Method for delivering a medication

Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...

Reexamination Certificate

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C604S891100, C604S093010, C604S514000, C604S517000

Reexamination Certificate

active

06183461

ABSTRACT:

BACKGROUND OF THE INVENTION
I. Field of the Invention
The present invention relates to an infuser suitable for use within the bladder and methods of using the infuser.
II. Description of the Related Art
Delivery of drugs to the bladder is typically accomplished systemically. Systemic drug delivery through oral, intravenous, intramuscular, or transdermal administration methods carries with it the obvious drawbacks of any systemic treatment, such as side effects. The drug may also be metabolized or altered by physiological processes, and the ultimate quantity of active drug that reaches the bladder may be reduced. In addition, because many drugs are not well tolerated systemically, the dosage must be limited, thereby reducing the total effective dose that reaches the bladder.
Delivery of drugs to the bladder can also be accomplished by retrograde injection of the drug into the bladder via catheter. Retrograde introduction of drug via a urethral catheter, however, is suitable only for limited situations and has inherent drawbacks. See for example, Bladder Tissue Pharmacokinetics of Intravesical Taxol, Song, D, Wientjes, MG, Au, JL, Cancer Chemotherapy and Pharmacology, 1997, 40(4): 285-92; The Pharmacokinetics of Intravesical and Oral Oxybutynin Chloride, Massad, CA, Kogan, BA, Trigo-Rocha, FE, Journal of Urology, 1992, August, 148(2 Pt 2): 595-7; Advances in Drug Delivery and Targeting, Goldstein, D, Lewis, C, Current Opinion in Oncology, 1991 December 3(6): 1096-104; and Intravesical Hyaluronic Acid in the Treatment of Refractory Interstitial Cystitis, Morales, A, Emerson, L, Nickel, JC, Urology 49 (Suppl 5A): 111-113, 1997. Retrograde introduction of drug via urethral catheter is primarily used only in a hospital or managed care situation. It is not suitable for treatment of chronic urinary-tract conditions.
Stephen et al., U.S. Pat. No. 5,301,688, discloses a method for treating bladder cancers through electromotive administration of drugs into the bladder via a catheter. This type of treatment is suitable primarily for care administered on an in-patient or out-patient basis, not for chronic treatment.
Tsukada, U.S. Pat. No. 5,219,334 discloses an infuser for connection to a catheter that is suitable for long-term delivery of drug into a patient through the catheter. This device requires continuous catheterization in order to function adequately.
Pryor et al., U.S. Pat. No. 5,062,829, discloses a helical device for insertion into a body cavity, e.g., the rumen of a bovine. The helical device includes a drug that can be released over time and further includes a biodegradable portion so that, upon exhaustion of the drug, the device can break up and be naturally eliminated.
Garay et al., U.S. Pat. No. 4,925,446, discloses an infusion device having an annular shape that is suitable for delivering materials into the stomach over a prolonged period of time.
None of these prior art devices address the problem of intravesical drug delivery where drug delivery is intended to continue over a prolonged period of time while the patient maintains an active lifestyle.
Two of the major causes of urge incontinence are detrusor instability and hyperreflexia. Oxybutynin is a pharmacological agent that has been used to treat urge incontinence with some success. This drug is an anticholinergic agent that blocks contraction to the bladder and has direct smooth muscle relaxant properties. Unfortunately, this drug is associated with significant side effects upon oral administration, including dry skin, dry mouth, blurred vision, constipation, and urinary retention. In patients with cardiovascular disease, oxybutynin may lead to tachycardia. Because of the side effects, the accepted oral dose of oxybutynin is limited to 10-15 mg per day.
Interstitial cystitis is a debilitating condition in which the lining of the bladder is irritated, creating a sense of urgency and pain. The condition results in extreme frequency of urination, sometimes as many as 40, 50, or more times per day and can lead to cystectomy. Sufferers of interstitial cystitis can be treated by administration of certain drugs, including pentosanpolysulfate, manufactured by Bene of Munich, Germany and distributed by ALZA Corporation of Palo Alto, Calif. under the trademark ELMIRON. However, there is currently no satisfactory method for delivery of pentosanpolysulfate to a patient over a prolonged period of time while permitting the patient to enjoy a relatively normal lifestyle.
There is a need for a site specific delivery system of drugs for treating bladder and urinary tract disease that will avoid the side effects associated with these pharmacological agents and allow the patient to enjoy an active lifestyle.
SUMMARY OF THE INVENTION
In one aspect of the present invention, there is provided an implantable infusion device comprised of a reservoir containing a drug and a flow-restricted exit port in fluid communication with the drug in the reservoir. The device also is comprised of a coating adapted to inhibit deposition of material on the device when implanted in a body cavity of a mammal. For example, the coating may inhibit deposition of materials present in the urinary tract. The coating may be a sulfated polysaccharide such as pentosanpolysulfate. The coating may be a surface coating on surfaces of the device exposed to the body upon implantation. The coating may be impregnated into the device. In addition or alternatively, a coating may be applied to the device to increase its lubricity.
The flow-restricted exit port may provide delivery of the drug over a period of at least 24 hours, 5 days, 15 days or more. The drug may be in a liquid form and the device may deliver the drug at a rate of less than about 400 &mgr;l/hour.
The device may assume a first shape during implantation and a second shape after implantation into the mammal. For example, the device may assume the first shape when empty and the second shape when filled. The first shape may be generally elongated and the second shape may be arcuate. The reservoir of the device may be elastomeric.
The drug within the device may be effective to treat incontinence such as urge incontinence. For example, the drug may be oxybutynin. The drug may also be an anesthetic, analgesic, antibiotic, or anti-cancer agent. Additionally, the drug may be used to treat cystitis.
The device may have a first end and a second end. One of the ends may be buoyant or both the first end and the second end may be buoyant. The device may be sized to fit through a urethra into a mammalian bladder.
Another aspect of the present invention relates to an implantable infusion device comprised of an elongated elastomeric portion having a first end and a second end and adapted to contain and pressurize a liquid. The device may also comprise a flow controller providing an exit port in fluid communication with the liquid in the elastomeric portion. The flow controller may provide for controlled release of the liquid from the device. The device may also comprise a relatively inextensible member connecting the first and second ends of the elastomeric portion in such a way as to allow a relatively straight configuration of the device when unfilled with the liquid and to urge a curved configuration of the device when filled with the liquid. The relatively inextensible member may be inside the elastomeric portion. The elastomeric portion may include a wall and the relatively inextensible member may be associated with the wall. Alternatively, the relatively inextensible member may form a part of the wall. The relatively inextensible member may also be outside of the elastomeric portion.
The implantable infusion device may further comprise an encrustation-resistant coating on the device. For example, the coating may be pentosanpolysulfate. The device may comprise a buoyant portion at the first end. In addition, the device may comprise a buoyant portion at the second end.
Another aspect of the present invention relates to a system for implanting an infusion device. The system is comprised of an elongated infusion device

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