Sorry Paula,

Much occupied but will tell you all I know about asap.
Moderation must be the main word, because all is not due to and/or against the use of levo-dopa with carbidopa (or benserazide).
It depends on....several considerations


1. Pharmacology, kinetics of drugs; chronopharmacology

When we talk about any drug and then more specially about dopaminergic ones , we have to consider different topics, parameters, factors and situations and of course to separate as far as possible, PD factors from drugs effects.

So for Levodopa and Carbidopa
- the molecules by themselves (pharmacology, effects in brain, in body)
- the two types of levo-dopa-carbidopa (standard CR)
- the pharmacokinetics data ( time to maximal concentration, intestinal and BBB crossing, duration of effects, elimination from body)
- the medical case it is given to (the case of the patient , the stage and complications of PD, of drug, of PD+drug )
- the way it is prescribed (dosages, schedule of intakes, schedule and type of meals, association to other drugs)
- the way it is taken, alternative drugs intakes
- the way it is understood by patients and carers and helpers (this means first explained, taught)
- and then the way it is adapted to the patient daily conditions, variability of levels, threshold and all or nothing effect, circadian rhythms...


2. Scientific data about CNS PNS body, in PD, and with Levodopa

The most shocking is first of all the "absence of consideration" to any other place in body and brain except substantia nigra,
and thus to the proper balance of several main regulations in CNS and PNS

2.1 upon neurotransmitters sytems in CNS
- CNS dopaminergic systems other than Substantia Nigra
- CNS norepinephrin (NE) systems, as in these, Dopamine is 'only' a precursor to release of NE, and as so, L-Dopa
- CNS balance of neurotransmitters, neuroplasticity, neurogenesis, neurophicity, neuroendocrine and immune functions, stress regulation...
- and their relations to general immunity, to enteric nervous system, etc....

2.2 upon neurotransmitters sytems in PNS
-Peripheral Nervous System effects L-Dopa upon DA and NA in autonomous system
-Peripheral effects of Levo-dopa and of carbidopa upon heart,vessels, kidneys, adrenals..

2.3 upon muscles, nerves, sensory receptors....


3. Levodopa + Carbidopa and other drugs

- Levodopa and carbidopa, and benserazide
- Same with ICOMT (stalevo) , with IMAO
-...and with agonists...


Excellent works to understand the complex regulation of balance of neurotransmitters systems in Brain
are those of Roshan Cools and allied teams she collaborates with
Chemistry of the adaptive brain (2004) and following ones.

More to come, depending on own possibilities...

As for the question, "Gold Standard drug: yes, but who gets the gold?",
I bet everyone will find who takes the standard drug and who gets the Gold...


Yours
Anne.