs may be in any form capable of associating with the hydrogel and subsequently being released fro
Barry James J.
Rosenthal Arthur
Sahatjian Ronald
Bianco Patricia
Kenyon & Kenyon
Scimed Life Systems Inc.
Sykes Angela D.
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