title: Transport mechanisms at the pulmonary mucosa: implications for drug delivery.
abstract: BACKGROUND
  Over the past years, a significant number of papers have substantiated earlier findings proposing a role for drug transporter proteins in pulmonary drug disposition. Whilst the majority of reports present data from in vitro models, a growing number of publications advance the field by introducing sophisticated ex vivo and in vivo techniques. In a few cases, evidence from clinical studies in human volunteers is complementing the picture.
  
  
  METHODS
  In this review, recent advances in pulmonary drug transporter research are critically evaluated. Transporter expression data in tissues and cell-based in vitro models is summarized and information on transport activity assessed. Novel techniques allowing for better quantification of transporter-related effects following pulmonary delivery are also described.
  
  
  CONCLUSIONS
  Different tissue and cell populations of the lung have distinct transporter expression patterns. Whether these patterns are affected by disease, gender and smoking habits requires further clarification. Transporters have been found to have an impact on drug absorption processes, at least in vitro. Recent ex vivo experiments using isolated, perfused lung models, however, suggest that mainly efflux pumps have significant effects on absorption into the pulmonary circulation. Whether these rodent-based ex vivo models predict the human situation is basis for further research.
authors.affiliation: a School of Pharmacy and Pharmaceutical Sciences and Trinity Biomedical Sciences Institute , Trinity College Dublin , Dublin , Ireland.
authors.forename: Sabrina
authors.initials: S
authors.lastname: Nickel
authors.affiliation: a School of Pharmacy and Pharmaceutical Sciences and Trinity Biomedical Sciences Institute , Trinity College Dublin , Dublin , Ireland.
authors.forename: Caoimhe G
authors.initials: CG
authors.lastname: Clerkin
authors.affiliation: a School of Pharmacy and Pharmaceutical Sciences and Trinity Biomedical Sciences Institute , Trinity College Dublin , Dublin , Ireland.|b Faculty of Pharmacy , Kufa University , Al-Najaf , Iraq.
authors.forename: Mohammed Ali
authors.initials: MA
authors.lastname: Selo
authors.affiliation: a School of Pharmacy and Pharmaceutical Sciences and Trinity Biomedical Sciences Institute , Trinity College Dublin , Dublin , Ireland.
authors.forename: Carsten
authors.initials: C
authors.lastname: Ehrhardt
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000378:metabolism; D001692:Biological Transport; D016503:Drug Delivery Systems; D006801:Humans; D008168:Lung / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000378:metabolism; D009092:Mucous Membrane / Q000378:metabolism; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000378:metabolism; D009363:Neoplasm Proteins / Q000378:metabolism; D027701:Organic Cation Transport Proteins / Q000378:metabolism; D004364:Pharmaceutical Preparations / Q000008:administration & dosage*
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D026901:Membrane Transport Proteins; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D009363:Neoplasm Proteins; D027701:Organic Cation Transport Proteins; D004364:Pharmaceutical Preparations; C116614:ABCG2 protein, human; C421109:multidrug resistance-associated protein 1
keywords: BCRP; Drug transporters; Inhalation; MRP1; Organic cation transporters; P-glycoprotein; Peptide transporters; Pulmonary drug disposition