03 Hematology and Coagulation Medications

Preventing, limiting, and dissolving clots

These three medicine groups act at different stages of clotting. Anticoagulants reduce formation or extension of fibrin clots, antiplatelet drugs reduce platelet activation and aggregation, and thrombolytics promote breakdown of clots that already exist.

Anticoagulants and their uses

Unfractionated heparin is an injectable anticoagulant that enhances antithrombin activity. It is used to treat or prevent venous thromboembolism (VTE) and in acute-care settings. Protamine can reverse its effect.

Enoxaparin is an injectable low-molecular-weight heparin used to prevent or treat VTE. Protamine reverses its effect only partially.

Warfarin is a vitamin K antagonist used for VTE, stroke prevention related to atrial fibrillation, and mechanical heart valves. Monitor it with PT/INR and keep vitamin K intake consistent. Warfarin has many food and drug interactions.

Apixaban, rivaroxaban, and edoxaban are oral direct factor Xa inhibitors. They are commonly used for VTE and for stroke prevention in eligible patients with atrial fibrillation. Dabigatran is an oral direct thrombin inhibitor used for VTE and stroke prevention in eligible patients with atrial fibrillation.

DOACs generally do not require routine INR monitoring. They are not substitutes for warfarin in patients with mechanical heart valves. Anticoagulants increase bleeding risk.

Anticoagulant reversal and safety

Reversal depends on the medicine. Protamine reverses unfractionated heparin and reverses enoxaparin only partially. For major bleeding or urgent procedures involving warfarin, reversal commonly uses vitamin K plus four-factor prothrombin complex concentrate (4F-PCC). Idarucizumab reverses dabigatran in emergencies.

Andexanet alfa was the specific reversal agent for apixaban and rivaroxaban. The FDA reported that U.S. commercial sales ended on December 22, 2025, because it judged the serious thromboembolic risks to outweigh the benefits. Current alternatives and protocols depend on the clinical situation.

Antiplatelet medicines

Aspirin irreversibly inhibits platelet COX-1 and thromboxane $A_2$ formation. It is used in selected cardiovascular and cerebrovascular disease.

Clopidogrel, prasugrel, and ticagrelor inhibit P2Y₁₂. They are commonly paired with aspirin as dual antiplatelet therapy, particularly after acute coronary syndrome or coronary stenting. Choice of treatment and its duration depend on the patient's risks and clinical context.

Cangrelor is an intravenous P2Y₁₂ inhibitor used in selected patients undergoing percutaneous coronary intervention. Eptifibatide and tirofiban are intravenous glycoprotein IIb/IIIa inhibitors that block platelet aggregation and are used in selected acute coronary-care settings. Bleeding is the main adverse effect of antiplatelet therapy.

Thrombolytic treatment

Alteplase is a tissue plasminogen activator (tPA) used in selected cases of acute ischemic stroke, acute myocardial infarction, or pulmonary embolism. Tenecteplase is a modified tPA used for acute myocardial infarction and, under current labeling, selected patients with acute ischemic stroke.

Thrombolytics dissolve existing clots by promoting plasmin formation. They are reserved for carefully selected, time-sensitive emergencies because they can cause major bleeding, including intracranial hemorrhage. For suspected stroke, brain imaging must first exclude hemorrhage; emergency protocols determine eligibility and treatment windows.

Medicines for anemia

Treatment depends on the cause of the anemia. Identify and address the underlying deficiency or illness; iron should not be used simply because anemia is present.

Ferrous sulfate and other oral iron salts, as well as intravenous iron preparations, replace iron in confirmed iron-deficiency anemia. Intravenous iron may be used when oral treatment is unsuitable or insufficient, or when more rapid replacement is needed.

Cyanocobalamin or hydroxocobalamin replaces vitamin B₁₂ in B₁₂-deficiency anemia. It may be given orally or by injection, depending on the cause and the patient. Folic acid replaces folate in folate-deficiency anemia. Check for B₁₂ deficiency as well, because folate does not treat B₁₂-related neurologic injury.

Epoetin alfa and darbepoetin alfa are erythropoiesis-stimulating agents used for selected anemias, including anemia of chronic kidney disease. They stimulate red-cell production, require monitoring, and can increase thrombotic risk; they are not general-purpose anemia treatments. Severe anemia or blood loss may also require transfusion or treatment of the bleeding source.

Medicines for bleeding disorders

Treatment for bleeding disorders is specific to the disorder and the patient's response. Factor VIII concentrates replace the missing factor in hemophilia A; factor IX concentrates provide replacement therapy for hemophilia B.

Desmopressin promotes the release of von Willebrand factor (VWF) and factor VIII. It can be useful for selected patients with mild hemophilia A or von Willebrand disease, depending on the patient's response and the von Willebrand disease subtype. It is not appropriate for every subtype or every bleeding episode.

Emicizumab is a monoclonal antibody that bridges factors IXa and X, mimicking factor VIII function. It is used as prophylaxis for hemophilia A, including in patients with factor VIII inhibitors.

Tranexamic acid helps preserve formed clots by slowing clot breakdown. It is used for selected mucosal, dental, menstrual, or procedural bleeding. Phytonadione, or vitamin K₁, replaces vitamin K in deficiency-related bleeding and helps reverse warfarin.

• Dual antiplatelet therapy (DAPT)

• Erythropoiesis-stimulating agents (ESAs)