Question

Plasma digoxin levels for Margaret D (68 kg, 47 years old) 12 and 24 hours following an oral administration of a 0.25 mg dose are determined to be 0.72 and 0.33 mcg/L respectively. If the therapeutic concentration range for digoxin is 0.8 – 2 mcg/L,

predict Mary’s digoxin trough concentrations at steady state if the drug is continued at a dosing rate of 0.25 mcg Q24 h

Answer 1

Although there is considerable variation between patients, historically plasma digoxin concentrations of 1 to 2 therapeutic range. 1, 2 Data now indicate that a therapeutic range of 0.5 to 0.9 mcg/L is indicated for patients with CHF. 3–6.

This lower target range is fact that most patients with left ventricular dysfunction do not demonstrate additional therapeutic benefits from higher digoxin concentrations and are at greater risk for toxicity with digoxin concentrations 1.2 mcg/L. 7–9 For patients on digoxin for atrial fibrillation, the goal for digoxin is rate control. 10 Rate control is achieved by atrioventricular (AV) nodal blockade and may require higher digoxin concentrations. The use of pharmacokinetics to adjust the dosing regimen can reduce the digoxin toxicity. 2, 11–13.