WATER FOR INJECTION   BACKGROUND ​Water for Injection (WFI) international pharmacopoeial standards have been brought closer through harmonization efforts, but significant differences still exist. The USP WFI monograph allows production by "distillation or a purification process proven to be equal to or superior to distillation." USP language is the least restrictive in terms of acceptable processes among the major pharmacopoeial groups. The Japanese Pharmac...