Lanoxin

(Digoxin)

Check Drug InteractionsCheck known drug interactions.

Lanoxin Prescribing Information

LANOXIN is a cardiac glycoside indicated for:

•Treatment of mild to moderate heart failure in adults. (
1.1 Heart Failure in Adults
LANOXIN is indicated for the treatment of mild to moderate heart failure in adults. LANOXIN increases left ventricular ejection fraction and improves heart failure symptoms, as evidenced by improved exercise capacity and decreased heart failure-related hospitalizations and emergency care, while having no effect on mortality. Where possible, LANOXIN should be used in combination with a diuretic and an angiotensin-converting enzyme (ACE) inhibitor.
)
•Increasing myocardial contractility in pediatric patients with heart failure. (
1.2 Heart Failure in Pediatric Patients
LANOXIN increases myocardial contractility in pediatric patients with heart failure.
)
•Control of resting ventricular rate in adults with chronic atrial fibrillation. (
1.3 Atrial Fibrillation in Adults
LANOXIN is indicated for the control of ventricular response rate in adult patients with chronic atrial fibrillation.
)

LANOXIN dose is based on patient-specific factors (age, lean body weight, renal function, etc.). See full prescribing information. Monitor for toxicity and therapeutic effect. (

2 DOSAGE AND ADMINISTRATION

LANOXIN dose is based on patient-specific factors (age, lean body weight, renal function, etc.). See full prescribing information. Monitor for toxicity and therapeutic effect.

Intravenous administration is preferable to intramuscular. Avoid bolus administration.

2.1 Important Dosing and Administration Information

In selecting a LANOXIN dosing regimen, it is important to consider factors that affect digoxin blood levels (e.g., body weight, age, renal function, concomitant drugs) since toxic levels of digoxin are only slightly higher than therapeutic levels. Dosing can be either initiated with a loading dose followed by maintenance dosing if rapid titration is desired

initiated with maintenance dosing without a loading dose.

Parenteral administration of digoxin should be used only when the need for rapid digitalization is urgent or when the drug cannot be taken orally. Intramuscular injection can lead to severe pain at the injection site, thus intravenous administration is preferred. If the drug must be administered by the intramuscular route, it should be injected deep into the muscle followed by massage. For adults, no more than 500 mcg of LANOXIN Injection should be injected into a single site. For pediatric patients, no more than 200 mcg of LANOXIN Injection Pediatric should be injected into a single site.

Administer the dose over a period of 5 minutes or longer and avoid bolus administration to prevent systemic and coronary vasoconstriction. Mixing of LANOXIN Injection and Injection Pediatric with other drugs in the same container or simultaneous administration in the same intravenous line is not recommended.

LANOXIN Injection and Injection Pediatric can be administered undiluted or diluted with a 4-fold or greater volume of Sterile Water for Injection, 0.9% Sodium Chloride Injection, or 5% Dextrose Injection. The use of less than a 4-fold volume of diluent could lead to precipitation of the digoxin. Immediate use of the diluted product is recommended.

Consider interruption or reduction in LANOXIN dose prior to electrical cardioversion

[see Warnings and Precautions ].

Discard unused portion of LANOXIN Injection and LANOXIN Injection Pediatric.

2.2 Loading Dosing Regimen in Adults and Pediatric Patients

Table 1. Recommended LANOXIN Injection Loading Dose
mcg = microgram
Age	Total IV Loading Dose (mcg/kg) Administer half the total loading dose initially, then ¼ the loading dose every 6-8 hours twice
Premature	15-25
Full-Term	20-30
1-24 Months	30-50
2-5 Years	25-35
5-10 Years	15-30
Adults and pediatric patients over 10 years	8-12

2.3 Maintenance Dosing in Adults and Pediatric Patients Over 10 Years Old

The maintenance dose is based on lean body weight, renal function, age, and concomitant products

[see Clinical Pharmacology ]

The recommended

starting

maintenance doses in adults and pediatric patients over 10 years old with normal renal function are given in Table 2. Doses may be increased every 2 weeks according to clinical response, serum drug levels, and toxicity.

Table 2. Recommended Starting LANOXIN Injection Maintenance Dosage in Adults and Pediatric Patients Over 10 Years Old
mcg = microgram
Age	Total Intravenous Maintenance Dose, mcg/kg/day (given once daily)
Adults and pediatric patients over 10 years	2.4-3.6

Table 3provides the recommended (once daily) maintenance dose for adults and pediatric patients over 10 years old (to be given once daily) according to lean body weight and renal function. The doses are based on studies in adult patients with heart failure. Alternatively, the maintenance dose may be estimated by the following formula (peak body stores lost each day through elimination):

Total Maintenance Dose = Loading Dose (i.e., Peak Body Stores) x % Daily Loss/100

(% Daily Loss = 14 + Creatinine clearance/5)

Reduce the dose of LANOXIN in patients whose lean weight is an abnormally small fraction of their total body mass because of obesity or edema.

Table 3. Recommended Maintenance Dose (in micrograms given once daily) of LANOXIN Injection in Pediatric Patients Over 10 Years Old and Adults by Lean Body Weight and by Renal Function
^a For adults , creatinine clearance was corrected to 70-kg body weight or 1.73 m²body surface area. If only serum creatinine concentrations (Scr) are available, a corrected Ccr may be estimated in men as (140 – Age)/Scr. For women, this result should be multiplied by 0.85. For pediatric patients, the modified Schwartz equation may be used. The formula is based on height in cm and Scr in mg/dL where k is a constant. Ccr is corrected to 1.73 m²body surface area. During the first year of life, the value of k is 0.33 for pre-term babies and 0.45 for term infants. The k is 0.55 for pediatric patients and adolescent girls and 0.7 for adolescent boys. GFR (mL/min/1.73 m²) = (k x Height)/Scr ^bIf no loading dose administered ^cThe doses listed assume average body composition.
Corrected Creatinine Clearance^a	Lean Body Weight^c								Number of Days Before Steady State Achieved^b
	kg	40	50	60	70	80	90	100

10 mL/min		64	80	96	112	128	144	160	19
20 mL/min		72	90	108	126	144	162	180	16
30 mL/min		80	100	120	140	160	180	200	14
40 mL/min		88	110	132	154	176	198	220	13
50 mL/min		96	120	144	168	192	216	240	12
60 mL/min		104	130	156	182	208	234	260	11
70 mL/min		112	140	168	196	224	252	280	10
80 mL/min		120	150	180	210	240	270	300	9
90 mL/min		128	160	192	224	256	288	320	8
100 mL/min		136	170	204	238	272	306	340	7

2.4 Maintenance Dosing in Pediatric Patients Less Than 10 Years Old

The starting maintenance dose for heart failure in pediatric patients less than 10 years old is based on lean body weight, renal function, age, and concomitant products

[see Clinical Pharmacology ]

. The recommended

starting

maintenance doses for pediatric patients are given in Table 4. These recommendations assume the presence of normal renal function.

Table 4. Recommended Starting LANOXIN Injection Maintenance Dosage in Pediatric Patients Less Than 10 Years Old
mcg = microgram
Age	Dose Regimen, mcg/kg/dose (given TWICE daily)
Premature	1.9-3.1
Full-Term	3-4.5
1-24 Months	4.5-7.5
2-5 Years	3.8-5.3
5-10 Years	2.3-4.5

Table 5provides average daily maintenance dose requirements for pediatric patients less than 10 years old (to be given twice daily) with heart failure based on age, lean body weight, and renal function.

Table 5. Recommended Maintenance Dose (in micrograms given TWICE daily) of LANOXIN Injection in Pediatric Patients Less Than 10 Years of Age^aBased upon Lean Body Weight and Renal Function^a
^aRecommended are doses to be given twice daily. ^bThe modified Schwartz equation may be used to estimate creatinine clearance. See footnote a under Table 3. ^cIf no loading dose administered.
Corrected Creatinine Clearance^b	Lean Body Weight								Number of Days Before Steady State Achieved^c
	kg	5	10	20	30	40	50	60

10 mL/min		8	16	32	48	64	80	96	19
20 mL/min		9	18	36	54	72	90	108	16
30 mL/min		10	20	40	60	80	100	120	14
40 mL/min		11	22	44	66	88	110	132	13
50 mL/min		12	24	48	72	96	120	144	12
60 mL/min		13	26	52	78	104	130	156	11
70 mL/min		14	28	56	84	112	140	168	10
80 mL/min		15	30	60	90	120	150	180	9
90 mL/min		16	32	64	96	128	160	192	8
100 mL/min		17	34	68	102	136	170	204	7

2.5 Monitoring to Assess Safety, Efficacy, and Therapeutic Blood Levels

Monitor for signs and symptoms of digoxin toxicity and clinical response. Adjust dose based on toxicity, efficacy, and blood levels.

Serum digoxin levels less than 0.5 ng/mL have been associated with diminished efficacy, while levels above 2 ng/mL have been associated with increased toxicity without increased benefit.

Interpret the serum digoxin concentration in the overall clinical context, and do not use an isolated measurement of serum digoxin concentration as the basis for increasing or decreasing the LANOXIN dose. Serum digoxin concentrations may be falsely elevated by endogenous digoxin-like substances

[see Drug Interactions ]

. If the assay is sensitive to these substances, consider obtaining a baseline digoxin level before starting LANOXIN and correct post-treatment values by the reported baseline level.

Obtain serum digoxin concentrations just before the next scheduled LANOXIN dose or at least 6 hours after the last dose. The digoxin concentration is likely to be 10-25% lower when sampled right before the next dose (24 hours after dosing) compared to sampling 8 hours after dosing (using once-daily dosing). However, there will be only minor differences in digoxin concentrations using twice daily dosing whether sampling is done at 8 or 12 hours after a dose.

2.6 Switching from Intravenous Digoxin to Oral Digoxin

When switching from intravenous to oral digoxin formulations, make allowances for differences in bioavailability when calculating maintenance dosages (see Table 6).

Table 6. Comparison of the Systemic Availability and Equivalent Doses of Oral and Intravenous LANOXIN
	Absolute Bioavailability	Equivalent Doses (mcg)
LANOXIN Tablets	60-80%	62.5	125	250	500
LANOXIN Intravenous Injection	100%	50	100	200	400

)

Intravenous administration is preferable to intramuscular. Avoid bolus administration. (

2 DOSAGE AND ADMINISTRATION

LANOXIN dose is based on patient-specific factors (age, lean body weight, renal function, etc.). See full prescribing information. Monitor for toxicity and therapeutic effect.

Intravenous administration is preferable to intramuscular. Avoid bolus administration.

2.1 Important Dosing and Administration Information

initiated with maintenance dosing without a loading dose.

Consider interruption or reduction in LANOXIN dose prior to electrical cardioversion

[see Warnings and Precautions ].

Discard unused portion of LANOXIN Injection and LANOXIN Injection Pediatric.

2.2 Loading Dosing Regimen in Adults and Pediatric Patients

Table 1. Recommended LANOXIN Injection Loading Dose
mcg = microgram
Age	Total IV Loading Dose (mcg/kg) Administer half the total loading dose initially, then ¼ the loading dose every 6-8 hours twice
Premature	15-25
Full-Term	20-30
1-24 Months	30-50
2-5 Years	25-35
5-10 Years	15-30
Adults and pediatric patients over 10 years	8-12

2.3 Maintenance Dosing in Adults and Pediatric Patients Over 10 Years Old

The maintenance dose is based on lean body weight, renal function, age, and concomitant products

[see Clinical Pharmacology ]

The recommended

starting

Table 2. Recommended Starting LANOXIN Injection Maintenance Dosage in Adults and Pediatric Patients Over 10 Years Old
mcg = microgram
Age	Total Intravenous Maintenance Dose, mcg/kg/day (given once daily)
Adults and pediatric patients over 10 years	2.4-3.6

Total Maintenance Dose = Loading Dose (i.e., Peak Body Stores) x % Daily Loss/100

(% Daily Loss = 14 + Creatinine clearance/5)

Reduce the dose of LANOXIN in patients whose lean weight is an abnormally small fraction of their total body mass because of obesity or edema.

Table 3. Recommended Maintenance Dose (in micrograms given once daily) of LANOXIN Injection in Pediatric Patients Over 10 Years Old and Adults by Lean Body Weight and by Renal Function
^a For adults , creatinine clearance was corrected to 70-kg body weight or 1.73 m²body surface area. If only serum creatinine concentrations (Scr) are available, a corrected Ccr may be estimated in men as (140 – Age)/Scr. For women, this result should be multiplied by 0.85. For pediatric patients, the modified Schwartz equation may be used. The formula is based on height in cm and Scr in mg/dL where k is a constant. Ccr is corrected to 1.73 m²body surface area. During the first year of life, the value of k is 0.33 for pre-term babies and 0.45 for term infants. The k is 0.55 for pediatric patients and adolescent girls and 0.7 for adolescent boys. GFR (mL/min/1.73 m²) = (k x Height)/Scr ^bIf no loading dose administered ^cThe doses listed assume average body composition.
Corrected Creatinine Clearance^a	Lean Body Weight^c								Number of Days Before Steady State Achieved^b
	kg	40	50	60	70	80	90	100

10 mL/min		64	80	96	112	128	144	160	19
20 mL/min		72	90	108	126	144	162	180	16
30 mL/min		80	100	120	140	160	180	200	14
40 mL/min		88	110	132	154	176	198	220	13
50 mL/min		96	120	144	168	192	216	240	12
60 mL/min		104	130	156	182	208	234	260	11
70 mL/min		112	140	168	196	224	252	280	10
80 mL/min		120	150	180	210	240	270	300	9
90 mL/min		128	160	192	224	256	288	320	8
100 mL/min		136	170	204	238	272	306	340	7

2.4 Maintenance Dosing in Pediatric Patients Less Than 10 Years Old

The starting maintenance dose for heart failure in pediatric patients less than 10 years old is based on lean body weight, renal function, age, and concomitant products

[see Clinical Pharmacology ]

. The recommended

starting

maintenance doses for pediatric patients are given in Table 4. These recommendations assume the presence of normal renal function.

Table 4. Recommended Starting LANOXIN Injection Maintenance Dosage in Pediatric Patients Less Than 10 Years Old
mcg = microgram
Age	Dose Regimen, mcg/kg/dose (given TWICE daily)
Premature	1.9-3.1
Full-Term	3-4.5
1-24 Months	4.5-7.5
2-5 Years	3.8-5.3
5-10 Years	2.3-4.5

Table 5. Recommended Maintenance Dose (in micrograms given TWICE daily) of LANOXIN Injection in Pediatric Patients Less Than 10 Years of Age^aBased upon Lean Body Weight and Renal Function^a
^aRecommended are doses to be given twice daily. ^bThe modified Schwartz equation may be used to estimate creatinine clearance. See footnote a under Table 3. ^cIf no loading dose administered.
Corrected Creatinine Clearance^b	Lean Body Weight								Number of Days Before Steady State Achieved^c
	kg	5	10	20	30	40	50	60

10 mL/min		8	16	32	48	64	80	96	19
20 mL/min		9	18	36	54	72	90	108	16
30 mL/min		10	20	40	60	80	100	120	14
40 mL/min		11	22	44	66	88	110	132	13
50 mL/min		12	24	48	72	96	120	144	12
60 mL/min		13	26	52	78	104	130	156	11
70 mL/min		14	28	56	84	112	140	168	10
80 mL/min		15	30	60	90	120	150	180	9
90 mL/min		16	32	64	96	128	160	192	8
100 mL/min		17	34	68	102	136	170	204	7

2.5 Monitoring to Assess Safety, Efficacy, and Therapeutic Blood Levels

Monitor for signs and symptoms of digoxin toxicity and clinical response. Adjust dose based on toxicity, efficacy, and blood levels.

Serum digoxin levels less than 0.5 ng/mL have been associated with diminished efficacy, while levels above 2 ng/mL have been associated with increased toxicity without increased benefit.

[see Drug Interactions ]

. If the assay is sensitive to these substances, consider obtaining a baseline digoxin level before starting LANOXIN and correct post-treatment values by the reported baseline level.

2.6 Switching from Intravenous Digoxin to Oral Digoxin

When switching from intravenous to oral digoxin formulations, make allowances for differences in bioavailability when calculating maintenance dosages (see Table 6).

Table 6. Comparison of the Systemic Availability and Equivalent Doses of Oral and Intravenous LANOXIN
	Absolute Bioavailability	Equivalent Doses (mcg)
LANOXIN Tablets	60-80%	62.5	125	250	500
LANOXIN Intravenous Injection	100%	50	100	200	400

)

•Pediatric patients: Newborn infants display variability in tolerance to LANOXIN. (
8 USE IN SPECIFIC POPULATIONS
•Pediatric patients: Newborn infants display variability in tolerance to LANOXIN.
•Geriatric patients: Consider renal function in dosage selection, and carefully monitor for side effects.
•Renal impairment: LANOXIN is excreted by the kidneys. Consider renal function during dosage selection.
8.1 Pregnancy
Risk Summary
Experience with digoxin in pregnant women over several decades, based on published retrospective clinical studies and case reports, has not led to the identification of a drug associated risk of major birth defects, miscarriage or adverse maternal and fetal outcomes. Untreated underlying maternal conditions, such as heart failure and atrial fibrillation, during pregnancy pose a risk to the mother and fetus
(see Clinical Consideration)
. Animal reproduction studies have not been conducted with digoxin.
The estimated background risk of major birth defects and miscarriage for the indicated population(s) are unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2-4% and 15-20%, respectively.
Clinical Considerations
Disease-associated maternal and/or embryo/fetal risk
Pregnant women with heart failure are at increased risk for preterm birth. Clinical classification of heart disease may worsen with pregnancy and lead to maternal or fetal death.
Pregnant women with atrial fibrillation are at an increased risk of delivering a low birth weight infant. Atrial fibrillation may worsen with pregnancy and can lead to maternal or fetal death.
Fetal/neonatal adverse reactions
Digoxin has been shown to cross the placenta and is found in amniotic fluid. Monitor neonates for signs and symptoms of digoxin toxicity, including vomiting, and cardiac arrhythmias
[see Warnings and Precautions (5.3)]
.
Dose adjustments during pregnancy and the postpartum period
LANOXIN requirements may increase during pregnancy and decrease in the postpartum period. Monitor serum digoxin levels during pregnancy and the postpartum period
[see Dosage and Administration (2.5)]
.
Labor or Delivery
Risk of arrhythmias may increase during the labor and delivery. Monitor patients continuously during labor and delivery
[see Warnings and Precautions (5.1 and 5.2)]
.
8.2 Lactation
Risk Summary
The digoxin dose received through breastfeeding is up to 4% of the neonatal maintenance dosage, which is unlikely to be clinically relevant. There are no data on the effects of digoxin on the breastfed infant or the effects on milk production.
Data
Based on data from two lactation studies in a total of 13 breastfed infants, the digoxin concentrations in breast milk were between 0.4 – 1.0 ng/mL following 0.25 mg once daily dose of digoxin in the lactating mother. Thus, the amount of digoxin ingested daily by the infants is estimated to be between 0.03 to 0.16 mcg/kg/day. This translates to a relative infant dose of digoxin between 1 to 7% of the maternal weight-adjusted dose and about 0.2 to 4% of the neonatal maintenance dose.
8.4 Pediatric Use
The safety and effectiveness of LANOXIN in the control of ventricular rate in children with atrial fibrillation have not been established.
The safety and effectiveness of LANOXIN in the treatment of heart failure in children have not been established in adequate and well-controlled studies. However, in published literature of children with heart failure of various etiologies (e.g., ventricular septal defects, anthracycline toxicity, patent ductus arteriosus), treatment with digoxin has been associated with improvements in hemodynamic parameters and in clinical signs and symptoms.
Newborn infants display considerable variability in their tolerance to digoxin. Premature and immature infants are particularly sensitive to the effects of digoxin, and the dosage of the drug must not only be reduced but must be individualized according to their degree of maturity.
8.5 Geriatric Use
The majority of clinical experience gained with digoxin has been in the elderly population. This experience has not identified differences in response or adverse effects between the elderly and younger patients. However, this drug is known to be substantially excreted by the kidney, and the risk of toxic reactions to this drug may be greater in patients with impaired renal function. Because elderly patients are more likely to have decreased renal function, care should be taken in dose selection, which should be based on renal function, and it may be useful to monitor renal function
[see Dosage and Administration ]
.
8.6 Renal Impairment
The clearance of digoxin can be primarily correlated with the renal function as indicated by creatinine clearance. Table 3and Table 5provide the usual daily maintenance dose requirements for digoxin based on creatinine clearance
[see Dosage and Administration ]
.
Digoxin is primarily excreted by the kidneys; therefore, patients with impaired renal function require smaller than usual maintenance doses of digoxin
[see Dosage and Administration ]
. Because of the prolonged elimination half-life, a longer period of time is required to achieve an initial or new steady-state serum concentration in patients with renal impairment than in patients with normal renal function. If appropriate care is not taken to reduce the dose of digoxin, such patients are at high risk for toxicity, and toxic effects will last longer in such patients than in patients with normal renal function.
8.7 Hepatic Impairment
Plasma digoxin concentrations in patients with acute hepatitis generally fall within the range of profiles in a group of healthy subjects.
8.8 Malabsorption
The absorption of digoxin is reduced in some malabsorption conditions such as chronic diarrhea.
)
•Geriatric patients: Consider renal function in dosage selection, and carefully monitor for side effects. (
8.5 Geriatric Use
The majority of clinical experience gained with digoxin has been in the elderly population. This experience has not identified differences in response or adverse effects between the elderly and younger patients. However, this drug is known to be substantially excreted by the kidney, and the risk of toxic reactions to this drug may be greater in patients with impaired renal function. Because elderly patients are more likely to have decreased renal function, care should be taken in dose selection, which should be based on renal function, and it may be useful to monitor renal function
[see Dosage and Administration ]
.
)
•Renal impairment: LANOXIN is excreted by the kidneys. Consider renal function during dosage selection. (
8.6 Renal Impairment
The clearance of digoxin can be primarily correlated with the renal function as indicated by creatinine clearance. Table 3and Table 5provide the usual daily maintenance dose requirements for digoxin based on creatinine clearance
[see Dosage and Administration ]
.
Digoxin is primarily excreted by the kidneys; therefore, patients with impaired renal function require smaller than usual maintenance doses of digoxin
[see Dosage and Administration ]
. Because of the prolonged elimination half-life, a longer period of time is required to achieve an initial or new steady-state serum concentration in patients with renal impairment than in patients with normal renal function. If appropriate care is not taken to reduce the dose of digoxin, such patients are at high risk for toxicity, and toxic effects will last longer in such patients than in patients with normal renal function.
)

LANOXIN is contraindicated in patients with:

•Ventricular fibrillation
[see Warnings and Precautions (
5.1 Ventricular Fibrillation in Patients With Accessory AV Pathway (Wolff-Parkinson-White Syndrome)
Patients with Wolff-Parkinson-White syndrome who develop atrial fibrillation are at high risk of ventricular fibrillation. Treatment of these patients with digoxin leads to greater slowing of conduction in the atrioventricular node than in accessory pathways, and the risks of rapid ventricular response leading to ventricular fibrillation are thereby increased.
)]
•Known hypersensitivity to digoxin (reactions seen include unexplained rash, swelling of the mouth, lips or throat or a difficulty in breathing). A hypersensitivity reaction to other digitalis preparations usually constitutes a contraindication to digoxin.

•Risk of rapid ventricular response leading to ventricular fibrillation in patients with AV accessory pathway. (
5.1 Ventricular Fibrillation in Patients With Accessory AV Pathway (Wolff-Parkinson-White Syndrome)
Patients with Wolff-Parkinson-White syndrome who develop atrial fibrillation are at high risk of ventricular fibrillation. Treatment of these patients with digoxin leads to greater slowing of conduction in the atrioventricular node than in accessory pathways, and the risks of rapid ventricular response leading to ventricular fibrillation are thereby increased.
)
•Risk of advanced or complete heart block in patients with sinus node disease and AV block. (
5.2 Sinus Bradycardia and Sino-atrial Block
LANOXIN may cause severe sinus bradycardia or sinoatrial block particularly in patients with pre-existing sinus node disease and may cause advanced or complete heart block in patients with pre-existing incomplete AV block. Consider insertion of a pacemaker before treatment with digoxin.
)
•Digoxin toxicity: Indicated by nausea, vomiting, visual disturbances, and cardiac arrhythmias. Advanced age, low body weight, impaired renal function and electrolyte abnormalities predispose to toxicity. (
5.3 Digoxin Toxicity
Signs and symptoms of digoxin toxicity include anorexia, nausea, vomiting, visual changes and cardiac arrhythmias [first-degree, second-degree (Wenckebach), or third-degree heart block (including asystole); atrial tachycardia with block; AV dissociation; accelerated junctional (nodal) rhythm; unifocal or multiform ventricular premature contractions (especially bigeminy or trigeminy); ventricular tachycardia; and ventricular fibrillation]. Toxicity is usually associated with digoxin levels greater than 2 ng/mL although symptoms may also occur at lower levels. Low body weight, advanced age or impaired renal function, hypokalemia, hypercalcemia, or hypomagnesemia may predispose to digoxin toxicity. Obtain serum digoxin levels in patients with signs or symptoms of digoxin therapy and interrupt or adjust dose if necessary
[see Adverse Reactions and Overdosage ].
Assess serum electrolytes and renal function periodically.
The earliest and most frequent manifestation of digoxin toxicity in infants and children is the appearance of cardiac arrhythmias, including sinus bradycardia. In children, the use of digoxin may produce any arrhythmia. The most common are conduction disturbances or supraventricular tachyarrhythmias, such as atrial tachycardia (with or without block) and junctional (nodal) tachycardia. Ventricular arrhythmias are less common. Sinus bradycardia may be a sign of impending digoxin intoxication, especially in infants, even in the absence of first-degree heart block. Any arrhythmias or alteration in cardiac conduction that develops in a child taking digoxin should initially be assumed to be a consequence of digoxin intoxication.
Given that adult patients with heart failure have some symptoms in common with digoxin toxicity, it may be difficult to distinguish digoxin toxicity from heart failure. Misidentification of their etiology might lead the clinician to continue or increase LANOXIN dosing, when dosing should actually be suspended. When the etiology of these signs and symptoms is not clear, measure serum digoxin levels.
)
•Risk of ventricular arrhythmias during electrical cardioversion. (
5.4 Risk of Ventricular Arrhythmias During Electrical Cardioversion
It may be desirable to reduce the dose of or discontinue LANOXIN for 1-2 days prior to electrical cardioversion of atrial fibrillation to avoid the induction of ventricular arrhythmias, but physicians must consider the consequences of increasing the ventricular response if digoxin is decreased or withdrawn. If digitalis toxicity is suspected, elective cardioversion should be delayed. If it is not prudent to delay cardioversion, the lowest possible energy level should be selected to avoid provoking ventricular arrhythmias.
)
•Not recommended in patients with acute myocardial infarction (
5.5 Risk of Ischemia in Patients With Acute Myocardial Infarction
LANOXIN is not recommended in patients with acute myocardial infarction because digoxin may increase myocardial oxygen demand and lead to ischemia.
)
•Avoid LANOXIN in patients with myocarditis. (
5.6 Vasoconstriction In Patients With Myocarditis
LANOXIN can precipitate vasoconstriction and may promote production of pro-inflammatory cytokines; therefore, avoid use in patients with myocarditis.
)

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