DIGOXIN (di-jox'in) Lanoxicaps, Lanoxin Classifications: cardiovascular agent; cardiac glycoside; antiarrhythmic Pregnancy Category: A
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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
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.
Increases the contractility of the heart muscle (positive inotropic effect).
Rapid digitalization and for maintenance therapy in CHF, atrial fibrillation, atrial flutter, paroxysmal atrial tachycardia.
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.
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.
Digitalizing Dose Adult: PO 1015 mcg/kg (1 mg) in divided doses over 2448 h IV 1015 mcg/kg (1 mg) in divided doses over 24 h Child: PO/IV
<2 y, 4060 mcg/kg; 210 y, 2040 mcg/kg; >10 y, 1015 mcg/kg (1.52 mg) Neonate: PO/IV 3050 mcg/kg Premature neonate: PO/IV 20 mcg/kg
Maintenance Dose Adult: PO/IV 0.10.375 mg/d Child: PO/IV
<2 y, 7.59 mcg/kg/d; 210 y, 67.5 mcg/kg/d; >10 y, 0.1250.25 mg/d Neonate: 67.5 mcg/kg/d Premature neonate: 3.75 mcg/kg/d
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Oral
- Give without regard to food. Administration after food may slightly delay rate of absorption, but total amount absorbed is
not affected.
- Crush and mix with fluid or food if patient cannot swallow it whole.
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.
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- Store tablets, elixir, and injection solution at 25° C (77° F) or at 15°30° C (59°86°
F).
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.
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.
Absorption: 70% PO tablets; 90% PO liquid and capsules. Onset: 12 h PO; 530 min IV. Peak: 68 h PO; 15 h IV. Duration: 34 d in fully digitalized patient. Distribution: Widely distributed; tissue levels significantly higher than plasma levels; crosses placenta. Metabolism: Approximately 14% in liver. Elimination: 8090% excreted by kidneys; may appear in breast milk. Half-Life: 3444 h.
Assessment & Drug Effects
- Take apical pulse for 1 full min, noting rate, rhythm, and quality before administering drug.
- Withold medication and notify physician if apical pulse falls below ordered parameters (e.g., <50 or 60/min in adults and
<60 or 70/min in children).
- Be familiar with patient's baseline data (e.g., quality of peripheral pulses, blood pressure, clinical symptoms, serum electrolytes,
creatinine clearance) as a foundation for making assessments.
- Lab tests: Baseline and periodic serum digoxin, potassium, magnesium, and calcium. Draw blood samples for determining plasma
digoxin levels at least 6 h after daily dose and preferably just before next scheduled daily dose.
- Monitor for S&S of drug toxicity: In children, cardiac arrhythmias are usually reliable signs of early toxicity. Early indicators
in adults (anorexia, nausea, vomiting, diarrhea, visual disturbances) are rarely initial signs in children.
- Monitor I&O ratio during digitalization, particularly in patients with impaired renal function. Also monitor for edema daily
and auscultate chest for rales.
- Monitor serum digoxin levels closely during concurrent antibioticdigoxin therapy, which can precipitate toxicity because
of altered intestinal flora.
- Observe patients closely when being transferred from one preparation (tablet, elixir, or parenteral) to another; when tablet
is replaced by elixir potential for toxicity increases since 30% of drug
is absorbed.
Patient & Family Education
- Report to physician if pulse falls below 60 or rises above 110 or if you detect skipped beats or other changes in rhythm,
when digoxin is prescribed for atrial fibrillation.
- Suspect toxicity and report to physician if any of the following occur: Anorexia, nausea, vomiting, diarrhea, or visual disturbances.
- Weigh each day under standard conditions. Report weight gain >1 kg (2 lb)/d.
- Take digoxin PRECISELY as prescribed, do not skip or double a dose or change dose intervals, and take it at same time each day.
- Do not to take OTC medications, especially those for coughs, colds, allergy, GI upset, or obesity, without prior approval
of physician.
- Continue with brand originally prescribed unless otherwise directed by physician.
- Do not breast feed while taking this drug without consulting physician.