Indications
Heart failure. Atrial fibrillation and atrial flutter (slows
ventricular rate). Paroxysmal atrial tachycardia.
Action
Increases the force of myocardial contraction. Prolongs
refractory period of the AV node. Decreases conduction
through the SA and AV nodes. Therapeutic Effects:
Increased cardiac output (positive inotropic effect) and
slowing of the heart rate (negative chronotropic effect).
Pharmacokinetics
Absorption: 60–80% absorbed after oral administration
of tablets; 70–85% absorbed after administration
of elixir; 80% absorbed from IM sites (IM route
not recommended due to pain/irritation).
Distribution: Widely distributed; crosses placenta
and enters breast milk.
Metabolism and Excretion: Excreted almost entirely
unchanged by the kidneys.
Half-life: 36–48 hr (qin renal impairment).
TIME/ACTION PROFILE (antiarrhythmic or
inotropic effects, provided that a loading
dose has been given)
ROUTE ONSET PEAK DURATION
Digoxin–PO 30–120 min 2–8 hr 2–4 days†
Digoxin–IM 30 min 4–6 hr 2–4 days†
Digoxin–IV 5–30 min 1–4 hr 2–4 days†
†Duration listed is that for normal renal function; in impaired
renal function, duration will be longer.
Contraindications/Precautions
Contraindicated in: Hypersensitivity; Uncontrolled
ventricular arrhythmias; AV block (in absence of pacemaker);
Idiopathic hypertrophic subaortic stenosis;
Constrictive pericarditis; Known alcohol intolerance
(elixir only).
Use Cautiously in: Hypokalemia (qrisk of digoxin
toxicity); Hypercalcemia (qrisk of toxicity, especially
with mild hypokalemia); Hypomagnesemia (qrisk of
digoxin toxicity); Diuretic use (may cause electrolyte
abnormalities including hypokalemia and hypomagnesemia);
Hypothyroidism; Myocardial infarction; Renal
impairment (doseprequired); Obesity (base dose on
ideal body weight); Geri: Very sensitive to toxic effects;
dose adjustments required for age-relatedpin renal
function and body weight; OB: Although safety has not
been established, has been used without adverse effects
on the fetus; Lactation: Similar concentrations in serum
and breast milk result in subtherapeutic levels in infant,
use with caution.
Adverse Reactions/Side Effects
CNS: fatigue, headache, weakness. EENT: blurred vision,
yellow or green vision. CV: ARRHYTHMIAS, bradycardia,
ECG changes, AV block, SA block. GI: anorexia,
nausea, vomiting, diarrhea. Hemat: thrombocytopenia.
Metab: electrolyte imbalances with acute digoxin
toxicity.
Interactions
Drug-Drug: Thiazide and loop diuretics, piperacillin,
amphotericin B, corticosteroids, and excessive
use of laxatives may cause hypokalemia which
mayqrisk of toxicity. Quinidine and ritonavir may
qlevels and lead to toxicity;pdigoxin dose by 30–
50%. Amiodarone mayqlevels and lead to toxicity;p
digoxin dose by 50%. Cyclosporine, itraconazole,
propafenone, quinine, spironolactone, and verapamil
mayqlevels and lead to toxicity; serum level
monitoring/dosepmay be required. Levels may bepby
some antineoplastics (bleomycin, carmustine, cyclophosphamide,
cytarabine, doxorubicin, methotrexate,
procarbazine, vincristine), activated
charcoal, cholestyramine, colestipol, kaolin/pectin,
metoclopramide, penicillamine, rifampin, or
sulfasalazine. In a small percentage (10%) of patients
gut bacteria metabolize digoxin to inactive compounds;
macrolide anti-infectives (erythromycin,
azithromycin, clarithromycin) and tetracyclines,
by killing these bacteria, will causeqlevels and toxicity;
dose may need to bepfor up to 9 wk. Additive bradycardia
may occur with beta blockers, diltiazem, verapamil,
clonidine, ivabradine, and other antiarrhythmics
(quinidine, disopyramide). Concurrent
use of sympathomimetics mayqrisk of arrthythmias.
Thyroid hormones mayptherapeutic effects.
Drug-Natural Products: Licorice and stimulant
natural products (aloe) mayqrisk of potassium depletion.
St. John’s wort mayplevels and effect.
Drug-Food: Concurrent ingestion of a high-fiber
meal maypabsorption. Administer digoxin 1 hour before
or 2 hours after such a meal.
Route/Dosage
For rapid effect, a larger initial loading/digitalizing dose
should be given in several divided doses over 12–24
hr. Maintenance doses are determined for digoxin by
renal function. All dosing must be evaluated by individual
response. In general, doses required for atrial arrhythmias
are higher than those for inotropic effect.
IV, IM (Adults): Digitalizing dose—0.5–1 mg given
as 50% of the dose initially and one quarter of the initial
dose in each of 2 subsequent doses at 6–12 hr intervals.
IV, IM (Children 10 yr): Digitalizing dose—8–
12 mcg/kg given as 50% of the dose initially and one
quarter of the initial dose in each of 2 subsequent doses
at 6–12 hr intervals.
IV, IM (Children 5–10 yr): Digitalizing dose—
15–30 mcg/kg given as 50% of the dose initially and
one quarter of the initial dose in each of 2 subsequent
doses at 6–12 hr intervals.
IV, IM (Children 2–5 yr): Digitalizing dose—25–
35 mcg/kg given as 50% of the dose initially and one
quarter of the initial dose in each of 2 subsequent doses
at 6–12 hr intervals.
IV, IM (Children 1–24 mo): Digitalizing dose—
30–50 mcg/kg given as 50% of the dose initially and
one quarter of the initial dose in each of 2 subsequent
doses at 6–12 hr intervals.
IV, IM (Infants–full term): 20–30 mcg/kg given as
50% of the dose initially and one quarter of the initial
dose in each of 2 subsequent doses at 6–12 hr intervals.
IV, IM (Infants–premature): Digitalizing dose—
15–25 mcg/kg given as 50% of the dose initially and
one quarter of the initial dose in each of 2 subsequent
doses at 6–12 hr intervals.
PO (Adults): Digitalizing dose—0.75–1.5 mg given
as 50% of the dose initially and one quarter of the initial
dose in each of 2 subsequent doses at 6–12 hr intervals.
Maintenance dose—0.125–0.5 mg/day depending
on patient’s lean body weight, renal function, and
serum level.
PO (Geriatric Patients): Initial daily dosage should
not exceed 0.125 mg.
PO (Children 10 yr): Digitalizing dose—10–15
mcg/kg given as 50% of the dose initially and one quarter
of the initial dose in each of 2 subsequent doses at
6–12 hr intervals. Maintenance dose—2.5–5 mcg/
kg given daily as a single dose.
PO (Children 5–10 yr): Digitalizing dose—20–35
mcg/kg given as 50% of the dose initially and one quarter of the initial dose in each of 2 subsequent doses at
6–12 hr intervals. Maintenance dose—5–10 mcg/kg
given daily in 2 divided doses.
PO (Children 2–5 yr): Digitalizing dose—30–40
mcg/kg given as 50% of the dose initially and one quarter
of the initial dose in each of 2 subsequent doses at
6–12 hr intervals. Maintenance dose—7.5–10 mcg/
kg given daily in 2 divided doses.
PO (Children 1–24 mo): Digitalizing dose—35–
60 mcg/kg given as 50% of the dose initially and one
quarter of the initial dose in each of 2 subsequent doses
at 6–12 hr intervals. Maintenance dose—10–15
mcg/kg given daily in 2 divided doses.
PO (Infants–full term): Digitalizing dose—25–35
mcg/kg given as 50% of the dose initially and one quarter
of the initial dose in each of 2 subsequent doses at
6–12 hr intervals. Maintenance dose—6–10 mcg/kg
given daily in 2 divided doses.
PO (Infants–premature): Digitalizing dose—20–
30 mcg/kg given as 50% of the dose initially and one
quarter of the initial dose in each of 2 subsequent doses
at 6–12 hr intervals. Maintenance dose—5–7.5
mcg/kg given daily in 2 divided doses.
Availability (generic available)
Tablets: 0.0625 mg, 0.125 mg, 0.1875 mg, 0.25 mg.
Cost: Generic—All strengths $27.75/10. Elixir (lime
flavor): 0.05 mg/mL. Cost: Generic—$42.10/60 mL.
Injection: 0.25 mg/mL. Pediatric injection: 0.1 mg/
mL.
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