Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
1999-12-03
2001-07-31
Michl, Paul R. (Department: 1714)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
C523S108000, C526S264000
Reexamination Certificate
active
06268511
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention provides a novel itaconic acid derivative which is useful as a constituting component of a polymer, and also provides a copolymer containing the novel itaconic acid derivative as a constituting component, and an intraocular lens formed from the copolymer, particularly a foldable intraocular lens which can be implanted into eyes in the state of being folded (hereinafter abbreviated as “foldable IOL”).
2. Background Information
A number of studies on an acrylic acid monomer as a constituting component of a polymer have been made. However, there have not been so many studies made on the use of an itaconic acid derivative having two carboxyl groups as a monomer. The itaconic acid derivative of the present invention, which is represented by the general formula [1] or [2] and is useful as a polymer component, has such a structural feature that a pyrrolidone group is contained. The itaconic acid derivative having such a feature is a compound which is unknown in the literature as a monomer. As a matter of course, a polymer containing the monomer as a constituting component is also unknown in the literature.
A main object of the present invention is to prepare a novel polymer containing the above-described itaconic acid derivative as a constituting component and to develop a novel material to be applied to intraocular lenses, particularly foldable intraocular lenses.
An intraocular lens (IOL) is used for implanting in place of a crystalline lens removed on cataract surgery. Since IOL was first used in transplanting in 1949, various studies have been made on IOL materials. As there is a great evolution on operation methods, with the advancement of operation methods, demands on the characteristics of IOL have also changed a lot. Recently, with the popularity of the phacoemulsification procedure etc., it is possible to open a very small incision to remove the opaque crystalline lens and finish the operation. Accordingly, demands on characteristics of IOL to be implanted have been changing. For example, characteristics of so-called foldable IOL make it possible to implant an IOL through the small incision in foldable form and open an IOL in lens the capsule. At the same time, various studies have been made on IOL materials. Polymethyl methacrylate (PMA), Silicone, acrylic resin or the like have widely been used an the IOL materials heretofore, while silicone or acrylic resin can be used as foldable IOL materials. A Copolymer of hydroxyethyl methacrylate and methyl methacrylate may also have been used recently. On the other hand, during the studies on these kinds of materials in order to prevent the effect of UV rays on the retina, they can contain an UV absorber such as hydroxybenzophenone, hydroxyphenyl benzotriazole and so on. Moreover, in order to raise biocompatiability and prevent deposition of cells, a polysaccharide such as heparin in coated on the IOL surface in practice.
The itaconic acid derivative of the present invention is characterized by having a pyrrolidone group, and there has been no report on a polymer made up of the itaconic acid derivative. Paying attention to polymers containing a monomer having a pyrrolidone group as a constituting component, particularly polymers used for the purpose of being applied to an intraocular lens, some prior arts are shown below for reference. These prior arts relate to the polymers whose partial constituting component is an acrylic monomer having a pyrrolidone group. Examples of such polymers are a copolymer of methacryloyloxyethyl-2-pyrrolidone and acrylic acid (JP Laid-Open 28705/1992), a polymer polymerized from the monomer which is formed from amidation of acrylic acid and pyrrolidone (JP Laid-Open 43208/1990). a polymer of polyoxyalkylene structure a with pyrrolidone group (JP Laid-open 8218/1990) and so on. As for copolymers formed form three components, there have been reports only an a copolymer of vinyl pyrrolidone, hydroxyethyl methacrylic acid and methyl methacrylate (JP Laid-Open 105250/1978), and a copolymer of methacryloyloxy ethyl-2-pyrrolidone, alkyl methacrylate and fluoroalkyl methacrylate (JP Laid-Open 150197/1993). Incidentally, the main object of these studies is the application on a soft contact lens and not on an IOL. There have been no report especially on the possibility of application of a foldable IOL in the present invention.
A main object of the present invention is to develop an intraocular lens, more particularly materials of a foldable IOL. During the studies on foldable IOL materials, it is necessary to consider refractive index, tensile strength and recovery speed of the materials. For example:
1) When the refractive index is too low the thickness of IOL increases too much. Contrarily when the refractive index is too high, the aberration of peripheral portion becomes large. Accordingly, it is necessary to choose proper refractive index. Specifically, the preferable range is 1.4-1.6.
2) Because forceps are used to implant a foldable IOL, tensile strength bearing their operation is needed. It is an important factor that marks do not remain on the IOL surface after the operation with the forceps.
3) After foldable IOL are implanted, they must be recovered to thee original form in the lens capsule. Recovering speeds vary depending on an operator's custom and competence. The possibility of mechanical invasion of peripheral tissue usually increases with the acceleration of recovering speed. On the other hand, with the slowdown of recovering speed and the elongation of an operation, the possibility of mechanical invasion of peripheral tissue increases. Accordingly, for the foldable IOL, suitable recovering speed is needed.
Moreover, easy formability should be taken into consideration.
Based on these opinions, though various foldable IOL have been used in practice, it is desired to develop an more preferable material.
SUMMARY OF THE INVENTION
The Inventor, with the consideration of the above problems, studied on more applicable materials of foldable IOL. First, the inventor has focused attention and studied on itaconic acid having two carboxyl groups, capable of synthesizing various derivatives, and succeeded in the preparation of a series of novel itaconic acid derivatives having a pyrrolidone group. Itaconic acid is an very useful compound capable of being converted into various derivatives according to purposes because of two carboxyl groups as described above. As a result of studies on preparation of various polymers using the itaconic acid derivative as one of monomers, the inventor found that the itaconic acid derivative can be suitably used as the monomer and that the resulting polymer, particularly a copolymer with an hydroxyalkyl acrylate derivative and an alkyl acrylate derivative can be used as the material of particularly excellent foldable IOL.
The present invention is composed of the following four constituent features:
(1) A novel itaconic acid derivative represented by the following general formula [1] or [2]:
[wherein R
1
represents hydrogen atom, lower alkyl group or phenyl lower alkyl group, and phenyl ring of the phenyl lower alkyl group can be substituted by lower alkyl group(s); R
2
represents hydrogen atom or lower alkyl group; and “A” represents lower alkylene group; the same rule applies correspondingly to the following] which is useful as a polymer constituting component, or a salt thereof;
(2) Use of the novel itaconic acid derivative represented by the general formula [1] or [2] as a polymer constituting component;
(3) A copolymer comprising constituent units represented by the following formulas [3] and, [4] or [5], and [6]:
[wherein R
3
represents hydrogen atom or lower alkyl group; R
4
represents lower alkylene group, and the alkylene group can be substituted by hydroxy group(s) and can have oxygen atom(s) in the alkylene chain];
[wherein R
1
represents hydrogen atom, lo
Frishauf, Holtz Goodman, Langer & Chick, P.C.
Michl Paul R.
Santen Pharmaceutical Co. Ltd.
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