Isak forced through a move to Liverpool in August, which included refusing to train and even spending time away from Tyneside.
Isak will miss tonight's clash at Anfield due to injury and Howe admitted on Friday: "You lose a player like Alex...
"And let's put this right, Liverpool paid the money they did because he's an outstanding footballer, an unbelievable talent. We were privileged to have him for the years that we had him. We loved working with him.
"He was an outstanding player. When you take that player away from your team, it's going to change the dynamics, that's for sure."
Liverpool host Newcastle sitting two points outside the top four and three points ahead of the Magpies.
