Parkinson's excess saliva

My grandfather is 84 years old and has been suffering from Parkinson's disease for the past 8-9 years. He takes allopathic medicines. Recently he has been suffering from excess salivation, which occurs throughout the day. The saliva fills his mouth and keeps dripping so normally he needs to keep a few cloths by him to absorb it. He is not able to talk properly during this time. He is not sufficiently motivated to try alternative remedies for Parkinson's properly and has often given them up within a few weeks or less if there is no observable effect by that time. I understand that treatment of Parkinson's with homeopathy can take a long time so at least at the moment I do not think it will be possible to persuade him to take homeopathic remedies for the disease as a whole. However, I would like to know if there are any remedies that could provide reasonably fast-acting relief for the excess saliva problem.