There is a lot of info in this link.

Personally (& I am not a doctor) I would try it. I would use the suggested dosage in the package which is several drops the first day (Load dose) and then down to a maintenance dose. We do 2 drops before bed as a maintenance. (we don't use/ haven't needed pulmozyme)

It is similar to a homeopathic remedy - so the dose doesn't really change according to weight. It is just sending the body a signal. According to the info is works mainly on P2Y receptors which are mainly in the ears & lungs - but maybe it would be helpful to keep the lungs OK as you get through the cold? It also works to balance Th1 & Th2, which is off balance in CF.

The doctors that developed Mucolyxir are at coem.com. look back in the posts, I think someone spoke to them recently.