Pharmacology of Cardiovascular Drugs
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Questions and Answers

Which of the following drugs can be used to treat hypertension?

  • Anti-arrhythmic agents
  • Calcium channel blockers (correct)
  • Anticoagulants
  • Beta-blockers (correct)

What is a common cause of arrhythmias?

  • Decreased heart rate variability
  • High levels of potassium
  • Ectopic pacemaker activity (correct)
  • Increased vagal tone

What condition is characterized by a prolonged QT interval?

  • After-depolarizations (correct)
  • Bradycardia
  • Tachycardia
  • Atrial flutter

What is the effect of drugs that block voltage-sensitive sodium channels?

<p>Stabilize cardiac membranes (C)</p> Signup and view all the answers

Which type of arrhythmia involves multiple small re-entry loops?

<p>Atrial fibrillation (D)</p> Signup and view all the answers

What mechanism allows for the development of a circus of excitation in arrhythmias?

<p>Unidirectional conduction block (A)</p> Signup and view all the answers

What happens during ventricular tachycardia?

<p>The heart beats too quickly due to abnormal pacemaker activity (D)</p> Signup and view all the answers

Which factor does NOT influence blood volume in the cardiovascular system?

<p>Coronary artery blood flow (A)</p> Signup and view all the answers

What is the primary action of dobutamine?

<p>Acts on β1 receptors (D)</p> Signup and view all the answers

Which of the following is NOT a use for dobutamine?

<p>Hypertension treatment (B)</p> Signup and view all the answers

What is a primary mechanism by which ACE-inhibitors aid in heart failure treatment?

<p>Prevent Na+ and water re-absorption (C)</p> Signup and view all the answers

Which class of drugs helps reduce the preload on the heart?

<p>Diuretics (C)</p> Signup and view all the answers

What condition leads to angina due to inadequate oxygen supply?

<p>Coronary artery narrowing (C)</p> Signup and view all the answers

Which of these is a primary method to improve blood supply to the heart?

<p>Calcium channel antagonists (D)</p> Signup and view all the answers

What substance is released when organic nitrates react with thiols in the vascular smooth muscle?

<p>Nitric Oxide (NO) (B)</p> Signup and view all the answers

What is the ultimate effect of Nitric Oxide on vascular smooth muscle cells?

<p>Muscle relaxation (B)</p> Signup and view all the answers

What is the primary mechanism by which lidocaine exerts its effects on the heart?

<p>Blocking voltage-gated Na+ channels in open or inactive states (A)</p> Signup and view all the answers

Beta-blockers are beneficial after a myocardial infarction primarily because they...

<p>Block β1-adrenoreceptors, reducing O2 demand (D)</p> Signup and view all the answers

Which class of anti-arrhythmic drugs is known for prolonging the absolute refractory period?

<p>Class III (B)</p> Signup and view all the answers

Amiodarone is unique among class III anti-arrhythmics because it also...

<p>Has additional pharmacological actions beyond K+ channel blocking (D)</p> Signup and view all the answers

What effect does verapamil, a class IV drug, have on the heart?

<p>Decreases the force of contraction (C)</p> Signup and view all the answers

Which of the following is NOT a common target of anti-arrhythmic drugs?

<p>Chloride channels (C)</p> Signup and view all the answers

How does adenosine function as an anti-arrhythmic agent?

<p>It enhances potassium conductance at the AV node (C)</p> Signup and view all the answers

The term 'inotropic drug' refers to drugs that impact which aspect of cardiac function?

<p>Force of contraction (A)</p> Signup and view all the answers

After a myocardial infarction, which class of drug is NOT typically used prophylactically?

<p>Lidocaine (C)</p> Signup and view all the answers

What is a significant risk associated with drugs that block potassium channels?

<p>Pro-arrhythmia due to prolonged action potential (D)</p> Signup and view all the answers

What is the primary effect of negatively inotropic drugs on the heart?

<p>Reduce workload of the heart (D)</p> Signup and view all the answers

Which of the following is an example of a positive inotropic drug?

<p>Dobutamine (B)</p> Signup and view all the answers

What is the effect of cardiac glycosides on intracellular calcium concentration?

<p>Increase intracellular calcium levels (B)</p> Signup and view all the answers

How do cardiac glycosides influence heart rate?

<p>Slow the heart rate by increasing vagal activity (A)</p> Signup and view all the answers

What condition is characterized by the heart's failure to provide sufficient output to meet the body's requirements?

<p>Heart failure (D)</p> Signup and view all the answers

Which of the following is NOT a feature of heart failure?

<p>Increased cardiac output (C)</p> Signup and view all the answers

What action does digoxin take on the Na+/K+ ATPase?

<p>Inhibits its function (B)</p> Signup and view all the answers

Which type of drug would be used to increase cardiac output in a patient experiencing cardiogenic shock?

<p>Positive inotropic drugs (D)</p> Signup and view all the answers

The mechanism by which cardiac glycosides increase the force of contraction involves which exchanger?

<p>Na+/Ca2+ exchanger (B)</p> Signup and view all the answers

What physiological effect do β-blockers primarily have?

<p>Reduce heart rate and workload (B)</p> Signup and view all the answers

What is the primary action of venodilation on the heart?

<p>Reduces workload and lowers O2 demand (B)</p> Signup and view all the answers

Which condition does NOT carry an increased risk of thrombus formation?

<p>Hypertension (B)</p> Signup and view all the answers

What is the mechanism of action of warfarin?

<p>Antagonises the action of vitamin K (B)</p> Signup and view all the answers

How do organic nitrates primarily affect collateral arteries?

<p>Dilate collateral arteries to increase blood flow (C)</p> Signup and view all the answers

Which of the following is NOT an anti-platelet drug?

<p>Warfarin (B)</p> Signup and view all the answers

What is the effect of blood volume increase associated with hypertension?

<p>Increased blood pressure (A)</p> Signup and view all the answers

Which form of heparin is administered intravenously for acute treatments?

<p>Heparin (B)</p> Signup and view all the answers

Which best describes the secondary action of nitrates on the coronary arteries?

<p>Improving oxygen delivery to ischaemic myocardium (C)</p> Signup and view all the answers

Flashcards

Arrhythmias

Abnormalities in the heart's rhythm, affecting the speed or regularity of heartbeat.

Tachycardia

An increase in heart rate. It can be caused by various factors, including exercise, stress, or certain medical conditions.

Ventricular Tachycardia

Fast heart rate originating from the ventricles (lower chambers of the heart).

Supraventricular Tachycardia

A type of tachycardia originating from the upper chambers of the heart, the atria.

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Bradycardia

A slower than normal heart rate.

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Atrial Flutter

Rapid fluttering of the atrial chambers of the heart.

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Atrial Fibrillation

A rapid and irregular heartbeat originating from the atria (upper chambers of the heart).

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Ventricular Fibrillation

A life-threatening arrhythmia where the ventricles (lower chambers of the heart) quiver ineffectively, leading to no blood pumping.

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What is dobutamine used for?

A medication that stimulates beta-1 receptors, increasing heart contractility and improving cardiac output.

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What is the main mechanism of action of ACE inhibitors?

A class of medications that block the conversion of angiotensin I to angiotensin II, a powerful vasoconstrictor and stimulator of sodium and water retention.

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How do ACE inhibitors reduce the workload of the heart?

ACE inhibitors reduce the work load of the heart by lowering blood pressure, decreasing afterload, reducing fluid retention (preload), and therefore minimizing the heart's workload.

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How do diuretics reduce the work load of the heart?

Diuretics work by increasing urine production, which reduces the amount of fluid in the body, thereby decreasing preload (the amount of blood filling the heart).

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How do β-blockers reduce the workload of the heart?

β-blockers reduce the heart's workload by decreasing heart rate, contractility, and oxygen demand.

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What is angina?

Angina occurs when the heart's oxygen demand exceeds supply, leading to chest pain, usually triggered by exertion. This is caused by narrowing of the coronary arteries.

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How do organic nitrates help treat angina?

Nitrates work by releasing nitric oxide, a powerful vasodilator, which relaxes smooth muscle in blood vessels, leading to vasodilation and improved blood flow to the heart.

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How do calcium channel blockers help treat angina?

Calcium channel blockers can help alleviate angina by dilating coronary arteries, increasing blood flow to the heart, and reducing the heart's workload.

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What is heart failure?

Failure of the heart to pump blood effectively, causing inadequate blood flow to meet the body's needs.

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What are positive inotropic drugs?

A type of drug that increases the heart's strength of contraction, leading to improved blood pumping.

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What are negative inotropic drugs?

A type of drug that decreases the workload on the heart by reducing the force of contraction.

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What are cardiac glycosides?

A group of medications used to treat heart failure that increase the force of heart muscle contraction.

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What is Digoxin?

The primary drug in the cardiac glycoside class, extracted from the foxglove plant.

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How do cardiac glycosides work?

Cardiac glycosides block the Na+/K+ ATPase pump, leading to increased intracellular sodium levels.

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Explain the mechanism of cardiac glycosides.

By blocking the Na+/K+ pump, cardiac glycosides indirectly increase intracellular calcium levels, which strengthens heart contractions.

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Why do cardiac glycosides slow down heart rate?

Cardiac glycosides also have a vagal effect, slowing down heart rate by affecting the electrical conduction system.

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What are beta-adrenergic agonists?

A class of drugs that can increase heart contractility by stimulating beta-adrenergic receptors.

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Give examples of beta-adrenergic agonists used in heart failure.

Examples of beta-adrenergic agonists include dobutamine, dopamine, and isoprenaline, which are used to treat heart failure.

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Class I Anti-arrhythmic Drugs

Drugs that block voltage-gated sodium channels. They primarily affect the open or inactive state of these channels, allowing normal function during the closed state.

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Lidocaine: A Class I Anti-arrhythmic

The local anesthetic lidocaine is a common example. It is sometimes used to treat ventricular tachycardia after a heart attack (MI).

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Beta-blockers (Class II)

A group of drugs that block beta-adrenoreceptors, typically aiming to reduce sympathetic activity, especially at the heart (beta1 receptors).

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Beta-blockers: Post-MI Use

Beta-blockers like propranolol and atenolol may be prescribed after a heart attack to prevent arrhythmias and minimize heart damage.

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Class III Anti-arrhythmic Drugs

Class III anti-arrhythmic drugs primarily block potassium channels, prolonging the action potential and the absolute refractory period of heart cells.

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Amiodarone: A Class III Anti-arrhythmic

Amiodarone is a notable exception. It is used to treat tachycardia associated with a specific heart condition known as Wolff-Parkinson-White syndrome.

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Calcium Channel Blockers (Class IV)

Drugs like verapamil work by blocking calcium channels, affecting heart rate, conduction, and contractility.

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Adenosine: A Special Anti-arrhythmic

A naturally produced substance that acts on A1 receptors in the AV node, enhancing potassium conductance and influencing heart rhythm.

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Inotropic Drugs

Drugs that affect the strength of the heart's contractions. They can be used to either increase (positive inotropic effect) or decrease (negative inotropic effect) contractility.

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Positive and Negative Inotropic Effects

Positive inotropic drugs are used to strengthen the heart's contractions, particularly when the heart is weakened as in heart failure, while negative inotropic drugs are used to reduce contractility when the heart is working too hard.

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What is the primary action of organic nitrates?

Organic nitrates dilate veins, reducing the amount of blood returning to the heart (preload). This lowers the heart's workload and oxygen demand.

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How do organic nitrates improve oxygen delivery to the heart?

Nitrates improve oxygen delivery to the heart muscle by dilating collateral arteries, which are small vessels that bypass blocked arteries.

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What conditions increase the risk of thrombus formation?

Conditions that increase the risk of blood clots forming in the heart. Examples include atrial fibrillation, heart attacks, and artificial heart valves.

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What are anti-thrombotic drugs and how are they categorized?

Drugs that prevent blood clots from forming. They can be classified as anticoagulants or anti-platelet drugs.

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What is heparin and how does it work?

Heparin is a type of anticoagulant that works by inhibiting thrombin, an enzyme essential for blood clotting. It is typically given intravenously for short-term use due to its fast action.

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What is warfarin and how does it work?

Warfarin is an anticoagulant that prevents blood clotting by interfering with vitamin K, a crucial factor in blood clotting. It is typically administered orally for long-term use.

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What are the examples of anti-platelet drugs and how do they work?

Aspirin, dipyridamol, and clopidogrel are anti-platelet drugs used to prevent blood clots by inhibiting platelet aggregation. They are typically used after a heart attack or for high-risk individuals.

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What is the association between hypertension and blood volume?

High blood pressure is often associated with increased blood volume, which can increase the workload on the heart.

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Study Notes

Action of Drugs on the Cardiovascular System

  • Cardiovascular drugs treat various conditions, including arrhythmias, heart failure, blood clotting disorders, ischemic heart diseases, and hypertension.
  • Drugs can alter heart rate, rhythm, myocardial contractility, peripheral resistance, blood volume, and coronary artery blood flow.
  • Some drugs affect multiple sites.

Types of Arrhythmias

  • Arrhythmias are disturbances of cardiac rhythm.
  • Tachycardia involves an abnormally fast heart rate, including ventricular and supraventricular tachycardias.
  • Bradycardia is an abnormally slow heart rate.
  • Atrial flutter and fibrillation, and ventricular fibrillation are further examples of arrhythmias..

Causes of Arrhythmias

  • Ectopic pacemaker activity: Damaged myocardial areas fire spontaneously.
  • Latent pacemaker regions, activated due to ischemia (reduced blood flow).
  • Abnormal depolarizations after action potential, potentially due to high intracellular calcium.
  • Longer action potentials result in longer QT intervals.
  • Re-entry loop: Incomplete conduction damage allows impulses to circle in a damaged area.

Anti-Arrhythmic Drugs

  • Four basic classes exist:
    • Drugs that block voltage-sensitive sodium channels (e.g., lidocaine).
    • Antagonists of β-adrenoreceptors (e.g., propranolol, atenolol).
    • Drugs that block potassium channels (e.g., amiodarone).
    • Drugs that block calcium channels (e.g., verapamil).
  • Lidocaine is used to manage ventricular tachycardia following myocardial infarction (MI).
  • Beta blockers reduce sympathetic activity, limiting arrhythmias after MI and decreasing oxygen demand.
  • Amiodarone, a type III anti-arrhythmic, also has other actions besides blocking potassium channels and is used for Wolff-Parkinson-White syndrome tachycardias.
  • Verapamil is a calcium channel blocker that slows AV nodal conduction and reduces heart contractility.
  • Adenosine, used intravenously to treat arrhythmias, doesn't fall into typical anti-arrhythmic classes.

Inotropic Drugs

  • Inotropic drugs affect the force of heart contraction.
  • Negatively inotropic drugs reduce workload, useful after a myocardial infarction to limit damage. Beta-blockers are one example.
  • Positively inotropic drugs increase the force of contraction needed to improve cardiac function for conditions such as cardiogenic shock or acute heart failure. Examples include dobutamine and isoprenaline.

Heart Failure

  • Heart failure occurs when the heart cannot meet the body's blood flow demands.
  • Features include reduced force of contraction, reduced cardiac output, reduced tissue perfusion, and edema.
  • Positive inotropic drugs (e.g., cardiac glycosides, dobutamine, dopamine, isoprenaline) increase cardiac output.
  • Drugs that reduce workload (e.g., ACE inhibitors, diuretics) are also important in treating heart failure.

Cardiac Glycosides

  • Cardiac glycosides, such as digoxin, have been used for over 200 years to treat heart failure.
  • Digoxin improves symptoms but doesn't always improve long-term outcomes.
  • It's extracted from foxglove plants and works by inhibiting the Na+/K+ ATPase pump.
  • This increases intracellular calcium, which bolsters cardiac contraction force.
  • Cardiac glycosides also slow the heart rate via vagal activity.

Drugs for Myocardial Ischemia (Angina)

  • Angina happens when blood flow to the heart isn't sufficient to meet the oxygen demands, causing ischemia and pain, typically during exertion.
  • Treatments reduce workload, use beta-blockers, calcium channel antagonists, and organic nitrates to improve blood flow.

Thrombosis

  • Certain conditions—including atrial fibrillation, acute myocardial infarction, and mechanical heart valves—increase thrombus formation risk.
  • Anticoagulants like heparin (short-term) and warfarin (long-term) prevent clots.
  • Anti-platelet drugs like aspirin, dipyridamole, and clopidogrel are often used after an MI or in patients at high risk for MI

Hypertension

  • Hypertension (high blood pressure) usually involves increased blood volume due to sodium and water retention by kidneys.
  • Treatments include diuretics, ACE inhibitors, beta-blockers, calcium channel blockers, and alpha-1-adrenceptor antagonists. These often cause vasodilation.

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Description

This quiz explores various pharmacological concepts related to cardiovascular drugs used for treating conditions such as hypertension and arrhythmias. Test your knowledge on drug mechanisms, conditions related to the cardiovascular system, and specific drug actions like those of dobutamine and ACE-inhibitors.

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