Impact of telavancin on prothrombin time and activated partial thromboplastin time as determined using point-of-care coagulometers

Telavancin is approved in the United States, Canada, and Europe (At the time of submission, the telavancin European marketing authorization for nosocomial pneumonia was suspended until Theravance provides evidence of a new European Medicines Agency approved supplier) as an antibiotic to treat certain Gram-positive bacterial skin infections. Telavancin has been shown to prolong plasmatic prothrombin (PT) and activated partial thromboplastin (aPTT) clotting times in clinical diagnostic lab-based assays. In this study, we evaluated the potential for telavancin to prolong whole blood PT/International Normalized Ratio (INR) and aPTT tests on point-of-care (POC) instruments. Whole blood collected from 8 healthy subjects was supplemented with telavancin to final concentrations of 0, 10, 20, and 100 μg/ml. Final concentrations were selected to match trough, twice trough, and peak plasma levels following the approved 10 mg/kg dose. Four widely employed POC coagulation instruments were chosen to be representative of the POC platforms currently in use.. These systems were the Roche Coaguchek XS, the Abbott iSTAT, the ITC Hemochron SIG+, and the Alere INRatio2 POC devices. The PT/INR measured by the Coaguchek XS showed the greatest sensitivity to the presence of telavancin. The PT/INR measured by the Hemochron SIG+ and iSTAT were sensitive to telavancin but to a lesser extent. The INRatio2 was the least sensitive to the presence of telavancin when testing the whole blood PT/INR. Only the Hemochron SIG+ device was capable of measuring aPTT and showed a concentration-dependent increase in aPTT. This study supports the current recommendation that PT and aPTT monitoring be conducted immediately to the next dose of telavancin when coagulation parameters are tested using POC instrumentation.