Podcast
Questions and Answers
What are the two main clinical indications for digoxin?
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?
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?
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?
What is the primary site of absorption of digoxin?
Which factor can increase the bioavailability of digoxin?
Which factor can increase the bioavailability of digoxin?
Where does digoxin concentrate in the body?
Where does digoxin concentrate in the body?
How is the pharmacokinetics of digoxin affected by obesity?
How is the pharmacokinetics of digoxin affected by obesity?
What is the primary site of metabolism of digoxin?
What is the primary site of metabolism of digoxin?
Which statement about the distribution volume (VD) of digoxin is correct?
Which statement about the distribution volume (VD) of digoxin is correct?
What is the effect of E. lentum on the absorption of digoxin?
What is the effect of E. lentum on the absorption of digoxin?
What is the therapeutic range of digoxin concentrations for patients with atrial fibrillation?
What is the therapeutic range of digoxin concentrations for patients with atrial fibrillation?
Which condition is associated with a decrease in digoxin non-renal clearance?
Which condition is associated with a decrease in digoxin non-renal clearance?
What is the recommended treatment for digoxin overdose?
What is the recommended treatment for digoxin overdose?
Which drug inhibits renal/extrarenal digoxin clearance and increases digoxin concentration by 50-75%?
Which drug inhibits renal/extrarenal digoxin clearance and increases digoxin concentration by 50-75%?
What percentage of digoxin is eliminated unchanged by glomerular filtration rate (GFR) and active tubular secretion?
What percentage of digoxin is eliminated unchanged by glomerular filtration rate (GFR) and active tubular secretion?
What is the half-life of digoxin for creatinine clearance greater than 80 mL/min?
What is the half-life of digoxin for creatinine clearance greater than 80 mL/min?
What is the primary cause of digoxin toxicity?
What is the primary cause of digoxin toxicity?
Which electrolyte disturbance is associated with an increased pharmacologic response to digoxin?
Which electrolyte disturbance is associated with an increased pharmacologic response to digoxin?
What is the maintenance dose of digoxin for heart failure?
What is the maintenance dose of digoxin for heart failure?
What is the loading dose of digoxin for atrial fibrillation?
What is the loading dose of digoxin for atrial fibrillation?
What is the primary clinical use of lithium?
What is the primary clinical use of lithium?
How does lithium affect suicide risk in patients?
How does lithium affect suicide risk in patients?
What is the mechanism of action of lithium?
What is the mechanism of action of lithium?
What is the bioavailability of immediate-release lithium?
What is the bioavailability of immediate-release lithium?
Where is lithium almost completely absorbed from?
Where is lithium almost completely absorbed from?
What is the primary site of absorption of lithium?
What is the primary site of absorption of lithium?
What is the effect of food on the absorption of lithium?
What is the effect of food on the absorption of lithium?
What is the peak concentration of lithium carbonate regular-release tablets/capsules?
What is the peak concentration of lithium carbonate regular-release tablets/capsules?
What is the peak concentration of lithium for immediate release?
What is the peak concentration of lithium for immediate release?
What is the peak concentration of lithium for extended release?
What is the peak concentration of lithium for extended release?
What is the primary form of absorption of lithium after oral administration?
What is the primary form of absorption of lithium after oral administration?
What is the primary mechanism of absorption of lithium from the small intestine?
What is the primary mechanism of absorption of lithium from the small intestine?
What is the bioavailability of oral syrup lithium?
What is the bioavailability of oral syrup lithium?
What is the primary route of elimination for lithium?
What is the primary route of elimination for lithium?
At what time post-dose should blood samples be drawn for accurate lithium levels?
At what time post-dose should blood samples be drawn for accurate lithium levels?
What is the therapeutic range for lithium concentrations?
What is the therapeutic range for lithium concentrations?
How long does it take to reach steady state for lithium?
How long does it take to reach steady state for lithium?
What is the starting dose range for lithium in bipolar disorder?
What is the starting dose range for lithium in bipolar disorder?
Which organs preferentially take up lithium during distribution?
Which organs preferentially take up lithium during distribution?
What factor affects lithium levels among others?
What factor affects lithium levels among others?
What type of tablets have a peak concentration of lithium at 4 to 12 hours?
What type of tablets have a peak concentration of lithium at 4 to 12 hours?
How is clearance of lithium related to renal function?
How is clearance of lithium related to renal function?
What is the dosing adjustment increment typically made for lithium?
What is the dosing adjustment increment typically made for lithium?
What should be maintained to avoid lithium toxicity?
What should be maintained to avoid lithium toxicity?
What is essential for monitoring when using lithium?
What is essential for monitoring when using lithium?
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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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.
