• Unfractionated heparin: parenteral, rapid onset via antithrombin, commonly monitored with aPTT or anti-Xa depending on protocol, and reversible with protamine; low-molecular-weight heparins such as enoxaparin are given subcutaneously, act more predictably, usually need less routine monitoring, and are only partially reversed by protamine.
• Warfarin: oral, slow onset, inhibits vitamin-K factors II/VII/IX/X, monitored by INR, reversed by vitamin K.
• DOACs (e.g. apixaban) are newer oral agents needing no routine coagulation monitoring.