title: Hydrosoluble fiber (Plantago ovata husk) and levodopa I: experimental study of the pharmacokinetic interaction.
abstract: Fiber therapy could be used in patients with Parkinson disease to reduce the symptoms of gastrointestinal disorders; however, it could interact with levodopa reducing its effectiveness. In this experimental study we have investigated whether the presence of Plantago ovata husk (water-soluble fiber) modifies in rabbits the bioavailability and other pharmacokinetic parameters of levodopa (20 mg/kg) when administered by the oral route at the same time. We have also studied whether pharmacokinetic modifications are fiber-dose dependent (100 and 400 mg/kg). The extent of levodopa absorbed when administering 100 mg/kg of fiber (AUC=43.4 mug min ml(-1)) is approximately the same as when levodopa is administered alone (AUC=47.1 microg min ml(-1)); however, Cmax is lower (1.04 versus 1.43 microg ml(-1)). Results obtained indicate that fiber at the higher dose increases the extent of levodopa absorbed (AUC=62.2 microg min ml(-1)), being the value of Cmax similar (1.46 microg ml(-1)). The value of tmax increases from 10 min when levodopa is administered alone to 20 min when the animals receive fiber. On the other hand, since certain time on, levodopa concentrations are always higher in the groups that receive fiber: 60 min with 100 mg/kg fiber and 20 min with 400 mg/kg fiber. Fiber also increases the mean residence time (MRT). P. ovata husk administration with levodopa could be beneficial, not only in patients with constipation, due to: lower adverse reactions (lower values of Cmax) and longer and more stable effects (higher final concentrations and more time in the body).
authors.affiliation: Area de Farmacologia, Universidad de Leon, 24071 Leon, Spain.
authors.forename: Juan J
authors.initials: JJ
authors.lastname: Garcia
authors.forename: Nelida
authors.initials: N
authors.lastname: Fernandez
authors.forename: Demetrio
authors.initials: D
authors.lastname: Carriedo
authors.forename: M Jose
authors.initials: MJ
authors.lastname: Diez
authors.forename: Ana
authors.initials: A
authors.lastname: Sahagun
authors.forename: Aranzazu
authors.initials: A
authors.lastname: Gonzalez
authors.forename: Angela
authors.initials: A
authors.lastname: Calle
authors.forename: Matilde
authors.initials: M
authors.lastname: Sierra
mesh_terms: D000284:Administration, Oral; D000818:Animals; D019540:Area Under Curve; D001682:Biological Availability; D004043:Dietary Fiber / Q000008:administration & dosage / Q000494:pharmacology*; D006801:Humans; D007980:Levodopa / Q000008:administration & dosage / Q000493:pharmacokinetics* / Q000627:therapeutic use*; D023421:Models, Animal; D008517:Phytotherapy; D010943:Plantago; D011817:Rabbits
chemical_list: D004043:Dietary Fiber; D007980:Levodopa