i had the same problem! i have a pari- forget which model though- but people kept telling me it could be the cup and the medicine could be clogging it up. but it was very clean and not clogged. have you tried changing the cup? because i have done that and it seemed to go much faster- it would normally take 15 mins for me to administer .63 xopenex to my son, but it started taking 1/2 hour! when i changed the cup, it went faster.