title: Quantitative assessment of HIV-1 protease inhibitor interactions with drug efflux transporters in the blood-brain barrier.
abstract: OBJECTIVE
  To quantitatively characterize the drug efflux interactions of various HIV-1 protease inhibitors in an in vitro model of the blood-brain barrier (BBB) and to compare that with HIV-1 protease inhibitor stimulated P-glycoprotein (P-gp)-ATPase activity.
  
  
  METHODS
  Cellular accumulation of the P-gp sensitive probe, rhodamine 123 (R123), and the mixed P-gp/multidrug resistance-associated protein (MRP) probe, 2',7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF), were evaluated in primary cultured bovine brain microvessel endothelial cells (BBMEC) in the presence of various concentrations of HIV-1 protease inhibitors. The potency (IC50) and efficacy (Imax) of the drugs in the cell accumulation assays for P-gp and/or MRP was determined and compared to activity in a P-gp ATPase assay.
  
  
  RESULTS
  For R123 (P-gp probe), the rank order potency for inhibiting R123 accumulation in the BBMEC was saquinavir=nelfinavir>ritonavir=amprenavir>indinavir. This correlated well with the rank order affinity in the P-gp ATPase assay. The rank order potency for MRP-related drug efflux transporters, was nelfinavir>ritonavir>saquinavir>amprenavir>indinavir.
  
  
  CONCLUSIONS
  HIV-1 protease inhibitors potently interact with both P-gp and MRP-related transporters in BBMEC. Characterization of the interactions between the HIV-1 protease inhibitors and drug efflux transporters in brain microvessel endothelial cells will provide insight into potential drug-drug interactions and permeability issues in the BBB.
authors.affiliation: Department of Pharmaceutical Sciences, University of Nebraska Medical Center, 986025 Nebraska Medical Center, Omaha, Nebraska, USA.
authors.forename: Corbin J
authors.initials: CJ
authors.lastname: Bachmeier
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Spitzenberger
authors.forename: William F
authors.initials: WF
authors.lastname: Elmquist
authors.forename: Donald W
authors.initials: DW
authors.lastname: Miller
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B / Q000378:metabolism; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D001812:Blood-Brain Barrier / Q000502:physiology*; D002352:Carrier Proteins / Q000378:metabolism*; D002417:Cattle; D002478:Cells, Cultured; D004347:Drug Interactions; D042783:Endothelial Cells / Q000378:metabolism; D005452:Fluoresceins; D005456:Fluorescent Dyes; D017320:HIV Protease Inhibitors / Q000493:pharmacokinetics* / Q000494:pharmacology; D015497:HIV-1 / Q000201:enzymology*; D007202:Indicators and Reagents; D020112:Rhodamine 123
chemical_list: D018435:ATP Binding Cassette Transporter, Subfamily B; D002352:Carrier Proteins; D005452:Fluoresceins; D005456:Fluorescent Dyes; D017320:HIV Protease Inhibitors; D007202:Indicators and Reagents; D020112:Rhodamine 123; C043829:2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein; D000251:Adenosine Triphosphatases