Y1S2 004 I Pharmacology Cardiovascular: Medications and Mechanisms

Cardiovascular Drugs

Beta Blockers - Propranolol

• Non-selective β-antagonist, used to treat angina, hypertension, arrhythmias, and glaucoma
• Inhibits contraction of the heart by blocking β1 receptors, reducing heart rate and force of contraction
• Adverse effects: bronchi-constriction, cardiac failure, fatigue, and depression
• Route of administration: oral, with a half-life of 4 hours and high first-pass metabolism

Vasodilators - Nitroglycerin

• Dilates blood vessels, reducing blood pressure and workload on the heart
• Converted to nitric oxide (NO) by mitochondrial aldehyde dehydrogenase (MtALDH)
• Route of administration: intravenous, sublingual, with a peak concentration time of approximately 4.4 minutes
• Adverse effects: hypotension, vertigo, flushed skin, diaphoresis, fever, syncope, dyspnea, and bradycardia

Cardiac Glycosides - Digitalis (Digoxin)

• Increases force of contraction of the heart, used to treat congestive cardiac failure (CCF)
• Extracted from the foxglove plant (Digitalis spp.), with digoxin being the main drug in this class
• Acts on the heart, increasing intracellular Ca²⁺ concentrations, which leads to increased force of contraction
• Adverse effects: arrhythmia (tachycardia, atrioventricular block), hypokalemia, abdominal discomfort, nausea, and vomiting
• Route of administration: oral or intravenous, with a half-life of 36-40 hours

Antiplatelets - Aspirin

• Prevents clotting of blood by inhibiting the synthesis of thromboxane A2 (TXA2) in platelets
• Irreversible inhibition of cyclooxygenase (COX) enzyme, specifically COX 1 in platelets
• Route of administration: oral, with a dose of 160-320 mg/d, and a duration of 7-9 days
• Adverse effects: GIT irritation, and used at low doses to prevent platelet aggregation

Anticoagulants - Heparin and Low Molecular Weight Heparin (LMWH)

• Prevent clotting of blood by inactivating clotting factors IIa, IXa, Xa, XIa, and XIIa
• Inhibit coagulation cascade, preventing fibrin formation and blood clotting
• Route of administration: intravenous, subcutaneous, with a low therapeutic index
• Adverse effects: osteoporosis, hyperkalemia, hypersensitivity reactions, and heparin-induced thrombocytopenia

Anticoagulants - Warfarin

• Inhibits blood clot formation by preventing the synthesis of clotting factors II, VII, IX, and X
• Structurally related to vitamin K, with a slow onset of 48 hours and a peak anticoagulant effect at 72-96 hours
• Route of administration: oral, with a half-life of 25-60 hours, and a high plasma protein binding of 99%
• Adverse effects: diarrhea, bleeding, warfarin-induced skin necrosis, and a low therapeutic index
• Monitored using prothrombin time (PT) and international normalized ratio (INR)

Test your knowledge of cardiovascular drugs, including their mechanisms of action and effects on the heart and blood vessels. This quiz covers a range of medications, from beta blockers to anticoagulants, and their roles in managing cardiovascular health.