Baxter International Inc.

Paul DeAntonio

Cary J Reich

John T Sorensen

Kenneth G Mayhan

Stephen L Coulter

William J Bertrand

In an improved method for producing a surface graft of a hydrophilic polymer upon a preformed solid or semi-solid polymer substrate having hydroperoxide groups along its surface, n-vinyl pyrrolidone is utilized as the surface-grafting monomer, the substrate is selected to be insoluble in n-vinyl pyrrolidone, and the polymerization is carried out in aqueous alkaline conditions utilizing a combination of metal salts to provide a variable valence metal ion in a reduced state capable of oxidizing to suppress homopolymerization of the monomer in the solution. When the substrate is at least partially soluble in the n-vinyl pyrrolidone, an ethylenically unsaturated monomer having a higher reactivity with the substrate than n-vinyl pyrrolidone is added to the alkaline polymerization solution as a 'seeding' monomer. Addition of the 'seeding' monomer results in a surface-grafted copolymer effectively externalized from the substrate.

Polyvinyl pyrrolidone-grafted coatings on preformed polymers

Disclosed is a method for dissolving cholesterol-rich calculi, most preferably gallstones in vivo, comprising contacting the calculus with a fluid compound of the formula R-X, R having 2 to 4 carbon atoms with substituents consisting of hydrogen of halogen, X being halogen, and wherein if X is fluorine, at least one substituent is selected from the group consisting of hydrogen, chlorine, bromine, or iodine. Usually R-X is 2-bromo-2-chloro-1,1,1-trifluoroethane (also referred to as Halothane.) Other compounds of particular interest are 2-chloro-1,2,-dibromo-1,1,2-trifluoroethane, 1-bromo-2-chloro-1,1,2-trifluoroethane, 2,3-dibromo-1,1,1-trifluoropropane, 2-iodo-1,1,1-trifluoroethane, 1,2-dichloro-1,1-difluoroethane, 1,1,2-trichloro-2,3,3-trifluorocyclobutane, hexafluoro-1,1,3,4,-tetrachlorobutane, 1,1,1-trichlorotrifluoroethane, and 1,2-dibromo-tetrafluoroethane. Furthermore, Halothane and MtBE in combination effectively dissolve cholesterol-rich calculi. Finally, dissolution can be enhanced by adding to the dissolution solvent up to about 50 percent by volume of a lower alcohol. Usually the lower alcohol is ethanol in the amount of about 5 to 40, usually 10 to 30 and preferably about 10 percent by volume. Most preferably in this case, R-X is Halothane or 1,1,1-trichlorotrifluoroethane. Dissolution using previously known solvents such as MtBE is also enhanced by such addition of lower alcohols. In addition, the practical use of MtBE for dissolution can be improved by the addition of the compounds described above as R-X, particularly Halothane, and usually at levels of about 5 to 50 volume percent Halothane.

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Westminster, CA, United States of America

Paul DeAntonio