title: Intracellular 'boosting' of darunavir using known transport inhibitors in primary PBMC.
abstract: OBJECTIVE
  ABCB1, some ABCCs and SLCOs have been reported to affect the intracellular accumulation of various protease inhibitors in vitro and ex vivo. Darunavir is the most recently licensed protease inhibitor and we sought to investigate the ability of transport inhibitors to influence its intracellular accumulation in lymphocytes from healthy volunteers.
  
  
  METHODS
  The intracellular accumulation of radiolabelled darunavir was assessed using CEM cells and ABCB1-overexpressing CEM(VBL) cells. Apical and basolateral transport of radiolabelled darunavir through MDCKII monolayers was also studied. Finally the ability of known inhibitors to influence intracellular accumulation of darunavir in peripheral blood mononuclear cells (PBMC) was investigated.
  
  
  RESULTS
  CEM(VBL) cells (1.4 +/- 0.6, P < 0.001, 95% CI for the difference = 0.46, 0.80, n= 7) had significantly lower accumulation of darunavir compared with CEM cells (5.6 +/- 0.7, n= 7) and this was reversed by addition of tariquidar (30 nm, 4.6 +/- 0.8, P < 0.001, 95% CI =-0.64, -0.41, n= 4). In MDCKII-ABCBI cells, transport from the basal to the apical compartment was observed and this was also reversible with the addition of tariquidar. In PBMCs, dipyridamole (6.9 +/- 1.3, P < 0.01, 95% CI for the difference =-1.16, -0.30, (n= 8) significantly increased whilst montelukast (5.7 +/- 1.0, P < 0.01, 95% CI for the difference = 0.16, 0.79, n= 8) significantly decreased the intracellular accumulation of darunavir when compared with control (6.2 +/- 1.1, n= 8).
  
  
  CONCLUSIONS
  Darunavir is a substrate for efflux and influx transporters in PBMC and intracellular concentrations can be manipulated using known inhibitors.
authors.affiliation: Pharmacology and Therapeutics, University of Liverpool, Liverpool, UK.
authors.forename: Wai San
authors.initials: WS
authors.lastname: Kwan
authors.forename: Omar
authors.initials: O
authors.lastname: Janneh
authors.forename: Ruben
authors.initials: R
authors.lastname: Hartkoorn
authors.forename: Becky
authors.initials: B
authors.lastname: Chandler
authors.forename: Saye
authors.initials: S
authors.lastname: Khoo
authors.forename: David
authors.initials: D
authors.lastname: Back
authors.forename: Andrew
authors.initials: A
authors.lastname: Owen
mesh_terms: D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D002460:Cell Line; D000069454:Darunavir; D004285:Dogs; D017320:HIV Protease Inhibitors / Q000378:metabolism*; D006801:Humans; D015458:Leukemia, T-Cell / Q000188:drug therapy / Q000378:metabolism; D007963:Leukocytes, Mononuclear / Q000378:metabolism*; D049990:Membrane Transport Modulators / Q000494:pharmacology; D013449:Sulfonamides / Q000378:metabolism*
chemical_list: D017320:HIV Protease Inhibitors; D049990:Membrane Transport Modulators; D013449:Sulfonamides; D000069454:Darunavir