Materials and their use in the preparation of biocompatible surf

Details Materials and their use in the preparation of biocompatible surf Materials and their use in the preparation of biocompatible surf

1996-07-29

1998-04-14

Schofer, Joseph L.

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

Synthetic resins

Polymers from only ethylenic monomers or processes of...

5263077, 526289, 558166, 558199, 558214, C08F 3002, C08F 2058, C08F 2060, C07F 906, C07F 922, C07F 928

Patent

active

057392374

DESCRIPTION:

BRIEF SUMMARY
The present invention relates to new materials having improved biocompatibility and may be applied to or form a surface having improved biocompatibility. The materials have novel zwitterionic groups which are found to be less thrombogenic than existing materials, though having relatively high levels of platelet adhesion.
Materials used in medical devices where cell growth on the surface is desired, for example in cardiovascular stents and vascular grafts ideally must allow for the ready attachment of endothelial cells. As the mechanism of cell attachment and platelet adhesion are similar, it would be ideal if such a material did not activate platelets. Thus platelet adhesion without platelet activation would be a suitable combination of properties to ensure that thrombus formation does not occur, but endothelial cell growth is supported. With such a combination of properties, new devices which are currently impractical, such as small diameter vascular grafts, will become feasible.
It is known to reduce platelet activation by mimicking the surface of a red blood cell by coating a surface with phosphoryl choline zwitterionic groups. Various ways of introducing such groups at the surfaces of substrates are described in our earlier patent publications EP-A-0032622, EP-A-0157469, WO-A-9207858, WO-A-9113639, WO-A-9301221 and WO-A-9315775 and WO-A-9207885. In WO-A-9416748 (unpublished at the priority date of the present invention) various types of zwitterionic groups other than phosphoryl choline groups are described. For instance the trimethylammonium cation is replaced by various groups, including pyridinium groups. In other types of compound described in that document, the chain joining a phosphate ester and a quaternary nitrogen atom is increased in length or is an arylene group including heteroarylene. Further zwitterionic groups are also described in our earlier patent publication WO-A-9416749 (which was not published at the priority date of the present invention). One exemplified compound disclosed in WO-A-9416748 has a triphenylphosphonium group as the cation of the zwitterion (the priority date for that specific compound is the same as in the present application). The present inventors have discovered that the triphenylphosphonium derivative appears to provide reduced platelet activation, but without reducing platelet adhesion. This is thought to be a result of the cation having at least one aryl group as a monovalent substituent and the present invention is based on that discovery.
In the present invention there is provided a surface having pendant zwitterionic groups in which the atom carrying the cationic charge has at least one monofunctional (or monovalent) (that is one of the substituents at that atom other than the substituent which joins the atoms to the anionic group and/or the surface) substituent which is an aryl, heteroaryl or aralkyl group.
In the invention the pendant zwitterionic groups can be represented by the formula (I) substituent, and the other of Y and Z is an anionic moiety and in which W is an alkylene (including cycloalkylene and cycloalkyl alkylene), arylene, heteroarylene and alkarylene, in which any alkylene chain, including cycloalkylene, may be interrupted by one or more oxygen atoms, and any of which groups may be unsubstituted or substituted by nonionic non-interfering substituents.
Preferably the cationic moiety is positioned further from the surface than the anionic moiety, that is Z represents the cationic moiety.
Preferably the zwitterionic group has the formula II: ##STR1## in which B is a divalent anionic moiety, W is as defined above, aralkyl and alkyl groups and hydrogen atoms. Preferably each R.sup.1 is other than a hydrogen atom more preferably each is aryl, usually phenyl.
Preferably the group W separates the anionic and cationic moieties by a chain including at least 2 carbon atoms, preferably at least 5 carbon atoms and up to 20, more preferably up to 10 carbon atoms. The group W therefore preferably includes an alkylene group comprising at least 6, for instan

REFERENCES:
patent: 5422402 (1995-06-01), Bowers et al.
Pharmazie, 1979, vol. 34, H.12, pp. 345 (with English Translation of the Abstract.).
J. Amer. Soc. Artifical Internal Organs, 1994, vol. 40, No. 3, pp. 001-005, E.J. Campbell et al.
Blood, 1991, vol. 78, No. 3, pp. 673-680, R.A. Sheppeck et al.
P. Kertscher, H.-J. Ruger and P. Nuhn, Pharmazie 34, H. 12, 1979, p. 5.

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