Cardiovascular Pharmacology: Antiplatelets, Anticoagulants, Antiarrhythmics, Vasoactive and Lipid-Lowering Agents
Antiplatelets and anticoagulants
Aspirin irreversibly inhibits cyclooxygenase; P2Y12 inhibitors prevent ADP-mediated activation. Dual therapy is common after PCI. Heparin and LMWH activate antithrombin; monitor aPTT for unfractionated heparin and watch for heparin-induced thrombocytopenia. Warfarin requires INR monitoring; DOACs have fewer food interactions but depend on renal function. Reversal agents and bleeding precautions are essential.
Antiarrhythmics and vasoactive drugs
Antiarrhythmics are classified by mechanism; amiodarone affects multiple channels and can cause thyroid, pulmonary, and hepatic toxicity. Vasodilators reduce preload or afterload; inotropes increase contractility but may increase myocardial oxygen demand and arrhythmias. Norepinephrine raises blood pressure through vasoconstriction.
Lipid lowering
Statins lower LDL and reduce cardiovascular events; monitor for myopathy and liver effects. Ezetimibe and PCSK9 inhibitors add LDL reduction.
Traps
Do not give a DOAC in severe renal impairment without dose review. Do not assume warfarin is interchangeable with a DOAC for mechanical valves. Beta blockers can worsen cocaine-induced vasospasm. Amiodarone interacts with warfarin and digoxin.
Worked example
A patient on warfarin has an INR of 5.5 without bleeding; hold warfarin, assess bleeding risk, and follow the protocol for vitamin K or reversal depending on INR and clinical status.