SURGERY: Vascular, antiplatelet, anticoagulant and haemostatic PHARMACOLOGY

Clopidogrel

Drug class: P2Y12 platelet receptor inhibitor; antiplatelet. | Uses: Prevention of atherothrombotic events after myocardial infarction, ischaemic stroke or in peripheral arterial disease; after coronary stenting. | Side effects: Bleeding, bruising and gastrointestinal symptoms; rarely thrombotic thrombocytopenic purpura. | Contraindications: Active pathological bleeding and hypersensitivity. | Important cautions: Do not interrupt around surgery without assessing thrombotic risk, especially after coronary stenting. Omeprazole and esomeprazole can reduce activation.

Aspirin

Drug class: Irreversible cyclo-oxygenase-1 inhibitor; antiplatelet at low doses. | Uses: Secondary prevention of cardiovascular and cerebrovascular events. | Side effects: Dyspepsia, gastrointestinal ulceration or bleeding, bruising and bronchospasm in susceptible patients. | Contraindications: Active bleeding or ulceration and aspirin/NSAID hypersensitivity; check product-specific restrictions. | Important cautions: Assess bleeding, renal and asthma risks. Perioperative continuation depends on procedure and thrombotic risk.

NOAC/DOAC

Drug class: Direct oral anticoagulant; includes factor Xa inhibitors and direct thrombin inhibitor dabigatran. | Uses: Stroke prevention in non-valvular atrial fibrillation and treatment/prevention of venous thromboembolism, depending on agent. | Side effects: Bleeding, anaemia and agent-specific gastrointestinal effects. | Contraindications: Active clinically significant bleeding; other restrictions depend on agent, renal/hepatic function and indication. | Important cautions: Confirm the exact agent, dose, last dose, renal function and procedure bleeding risk. Perioperative interruption and reversal are drug-specific.

Unfractionated heparin

Drug class: Parenteral anticoagulant that potentiates antithrombin. | Uses: Treatment of thrombosis, selected prophylaxis and anticoagulation requiring rapid titration. | Side effects: Bleeding, heparin-induced thrombocytopenia and osteoporosis with prolonged use. | Contraindications: Active major bleeding and current or previous immune-mediated HIT. | Important cautions: Monitor according to protocol, including platelets and coagulation tests when indicated. Suspected HIT requires stopping heparin and urgent assessment.

Low-molecular-weight heparin

Drug class: Parenteral anticoagulant that enhances antithrombin inhibition of factor Xa. | Uses: Prevention and treatment of venous thromboembolism and selected acute coronary syndromes. | Side effects: Bleeding, bruising and thrombocytopenia/HIT. | Contraindications: Active major bleeding and current or previous immune-mediated HIT. | Important cautions: Check renal function, weight and timing around neuraxial procedures; dosing may need adjustment.

Enoxaparin

Drug class: Low-molecular-weight heparin anticoagulant. | Uses: Prevention and treatment of VTE and selected acute coronary syndromes. | Side effects: Bleeding, bruising, injection-site haematoma and thrombocytopenia/HIT. | Contraindications: Active major bleeding and current or previous immune-mediated HIT. | Important cautions: Adjust dose where indicated for renal impairment and check timing around neuraxial procedures.

Apixaban

Drug class: Direct factor Xa inhibitor; DOAC. | Uses: Stroke prevention in non-valvular atrial fibrillation and treatment/prevention of DVT/PE, according to indication and regimen. | Side effects: Bleeding, anaemia, bruising and nausea. | Contraindications: Active clinically significant bleeding and certain hepatic disorders associated with coagulopathy; check the SmPC. | Important cautions: Check renal/hepatic function, age, weight, interacting medicines and indication-specific dosing. Consider thrombotic risk before interruption.

Warfarin

Drug class: Vitamin K antagonist oral anticoagulant. | Uses: Stroke prevention in atrial fibrillation, treatment/prevention of VTE and anticoagulation for selected mechanical heart valves. | Side effects: Bleeding, bruising, rare skin necrosis and purple toe syndrome. | Contraindications: Pregnancy in most circumstances and active major bleeding; other conditions require assessment. | Important cautions: Requires INR monitoring. Many medicines, foods and acute illnesses alter its effect. Surgery may require planned interruption or specialist-directed bridging.

Tranexamic acid

Drug class: Antifibrinolytic; inhibits plasminogen activation and fibrin breakdown. | Uses: Reduction of bleeding in selected surgery, trauma and heavy menstrual bleeding. | Side effects: Nausea, vomiting and diarrhoea; rarely seizures or thromboembolic complications. | Contraindications: Active intravascular clotting and hypersensitivity; check route-specific restrictions. | Important cautions: Adjust for renal impairment when required. Intravenous tranexamic acid must never be administered intrathecally.

Vitamin K (phytomenadione)

Drug class: Coagulation-factor synthesis cofactor; reverses vitamin K antagonist effects. | Uses: Warfarin reversal and treatment/prevention of vitamin K deficiency. | Side effects: Injection-site reactions and rare serious hypersensitivity with parenteral administration. | Contraindications: Hypersensitivity to the formulation; check route-specific restrictions. | Important cautions: Reversal takes time. Major bleeding may require prothrombin complex concentrate as well as vitamin K under an emergency protocol.