Peripheral pharmacokinetic parameters of levodopa/carbidopa and the on-off phenomenon in parkinsonian patients.

The principal peripheral pharmacokinetic parameters of the levodopa/carbidopa association were investigated in 11 healthy volunteers and in 16 patients at various stages of Parkinson disease, with and without the on-off phenomenon. After oral administration of a standard dose of drug (levodopa 250 mg + carbidopa 25 mg) the peak plasma concentrations, peak onset time and area under the curve/time proved to be similar across the groups. There was no difference in peripheral pharmacokinetics of the association between parkinsonian patients with swings in response and those without.