Howe left the Swede out of his squad for their trip to Villa Park.
Before kickoff, the Toon manager said: "No different to how its been for a number of weeks really. He's not here today, we're without him, and we're adapting to that and still trying to be competitive.
"Today will be a big test for us. Aston Villa did very well last year, we know how difficult this ground is to come to and play but we're looking forward to it. I think it's a strong team we picked so fingers crossed we go well."
Asked if he felt let down by the situation, Howe also said: "I don't think now's the time to discuss that, we're about to play a game. All my emotions are towards this game and making sure we're competitive, driven, motivated. This is a tough place to come if you're one or two per cent down. We've got to be there mentally today, me included, the whole coaching staff. There's no feeling of anything other than wanting to give our best today."
Howe revealed in his pre-match press conference that he wanted Isak to train and play.
He said: "Of course, I've said many times I want him to train and play. I’ve had those conversations with him, but the details of these conversations need to remain private.’
"It (training alone) is not something you ever want to see. You want to see him with the squad, you want to see him happy and enjoying his football. He is contracted to us. He is here, so for me, that is an unfortunate situation."
Asked if he believes Isak could yet stay, Howe added: "Yes, I believe there is (a good chance). But of course, discussions and talks would need to take place for that to happen. But that’s for another day. Today is Aston Villa and making sure we perform as well as we can."