Dec 15 (Reuters) - Eagle Pharmaceuticals Inc (EGRX.O) said on Wednesday the U.S. health regulator approved its generic version of Endo International"s (ENDP.O) blood pressure drug, Vasostrict, sending its shares to a more than one-month high. The U.S. Food and Drug Administration"s approval comes just months after a Delaware federal court ruled that Eagle"s proposed generic, vasopressin, did not infringe on patents held by Endo subsidiary Par Pharmaceutical. Vasostrict brought in sales of more than $786 million last year, making it the Endo"s best-selling drug. Par sued Eagle in 2018 for seeking FDA approval of the generic, alleging it infringed its patents. Eagle had denied that, saying its formulation of the drug"s active ingredient had a pH value below the range covered by Par"s patents. Eagle said on Wednesday it expects a 180-day marketing exclusivity for vasopressin. Shares of Eagle were up 8.5% at $50.6 in afternoon trading, while those of Endo were down 2.3%.