A randomised clinical trial to evaluate the effects of Plantago ovata husk in Parkinson patients: changes in levodopa pharmacokinetics and biochemical parameters

BACKGROUND: Plantago ovata husk therapy could be used in patients with Parkinson disease to reduce the symptoms of gastrointestinal disorders, but it is important to know whether this compound modifies levodopa pharmacokinetics. The maintenance of constant plasma concentrations of levodopa abolishes the clinical fluctuations in parkinsonian patients. The aim of this randomised clinical trial was to establish the influence of the fiber Plantago ovata husk in the pharmacokinetics of levodopa when administered to Parkinson patients well controlled by their oral medication. METHODS: To evaluate the effects of this fiber on several biochemical parameters. 18 volunteers participated in the study and received alternatively two treatments (Plantago ovata husk or placebo) with their usual levodopa/carbidopa oral dose. On days 0 (initial situation), 14 and 35 of the study, blood samples were taken to assess levodopa pharmacokinetics and to determine biochemical parameters. RESULTS: Levodopa C(max) was very similar in the initial situation (603.2 ng/ml) and after placebo administration (612.0 ng/ml), being slightly lower (547.8 ng/ml) when Plantago ovata husk was given. AUC was very similar in the three groups: initial situation.- 62.87 μg.min/ml, fiber treatment.- 64.47 μg.min/ml and placebo treatment.- 65.10 μg.min/ml. Fiber reduced significantly the number of peaks observed in the levodopa concentrations, maintaining concentrations more stable. No significant differences were found in total cholesterol, LDL-cholesterol and triglycerides with the administration of Plantago ovata husk. CONCLUSIONS: Plantago ovata husk administration caused a smoothing and homogenization of levodopa absorption, providing more stable concentrations and final higher levels, resulting in a great benefit for patients. TRIAL REGISTRATION: EudraCT2006-000491-33