Surgery – Controlled release therapeutic device or system
Reexamination Certificate
2001-09-25
2004-02-03
Thanh, LoAn H. (Department: 3763)
Surgery
Controlled release therapeutic device or system
C604S002000, C604S011000
Reexamination Certificate
active
06685697
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally features devices and methods for therapeutically treating the inner ear. More particularly, the invention involves a specialized, minimally-invasive technique for transporting therapeutic agents (e.g. drugs and other pharmaceutical compositions) into the inner ear from the middle ear in a highly effective manner.
BACKGROUND OF THE INVENTION
In order to treat ear disorders, it may often be necessary to deliver therapeutic agents to various ear tissues in a controlled, safe, and efficient manner. For example, a variety of structures have been developed which are capable of delivering/administering therapeutic agents into the external auditory canal of the outer ear. U.S. Pat. No. 4,034,759 to Haerr discloses a hollow, cylindrical tube manufactured of sponge material (e.g. dehydrated cellulose) which is inserted into the external auditory canal of a patient. When liquid medicines are placed in contact with the tube, it correspondingly expands against the walls of the auditory canal. As a result, accidental removal of the tube is prevented. Furthermore, medicine materials absorbed by the tube are maintained in contact with the walls of the external auditory canal for treatment purposes. Other absorbent devices designed for treatment of the external auditory canal and related tissue structures are disclosed in U.S. Pat. No. 3,528,419 to Joechle, U.S. Pat. No. 4,159,719 to Haerr, and U.S. Pat. No. 2,642,065 to Negri. The Negri patent specifically describes a medicine delivery device with an intemally-mounted, frangible medicine container which, when broken, releases liquid medicines into an absorbent member.
However, the delivery of therapeutic agents in a controlled and effective manner is considerably more difficult with respect to tissue structures of the inner ear (e.g. those portions of the ear surrounded by the otic capsule bone and contained within the temporal bone which is the most dense bone tissue in the entire human body). The same situation exists in connection with tissue materials which lead into the inner ear (e.g. the round window membrane). Exemplary inner ear tissue structures of primary importance for treatment purposes include but are not limited to the cochlea, the endolymphatic sac/duct, the vestibular labyrinth, and all of the compartments (and connecting tubes) which include these components. Access to these and other inner ear tissue regions is typically achieved through a variety of structures, including but not limited to the round window membrane, the oval window/stapes footplate, the annular ligament, and the otic capsule/temporal bone, all of which shall be considered “middle-inner ear interface tissue structures” as described in greater detail below. Furthermore, as indicated herein, the middle ear shall be defined as the physiological air-containing tissue zone behind the tympanic membrane (e.g. the ear drum) and ahead of the inner ear.
The inner ear tissues listed above are of minimal size and only readily accessible through invasive microsurgical procedures. In order to treat various diseases and conditions associated with inner ear tissues, the delivery of medicines to such structures is often of primary importance. Representative medicines which are typically used to treat inner ear tissues include but are not limited to urea, mannitol, sorbitol, glycerol, lidocaine, xylocaine, epinephrine, immunoglobulins, sodium chloride, steroids, heparin, hyaluronidase, aminoglycoside antibiotics (streptomycin/gentamycin), antioxidants, neurotrophins, nerve growth factors, various therapeutic peptides, and polysaccharides. Of particular interest in this list are compounds which are used to alter the permeability of the round window membrane within the ear using, for example, hyaluronidase and iontophoretic techniques (defined below). Likewise, the treatment of inner ear tissues and/or fluid cavities may involve altering the pressure, volume, electrical activity, and temperature characteristics thereof. Specifically, a precise balance must be maintained with respect to the pressure of various fluids within the inner ear and its associated compartments. Imbalances in the pressure and volume levels of such fluids can cause various problems, including but not limited to conditions known as endolymphatic hydrops, endolymphatic hypertension, perilymphatic hypertension, perilymphatic hydrops, perilymphatic fistula, intracochlear fistula, Meniere's disease, tinnitus, vertigo, hearing loss related to hair cell or ganglion cell damage/malfunction, and ruptures in various membrane structures within the ear.
Conventional methods for delivery of therapeutic agents to the inner ear involve filling the middle ear with a solution or other carrier of the therapeutic agent (see, e.g., Shea
Otolaryngol Clin North Am.
30(6):1051-9 (1997)). Other methods use naturally-occurring materials such as gelatin (e.g., Gelfoam, see, e.g., Silverstein Ann Otol Rhinol Laryngol Suppl. 112:44-8. (1984); Lundman et al.
Otolaryngol
112:524 (1992); Nedzelski et al.
Am. J. Otol.
14:278-82 (1993); Silverstein et al.
Ear Nose Throat J
75:468-88 (1996); Ramsay et al.
Otolaryngol.
116:39 (1996); Ruan et al.
Hear Res
114:169 (1997); Wanamaker et al.
Am. J. Otology
19:170 (1998); Arriaga et al.
Laryngoscope
108:1682-5 (1998); and Husmann et al.
Hear Res
125:109 (1998)), hyaluronan or hyaluronic acid (see, e.g., WO 97/38698; Silver stein et al. Am J Otol. 19(2):196-201 (1998)), or fibrin glue or other fibrin-based vehicle (see, e.g., Balough et al.
Otolaryngol. Head Neck Surg.
119:427-31 (1998); Park et al.
Laryngoscope
107:1378-81 (1997)). Although these methods may ultimately result in delivery of drug into the inner ear (e.g., by perfusion through the round window membrane), delivery of the therapeutic agent is generally not well controlled and/or use of the carrier materials may be associated with adverse side effects. For example, use of gelatin-based materials such as Gelfoam can cause fibrosis in the middle ear cavity (see, e.g., Laurent et al.
Am. J. Otolaryngol
7(3):181-6 (1986); Liening et al.
Otolaryngol. Head Neck Surg.
116:454-7 (1997)). Furthermore, naturally-occurring carrier materials generally do not retain their shape following introduction into the ear (e.g., the materials are naturally viscous or become more liquid upon introduction into the ear). The changes in the shape of the carrier materials make it extremely difficult to completely retrieve the materials from the site of introduction if such should be desired (e.g., to terminate therapy). Changes in the shape of the carrier material may even prevent delivery of additional therapeutic agents in subsequent treatments (see, e.g., Silverstein et al.
Am J. Otol
18:586-9 (1997), describing how gelfoam becomes paste-like and prevents future injections of this material from reaching the inner ear fluids).
Of further interest regarding the delivery of therapeutic agents to the middle ear, inner ear, and middle-inner ear interface tissue structures described in U.S. Pat. Nos. 5,421,818; 5,474,529; and 5,476,446, each of which are incorporated herein by reference. U.S. Pat. No. 5,421,818 describes a treatment system which comprises a reservoir portion with an internal cavity designed to retain a supply of therapeutic fluid compositions therein. The device further comprises fluid transfer means (e.g. pores, a semi-permeable membrane, and the like) which allows fluid materials to be delivered on-demand to, for example, the round window membrane for subsequent diffusion into the inner ear. U.S. Pat. No. 5,474,529 involves a therapeutic treatment apparatus with a plurality of reservoir portions and multiple stem portions designed for implantation into, for example, the endolymphatic sac and duct using standard microsurgical techniques. Finally, U.S. Pat. No. 5,476,446 discloses a therapeutic treatment apparatus comprising a reservoir portion for retaining liquid medicine materials therein, and first and second stems. The second stem can reside within the
Arenberg Irving K.
Arenberg Michael H.
Berglund John A.
Lemke Christine
Bell Adam
Durect Corporation
Thanh LoAn H.
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