How does Digoxin Work? (EASY Pharmacology)

Summary

Dejin (Digoxin) is a heart medication used for atrial fibrillation and heart failure. It works by slowing the heart rate in the atria (via the parasympathetic system) and increasing the strength of ventricular contractions. Dejin’s narrow therapeutic index requires careful dosing, with target concentrations of 1-2 ng/mL for atrial fibrillation and 0.5-0.9 ng/mL for heart failure. Side effects include nausea, vomiting, bradycardia, altered mental status, and in severe cases, visual disturbances and even death. Monitoring drug levels is essential to avoid toxicity and ensure effectiveness in treatment.

Takeaways

• 😀 Digoxin works on both the atrial and ventricular sides of the heart, affecting heart rate and contractility.
• 😀 In atrial fibrillation, Digoxin helps slow down heart rate by activating the parasympathetic nervous system through the vagus nerve.
• 😀 For heart failure, Digoxin increases ventricular contractility by inhibiting the sodium-potassium pump, improving blood flow.
• 😀 The therapeutic concentration for Digoxin in atrial fibrillation is 1-2 ng/ml, and for heart failure, it's 0.5-0.9 ng/ml.
• 😀 Digoxin has a narrow therapeutic index, meaning it has a small margin between therapeutic and toxic levels.
• 😀 Common side effects of Digoxin toxicity include nausea, vomiting, bradycardia, and altered mental status.
• 😀 Unique signs of Digoxin toxicity include blue/green halo vision, which is specific to this drug.
• 😀 Overdosing on Digoxin can lead to life-threatening consequences, including death.
• 😀 Kidney function plays a critical role in dosing adjustments for Digoxin, especially in patients with declining renal function.
• 😀 Digoxin is used primarily for atrial fibrillation and heart failure, with different dosing ranges depending on the condition being treated.

Q & A

What are the two main effects of digoxin on the heart?

Digoxin can either slow down the heart rate (chronotropic effect) by working on the atria or increase cardiac output (ionotropic effect) by enhancing ventricular contractility.

How does digoxin slow down the heart rate in patients with atrial fibrillation?

Digoxin works by activating the parasympathetic nervous system through the vagus nerve, which releases acetylcholine in the SA and AV nodes to slow down contraction, thus reducing heart rate.

What is the role of digoxin in patients with heart failure?

In heart failure, digoxin helps increase ventricular contractility by inhibiting the sodium-potassium pump, which allows the ventricles to contract more forcefully, improving blood flow.

What is the therapeutic concentration range of digoxin for treating atrial fibrillation?

The therapeutic range for digoxin in atrial fibrillation is 1 to 2 ng/mL.

What is the recommended therapeutic range for digoxin in treating heart failure?

For heart failure, the target therapeutic range for digoxin is 0.5 to 0.9 ng/mL.

Why is digoxin considered to have a narrow therapeutic index?

Digoxin has a narrow therapeutic index because the difference between effective and toxic levels is small, making it easy for patients to reach toxic levels if not monitored carefully.

What are some common side effects of digoxin toxicity?

Common side effects of digoxin toxicity include nausea, vomiting, bradycardia, altered mental status, and blue/green halo vision.

What is the initial dosing range for digoxin in an outpatient setting?

The initial dosing range for digoxin in an outpatient setting is 0.125 mg to 0.25 mg daily.

What factors should be considered when adjusting the dosage of digoxin?

Kidney function must be considered when adjusting the dosage of digoxin, as impaired renal function can require a lower dose to avoid toxicity.

What is a specific visual symptom associated with severe digoxin toxicity?

A specific visual symptom of severe digoxin toxicity is the appearance of blue/green halos around objects, which occurs when toxicity reaches high levels.