Table 3  Most frequently evaluated antithrombotics in clinical trials for COVID-19 a.
Therapy  Type  Mechanism  No. of Interventional Clinical Trials b
Unfractionated heparin or Low molecular weight heparins (Enoxaparin, Dalteparin, Tinzaparin, and others)  Sulfated glycosaminoglycans  Activation of antithrombin to inhibit thrombin and factor Xa  ~23
Aspirin (Acetylsalicylic acid)  Small molecule  Cyclo-oxygenase inhibitor  ~8
Rivaroxaban(Xarelto)  Small molecule  Direct factor Xa inhibitor  ~5
Dipyridamole(Aggrenox)  Small molecule  Nucleoside transport inhibitor and a phosphodiesterase 3 inhibitor  ~3
Clopidogrel(Plavix)  Small molecule  Irreversible adenosine diphosphate receptor blocker  ~3
a From clinicaltrials.gov, b No. is as of 25 July 2020.