Gastric emptying in Parkinson's disease: patients with and without response fluctuations

Delayed gastric emptying may be an important pharmacokinetic mechanism underlying some of the response fluctuations that develop after long-term levodopa therapy. We performed a radionuclide gastric emptying study using a standard Tc-99m colloid-labeled solid meal in 30 patients with Parkinson's disease (PD), 15 fluctuators with "delayed-on" and "no-on" phenomena, and 15 nonfluctuators. Fasting patients were given the standard meal, and gastric emptying was monitored with a gamma camera positioned over the stomach, recording data for 1 hour. PD patients had prolonged gastric emptying measured after 60 minutes compared with the normal control subjects (70.7 +/- 16% versus < 60%). Gastric retention measured after 1 hour was increased in patients with fluctuations compared with patients without fluctuations (77.4 +/- 15.5% versus 64.0 +/- 14.3%; p < 0.05). Half-time emptying was significantly delayed in patients with, as compared with those without, response fluctuations (221 +/- 202 minutes versus 85 +/- 31 minutes; p < 0.05). This demonstrates that delayed gastric emptying is common in PD patients and is more marked in those with response fluctuations. The stomach is an important target organ in PD, affected either by the basic PD pathology, chronic drug administration, or both.