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Digoxin
Aka: 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 Catecholamines
- 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 Blockers
- Propafenone
- Sotalol
- Medications that decrease Digoxin absorption
- Antacids (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 Interactions (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 Interactions (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