Potential in vitro interaction between tenecteplase and unfractionated heparin.

STUDY OBJECTIVE: To explore the potential of a direct drug interaction between unfractionated heparin (UFH) and tenecteplase that lowers the pharmacologic propensity of UFH to prolong the activated partial thromboplastin time (aPTT).

DESIGN: In vitro experiment.

SETTING: Texas Tech University School of Pharmacy, with sample analysis performed at an independent, contract laboratory. Samples. Blood samples collected from healthy volunteers.

INTERVENTION: Three separate in vitro experiments were conducted to explore the relative influence of various thrombolytic agents with and without UFH on aPTT prolongation. In each experiment, blood from healthy volunteers (12 for each experiment) was treated with different concentrations and combinations of tenecteplase and UFH.

MEASUREMENTS AND MAIN RESULTS: When the effects of tenecteplase plus UFH versus UFH alone on aPTT prolongation were compared, each experiment demonstrated attenuation of aPTT with the combination versus UFH alone. In contrast, findings for other thrombolytic agents combined with UFH demonstrate elevation of the aPTT compared with UFH alone.

CONCLUSION: The results indicate a possible drug interaction between tenecteplase and UFH, with tenecteplase attenuating the intensity of anticoagulation of UFH in vitro. Further investigation into this possible interaction is warranted in the clinical setting.