Medical instrument with a hydrophilic, low-friction coating and

Details Medical instrument with a hydrophilic, low-friction coating and Medical instrument with a hydrophilic, low-friction coating and

1993-04-29

1998-05-26

Resan, Stevan A.

Coating processes

Medical or dental purpose product; parts; subcombinations;...

Flexible web, sheet, film, or filament base

427 21, 4273884, 427409, 4274121, 428515, A61L 2900

Patent

active

057561443

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a method of providing a medical instrument for insertion into a body cavity, such as a guide wire and a catheter, with a hydrophilic, low-friction coating, comprising the steps of treating the instrument with a first aqueous coating composition to form a inner layer of a water-insoluble polymer and subsequently treating it with a second aqueous coating composition to form an outer layer of a water-soluble hydrophilic polymer.
By providing medical instruments for insertion into body cavities with a coating of the above mentioned type, the insertion of the instrument is facilitated and the risk of damaging body tissue is reduced.
2. Description of the Prior Art
U.S. Pat. No. 4,642,267 (Creasy et al.) discloses a low-friction coating composition consisting of a blend of a first polymer in the form of thermoplastic polyurethane having no reactive isocyanate groups and a second polymer in the form of a hydrophilic poly (N-vinyl lactam).
Low-friction coatings formed by such a polymer blend suffer from the drawback that they do not adhere sufficiently well to e.g. guide wires to prevent the coating from being scraped off during the bendings which such wires inevitably will be exposed to during use.
GB patent specification No. 1,600,963 discloses a method of providing an article with a hydrophilic coating by forming thereon a layer of polyurethane having reactive isocyanate groups and by reacting polyurethane with polyvinylpyrrolidone to form a coating of a polyvinylpyrrolidone-polyurethane interpolymer.
EP patent publication No. 0,093,094 A1 discloses a method of providing the surface of an article of a polymer with a hydrophilic coating having a low-friction coefficient when wetted. In this known method a solution of a compound containing at least two reactive isocyanate groups per molecule is applied to the polymer article and subsequently a polyethylenoxide solution is applied followed by the removal of the solvent in the latter solution by evaporation and curing of the coating thus formed at an elevated temperature.
DK patent application No. 1709/83 discloses a method of forming on a polymer surface a hydrophilic coating having a low-friction coefficient by applying to the surface a solution containing a compound having at least two unreacted isocyanate groups per molecule and subsequently evaporating the solvent followed by application to the polymer surface thus treated of a solution containing a polyvinylpyrrolidone and evaporation of the solvent. Finally, the coating is cured at elevated temperature.
A common feature of the coatings prepared by the methods described in GB patent specification No. 1,600,963, EP patent publication No. 0,093,094 A1 and DK patent application No. 1709/83 is that they involve the use of polyurethanes with reactive isocyante groups which suffer from the drawback that they can form aromatic carcinogenic amines by reaction with water.
A further drawback of said known methods is that in forming the coatings it is necessary to use organic, including toxic, solvents so as to exclude water to prevent an unintentional reaction with the reactive isocyanate groups.
EP patent publication No. 0,166,998 A2 discloses a method of the type mentioned above wherein the article is initially treated with a solution of a polymer having a reactive functional group in a organic solvent which i.a. serves to dissolve or swell either the material of which the articles is made, or optionally a surface layer on the article.
After evaporation of the solvent by drying the article is treated with a solution containing a water-soluble polymer in the form of a cellulosic polymer, a maleic acid anhydride polymer, a polyarylamide or a nylon. Subsequently, the article thus treated is dried to remove the solvent before dipping it into water with the object of increasing the affinity of the coating to water. Eventually, the article thus treated is subjected to a final drying.
EP-A1-0389632 describes medical instruments such as c

REFERENCES:
patent: 4642267 (1987-02-01), Creasy et al.
patent: 4876126 (1989-10-01), Takemura et al.
patent: 5107852 (1992-04-01), Davidson et al.
patent: 5129890 (1992-07-01), Bates et al.

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