Drug – bio-affecting and body treating compositions – Solid synthetic organic polymer as designated organic active... – Monomer contains oxygen
Patent
1995-01-24
1997-08-19
Azpuru, Carlos A.
Drug, bio-affecting and body treating compositions
Solid synthetic organic polymer as designated organic active...
Monomer contains oxygen
424 7817, 424424, A61K 31765, A61K 3174, A61K 4748, A61F 202
Patent
active
056585616
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a method of producing a material having improved anti-thrombogenicity, to certain materials produced thereby and in particular a regenerated cellulose membrane which is particularly suitable for use in artificial kidneys. The invention further provides a device such as a contact lens, biomedical or blood-contacting device or filtration membrane comprising such a material.
At present, methods for prolonging the lives of patients with chronic renal insufficiency include blood dialysis, blood filtration and other blood-purification methods. In Japan, more than 100,000 patients are treated with such blood-purification methods.
The principles of blood purification involve bringing the blood and a dialysate into contact via a membrane, allowing the diffusion of the waste products and the metabolic products contained in the blood into the dialysate and their subsequent removal, and removing the water surplus by taking advantage of the pressure differences.
As is generally known, regenerated cellulose membranes, especially cellulose membranes regenerated by the copper ammonium method, are commonly used in the method of artificial dialysis in particular, with progress in dialyzers and dialysis techniques, they have come to play an important role in the life prolongation and social recovery of patients with renal insufficiency; this is because the regenerated cellulose membrane is characterized not only by a superior dialysis capacity and mechanical strength, but also by high safety confirmed by years of experience.
Despite the process in dialysis methods, however, various problems associated with dialysis have still remained unsolved. One of these is the problem of various side effects which are believed to result from the long-term administration of high doses of anticoagulants.
Currently, in cases in which artificial dialysis is conducted, anticoagulants such as heparin are continuously administered in order to suppress the blood clotting reaction in the artificial dialyzer. Despite current improvements in the removal of solute in artificial dialyzers, as well as the possibility of achieving long-term life prolongation of up to 20 years, a number of problems caused by the use of heparin have been pointed out continuously. In particular, it has become apparent that long-term administration of heparin produces in patients side effects such as liver disorders and other lipid metabolic disorders, and prolongs the bleeding time and allergic reactions.
As a result of the above-mentioned points, there has been strong demand for the development of an artificial dialyzer which will not cause blood clotting, even with reduced doses of anticoagulants administered during the artificial dialysis, or with no anticoagulants at all. In addition, the manufacture of anti-thrombogenic dialyzers which are completely portable is expected to considerably facilitate home treatments, which will promote the social recovery of patients who [otherwise] would have to be restricted to a hospital for approximately five hours every two or three days of the week.
It has been suggested that some membranes made of synthetic macromolecules have excellent anti-thrombogenicity; but membranes made of synthetic macromolecules have low mechanical strength and are susceptible to the formation of pinholes, they are of limited use in sterilization methods due to insufficient heat resistance, and they lack balanced performance, i.e., the balance between water permeability and substance permeability, so that there are many disadvantages in terms of practical use.
On the other hand, methods have been offered for improving the anti-thrombogenicity of regenerated cellulose membranes, without sacrificing their other excellent properties. For example, a method of imparting anti-thrombogenicity by heparinizing the membrane surface was offered in Japanese Laid-Open Patent Application 51-194, but since no satisfactory results could be obtained, and the cost of such a method was high, it has not been applied.
The attempts made so far
REFERENCES:
patent: 5368733 (1994-11-01), Nakabayashi et al.
patent: 5453467 (1995-09-01), Bamford et al.
Shirakawa et al., "Preparation of Epoxy Resins Containing Phosphate Zwitterionic Group", Jpn. Kokai, Tokkykoho, 8 pp. (Abstract Only).
Ishihara et al., "Improvement of Blood Compatibility on Cellulose Dialysis Membrane", Biomaterials, 13(1992) No. 3, pp. 145-149; No. 4, pp. 235-239.
Kishida, et al., Biomaterials 13 (1992), No. 2, "Interactions of poly(ethylene glycol)-grafted cellulose membranes with proteins and platelets", pp. 113-118.
Ishihara, et al., Journal of Biomedical Materials Research, vol. 25, No. 11, Nov. 1991 "Protein adsorption from human plasma is reduced on phospholipid polymers" pp. 1397-1407.
Ishihara Kazuhiko
Nakabayashi Nobuo
Azpuru Carlos A.
Biocompatibles Limited
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