The contribution of the peripheral and central pharmacokinetic mechanisms of levodopa to the pathogenesis of the motor fluctuations that complicate its long‐term administration was studied in 28 parkinsonian patients. The rate of levodopa clearance from the general circulation, its plasma half‐life, and apparent volume of distribution were indistinguishable between patients with the on‐off or the wearing‐off phenomenon and those with a stable response to levodopa or those who had not been previously treated with levodopa. Peripheral pharmacokinetic factors are thus unlikely to account for the development of these response fluctuations. Conversely, the efficacy half‐time of levodopa differed markedly among the four response groups studied and may provide a quantitative index of central mechanisms that favor the development of the wearing‐off and on‐off phemonena. Although symptom duration was the best predictor of the severity of untreated parkinsonism, levodopa dose correlated best with response half‐time. The wearing‐off phenomenon may primarily reflect the loss of buffering capacity caused by degeneration of the dopamine neurons, while the development of the on‐off phenomenon appears to require additional postsynaptic changes, possibly at the receptor level.
Annals of Neurology – Wiley
Published: Apr 1, 1987
It’s your single place to instantly
discover and read the research
that matters to you.
Enjoy affordable access to
over 18 million articles from more than
15,000 peer-reviewed journals.
All for just $49/month
Query the DeepDyve database, plus search all of PubMed and Google Scholar seamlessly
Save any article or search result from DeepDyve, PubMed, and Google Scholar... all in one place.
Get unlimited, online access to over 18 million full-text articles from more than 15,000 scientific journals.
Read from thousands of the leading scholarly journals from SpringerNature, Wiley-Blackwell, Oxford University Press and more.
All the latest content is available, no embargo periods.
“Hi guys, I cannot tell you how much I love this resource. Incredible. I really believe you've hit the nail on the head with this site in regards to solving the research-purchase issue.”Daniel C.
“Whoa! It’s like Spotify but for academic articles.”@Phil_Robichaud
“I must say, @deepdyve is a fabulous solution to the independent researcher's problem of #access to #information.”@deepthiw
“My last article couldn't be possible without the platform @deepdyve that makes journal papers cheaper.”@JoseServera