I have taken premarin with my Parkinson's drugs since onset of PD (age 44) with no apparent adverse side effects. Ditropan: causes me a great problem with insomnia....I sleep only 1.5 hours out of 24 hours when I am on the drug. I tried on two occasions to take ditropan for 10 days....the second time around I gave up after 5 days of little sleep.........may or may not be the Parkinson's drugs interacting . Rita Weeks