I'm interested in some medicine concepts.
I'm hoping someone can tell me if this has been tried or if it makes sense since I know little about biology.

premises:

lack of dopamine is the main reason for PD
dopamine cant go through the blood brain barrier so we use l-dopa etc...etc...

question:
if we could find a way to get dopamine through the blood brain barrier, would that alleviate the symptoms better than ldopa?

question 2:

is it biologically possible (was there any research), on this kind of threatments:

chemical A chemical B = dopamine

chemical A and B can go through the blood brain barrier

applying the A and B in two phases, so they form dopamine once they are "behind" the blood brain barrier?

P.S. sorry if I'm talking rubbish, but I'm trying to learn/help