Posted 1/12/2012 12:10 PM (GMT -5)
Apparently your allergy medicine requires stomach acid (omeprazole, and other PPIs, suppress acid) to dissolve the coating, since it is most effectively absorbed into the system from the stomach, and can probably work quickly that way as well.
Talk to your doctor about this -- perhaps you can pre-dissolve the allergy medicine, or switch to another type?
-Bruce