Carbidopa Toxicity: My mother's PD-Neuro. wants medical-literature evidence; can someone provide this?

[SJS-OnTheNet <sjs-tv@xxxxxxxxxxxxxxxx>]

Dear All:

Yesterday, I took my mother (who has PD) to her new neurologist (a
movement-disorders specialist), who is said to have an excellent
reputation. As I am a subscriber to the PD Digest, and had read in the
Digest many comments about carbidopa-toxicity (She's on Sinemet), I asked
him about that toxicity; Mom is currently getting 2 x 10/100 Sinemet five
times a day (starting at 6:00am), plus 2-and-a-half 10/100 at midnight.

I mentioned to him that I'd read comments here that a person need not have
(and perhaps should not have) more than 70-100 mg of carbidopa per day
(=24hours?), regardless of the amount of levodopa, to avert toxicity.

He replied that he's only seen anecdotal information on
carbidopa-toxicity, and said he'd like to see solid information -- in the
medical literature -- about this toxicity-claim.

Can anyone out there direct me, therefore, to specific medical literature
references about this claim? It would be much appreciated.

I also asked him about other new meds for PD, such as NADH; he answered
that there's only one real paper on NADH and that comes from Dr. Birkmayer
(I've read the paper), and that this is not sufficient. So, does anyone
out there have any additional solid reference-material that they can refer
me to, about NADH -- such as bonafide studies done by scientists/doctors
*other than* Birkmayer?

Thanks.

-- SJS