title: Effects of telavancin on coagulation test results.
abstract: BACKGROUND
  The lipoglycopeptide antibiotic, telavancin, may interfere with some laboratory coagulation tests including prothrombin time (PT) and activated partial thromboplastin time (aPTT).
  
  
  OBJECTIVE
  To evaluate the effects of telavancin on PT and aPTT assays in common use.
  
  
  METHODS
  Pooled normal human plasma was spiked with telavancin 10, 20, 100 or 200 μg/ml (equivalent to trough, 2 × trough, peak and 2 × peak clinical plasma concentrations, respectively) or diluent control (0.9% sodium chloride). Samples were analysed using 16 PT reagents and seven aPTT reagents.
  
  
  RESULTS
  Telavancin 200 μg/ml (corresponding to 2 × peak clinical plasma concentration), produced significant PT prolongation (> 9% difference vs. diluent control) with all the 16 PT reagents (range 12% to > 600%). At lower telavancin concentrations, PT prolongation was dose-dependent and varied among reagents, but appeared greatest with preparations containing recombinant tissue factor. With telavancin 10 μg/ml (equivalent to trough), PT prolongation was 10% with HemosIL(®) PT-Fibrinogen Recombinant, while ranging from 5% to -1% with all other reagents. Significant (> 34% difference vs. baseline) and dose-dependent aPTT prolongation was observed with all the seven reagents in samples spiked with telavancin 100 or 200 μg/ml (range 65-142% at 200 μg/ml). aPTT reagents containing a silica activator appeared to be more sensitive to telavancin interference. Telavancin 10 μg/ml was not associated with increased aPTT with any of the reagents tested.
  
  
  CONCLUSIONS
  Telavancin has the potential to prolong both PT and aPTT in vitro. It is recommended that samples for PT or aPTT be obtained just prior to a telavancin dose (trough).
authors.affiliation: Theravance, Inc., South San Francisco, CA 94080, USA. sbarriere@theravance.com
authors.forename: S L
authors.initials: SL
authors.lastname: Barriere
authors.forename: M R
authors.initials: MR
authors.lastname: Goldberg
authors.forename: J W
authors.initials: JW
authors.lastname: Janc
authors.forename: D L
authors.initials: DL
authors.lastname: Higgins
authors.forename: P A
authors.initials: PA
authors.lastname: Macy
authors.forename: D M
authors.initials: DM
authors.lastname: Adcock
mesh_terms: D000617:Aminoglycosides / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001777:Blood Coagulation / Q000187:drug effects*; D000075202:Contraindications; D006801:Humans; D000077427:Lipoglycopeptides; D010314:Partial Thromboplastin Time / Q000592:standards; D011517:Prothrombin Time / Q000592:standards; D012016:Reference Values
chemical_list: D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D000077427:Lipoglycopeptides; C487637:telavancin