Digoxin Quiz
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Questions and Answers

What are the two main clinical indications for digoxin?

  • Congestive heart failure and atrial fibrillation (correct)
  • Hypertension and myocardial infarction
  • Pulmonary embolism and pericarditis
  • Arrhythmias and cardiogenic shock

    • What is the mechanism of action of digoxin in congestive heart failure?

  • Blocks calcium channels in the myocardium to reduce contractility
  • Binds to Na+/K+ ATPase in myocytes, increasing intracellular Na+ and Ca2+ to enhance myocardial contractility (correct)
  • Inhibits parasympathetic activity and vagal tone to increase heart rate
  • Activates beta receptors in the heart to increase contractility

    • How does digoxin exert a negative chronotropic effect in atrial fibrillation?

  • Directly inhibits the sinoatrial node to decrease heart rate
  • Activates sympathetic activity to increase heart rate
  • Increases parasympathetic activity and vagal tone to slow conduction and decrease ventricular heart rate (correct)
  • Enhances calcium influx in the atrial myocytes to decrease heart rate

    • What is the primary site of absorption of digoxin?

    <p>Small intestine</p> Signup and view all the answers

    Which factor can increase the bioavailability of digoxin?

    <p>Inhibition of p-glycoprotein</p> Signup and view all the answers

    Where does digoxin concentrate in the body?

    <p>Heart and kidneys</p> Signup and view all the answers

    How is the pharmacokinetics of digoxin affected by obesity?

    <p>Not affected due to its large binding to skeletal muscle</p> Signup and view all the answers

    What is the primary site of metabolism of digoxin?

    <p>Liver</p> Signup and view all the answers

    Which statement about the distribution volume (VD) of digoxin is correct?

    <p>VD is 5-9 L/kg, with an average of 7 L/kg</p> Signup and view all the answers

    What is the effect of E. lentum on the absorption of digoxin?

    <p>It inactivates digoxin in the gut</p> Signup and view all the answers

    What is the therapeutic range of digoxin concentrations for patients with atrial fibrillation?

    <p>0.8-1.5 ng/mL</p> Signup and view all the answers

    Which condition is associated with a decrease in digoxin non-renal clearance?

    <p>Moderate/severe heart failure</p> Signup and view all the answers

    What is the recommended treatment for digoxin overdose?

    <p>Digoxin immune Fab (DigiFab)</p> Signup and view all the answers

    Which drug inhibits renal/extrarenal digoxin clearance and increases digoxin concentration by 50-75%?

    <p>Verapamil</p> Signup and view all the answers

    What percentage of digoxin is eliminated unchanged by glomerular filtration rate (GFR) and active tubular secretion?

    <p>75%</p> Signup and view all the answers

    What is the half-life of digoxin for creatinine clearance greater than 80 mL/min?

    <p>24-48 hours</p> Signup and view all the answers

    What is the primary cause of digoxin toxicity?

    <p>Hypokalemia</p> Signup and view all the answers

    Which electrolyte disturbance is associated with an increased pharmacologic response to digoxin?

    <p>Hypokalemia</p> Signup and view all the answers

    What is the maintenance dose of digoxin for heart failure?

    <p>0.125-0.25 mg/daily</p> Signup and view all the answers

    What is the loading dose of digoxin for atrial fibrillation?

    <p>No loading doses</p> Signup and view all the answers

    What is the primary clinical use of lithium?

    <p>Treatment for acute mania and maintenance treatment of bipolar I and II</p> Signup and view all the answers

    How does lithium affect suicide risk in patients?

    <p>It reduces suicide risk</p> Signup and view all the answers

    What is the mechanism of action of lithium?

    <p>It is unknown, but it is thought to modulate neurotransmission at both the neuronal and intracellular levels</p> Signup and view all the answers

    What is the bioavailability of immediate-release lithium?

    <p>95 to 100%</p> Signup and view all the answers

    Where is lithium almost completely absorbed from?

    <p>The small intestine</p> Signup and view all the answers

    What is the primary site of absorption of lithium?

    <p>Small intestine</p> Signup and view all the answers

    What is the effect of food on the absorption of lithium?

    <p>Food does not affect absorption</p> Signup and view all the answers

    What is the peak concentration of lithium carbonate regular-release tablets/capsules?

    <p>Varies</p> Signup and view all the answers

    What is the peak concentration of lithium for immediate release?

    <p>Varies</p> Signup and view all the answers

    What is the peak concentration of lithium for extended release?

    <p>Varies</p> Signup and view all the answers

    What is the primary form of absorption of lithium after oral administration?

    <p>Complete dissociation to the lithium cation</p> Signup and view all the answers

    What is the primary mechanism of absorption of lithium from the small intestine?

    <p>Passive diffusion</p> Signup and view all the answers

    What is the bioavailability of oral syrup lithium?

    <p>~100%</p> Signup and view all the answers

    What is the primary route of elimination for lithium?

    <p>Renal</p> Signup and view all the answers

    At what time post-dose should blood samples be drawn for accurate lithium levels?

    <p>12 hours</p> Signup and view all the answers

    What is the therapeutic range for lithium concentrations?

    <p>0.6-1.5 mEq/L</p> Signup and view all the answers

    How long does it take to reach steady state for lithium?

    <p>5 days</p> Signup and view all the answers

    What is the starting dose range for lithium in bipolar disorder?

    <p>600-900 mg/day</p> Signup and view all the answers

    Which organs preferentially take up lithium during distribution?

    <p>Brain, kidney, thyroid, and bone</p> Signup and view all the answers

    What factor affects lithium levels among others?

    <p>Sodium intake</p> Signup and view all the answers

    What type of tablets have a peak concentration of lithium at 4 to 12 hours?

    <p>Extended-release tablets</p> Signup and view all the answers

    How is clearance of lithium related to renal function?

    <p>Proportional to glomerular filtration rate (GFR)</p> Signup and view all the answers

    What is the dosing adjustment increment typically made for lithium?

    <p>300 mg</p> Signup and view all the answers

    What should be maintained to avoid lithium toxicity?

    <p>Consistent salt intake</p> Signup and view all the answers

    What is essential for monitoring when using lithium?

    <p>Regular monitoring of lithium levels, baseline labs, and vital signs</p> Signup and view all the answers

    Study Notes

    Lithium Pharmacokinetics and Clinical Considerations

    • Lithium has different peak concentrations and absorption times depending on the formulation: extended-release tablets (4 to 12 hours), citrate solution (15 to 60 minutes).
    • Distribution of lithium occurs in a two-compartment model and is preferentially taken up by specific organs such as the brain, kidney, thyroid, and bone.
    • The elimination of lithium is mainly renal (95%) and it is not metabolized by the liver. Clearance is proportional to glomerular filtration rate (GFR) and blood flow to the kidney.
    • Lithium levels are affected by various factors including drug interactions, renal function, and sodium intake, and baseline labs and vitals are necessary for monitoring.
    • The therapeutic range for lithium is generally 0.6-1.5 mEq/L, with different ranges for acute mania (0.8-1.2 mEq/L) and maintenance (0.6-1.0 mEq/L) based on clinical situations.
    • Lithium dosing for bipolar disorder typically starts at 600-900 mg/day and can be titrated based on response and tolerability by 300 to 600 mg every 1 to 5 days.
    • It takes approximately 5 days to reach steady state for lithium, and dose adjustments are usually made in 300 mg increments with monitoring of serum levels.
    • Lithium toxicity occurs at levels greater than 1.5 mEq/L, and dosing adjustments should be made in elderly patients who may experience toxicity at lower levels.
    • Counseling points for lithium use include taking it with or without food, maintaining consistent salt intake, and avoiding excessive caffeine and dehydration.
    • Regular monitoring of lithium levels, baseline labs, and vital signs is essential, and blood samples need to be drawn 12 hours post-dose for accurate levels.
    • The complex concentration-time curve of lithium concentrations requires careful patient adherence to dosing instructions and consideration of individual variability in distribution.
    • It is important to consider individual patient factors, clinical response, tolerability, and serum concentration when making dose adjustments for lithium in bipolar disorder.

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    Related Documents

    DIGOXIN.docx
    DIGOXIN.docx

    Description

    Test your knowledge of digoxin with this quiz covering its two main clinical indications, mechanism of action, and the positive inotropic effects it has on congestive heart failure and atrial fibrillation.

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