Pharm
Digoxin
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Digoxin
, Lanoxin, Digitalis, Digitalis Glycoside
History
Derived from Foxglove (Digitalis) plant
Cardiac glycosides are also found in Lilly of the Valley
Originally used as herbal tea to cure "
Dropsy
"
First described by William Withering, England, 1775
Precautions
Chronic
Congestive Heart Failure
Do not need to routinely follow Digoxin levels
See Indications for Digoxin levels below
Acute
Congestive Heart Failure
management (not recommended)
High
Digoxin Toxicity
risk in critically ill patient
Parenteral inotropes are preferred over Digoxin
More potent
Less toxicity
Atrial Fibrillation Rate Control
(not recommended)
Avoid Digoxin for
Atrial Fibrillation Rate Control
outside of comorbid CHF
Increased mortaility when used for
Atrial Fibrillation Rate Control
Whitbeck (2012) Eur Heart J 10.1093/eurheartj/ehs348
http://eurheartj.oxfordjournals.org/content/early/2012/11/14/eurheartj.ehs348.full
Mechanism
Inotropic effect (Increases myocardial contractility)
Inhibits membrane-bound sodium
Potassium
ATPase
Increases
Calcium
in sarcoplasmic reticulum
Increases myocardial contractility
Not affected by
Beta Adrenergic Receptor
antagonist
Not dependent on endogenous
Catecholamine
s
Less Potent than parenteral inotropes
Sinoatrial Node
and
Atrioventricular Node
effects
Accelerates atrial conduction
Depresses conduction through
AV Node
Indications
Paroxysmal Supraventricular Tachycardia
(
PSVT
)
Rarely used for
PSVT
, but can be considered in a hemodynamically stable patient
Conversion to Normal Sinus Rhythm
Chronic
Congestive Heart Failure
(
Systolic Dysfunction
)
Third-line adjunct for symptomatic chronic
Systolic Dysfunction
Consider as adjunct if persistent symptoms despite ACE (or ARB),
Beta Blocker
,
Diuretic
and
Aldosterone Antagonist
Atrial Fibrillation
or
Atrial Flutter
Third line agent for Ventricular rate control
Use in reduced ejection fraction
Contraindications
Avoid in
Diastolic Dysfunction
Drug Interactions
Medications that increase Digoxin concentration
Quinidine
Verapamil
Diltiazem
Amiodarone
Carvedilol
Omeprazole
(
Prilosec
)
Propafenone
Spironolactone
(may yield falsely elevated levels)
Medications that decrease
Heart Rate
and AV Conduction
Verapamil
Diltiazem
Amiodarone
Beta Blocker
s
Propafenone
Sotalol
Medications that decrease Digoxin absorption
Antacid
s (space administration 2 hours apart)
Cholestyramine
Colestipol
Pharmacokinetics
Effects following intravenous dose
Onset
Intravenous: 5 to 30 minutes
Oral: 30 minutes to 2 hours
Peak: 1.5 to 3 hours
Half-Life: 36 hours
Preparations
Strengths (generic, $1/tab): 0.125 mg, 0.25 mg
Strengths (trade, $2.50/tab): 0.0625 mg, 0.1875 mg
Dose
Indications to lower Digoxin dose by 50%
Drug Interaction
s (see above)
Severe
Renal Insufficiency
(0.0625 mg daily)
Chronic
Congestive Heart Failure
Standard Dose: 0.125 mg orally daily
Low Dose: 0.0625 mg daily or 0.125 mg every other day
Elderly patients
Underweight patients
Chronic Kidney Disease
Rapid
Atrial Fibrillation
Rarely used for
Atrial Fibrillation Rate Control
in 2014
See precautions above
Indicated only if refractory or intollerant of other preferred agents (
Metoprolol
,
Diltiazem
)
Load
First Dose: 0.5 mg IV
Second and Third Dose: 0.25 mg IV q6h for 2 doses
Maintenance
Start: 0.125 IV or orally daily
May titrate dose to 0.375 mg IV or orally daily
Target
Heart Rate
<80 resting and <110 on exertion
Labs
Digoxin level monitoring
Low dose Digoxin does not require routine level monitoring (unless otherwise indicated)
Indications
Digoxin Toxicity
suspected
Elderly
Chronic Kidney Disease
Potential
Drug Interaction
s (e.g.
Amiodarone
)
Target level
Targeting a specific drug level range is not typically indicated (outside of avoiding
Digoxin Toxicity
)
Target is the lowest effective dose to control
Heart Rate
in
Atrial Fibrillation
or symptoms in
Congestive Heart Failure
Safe Digoxin range: 0.5 to 0.9 ng/ml
Efficacy
Congestive Heart Failure
(Stages C and D)
Low doses (0.125 mg qd) are effective
Digoxin Serum level 0.5 to 1.0 ng/ml
Reduced morbidity
Reduced
Congestive Heart Failure
signs and symptoms
Neutral effect on mortality
No benefit in acute
Congestive Heart Failure
RADIANCE trial (supports continued use of Digoxin)
Packer (1993) N Engl J Med 329:1-7 [PubMed]
Smith (1993) N Engl J Med 329:51-53 [PubMed]
Efficacy
Atrial Fibrillation
Not recommended for
Atrial Fibrillation Rate Control
unless comorbid
Congestive Heart Failure
Not a great drug for rate control with activity
Delayed onset of action
Not first line for emergent rapid
Atrial Fibrillation
Higher mortality - see precautions below
References
(2014) Presc Lett 21(4): 23
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