Digoxin Dosage

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Usual Adult Dose for:

Usual Pediatric Dose for:

Additional dosage information:

Usual Adult Dose for Congestive Heart Failure

Rapid Digitalization with a Loading Dose:
Peak digoxin body stores of 8 to 12 mcg/kg generally provide a therapeutic effect with minimum risk of toxicity in most patients with heart failure and normal sinus rhythm.

The loading dose should be administered in several fractions, with approximately half the total given as the first dose. Additional fractions of the total dose may be given at 6 to 8 hour intervals. Careful assessment of the patient's clinical response should be considered before each additional dose. If the patient's response necessitates a change from the calculated loading dose of digoxin, then calculation of the maintenance dose should be based upon the amount actually given.

Tablets:
Initial: 500 to 750 mcg usually produces a detectable effect in 0.5 to 2 hours with a maximal effect in 2 to 6 hours. Additional doses of 125 to 375 mcg may be given at 6 to 8 hour intervals until clinical evidence of an adequate effect is noted. The usual amount of digoxin tablets that a 70 kg patient requires to achieve 8 to 12 mcg/kg peak body stores is 750 to 1250 mcg.

Capsules:
Initial: 400 to 600 mcg of digoxin capsules generally produces a detectable effect in 0.5 to 2 hours with a maximal effect in 2 to 6 hours. Additional doses of 100 to 300 mcg may be given cautiously at 6 to 8 hour intervals until clinical evidence of an adequate effect is noted. The usual amount of digoxin capsules that a 70 kg patient requires to achieve 8 to 12 mcg/kg peak body stores is 600 to 1000 mcg.

Injection:
Initial: 400 to 600 mcg of digoxin intravenously usually produces a detectable effect in 5 to 30 minutes with a maximal effect in 1 to 4 hours. Additional doses of 100 to 300 mcg may be given cautiously at 6 to 8 hour intervals until clinical evidence of an adequate effect is noted. The usual amount of digoxin injection that a 70 kg patient requires to achieve 8 to 12 mcg/kg peak body stores is 600 to 1000 mcg. The injectable route is frequently used to achieve rapid digitalization, with conversion to digoxin tablets or digoxin capsules for maintenance therapy.

Maintenance Dose:
The doses of digoxin tablets used in controlled trials in patients with heart failure have ranged from 125 to 500 mcg once daily. In these studies, the digoxin dose has been generally titrated according to the patient's age, lean body weight, and renal function. Therapy is generally initiated at a dose of 250 mcg once daily in patients under age 70 with good renal function.

Usual Adult Dose for Atrial Fibrillation

Peak digoxin body stores larger than the 8 to 12 mcg/kg required for most patients with heart failure and normal sinus rhythm have been used for control of ventricular rate in patients with atrial fibrillation. Doses of digoxin used for the treatment of chronic atrial fibrillation should be titrated to the minimum dose that achieves the desired ventricular rate control without causing undesirable side effects.

Usual Pediatric Dose for Atrial Fibrillation

Do not give full total digitalizing dose at once. Administer loading doses in several portions, give roughly half the total as the first dose. Give additional fractions of the total dose at 6 to 8 hour intervals (oral) or 4 to 8 hour intervals (parenteral). Divided daily dosing is recommended for infants and young children under 10 years of age.

Parenteral administration should be used only when the need for rapid digitalization is urgent or when the drug cannot be taken orally. Intravenous administration is preferred over intramuscular injection as it can lead to severe pain at the injection site. If it is necessary to administer the drug by the intramuscular route, it should be injected deep into the muscle followed by massage. No more than 500 mcg should be injected into a single site.

Calculated doses should be based on lean body weight.

Premature:
Digitalizing (Loading) dose: Oral elixir: 20 to 30 mcg/kg; Intravenous: 15 to 25 mcg/kg
Maintenance dose: oral 5 to 7.5 mcg/kg; intravenous 4 to 6 mcg/kg

Full Term:
Digitalizing (Loading) dose: Oral elixir: 25 to 35 mcg/kg; Intravenous: 20 to 30 mcg/kg
Maintenance dose: oral 6 to 10 mcg/kg; intravenous 5 to 8 mcg/kg

1-24 months:
Digitalizing (Loading) dose: Oral elixir: 35 to 60 mcg/kg; Intravenous: 30 to 50 mcg/kg
Maintenance dose: 10 to 15 mcg/kg oral; intravenous 7.5 to 12 mcg/kg

3 to 5 years:
Digitalizing (Loading) dose: Oral elixir: 30 to 40 mcg/kg; Intravenous: 25 to 35 mcg/kg
Maintenance dose: oral 7.5 to 10 mcg/kg; intravenous 6 to 9 mcg/kg

6 to 10 years:
Digitalizing (Loading) dose: Oral elixir: 20 to 35 mcg/kg; Intravenous: 15 to 30 mcg/kg
Maintenance dose: oral 5 to 10 mcg/kg; intravenous 4 to 8 mcg/kg

11 years and older:
Digitalizing (Loading) dose: Oral elixir: 10 to 15 mcg/kg; Intravenous: 8 to 12 mcg/kg
Maintenance dose: oral 2.5 to 5 mcg/kg; intravenous 2 to 3 mcg/kg

Renal Dose Adjustments

CrCl <10 mL/min: Loading dose: Generally reduced by 50%.
Maintenance dose: Can be administered as 10% to 25% of maintenance dose or the interval increased to every 48 hours.

CrCl 10 to 50 mL/min: Total digitalizing dose: 0.5 to 1 mg (the initial dose is usually one-half of the total digitalizing dose, followed by 1/4 of the digitalizing dose in each of two subsequent doses at 6 and 12 hour intervals). Maintenance dose: 25% to 75% of the normal daily dose or administer normal dose every 36 hours.

In general, a maintenance dose of 125 mcg orally once daily is recommended in patients with impaired renal function, and at a dose of 62.5 mcg is recommended in patients with marked renal impairment. Doses may be increased every 2 weeks according to clinical response.

Because of altered digoxin distribution and elimination, projected peak body stores for patients with renal insufficiency should be conservative (i.e., 6 to 10 mcg/kg).

Liver Dose Adjustments

No adjustment recommended

Dose Adjustments

If patients are switched from intravenous to oral formulations, allowances must be made for differences in bioavailability when calculating maintenance dosages. When changing from oral formulations to IM or IV therapy, dosage should be reduced by 20% to 25%.

Lanoxicaps (gelatin capsules) have greater bioavailability than standard tablets, and the recommended oral doses are only 80% of those for tablets and elixir. Therefore, the 0.2 mg capsule is equivalent to 0.25 mg tablets; the 0.1 mg capsule is equivalent to 0.125 mg tablets; and the 0.05 mg capsule is equivalent to 0.0625 mg. Divided dosage of the capsule formulation is preferred in patients that require a daily dose greater than 300 mcg, those with a previous history of digitalis toxicity, and in patients who may be more likely to become toxic.

Hyperthyroid patients generally require a slightly higher loading dose (10%). Hypothyroid patients generally require a slightly lower loading dose (10%).

Dialysis

Digoxin is not removed by hemo- or peritoneal dialysis.

Other Comments

Calculated doses should be based on lean body weight.

While most patients with signs and symptoms of toxicity have serum digoxin levels greater than 2.0 ng/mL, there is a somewhat poor correlation between levels, effect and toxicity. Therefore, serum level monitoring is usually only recommended to assess patient compliance, to evaluate clinical deterioration following an initially good response, to evaluate unsuspected toxicity, and to assess patients who are at a higher risk of toxicity. Such patients may include individuals with underlying renal or cardiopulmonary disease, thyroid disease, and electrolyte imbalances such as hypokalemia, hypomagnesemia, or hypercalcemia. Patients > 65 years of age are also at higher risk for toxicity. The best time to sample a trough serum digoxin level is just before a dose 7 to 14 days after initiation of therapy. If the patient is also taking quinidine when serum digoxin levels are needed, the blood sample may be drawn just before both drugs are given. A common mistake is checking serum digoxin levels immediately after a loading or maintenance dose. Because digoxin distributes slowly into peripheral tissues over at least 6 hours, assays performed before this period do not indicate steady-state levels.

Intramuscular injection is extremely painful and offers no advantages unless other routes of administration are contraindicated.

A post-hoc analysis of a large study (DIG trial) involving patients with chronic heart failure (HF) receiving long-term digoxin therapy, revealed that discontinuation of digoxin was associated with a significant increase in all-cause hospitalization and hospitalization for HF, but had no effect on all-cause mortality. In contrast, continuation of digoxin at low serum concentrations (0.5 to 0.9 ng/mL) was associated with a reduction in all-cause mortality, all-cause hospitalizations, and hospitalizations for HF. In addition, heart failure guideline recommendations include that if a patient with HF is already receiving digoxin but not an ACEI or beta-blocker, treatment with digoxin should not be discontinued.

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