Hi, My GrandPa has been suffering from PD for the past 2 years. The only medicine he has been taking is the L-dopa (levodopa). He has a dosage of CR and non-CR daily. (I dont remember the exact dosage though). In the postings here, I have seen many drugs being mentioned.. 1)Sinemet 2)Mirapex 3)Carbidopa Can you please help me understand the need for these drugs, when they are used and the advantages compared with levodopa? Essentially do ALL these help in producing dopamine or do they do anything different ? thanks in advance, murthy