title: In Vitro Assessment of Uptake and Lysosomal Sequestration of Respiratory Drugs in Alveolar Macrophage Cell Line NR8383.
abstract: OBJECTIVE
  To assess accumulation and lysosomal sequestration of 9 drugs used in respiratory indications (plus imipramine as positive control) in the alveolar macrophage (AM) cell line NR8383.
  
  
  METHODS
  For all drugs, uptake at 5 μM was investigated at 37 and 4°C to delineate active uptake and passive diffusion processes. Accumulation of basic clarithromycin, formoterol and imipramine was also assessed over 0.1-100 μM concentration range. Lysosomal sequestration was investigated using ammonium chloride (NH4Cl), monensin and nigericin. Impact of lysosomal sequestration on clarithromycin accumulation kinetics was investigated.
  
  
  RESULTS
  Both cell-to-medium concentration ratio (Kp) and uptake clearance (CLuptake) ranged > 400-fold for the drugs investigated. The greatest Kp was observed for imipramine (391) and clarithromycin (82), in contrast to no accumulation seen for terbutaline. A concentration-dependent accumulation was evident for the basic drugs investigated. Imipramine and clarithromycin Kp and CLuptake were reduced by 59-85% in the presence of NH4Cl and monensin/nigericin, indicating lysosomal accumulation, whereas lysosomal sequestration was not pronounced for the other 8 respiratory drugs. Clarithromycin uptake rate was altered by NH4Cl, highlighting the impact of subcellular distribution on accumulation kinetics.
  
  
  CONCLUSIONS
  This study provides novel evidence of the utility of NR8383 for investigating accumulation and lysosomal sequestration of respiratory drugs in AMs.
authors.affiliation: Centre for Applied Pharmacokinetic Research, Manchester Pharmacy School, The University of Manchester, Stopford Building, Oxford Road, Manchester, M13 9PT, UK.
authors.forename: Ayşe
authors.initials: A
authors.lastname: Ufuk
authors.affiliation: GlaxoSmithKline, Medicines Research Centre, Stevenage, UK.
authors.forename: Graham
authors.initials: G
authors.lastname: Somers
authors.affiliation: Centre for Applied Pharmacokinetic Research, Manchester Pharmacy School, The University of Manchester, Stopford Building, Oxford Road, Manchester, M13 9PT, UK.
authors.forename: J Brian
authors.initials: JB
authors.lastname: Houston
authors.affiliation: Centre for Applied Pharmacokinetic Research, Manchester Pharmacy School, The University of Manchester, Stopford Building, Oxford Road, Manchester, M13 9PT, UK. Aleksandra.Galetin@manchester.ac.uk.
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Galetin
mesh_terms: D018759:Adrenergic Uptake Inhibitors / Q000378:metabolism; D000890:Anti-Infective Agents / Q000378:metabolism; D001993:Bronchodilator Agents / Q000378:metabolism; D002460:Cell Line; D017291:Clarithromycin / Q000378:metabolism; D006801:Humans; D007099:Imipramine / Q000378:metabolism; D008247:Lysosomes / Q000378:metabolism*; D016676:Macrophages, Alveolar / Q000166:cytology / Q000378:metabolism*; D004364:Pharmaceutical Preparations / Q000378:metabolism*; D013726:Terbutaline / Q000378:metabolism
chemical_list: D018759:Adrenergic Uptake Inhibitors; D000890:Anti-Infective Agents; D001993:Bronchodilator Agents; D004364:Pharmaceutical Preparations; D017291:Clarithromycin; D013726:Terbutaline; D007099:Imipramine
keywords: NR8383; alveolar macrophages; lysosomal sequestration; respiratory drugs