Digoxin Quiz

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Questions and Answers

What is the main route of elimination for digoxin?

Renal excretion (correct)

Nonrenal routes

Biliary excretion

Enterohepatic cycle

Which plasma concentration range of digoxin is considered to be within the therapeutic range?

$3-4 rac{ ext{mcg}}{L}$

$1-2 rac{ ext{mcg}}{L}$ (correct)

$2-3 rac{ ext{mcg}}{L}$

$0.5-1 rac{ ext{mcg}}{L}$

What percentage of an oral dose of digoxin is absorbed in the small intestine?

50-60%

30-40%

90-100%

70-80% (correct)

What is the loading dose range for digoxin?

$0.01-0.02 rac{ ext{mg}}{kg}$ Signup and view all the answers

What percentage of digoxin is eliminated by nonrenal routes?

~25-28% Signup and view all the answers

Which patients require dosage adjustments for digoxin due to their condition?

Patients with congestive heart failure (CHF) Signup and view all the answers

What is the approximate percentage of unchanged digoxin excreted in urine?

Nearly all Signup and view all the answers

What is the long elimination half-life for adults receiving ionotropic agents like digoxin?

Once daily Signup and view all the answers

What is the recognized therapeutic range of dihydrodigoxin as a metabolite?

Remains to be resolved Signup and view all the answers

What might rise up to 30% of a given dose due to variation?

Biliary excretion Signup and view all the answers

What seems to be of minor importance in the elimination process according to the text?

Enterohepatic cycle Signup and view all the answers

What is the range of metabolic clearance of digoxin in mL/kg/min?

0.57 to 0.86 Signup and view all the answers

What is the effect of St. John’s wort on the bioavailability of digoxin in healthy individuals via intravenous route?

Decreases by 25% Signup and view all the answers

What can alter digoxin concentrations and clearance?

Antibiotics, particularly macrolides Signup and view all the answers

What is the half-life range of digoxin?

7 to 14 days Signup and view all the answers

Where should routine plasma samples for digoxin monitoring be obtained?

Just before the next dose Signup and view all the answers

What percentage of digoxin is free in blood plasma?

70-80% Signup and view all the answers

What is the total digoxin clearance (Clt) in elixir form?

0.8 Signup and view all the answers

How long does it take to achieve steady state for digoxin?

15 to 20 days Signup and view all the answers

What factors can affect the volume of distribution of digoxin?

Creatinine clearance, hypothyroidism, and obesity Signup and view all the answers

In which model does the distribution of digoxin follow?

Two-compartment model Signup and view all the answers

When do plasma digoxin levels accurately reflect the drug’s pharmacological effect?

After equilibration is complete Signup and view all the answers

What is the range of metabolic clearance of digoxin in mL/kg/min?

0.57 - 0.86 Signup and view all the answers

What is the total digoxin clearance (Clt) in elixir form?

0.8 Signup and view all the answers

What percentage of digoxin is free in blood plasma?

70-80% Signup and view all the answers

What might alter digoxin concentrations and clearance?

Antibiotics, particularly macrolides Signup and view all the answers

What is the recognized effect of St. John’s wort on the bioavailability of digoxin in healthy individuals via intravenous route?

-25% Signup and view all the answers

What is the half-life range of digoxin?

7 - 14 days Signup and view all the answers

Study Notes

Pharmacokinetics of Digoxin

Digoxin clearance varies between 0.5 and 0.9 in tablet form and 0.8 in elixir form.
Total digoxin clearance (Clt) is the sum of metabolic (Clm) and renal (Clr) clearances.
Metabolic clearance of digoxin ranges from 0.57 to 0.86 mL/kg/min.
Bioavailability in healthy individuals via intravenous route is 100%, but it decreases by 25% with St. John’s wort.
Antibiotics, particularly macrolides, can alter digoxin concentrations and clearance.
The half-life of digoxin ranges from 7 to 14 days, and it takes 15 to 20 days to achieve steady state.
Digoxin is extensively distributed in tissues, with 70-80% free in blood plasma.
Volume of distribution is affected by factors such as renal function, hypothyroidism, and drug interactions.
Routine plasma samples for digoxin monitoring should be obtained just before the next dose.
Pharmacokinetics of digoxin is altered in patients with end-stage renal disease and hypothyroidism.
The distribution of digoxin follows a two-compartment model, with initial high serum concentrations not reflective of therapeutic or toxic potential.
Plasma digoxin levels may not accurately reflect the drug’s pharmacological effect until after equilibration is complete.

Pharmacokinetics of Digoxin

Digoxin clearance varies between 0.5 and 0.9 in tablet form and 0.8 in elixir form.
Total digoxin clearance (Clt) is the sum of metabolic (Clm) and renal (Clr) clearances.
Metabolic clearance of digoxin ranges from 0.57 to 0.86 mL/kg/min.
Bioavailability in healthy individuals via intravenous route is 100%, but it decreases by 25% with St. John’s wort.
Antibiotics, particularly macrolides, can alter digoxin concentrations and clearance.
The half-life of digoxin ranges from 7 to 14 days, and it takes 15 to 20 days to achieve steady state.
Digoxin is extensively distributed in tissues, with 70-80% free in blood plasma.
Volume of distribution is affected by factors such as renal function, hypothyroidism, and drug interactions.
Routine plasma samples for digoxin monitoring should be obtained just before the next dose.
Pharmacokinetics of digoxin is altered in patients with end-stage renal disease and hypothyroidism.
The distribution of digoxin follows a two-compartment model, with initial high serum concentrations not reflective of therapeutic or toxic potential.
Plasma digoxin levels may not accurately reflect the drug’s pharmacological effect until after equilibration is complete.

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Description

Test your knowledge on the ionotropic agent primarily used to treat atrial fibrillation in patients with congestive heart failure (CHF). Explore dosage, administration, and considerations for patients with renal impairment.