How important is a levodopa based treatment? by Connie b. Dellobuono
Answer by Connie b. Dellobuono:
Levodopa has been the gold standard for symptomatic therapy of Parkinson’s disease (PD)during the last 50 years.
But:
Still, for all the good this medication imparts, it has its limitations. For one, it unfortunately does little for the non-motor symptoms of PD. Secondly, as a consequence of its short half-life, levodopa requires frequent dosing. Even in conjunction with carbidopa, a decarboxylase inhibitor that prevents peripheral breakdown, the half-life is a mere 90 minutes and the duration of action only three to four hours. Finally, this recurrent cycle of medication kicking in and then wearing off with each administration leads to oscillations in plasma drug concentrations that, with chronic use (five to 10 years), contribute to motor complications in a good number of patients.4 Additional causative factors include higher total daily dosages of levodopa; the drug’s pulsatile, non-physiologic stimulation of degenerating neurons; and longer duration of PD.
https://www.michaeljfox.org/files/foundation/Levodopa2.0.pdf