75 y/o F – recently discharged post repair of a fractured neck of the femur – came to ER in respiratory distress – BP 80/50 – becomes unresponsive – pulmonary angiogram shows a saddle embolus in the bifurcation of the pulmonary trunk – clot is removed and patient started on appropriate pharmacotherapy – 10 days later: platelet count 50,000 – initial platelet count on admission (10 days prior) 250,000 the thrombocytopenia is most likely caused by a drug with what mechanism of action?