I would bring the Pulmozyme box w/ the pham. label on it with just however many vials you'll be needing in it... with a good-quality ice pack to keep it cold. Doesn't the HTS also come in single-use vials as well that you mix up as you use it? (we don't use it but I've seen pix of the kits.) I'd do the same with that. I would think as long as the boxes have the pharm. label on them you wouldn't need a dr. note, since your child's name, prescribing doctor, and drug description/dosage instructions (i.e. 'inhale one vial daily') are right on the label. They may want to see the equipment (neb, vest); different airports vary in their security protocol so I would call the airport ahead to ask about the easiest way to check in & board with that stuff.