Liquid melevodopa versus standard levodopa in patients with Parkinson disease and small intestinal bacterial overgrowth

Clin Neuropharmacol. 2014 Jul-Aug;37(4):91-5. doi: 10.1097/WNF.0000000000000034.


Objectives: Patients with Parkinson disease exhibit a highly increased prevalence of small intestinal bacterial overgrowth (SIBO), which has been also associated with the severity of motor fluctuations. Aim of this study was to test the efficacy of liquid levodopa with higher bioavailability in patients with SIBO.

Methods: Thirty-three patients with Parkinson disease underwent both lactulose and glucose breath tests to assess the presence of SIBO. A urea breath test was performed to assess the presence of a concomitant Helicobacter pylori infection. Patients were challenged with 250 mg of levodopa and 314 mg of levodopa methylester. Drug challenges were performed on different days and at baseline and 1 month after SIBO eradication. During the tests, the motor condition and the plasma levodopa concentrations were evaluated.

Results: At baseline, the onset of motor benefit was significantly shorter after melevodopa than after standard levodopa, as confirmed by the latency to motor on condition and t max (time to the on condition, 28.8±11.5 vs 55.5±40.2 minutes; P=0.0004; and t max, 28.2±9.7 vs 50.0±11.0 minutes; P=0.002). The duration of the on time or area under the curve was not significantly different. The underlying gastrointestinal condition did not influence these results.

Conclusions: The reduction of the latency to the on condition in the absence of a reduction of the on duration is a promising feature of melevodopa because this effect would increase the total daily on duration. Future studies that evaluate the usefulness of melevodopa beyond the acute challenge (eg, using motor diaries) in patients with gastrointestinal infections are warranted.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Analysis of Variance
  • Antiparkinson Agents
  • Breath Tests
  • Female
  • Gastrointestinal Agents / therapeutic use
  • Glucose / metabolism
  • Helicobacter Infections / diagnosis
  • Helicobacter Infections / drug therapy
  • Helicobacter Infections / epidemiology*
  • Helicobacter pylori / pathogenicity*
  • Humans
  • Lactulose / metabolism
  • Levodopa / analogs & derivatives*
  • Levodopa / therapeutic use*
  • Male
  • Middle Aged
  • Parkinson Disease / drug therapy*
  • Parkinson Disease / epidemiology
  • Rifamycins / therapeutic use
  • Rifaximin
  • Severity of Illness Index


  • Antiparkinson Agents
  • Gastrointestinal Agents
  • Rifamycins
  • Lactulose
  • Levodopa
  • Glucose
  • Rifaximin
  • levodopa methyl ester