A federal judge Tuesday permanently blocked a Canadian maker of a cheap generic version of blood thinner Plavix from marketing the drug, saying its version infringed on a valid patent for Plavix.

U.S. District Judge Sidney H. Stein said Apotex Inc. had failed to prove during a trial in Manhattan that lasted from Jan. 22 through Feb. 15 that the patent was invalid. He said damages will be set in an amount to be determined at future proceedings.