Hydrophilic biomedical composition

Details Hydrophilic biomedical composition Hydrophilic biomedical composition

2002-05-31

2004-08-10

Pezzuto, Helen L. (Department: 1713)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C526S260000, C526S266000, C526S303100, C526S310000, C526S320000, C526S347000

Reexamination Certificate

active

06774197

ABSTRACT:

CROSS-REFERENCE TO RELATED APPLICATIONS
This application is the U.S. national stage application of International Application PCT/AU00/00916, filed Aug. 2, 2000, which international application was published on Feb. 8, 2001, as International Publication WO 01/08604 in the English language. The International Application claims priority of Australian Patent Application No. PQ 1977, filed Aug. 2, 1999.
TECHNICAL FIELD OF THE INVENTION
This invention relates to hydrophilic ethylenically unsaturated macromonomers that are suitable for use in biomedical applications.
BACKGROUND OF THE INVENTION
The use of polymeric prostheses and biomedical mouldings has grown rapidly in recent times. Such mouldings may be used for contact lenses or for specific ophthalmic purposes. For example, they may be used for intraocular lenses and eye bandages. They may also be used for surgical mouldings such as heart valves and artificial arteries. Other applications include wound dressings, biomedical adhesives and tissue scaffolds. Use in drug delivery is a further application.
Disease of the lens material of the eye is often in the form of cataracts. The ideal cataract procedure is considered to be one where the lens capsule bag is maintained with the cataractous lens material removed through a small opening in the capsule. The residual lens epithelial cells are removed chemically and/or with ultrasound or lasers. A biocompatible material with appropriate optical clarity, refractive index and mechanical properties is inserted into the capsular bag to restore the qualities of the crystalline lens.
There have been recent advances in methods of inserting intraocular lens. For example, U.S. Pat. No. 5,772,667 assigne to Pharmacia Lovision Inc, discloses a novel intraocular lens injector. This device compresses an intraocular lens by rolling the lens into a tight spiral. The device injects the compressed lens through a relatively small incision in the eye, approximately 2-3 millimeters in length, resulting from a phacoemulsification procedure. The intraocular lens is inserted into a receiving channel of the injector in an uncompressed state and is urged into a cylindrical passageway. As the intraocular lens advances into the cylindrical passageway, the lens will roll upon itself into a tightly rolled spiral within the confines of the cylindrical passageway. An insertion rod is inserted into an open end of the cylindrical passageway and advances the compressed lens down the passageway. As the lens exits the passageway and enters the eye, the lens will expand back to its uncompressed state.
To avoid the need for such injection devices, it has been proposed that intraocular lenses be formed in situ after being injected as a liquid flowable form into the lens capsule bag. However, while this concept is attractive in that smaller incisions would be required, it raises further difficulties in that further polymeric reactions are required to take place and these are required to be not harmful to the patient. It is also a requirement that the reaction can take place over a relatively short time under mild reaction conditions. A further requirement is that the reaction is not appreciably inhibited by oxygen. A still further requirement is that no byproducts or residues are produced that are leachable and which may have an adverse biological effect on the patient. It is desirable that the refractive index of the polymer composition for ophthalmic applications is close to 1.41 being the refractive index of the natural biological lens material.
Patent Application PCT/EP96/00246 in the name of AG Ciba-Geigy discloses water soluble cross-linkable polymers which may be crosslinked in solution to form moulded compositions. These compositions have particular application in contact lenses. The polymers are derivatives of polyvinyl alcohols. A portion of the hydroxyl groups are preferably reacted with 2-vinyl-4,4-dimethylazlactone to produce ethylenically unsaturated macromonomers.
SUMMARY OF THE INVENTION
This invention provides in one form a hydrophilic ethylenically unsaturated macromonomer comprising units of structure:
where:
m=an integer ≧1
n=an integer ≧1
r=an integer ≧1
A is a non-reacted moiety resulting from the addition polymerisation of ethylenically unsaturated monomers.
B is a moiety resulting from the additional polymerisation of ethylenically unsaturated groups that possess hydroxyl or amino groups. Examples of suitable monomers are hydroxybutylacrylate and N hydroxy ethylacrylamide
C has the following structure:
where:
R
1
=H, Me
X=O, NH
Z=O, NH, NR, S, CO
2
where R is C
1
-C
8
alkyl
W=linear, branched cyclic hydrocarbyl chains, polyether chains or heterochains, linear or cyclic.
It may include a mixture of moieties resulting from the use of a number of different ethylenically unsaturated monomers. The moieties are “non-reacted”. By “non-reacted” we mean that under the reaction conditions that will allow appropriate side groups to be introduced into the copolymer backbone these “non-reacted” side groups will not form covalent bonds with other groups. Thus by this definition certain chemical groups may be included as being “non-reacted”. The A moiety may be “non-reacted” in that under the reaction conditions side groups will not form covalent bonds. However, the A moiety may also be “non-reacted” because of the stoichiometry of the side groups. Thus it is possible for the A and B moieties to be the same and the A moiety remains unreacted because the number of equivalents of side groups is less than the equivalents of A and B. For example, A may include hydroxybutylacrylate and B may also be hydroxybutylacrylate.
The balance of the addition copolymer backbone, namely that part of the composition consisting of A and B moieties may be a random or block copolymer.
Examples of W are polyethylene glycol, polyethylene, cyclic and heterocyclic species such as phenyl rings or piperidine or mixtures of hydrophilic or hydrophobic polymers prepared by processes that allow control over end groups such as chain transfer chemistries and substituted variants thereof.
C may contain optional groups that are not ethylenically unsaturated polymerisable groups.
Preferably C is formed by suitable reaction of 2-vinyl-4,4-dimethylazlactone, acryloyl or methacryloyl chloride or related compounds with the complimentary hydroxyl or amino groups on the copolymer backbone. Other methods include suitable reaction of isocyanatoethylmethacrylate, methacrylate anhydride, acrylate anhydride, active esters of acrylates or methacrylates. These can be prepared prior to reaction with the polymer or can be prepared in situ and attached to the copolymer by conventional coupling chemistries, for example the coupling of acrylic acid to alcohol groups on the backbone copolymer using carbodiimide chemistry.
The macromonomer is hydrophilic. By hydrophilic we mean the macromonomer may be diluted 10% w/w with water without affecting the visual clarity of the macromonomer when viewed through a 100 ml measuring cylinder.
In an alternative form this invention provides a method of treating presbyopia by removing a patient's lens from the lens capsule bag via an incision in the cornea, injecting into the lens capsule bag a macromonomer of Formula I and wherein the molecular weight of the macromonomer is in the range 10,000-300,000, and wherein the ethylenically unsaturated groups are provided by (meth) acrylamides, (meth) acrylate and styrenic moieties, and polymerising the macromonomer to a polymer having an E modulus in the range 0.01-100 kPa, preferably 0.1-10 kPa, and more preferably 0.5-5 kPa.
In a further alternative form this invention provides ethylenically unsaturated macromonomers comprising units of Formula I wherein the macromonomer or macromonomer solution has a viscosity at 25° C. in the range 1,000-20,000 cSt, and more preferably 1,000-10,000 cSt and after polymerisation to form biocompatible polymers having an E modulus in the range 0.01-100 kPa, preferably 0.1-10 kPa and more pre

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