Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form
Reexamination Certificate
1994-02-28
2002-05-14
Webman, Edward J. (Department: 1617)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
C427S492000, C427S495000, C427S496000, C427S498000, C427S507000, C427S535000, C427S536000, C427S539000, C427S491000, C427S002100, C427S002120, C606S151000, C606S159000, C604S093010, C623S008000, C523S106000
Reexamination Certificate
active
06387379
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to materials or articles, the surfaces of which are adapted for contact with human or non-human animal tissue, and methods for enhancing the biofunctional properties of the tissue contacting surfaces thereof.
2. Discussion of the Prior Art
At the present time, surgical instruments, various medical devices, catheters, prosthetic implants, endoscopic and minimal invasive surgical devices, contact lenses and the like which are intended for contact with blood or with sensitive tissue surfaces are constructed of materials having the necessary physical properties to enable their use for the intended application; however, they suffer from the disadvantage that due to the generally hydrophobic nature of the blood or tissue contacting surfaces thereof, they exhibit undesired thrombogenic properties and, as noted in the following discussion for ocular implants, significant damage may occur to various fragile or sensitive tissues (i.e., vascular and corneal endothelium, tracheal and ureteral serosal tissues, etc.) by adhesion and manipulation or movement on contact with these instruments.
In U.S. Pat. No. 4,961,954, there are described improved methods for producing hydrophilic, gamma irradiation induced polymerized and chemically grafted coatings on such instruments, devices and the like so constructed of a variety of polymeric materials.
The invention described in U.S. Pat. No. 4,961,954 is predicated on the discovery of certain process conditions and parameters that produce thin, hydrophilic, gamma or electron beam irradiation polymerized and chemically grafted coatings of N-vinylpyrrolidone (NVP [PVP]), copolymerized NVP and 2-hydroxyethylmethacrylate (HEMA) [P(NVP-HEMA)] or HEMA [PHEMA] on the surfaces of articles adapted for contact with living tissue of a human or non-human animal, e.g., surgical instruments, medical devices, prosthetic implants, contact lenses and the like constructed of a wide variety of plastic materials. For purposes of the following description of the present invention, the term “tissue” is intended to include blood as well as solid tissue surfaces.
The surface modifications or chemically grafted coatings of the present invention increase the hydrophilicity of the article surfaces and minimize adhesion and abrasive interactions between the surface and sensitive tissues and cells such as fragile ocular tissues (i.e., iris and corneal endothelium), blood cells, vascular endothelium, peritoneum, pericardium and the like, thereby minimizing tissue damage and complications occasioned by contact between the article and such tissues. The coatings produced are thin and reproducibly uniform. Moreover, they are chemically bound to the surface of the article and, therefore, are far more durable and less subject to removal, degradation or deterioration during or following utilization of the articles than the coatings produced by prior art methods.
Studies have shown that the surgical implantation of ocular implants such as intraocular lenses (IOLs) and the like can result in the loss of significant corneal endothelial tissue unless great care is taken to ensure a lack of contact between the device and the endothelium. Most ocular implants are constructed of hydrophobic polymethylmethacrylate (PMMA) polymers because of their superior optical qualities, resistance to biodegradation, and the like. It has been found, however, that PMMA surfaces adhere to endothelial cells upon even casual contact and that separation of the surface therefrom results in a tearing away of the endothelial tissue adhered to the polymer surface. Similar adhesive interactions with other ocular tissues, i.e., the iris, can also cause adverse tissue damage. Other hydrophobic polymers which are used or have been proposed for use in ocular implants (i.e., polypropylene, polyvinylidene fluoride, polycarbonate, polysiloxane) also can adhere to ocular tissue and thereby promote tissue damage.
It is well documented in the prior art that a significant disadvantage inherent in PMMA IOLs resides in the fact that any brief, non-traumatic contact between corneal endothelium and PMMA surfaces results in extensive damage to the endothelium. See Bourne et al, Am. J. Ophthalmol., Vol. 81, pp. 482-485 (1976); Forster et al, Trans. Am. Acad. Ophthalmol. Otolaryngol., Vol. 83, OP-195-OP-203 (1977); Katz et al, Trans. Am. Acad. Ophthalmol. Otolaryngol., Vol. 83, OP-204-OP-212 (1977); Kaufman et al, Science, Vol. 198, pp. 525-527 (1977) and Sugar et al, Arch. Ophthalmol., Vol. 96, pp. 449-450 (1978) for a discussion of the problems associated with implant surface/endothelium contact.
Since it is extremely difficult to avoid any contact between implant surfaces and endothelium during surgical procedures and especially to other sensitive ocular tissues during implant life, i.e., the iris, ciliary sulcus and the like, efforts have been undertaken to modify the PMMA ocular implant surfaces to reduce the tendency thereof to adhere to and damage corneal endothelium.
Ocular implant surfaces have been coated with various hydrophilic polymer solutions or temporary soluble coatings such as methylcellulose, polyvinylpyrrolidone (Katz et al and Knight et al [Chem. Abs., Vol. 92:203547f (1980)]), etc., to reduce the degree of adhesion between the implant surfaces and tissue cells. While offering some temporary protection, these methods have not proven entirely satisfactory since such coatings complicate surgery, do not adhere adequately to the implant surfaces, become dislodged or deteriorate after implantation, dissolve away rapidly during or soon after surgery or may produce adverse post-operative complications. Moreover, it is difficult to control the thicknesses and uniformity of such coatings.
Yalon et al [Acta: XXIV, International Congress of Ophthalmology, ed. Paul Henkind (1983)] and Knight et al, supra, have reported attempts to produce protective coatings on PMMA implant surfaces by gamma irradiation induced polymerization of vinylpyrrolidone thereon. Their efforts were not altogether successful, however, since their methods also presented problems in controlling the optical and tissue protective qualities of the coatings. Process conditions and parameters (i.e., monomer concentration solvent, dose and dose rate) were not specified. The resulting coatings were of poor quality and non-uniform mechanical stability.
In U.S. Pat. No. 4,806,382, issued Feb. 21, 1989, there are described improved methods for producing hydrophilic, gamma irradiation induced polymerized and chemically grafted coatings on ocular implants constructed of a variety of polymeric materials, which methods overcome the above-noted difficulties and disadvantages.
The invention described in that patent is predicated on the discovery of certain process conditions and parameters that produce thin hydrophilic gamma irradiation induced polymerized and chemically grafted coatings of N-vinylpyrrolidone (NVP) [PVP], copolymerized NVP and 2-hydroxyethylmethacrylate (HEMA) [P(NVP-HEMA)], or HEMA [PHEMA] and their copolymers, particularly with ionic comonomers on the surfaces of ocular implants constructed of materials including polymethylmethacrylate (PMMA) and of other process conditions and parameters which produce thin gamma irradiation induced graft PVP, P(NVP-HEMA), PHEMA or copolymer coatings on the surfaces of ocular implant articles constructed of materials including polypropylene (PP), polyvinylidene fluoride (PVDF), polycarbonate (PC) and polysiloxane or silicone (PDMSO). The coatings increase the hydrophilicity of the implant surface and minimize adhesion between the surface and sensitive ocular tissues such as corneal endothelium or iris, thereby minimizing tissue damage and post-operative complications occasioned by contact between the implant surface and ocular tissue. The coatings produced by the improved method of the invention described in U.S. Pat. No. 4,806,382 are thin and uniform. Mo
Erickson Theresa Rivero
Goldberg Eugene P.
Mentak Khalid
Seeger James
Yahiaoui Ali
Clarke Dennis P.
Miles & Stockbridge
University of Florida
Webman Edward J.
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