title: Thalidomide does not interact with P-glycoprotein.
abstract: BACKGROUND
  There is growing clinical interest in thalidomide for the treatment of various disorders due to its anti-inflammatory, immunomodulatory, and anti-angiogenic properties. In numerous clinical trials thalidomide is used as an adjunct to standard therapy. Therefore, clinicians should be aware of all possible drug-drug interactions that might occur with this drug. P-glycoprotein (P-gp), a drug efflux transporter that is expressed in many tissues, is the cause of several drug-drug interactions. P-gp induction or inhibition can lead to ineffective therapy or side-effects. In this study, we investigated thalidomide's potential to cause drug-drug interactions on the level of P-gp.
  
  
  METHODS
  LS180 cells were incubated with thalidomide for 72 h in order to determine P-gp induction using real-time RT-PCR. A human leukaemia cell line over-expressing MDR1 (CCRF-CEM/MDR1) was used to measure uptake of rhodamine 123, a P-gp substrate, in the presence of thalidomide. Dose-dependent and bi-directional transport of thalidomide through Caco-2 cell monolayers was performed to assess site-directed permeability. Transport rates were determined using HPLC including chiral separation of the thalidomide enantiomers.
  
  
  RESULTS
  Thalidomide did not induce P-gp expression in LS180 cells. The uptake of rhodamine 123 in CCRF cells over-expressing MDR1 was not influenced by co-incubation with thalidomide. The transport through Caco-2 monolayers was linear and the permeability was similar for both directions. No differences between the thalidomide enantiomers were observed.
  
  
  CONCLUSIONS
  Our study indicates that thalidomide is neither a substrate, nor an inhibitor or an inducer of P-gp. Therefore, P-gp-related drug-drug interactions with thalidomide are not likely.
authors.affiliation: Department of Clinical Pharmacology and Toxicology Petersgraben, University Hospital Basel and Department of Pharmaceutical Sciences, Petersgraben 4, CH-4031, Basel, Switzerland.
authors.forename: Christian
authors.initials: C
authors.lastname: Zimmermann
authors.forename: Heike
authors.initials: H
authors.lastname: Gutmann
authors.forename: Juergen
authors.initials: J
authors.lastname: Drewe
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D018938:Caco-2 Cells; D004347:Drug Interactions; D018432:Drug Resistance, Multiple; D006801:Humans; D007166:Immunosuppressive Agents / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D020112:Rhodamine 123 / Q000378:metabolism; D013792:Thalidomide / Q000378:metabolism*
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D007166:Immunosuppressive Agents; D012333:RNA, Messenger; D020112:Rhodamine 123; D013792:Thalidomide