Medication for Bed-wetting?

My 8-year-old son still wets the bed almost every night. We've tried waking him up and having him go to the bathroom in the night, and sometimes that helps, but he doesn't seem to be able to get up in the night to go by himself. The PA at our family doctor's office says that sometimes a medication is the best way to solve the problem - he said that his own son tried it at nine and did really well. In fact, he didn't even need to take the med after a few months. I'm curious . . . has anyone else used meds to help a child wetting the bed? Did it work? Were you able to quit the meds after a short time or did you have to continue them long-term?