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Short description

This the compartmental model for L-Dopa pharmocokinetics without simultaneous donation of benserazide described in the article:
A pharmacokinetic model to predict the PK interaction of L-dopa and benserazide in rats.
Grange S, Holford NH and Guentert TW.
Pharm Res. 2001 AUg; 18(8):1174-84 11587490


Abstract:

PURPOSE: To study the PK interaction of L-dopa/benserazide in rats. METHODS: Male rats received a single oral dose of 80 mg/kg L-dopa or 20 mg/kg benserazide or 80/20 mg/kg L-dopa/benserazide. Based on plasma concentrations the kinetics of L-dopa, 3-O-methyldopa (3-OMD), benserazide, and its metabolite Ro 04-5127 were characterized by noncompartmental analysis and a compartmental model where total L-dopa clearance was the sum of the clearances mediated by amino-acid-decarboxylase (AADC), catechol-O-methyltransferase and other enzymes. In the model Ro 04-5127 inhibited competitively the L-dopa clearance by AADC.

RESULTS: The coadministration of L-dopa/benserazide resulted in a major increase in systemic exposure to L-dopa and 3-OMD and a decrease in L-dopa clearance. The compartmental model allowed an adequate description of the observed L-dopa and 3-OMD concentrations in the absence and presence of benserazide. It had an advantage over noncompartmental analysis because it could describe the temporal change of inhibition and recovery of AADC.

CONCLUSIONS: Our study is the first investigation where the kinetics of benserazide and Ro 04-5127 have been described by a compartmental model. The L-dopa/benserazide model allowed a mechanism-based view of the L-dopa/benserazide interaction and supports the hypothesis that Ro 04-5127 is the primary active metabolite of benserazide.

The volumes and variables in this model are taken for a rat with 0.25 kg. The inital dose for L_Dopa (L_Dopa_per_kg_rat) is to be given in umole per kg. 80 mg/kg L-Dopa correspond to 404 umol/kg. To change the model to a different mass of rat the compartment volumes, and the parameters rat_body_mass and Q have to changed accordingly.

Format
SBML (L2V4)
Related Publication
  • A pharmacokinetic model to predict the PK interaction of L-dopa and benserazide in rats.
  • Grange S, Holford NH, Guentert TW
  • Pharmaceutical research , 8/ 2001 , Volume 18 , pages: 1174-1184
  • PRNS Non-Clinical Drug Safety, F. Hoffmann-La Roche Ltd, Basel, Switzerland. susan.grange@roche.com
  • PURPOSE: To study the PK interaction of L-dopa/benserazide in rats. METHODS: Male rats received a single oral dose of 80 mg/kg L-dopa or 20 mg/kg benserazide or 80/20 mg/kg L-dopa/benserazide. Based on plasma concentrations the kinetics of L-dopa, 3-O-methyldopa (3-OMD), benserazide, and its metabolite Ro 04-5127 were characterized by noncompartmental analysis and a compartmental model where total L-dopa clearance was the sum of the clearances mediated by amino-acid-decarboxylase (AADC), catechol-O-methyltransferase and other enzymes. In the model Ro 04-5127 inhibited competitively the L-dopa clearance by AADC. RESULTS: The coadministration of L-dopa/benserazide resulted in a major increase in systemic exposure to L-dopa and 3-OMD and a decrease in L-dopa clearance. The compartmental model allowed an adequate description of the observed L-dopa and 3-OMD concentrations in the absence and presence of benserazide. It had an advantage over noncompartmental analysis because it could describe the temporal change of inhibition and recovery of AADC. CONCLUSIONS: Our study is the first investigation where the kinetics of benserazide and Ro 04-5127 have been described by a compartmental model. The L-dopa/benserazide model allowed a mechanism-based view of the L-dopa/benserazide interaction and supports the hypothesis that Ro 04-5127 is the primary active metabolite of benserazide.
Contributors
Lukas Endler

Metadata information

Curation status
Curated
  • Model originally submitted by : Lukas Endler
  • Submitted: Mar 25, 2011 11:56:49 AM
  • Last Modified: May 18, 2017 12:32:28 PM
Revisions
  • Version: 2 public model Download this version
    • Submitted on: May 18, 2017 12:32:28 PM
    • Submitted by: Lukas Endler
    • With comment: Current version of Grange2001 - L Dopa PK model
  • Version: 1 public model Download this version
    • Submitted on: Mar 25, 2011 11:56:49 AM
    • Submitted by: Lukas Endler
    • With comment: Original import of Grange2001_L_Dopa_PK
Curator's comment:
(added: 28 Mar 2011, 00:21:40, updated: 28 Mar 2011, 00:21:40)
Time courses for a dose of 80 mg/kg L-Dopa as in figure 6 of the original article, has been reproduced here. The results were calculated using Copasi 4.6.33.
Due to problems with the use of initial assignments in Copasi, the model has to be evaluated once using either a short time-course simulation or a steady state computation to calculate and assign the correct starting values. After this, the model reproduces the correct results. Future versions of Copasi should not have this problem. The model was also tested with SBW 2.7.10, which did not exhibit this problem.