Draxxin is quite specific to the lungs, much like Micotil. We use it if it's an obvious respiratory issue, and it works well. Kind of slow though, so you have to be patient. Otherwise, if they're bad, it's been Nuflor. Haven't tried Zactran yet, but we'll sure check it out.
It's funny how that intranasal shot seems to help. We've had success with it too. I think there's a very local immune response right in the airway that seems to give them a kick start.