Variation in the dopaminergic response during the day in Parkinson disease

Alessandra Monge, Fabio Viselli, Fabrizio Stocchi, Luca Barbato, Andrea Bolner, Nicola Modugno, Michele Paradiso, Stefano Ruggieri, Gianpietro Nordera

Research output: Contribution to journalArticlepeer-review


Objective: In many parkinsonian patients with fluctuating disease the early morning levodopa dose is more effective than the following dose on the same day. In this study we investigated whether the poor responsiveness to the early afternoon dose of levodopa depends only on peripheral and central levodopa pharmacokinetics or also on pharmacodynamic factors. Methods: Ten parkinsonian patients experiencing postprandial drug-resistant off periods received two boluses of apomorphine by subcutaneous injection at 8 AM and 3 PM on two nonconsecutive days. On day 2, therapy was stopped at 11 AM. For each bolus we determined time to on, duration of the on state, magnitude of benefit, and levodopa and apomorphine plasma levels at baseline and immediately after patients reached the on state. Results: The mean duration of on phases was significantly shorter and the apomorphine plasma level needed to reach the on state was significantly higher in the afternoon than in the morning (P <0. 01 by paired t test). Conclusions: This study suggest that there is a change in responsiveness to dopaminergic stimulation during the day. The less effective dopaminergic response in afternoon depends on pharmacodynamic factors and not only on peripheral and central levodopa pharmacokinetic.

Original languageEnglish
Pages (from-to)116-118
Number of pages3
JournalClinical Neuropharmacology
Issue number3
Publication statusPublished - May 2004


  • Apomorphine
  • Dopaminergic response
  • Parkinson disease
  • Pharmacodynamic factors

ASJC Scopus subject areas

  • Pharmacology (medical)
  • Clinical Neurology
  • Neuroscience(all)
  • Pharmacology, Toxicology and Pharmaceutics(all)


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