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Lanoxin (Digoxin) - Indications and Dosage

 
 



INDICATIONS AND USAGE

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.

Heart Failure in Pediatric Patients

Digoxin increases myocardial contractility in pediatric patients with heart failure.

Atrial Fibrillation in Adults

LANOXIN is indicated for the control of ventricular response rate in adult patients with chronic atrial fibrillation.

DOSAGE AND ADMINISTRATION

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 or initiated with maintenance dosing without a loading dose.

Consider interruption or reduction in LANOXIN digoxin dose prior to electrical cardioversion [see Warnings and Precautions ].

Use digoxin solution to obtain the appropriate dose in infants, young pediatric patients, or patients with very low body weight.

Loading Dosing Regimen in Adults and Pediatric Patients

For adults and pediatric patients if a loading dosage is to be given, administer half the total loading dose initially, then ¼ the loading dose every 6-8 hours twice, with careful assessment of clinical response and toxicity before each dose. The recommended loading dose is displayed in Table 1.

Table 1. Recommended LANOXIN Oral Loading Dose
mcg = microgram

Age

     Total Oral Loading Dose (mcg/kg)     

Administer half the total loading dose initially,
then ¼ the loading dose every 6 to 8 hours twice

5 to 10 years

20-45

Adults and pediatric patients over 10 years     

10-15

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 dose in adults and pediatric patients over 10 years old with normal renal function is 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 Maintenance Dosage in Adults and Pediatric Patients Over 10 Years Old
mcg = microgram

Age

     Total Oral Maintenance Dose, mcg/kg/day     
(given once daily)

Adults and pediatric patients over 10 years     

3.4-5.1

Table 3 provides 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 in Pediatric Patients Over 10 Years Old and Adults by Lean Body Weight and by Renal Functiona
a  Doses are rounded to the nearest dose possible using whole LANOXIN tablets. Recommended doses approximately 30 percent lower than the calculated dose are designated with an *. Monitor digoxin levels in patients receiving these initial doses and increase dose if needed.
b  For adults, creatinine clearance was corrected to 70-kg body weight or 1.73 m2 body 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 m2 body 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
c  If no loading dose administered.
d  The doses listed assume average body composition.

Corrected
Creatinine
Clearanceb

Lean Body Weightd

Number of Days
Before Steady
State Achievedc

kg

40

50

60

70

80

90

100

  •  10 mL/min
  •  62.5*
  •  125
  •  125
  •  187.5
  •  187.5
  •  187.5
  •  250
  •  19
  •  20 mL/min
  •  125
  •  125
  •  125
  •  187.5
  •  187.5
  •  250
  •  250
  •  16
  •  30 mL/min
  •  125
  •  125
  •  187.5
  •  187.5
  •  250
  •  250
  •  312.5
  •  14
  •  40 mL/min
  •  125
  •  187.5
  •  187.5
  •  250
  •  250
  •  312.5
  •  312.5
  •  13
  •  50 mL/min
  •  125
  •  187.5
  •  187.5
  •  250
  •  250
  •  312.5
  •  312.5
  •  12
  •  60 mL/min
  •  125
  •  187.5
  •  250
  •  250
  •  312.5
  •  312.5
  •  375
  •  11
  •  70 mL/min
  •  187.5
  •  187.5
  •  250
  •  250
  •  312.5
  •  375
  •  375
  •  10
  •  80 mL/min
  •  187.5
  •  187.5
  •  250
  •  312.5
  •  312.5
  •  375
  •  437.5
  •  9
  •  90 mL/min
  •  187.5
  •  250
  •  250
  •  312.5
  •  375
  •  437.5
  •  437.5
  •  8
  •  100 mL/min
  •  187.5
  •  250
  •  312.5
  •  312.5
  •  375
  •  437.5
  •  500
  •  7

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 dose for pediatric patients between 5 years and 10 years old is given in Table 4. These recommendations assume the presence of normal renal function.

Table 4. Recommended Starting LANOXIN Oral Maintenance Dosage in Pediatric Patients between 5 and 10 Years Old

Age

Oral Maintenance Dose,
mcg/kg/dose

5 years to 10 years

3.2-6.4   Twice daily

Table 5 provides average daily maintenance dose requirements for pediatric patients between 5 and 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 in Pediatric Patients between 5 and 10 Years of Agea Based upon Lean Body Weight and Renal Functiona,b
a  Recommended are doses to be given twice daily.
b  The doses are rounded to the nearest dose possible using whole LANOXIN tablets. Recommended doses approximately 30 percent lower than the calculated dose are designated with an *. Monitor digoxin levels in patients receiving these initial doses and increase dose if needed.
c  The modified Schwartz equation may be used to estimate creatinine clearance. See footnote b under Table 3.
d  If no loading dose administered.

Corrected
Creatinine
Clearancec

Lean Body Weight

Number of Days
Before Steady
State Achievedd

kg

20

30

40

50

60

  •  10 mL/min
  •  -
  •  62.5
  •  62.5*
  •  125
  •  125
  •  19
  •  20 mL/min
  •  62.5
  •  62.5
  •  125
  •  125
  •  125
  •  16
  •  30 mL/min
  •  62.5
  •  62.5*
  •  125
  •  125
  •  187.5
  •  14
  •  40 mL/min
  •  62.5
  •  62.5*
  •  125
  •  187.5
  •  187.5
  •  13
  •  50 mL/min
  •  62.5
  •  125
  •  125
  •  187.5
  •  187.5
  •  12
  •  60 mL/min
  •  62.5
  •  125
  •  125
  •  187.5
  •  250
  •  11
  •  70 mL/min
  •  62.5
  •  125
  •  187.5
  •  187.5
  •  250
  •  10
  •  80 mL/min
  •  62.5*
  •  125
  •  187.5
  •  187.5
  •  250
  •  9
  •  90 mL/min
  •  62.5*
  •  125
  •  187.5
  •  250
  •  250
  •  8
  •  100 mL/min
  •  62.5*
  •  125
  •  187.5
  •  250
  •  312.5
  •  7

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.

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   

DOSAGE FORMS AND STRENGTHS

Unscored Tablets: 62.5 mcg are peach, round with “U3A” imprinted on one side.
Scored Tablets: 125 mcg are yellow, round, scored tablets with “Y3B” imprinted on one side.
Unscored Tablets: 187.5 mcg are blue, round with “F3F” imprinted on one side.
Scored Tablets: 250 mcg are white, round, scored tablets with “X3A” imprinted on one side.

HOW SUPPLIED/STORAGE AND HANDLING

LANOXIN Tablets have “LANOXIN” on one side and are supplied as follows:

Mcg

Scored

Color

Imprint

NDC 24987-xxx-xx

Bottle/100

Bottle/1000

Unit dose/100

62.5

No

Peach

U3A

240-55

240-75

Not applicable

125

Yes

Yellow

Y3B

242-55
242-57

242-75
242-76

242-56

187.5

No

Blue

F3F

245-55

245-75

Not applicable

250

Yes

White

X3A

249-55
249-57

249-75
249-76

249-56

Store at 25°C (77°F); excursions permitted to 15 to 30°C (59 to 86°F) in a dry place and protect from light. Keep out of reach of children.

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