Scopolamine is one of a group of drugs called anti-cholinergics. It is used primarily for the prevention of motion sickness. It can cause dryness of saliva and mucus and might help reduce the amount of mucous. You state that your asthma is, "...always out of control because of all this mucus". That could be true, especially if the mucus originates in the upper airways, rather than your lungs. However asthma is not infrequently characterized by excessive mucus and the mucus could be caused by your asthma.
Determination of the source of the mucus could be very helpful and attempts should be made to do that. You should be checked for gastroesophageal reflux disease (GERD), as it can also irritate the airways and cause excessive mucus to be produced. You are on good respiratory medicines but still might benefit from consultation with a pulmonary specialist to rule out auto-immune lung disease and immunodeficiency to rule out other lung diseases that could be superimposed on your asthma, such as bronchiectasis.
Thank You for your information. I have had all of the appropriate testing done to find out the cause of this mucus problem. I have had a ph probe to check for gerd and that was negative done at Uof Mich teaching hospital. Bronchiastasis (sp?) was also ruled out at same hospital by bronchosopy. The general consensus is that the sinusitis is the main culprit for the excessive mucus. ENT's just have nothing to add other than they don't know why I have this problem. I just recently had a very bad sinus infection and have been on antibiotics for 6 weeks before the green and black old blood has cleared. I'm back to whitish volumes of mucus. Something will trigger it most of the time, like a cough or a laugh, however sometimes it just errupts. I am very puzzeled since I never had anything even close to this before it all started 5 yrs. ago.