title: Development of a physiologically based pharmacokinetic/pharmacodynamic model to identify mechanisms contributing to entacapone low bioavailability.
abstract: Entacapone is an inhibitor of catechol-O-methyltransferase (COMT) and is being used to extend the therapeutic effect of levodopa in patients with advanced and fluctuating Parkinson's disease. Entacapone has low and variable oral bioavailability and the underlying mechanism(s) for this behavior have not been studied. To explain such behavior and to characterize the dynamic changes in the metabolism of entacapone, a physiologically based pharmacokinetic/pharmacodynamic (PBPK/PD) model was developed integrating in silico, in vitro and in vivo pharmacokinetic data. The model was developed and verified in healthy volunteers and subsequently expanded to predict the pharmacokinetic parameters of entacapone phosphate, a prodrug of entacapone, and to assess the impact of hepatic impairment on the pharmacokinetics of entacapone. Low and inter-individual variability in bioavailability could be attributed to the extensive first-pass metabolism by UGTs in the liver and, to a lesser extent, the small intestine. The predictive performance of this model was acceptable with predicted Cmax , AUC and PD parameters lying within 20% of the observed data. The model indicates that the low bioavailability could be attributed to the extensive first-pass effect of entacapone.
authors: Department of Basic Pharmaceutical Sciences, School of Pharmacy, University of Louisiana at Monroe, Monroe, LA, 71201, USA.
authors: Saeed
authors: S
authors: Alqahtani
authors: Department of Basic Pharmaceutical Sciences, School of Pharmacy, University of Louisiana at Monroe, Monroe, LA, 71201, USA.
authors: Amal
authors: A
authors: Kaddoumi
mesh_terms: D000328:Adult; D000818:Animals; D000978:Antiparkinson Agents / Q000097:blood / Q000737:chemistry / Q000378:metabolism / Q000493:pharmacokinetics*; D001682:Biological Availability; D001711:Biotransformation; D018938:Caco-2 Cells; D065098:Catechol O-Methyltransferase Inhibitors / Q000097:blood / Q000737:chemistry / Q000378:metabolism / Q000493:pharmacokinetics*; D002396:Catechols / Q000097:blood / Q000737:chemistry / Q000378:metabolism / Q000493:pharmacokinetics*; D019295:Computational Biology; D020895:Enterocytes / Q000378:metabolism; D005103:Expert Systems; D006801:Humans; D007408:Intestinal Absorption; D008099:Liver / Q000378:metabolism*; D008297:Male; D008657:Metabolic Clearance Rate; D008954:Models, Biological; D009570:Nitriles / Q000097:blood / Q000737:chemistry / Q000378:metabolism / Q000493:pharmacokinetics*; D010766:Phosphorylation; D011355:Prodrugs / Q000032:analysis / Q000737:chemistry / Q000378:metabolism / Q000493:pharmacokinetics*; D051381:Rats; D012995:Solubility; D014018:Tissue Distribution
chemical_list: D000978:Antiparkinson Agents; D065098:Catechol O-Methyltransferase Inhibitors; D002396:Catechols; D009570:Nitriles; D011355:Prodrugs; C071192:entacapone
keywords: PBPK-PD; entacapone; metabolism; prodrug; transporters