I'm sorry you haven't received more responses here. But welcome to the forum! I hesitated to answer your first post, because I have no very valuable information to offer. My own case of PD is different, and I am taking only a small dose of sinemet per day, so I don't have a lot of personal experience with it.
I started on Mirapex, a dopamine agonist, which reversed my early symptoms well at first. Then over the years, I have added other medications, including sinemet.
I wish you well and hope someone with a case more similar to yours (maybe someone else who has asthma) will post soon.