Original ArticlesImpact of Gastric Emptying on Levodopa Pharmacokinetics in Parkinson Disease PatientsMüller, Thomas MD*; Erdmann, Christoph MD*; Bremen, Dirk MD†; Schmidt, Wolfgang E. MD†; Muhlack, Siegfried MD*; Woitalla, Dirk MD*; Goetze, Oliver MD‡§Author Information From the *Department of Neurology, St. Josef Hospital, Ruhr University Bochum, Gudrunstrasse 56, 44791 Bochum, Germany; †Orion Pharma GmbH, Notkestr. 9, 22607 Hamburg, Germany; ‡Department of Medicine I, St. Josef Hospital, Ruhr-University Bochum, Gudrunstrasse 56, 44791 Bochum, Germany; §Present address: University Hospital Zurich, Division of Gastroenterology and Hepatology, 8091 Zürich, Switzerland. Reprints: Thomas Müller, MD, Department of Neurology, St. Josef Hospital, Ruhr University Bochum, Gudrunstrasse 56, 44791 Bochum, Germany (e-mail: firstname.lastname@example.org). Clinical Neuropharmacology: March-April 2006 - Volume 29 - Issue 2 - p 61-67 Buy Abstract Abstract: Adjunction of the catechol-O-methyltransferase (COMT) inhibitor entacapone (EN) to levodopa/carbidopa (LD/CD) improves motor symptoms in patients with Parkinson disease (PD) by a prolonged elimination of LD. But it is not known whether EN addition influences gastric emptying and thus LD pharmacokinetics and pharmacodynamics. Objectives were to simultaneously determine plasma LD elimination, gastric emptying, and clinical response after a single intake of the same LD dosage as LD/CD-or as (LD/CD/EN) formulation on 2 consecutive days. In both groups, PD patients with delayed gastric emptying had significant lower LD plasma concentrations. Addition of EN did not influence gastric emptying but significantly improved motor response, which was not different for patients with delayed gastric emptying. However, with and without EN adjunction gastric emptying distinctly contributes to the variability of plasma LD bioavailability. This may impact LD delivery to the brain and thus motor response in PD patients. Therefore, fine tuning of LD application, which considers gastric emptying, becomes more and more essential in advanced PD stages with a reduced striatal neuronal dopamine capacity, which is responsible for maintenance of motor response in early PD patients. © 2006 Lippincott Williams & Wilkins, Inc.