What are your experiences with medications for patients with dementia when you can't guarantee that it will be taken every day?

That's a big issue - to be effective medications need to be taken consistently. I'm not sure they'd be useless if a dose is skipped, but there are alarms and other medication devices online (www.alzstore.com is one source) that can help remind her. You might want to check with the doctor and see what kind of "wiggle room" there is in the medications.
Carol