"For another, when we start ldopa we are cautioned to avoid protein, amino acids, some B vitamins, "

avoid taking simultaneously. not stop taking. aren't you describing a situation that has to be managed with many drugs, namely a drug to food and drug to drug interaction? like not eating grapefruit within a few hr of taking some meds?

aren't you just referring to disease management?

i'm not absolutely sure but i think the problem that i see for companies developing new pd drugs for YOPD'ers is the FDA won't approve them unless the work much better than the current industry standard. so a new dopamine agonist has to be better than mirapex or requip.
i was in a phase3 trial by PHARMACIA for a new agonist called sumanirole. in the entire county where seattle resides they FOUND 3 VOLUNTEERS. The 1st part you got sumanirole, placebo or requip. that progressed to the open labell trial where everyone got to dose up to an effective dose of sumanirole. my pd was very mild but the sum. worked for me with no side affects, in the 1st part i assumed i got requip because of the side affects. what happened? the trial was cancelled. no explanation. PHARMACIA had been bought out though. it's likely they could not prove a big enough improvement over requip. that's another problem with getting fda approval, the difficulty in measuringpd symptoms. no lab tests, for drugs treating symptoms it's all subjective. thus for small diffferences you need a lot of subjects, very tough to do.
neurologix implied that for their future phase3 gabba gene therapy trial the FDA might require them to go head to head with DBS. it took 3years to get phase2 results, the last of the 44 phase2 subjects was treated 8 months ago. imagine the difficulty of finding DBS candidates along with finding those that will risk brain surgery and gene therapy. quite a challenge even in a perfect research world.

blame the drug companies all you want. i think some blame goes towards the FDA, the fact that it's hard to find candidates for clinical trials because sinemet works so well and it's very difficult to stop taking your current meds to try something that might be better. i'm personally amazed at the amount of pd research going on right now. ldopa patch, azilect, rigotine patch, numerous phase 2 gene therapies, lots of phase1, improved DBS's, spinal cord stim., electromagnets. sure it could be better.