Diuretics: Mechanism and Types

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Questions and Answers

What is a common adverse effect of nitroglycerin?

  • Nausea
  • Dizziness
  • Headaches (correct)
  • Dry mouth

What is the primary function of arterial dilators?

  • Increase heart rate
  • Enhance calcium absorption in the heart
  • Reduce systemic arteriolar resistance (correct)
  • Improve oxygenation of blood

What is one benefit of the fixed-dose combination of hydralazine and isosorbide dinitrate?

  • Increasing digoxin effectiveness
  • Improving symptoms and survival in black patients with HFrEF (correct)
  • Lowering heart rate in all patients
  • Eliminating the need for beta-blockers

What is the primary purpose of inotropic drugs?

<p>Enhance cardiac contractility (B)</p> Signup and view all the answers

What is the mechanism of action of digoxin?

<p>Inhibition of Na+/K+-ATPase (C)</p> Signup and view all the answers

Why is careful monitoring essential when administering digoxin?

<p>It has a narrow therapeutic index. (D)</p> Signup and view all the answers

Which of the following describes hydralazine?

<p>It reduces systemic vascular resistance. (A)</p> Signup and view all the answers

What adverse effect can hydralazine rarely cause?

<p>Drug-induced lupus (B)</p> Signup and view all the answers

What is the primary mechanism by which diuretics reduce the workload on the heart?

<p>They reduce plasma volume in the blood. (C)</p> Signup and view all the answers

Which diuretic is considered the most effective for heart failure management when significant diuresis is required?

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

What condition can result from an overdose of loop diuretics?

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

What is the primary therapeutic effect of venodilators?

<p>Decrease preload. (D)</p> Signup and view all the answers

What is the main purpose of arterial dilators in heart failure treatment?

<p>To reduce oxygen demand on the heart. (B)</p> Signup and view all the answers

Which of the following is a common example of a nitrate used as a vasodilator?

<p>Isosorbide Dinitrate (D)</p> Signup and view all the answers

Why are diuretics not associated with improved overall survival in heart failure patients?

<p>They primarily manage symptoms rather than modify the underlying disease course. (C)</p> Signup and view all the answers

What effect do diuretics have on blood pressure?

<p>Lower blood pressure. (B)</p> Signup and view all the answers

What is a significant characteristic of digitoxin's half-life compared to digoxin?

<p>Digitoxin's half-life is generally longer than digoxin's. (C)</p> Signup and view all the answers

In which method is digitoxin primarily eliminated from the body?

<p>Bile and feces (D)</p> Signup and view all the answers

Which of the following is NOT a common adverse effect of digitoxin?

<p>Dizziness (A)</p> Signup and view all the answers

What is essential for preventing digitoxin toxicity?

<p>Regular monitoring of serum levels (D)</p> Signup and view all the answers

Which statement about digitoxin and drug interactions is accurate?

<p>It interacts with drugs that affect renal function and P-glycoprotein. (B)</p> Signup and view all the answers

What management step is required for digitoxin toxicity?

<p>Discontinuation of the drug (B)</p> Signup and view all the answers

What is one of the specific visual disturbances associated with digitoxin use?

<p>Blurred vision and yellow vision (D)</p> Signup and view all the answers

What is a common usage of digitoxin in managing atrial fibrillation?

<p>Rate control of ventricular rate (D)</p> Signup and view all the answers

What is the primary reason for the decreased use of digitoxin in current medical practice?

<p>It has severe side effects and prolonged toxicity. (B)</p> Signup and view all the answers

What mechanism does digitoxin use to enhance cardiac contractility?

<p>Inhibition of Na+/K+-ATPase (A)</p> Signup and view all the answers

Which of the following effects is a result of digitoxin's mechanism of action?

<p>Slowed heart rate (D)</p> Signup and view all the answers

What was one of the historical therapeutic uses of digitoxin?

<p>To manage heart failure (A)</p> Signup and view all the answers

How does digitoxin affect the intracellular environment of cardiac muscle cells?

<p>Increases sodium concentration (C)</p> Signup and view all the answers

Which property of digitoxin contributes to its potential for toxicity?

<p>Prolonged duration of action (D)</p> Signup and view all the answers

What defines the absorption characteristics of digitoxin?

<p>Well-absorbed from the gastrointestinal tract (D)</p> Signup and view all the answers

In which situation would digitoxin have historically been indicated for use?

<p>For rate control in atrial fibrillation (C)</p> Signup and view all the answers

What is the primary effect of digoxin on intracellular sodium levels?

<p>It decreases intracellular sodium concentration. (B)</p> Signup and view all the answers

How does digoxin affect calcium accumulation in cardiac muscle cells?

<p>It increases calcium accumulation inside the cell. (B)</p> Signup and view all the answers

Which of the following statements about digoxin and cardiac output is true?

<p>Digoxin improves cardiac output by enhancing contractility. (A)</p> Signup and view all the answers

What effect does digoxin have on the heart rate?

<p>It decreases heart rate by enhancing vagal tone. (D)</p> Signup and view all the answers

For which condition is digoxin primarily indicated as a second-line treatment?

<p>Severe Heart Failure with reduced Ejection Fraction (HFrEF) (A)</p> Signup and view all the answers

What is the effective serum concentration range of digoxin for therapeutic use?

<p>0.5 to 0.8 ng/mL (C)</p> Signup and view all the answers

How does digoxin impact conduction through the AV node?

<p>It slows down conduction through the AV node. (B)</p> Signup and view all the answers

What is one of the main therapeutic uses of digoxin in patients with atrial fibrillation?

<p>It aids in controlling ventricular rates. (B)</p> Signup and view all the answers

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Study Notes

Diuretics

  • Diuretics lower plasma volume, reducing venous return (preload) to the heart, decreasing heart workload and oxygen demand.
  • They lower blood pressure, which reduces afterload on the heart.

Loop Diuretics

  • Most effective for heart failure (HF), especially in significant diuresis or renal insufficiency.
  • Common examples include:
    • Furosemide: Strong diuretic effect.
    • Bumetanide: More potent than furosemide.
    • Torsemide: Longer duration of action.
  • Important to monitor for hypovolemia from overdosing.
  • Diuretics manage symptoms of fluid overload but do not improve overall survival in HF.

Vasodilators

  • Purpose: To decrease preload by dilating venous blood vessels, thereby reducing volume returning to the heart.
  • Also decrease afterload by relaxing arterial resistance, facilitating easier heart pumping.

Types of Vasodilators

  • Nitrates: Primarily venous dilators.
    • Examples:
      • Isosorbide Dinitrate: Often used with other medications.
      • Nitroglycerin: Known for rapid action.
    • Common adverse effects include headaches, hypotension, and tachycardia.
  • Arterial Dilators: Reduce systemic arteriolar resistance.
    • Example: Hydralazine effectively lowers systemic vascular resistance.
  • Combination Therapy: Fixed-dose combinations of hydralazine and isosorbide dinitrate improve symptoms and survival in black patients with HFrEF.

Inotropic Drugs

  • Used to enhance cardiac contractility, improving cardiac output and heart function in heart failure.

Digitalis Glycosides

  • Digoxin: Derived from foxglove, improves cardiac contractility and is monitored closely due to its narrow therapeutic index.
Mechanism of Action
  • Inhibits Na+/K+-ATPase, increasing intracellular sodium and calcium, enhancing cardiac muscle contraction and output.
  • Increases vagal tone, slowing heart rate and reducing myocardial oxygen demand.
  • Slows conduction through the AV node, aiding in atrial fibrillation rate control.
Therapeutic Uses
  • Used for severe HFrEF alongside ACE inhibitors, β-blockers, and diuretics.
  • Effective at serum concentrations of 0.5 to 0.8 ng/mL for reducing hospitalizations and improving symptoms.
  • Benefits in controlling ventricular rates during atrial fibrillation.

Digitoxin

  • Similar to digoxin, but less commonly used today due to potential toxicity and longer duration of action.
Mechanism of Action
  • Also inhibits Na+/K+-ATPase, enhancing intracellular calcium levels, leading to improved cardiac contractility and output.
  • Slows heart rate through increased vagal tone.
Therapeutic Uses
  • Previously indicated for heart failure and atrial fibrillation, but use has diminished with the advent of new therapies.
Pharmacokinetics
  • Well-absorbed from gastrointestinal tract, large volume of distribution, and metabolized by the liver.
  • Long half-life necessitates careful monitoring.
Adverse Effects
  • Common effects: gastrointestinal disturbances, blurred vision, and potential toxicity with severe symptoms.
  • Regular monitoring of serum and electrolyte levels is crucial to prevent toxicity.

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