DIGOXIN
(di-jox'in)
Lanoxicaps, Lanoxin
Classifications: cardiovascular agent; cardiac glycoside; antiarrhythmic
Pregnancy Category: A

Availability

0.05 mg, 0.1 mg, 0.2 mg capsules; 0.125 mg, 0.25 mg, 0.5 mg tablets; 0.05 mg/mL elixir; 0.25 mg/mL, 0.1 mg/mL injection

Actions

Widely used cardiac glycoside of Digitalis lanata. Acts by increasing the force and velocity of myocardial systolic contraction (positive inotropic effect). It also decreases conduction velocity through the atrioventricular node. Action is more prompt and less prolonged than that of digitalis and digitoxin.

Therapeutic Effects

Increases the contractility of the heart muscle (positive inotropic effect).

Uses

Rapid digitalization and for maintenance therapy in CHF, atrial fibrillation, atrial flutter, paroxysmal atrial tachycardia.

Contraindications

Digitalis hypersensitivity, ventricular fibrillation, ventricular tachycardia unless due to CHF. Full digitalizing dose not given if patient has received digoxin during previous week or if slowly excreted cardiotonic glycoside has been given during previous 2 wk.

Cautious Use

Renal insufficiency, hypokalemia, advanced heart disease, acute MI, incomplete AV block, cor pulmonale; hypothyroidism; lung disease; pregnancy (category A), lactation, premature and immature infants, children, older adults, or debilitated patients.

Route & Dosage

Digitalizing Dose
Adult: PO 10–15 mcg/kg (1 mg) in divided doses over 24–48 h IV 10–15 mcg/kg (1 mg) in divided doses over 24 h
Child: PO/IV <2 y, 40–60 mcg/kg; 2–10 y, 20–40 mcg/kg; >10 y, 10–15 mcg/kg (1.5–2 mg)
Neonate: PO/IV 30–50 mcg/kg
Premature neonate: PO/IV 20 mcg/kg

Maintenance Dose
Adult: PO/IV 0.1–0.375 mg/d
Child: PO/IV <2 y, 7.5–9 mcg/kg/d; 2–10 y, 6–7.5 mcg/kg/d; >10 y, 0.125–0.25 mg/d
Neonate: 6–7.5 mcg/kg/d
Premature neonate: 3.75 mcg/kg/d

Administration

Oral
Intravenous

PREPARE: Direct: Give undiluted or diluted in 4 mL of sterile water, D5W, or NS (less diluent may cause precipitation).  

ADMINISTER: Direct: Give each dose over at least 5 min.  

INCOMPATIBILITIES Solution/additive: Dobutamine, doxapram. Y-site: Amiodarone.

  • Monitor IV site frequently. Infiltration of parenteral drug into subcutaneous tissue can cause local irritation and sloughing.

Adverse Effects (1%)

CNS: Fatigue, muscle weakness, headache, facial neuralgia, mental depression, paresthesias, hallucinations, confusion, drowsiness, agitation, dizziness. CV: Arrhythmias, hypotension, AV block. Special Senses: Visual disturbances. GI: Anorexia, nausea, vomiting, diarrhea. Other: Diaphoresis, recurrent malaise, dysphagia.

Interactions

Drug: antacids, cholestyramine, colestipol decrease digoxin absorption; diuretics, corticosteroids, amphotericin B, laxatives, sodium polystyrene sulfonate may cause hypokalemia, increasing the risk of digoxin toxicity; calcium IV may increase risk of arrhythmias if administered together with digoxin; quinidine, verapamil, amiodarone, flecainide significantly increase digoxin levels, and digoxin dose should be decreased by 50%; erythromycin may increase digoxin levels; succinylcholine may potentiate arrhythmogenic effects; nefazodone may increase digoxin levels. Herbal: Ginseng increase digoxin toxicity; ma huang, ephedra may induce arrhythmias.

Pharmacokinetics

Absorption: 70% PO tablets; 90% PO liquid and capsules. Onset: 1–2 h PO; 5–30 min IV. Peak: 6–8 h PO; 1–5 h IV. Duration: 3–4 d in fully digitalized patient. Distribution: Widely distributed; tissue levels significantly higher than plasma levels; crosses placenta. Metabolism: Approximately 14% in liver. Elimination: 80–90% excreted by kidneys; may appear in breast milk. Half-Life: 34–44 h.

Nursing Implications

Assessment & Drug Effects

Patient & Family Education


Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug