| Name: |
DIGOXIN (LanoxinR) |
| Classification: |
cardiac glycoside
- used in treatment of atrial fibrillation, atrial flutter, atrial tachycardia
- positive inotrope, negative chronotrope, negative dromotrope
- used to improve cardiac output in congestive heart failure
|
| Dose: |
- for congestive heart failure:
- loading dose: 8 - 10 mcg/kg lean body weight
- half of total dose given as first dose and additional fractions are given at 6 to 8 hour intervals
- maintenance dose:
- for atrial fibrillation:
- loading dose: 10 - 15 mcg/kg lean body weight administered as above
- reduce dosage in renal failure, hypothyroidism
|
| Administration: |
IV Direct:
- over 2 - 3 min or ADC in 50 ml D5W or NS over 5 - 10 min
- if diluting, dilute with four times or greater volume to avoid precipitation
- onset of action 5 - 30 minutes post IV bolus
|
| Adverse Effects: |
Symptoms of Toxicity:
- gastrointestinal effects: anorexia, nausea, vomiting (common early signs of toxicity)
- CNS effects: headache, fatigue, drowsiness, generalized muscle weaknessoccular effects: 'yellow and green' halo vision
Effects on potassium:
- chronic toxicity: hypokalemia
- acute toxicity: hyperkalemia
Cardiac effects:
- every kind of arrhythmia, AV block (PAT with block, atrial fibrillation with complete heart block very suggestive of digoxin toxicity)
- risk factors:
- potassium/magnesium deficiencies or hypercalcemia increase risk of toxicity
- febrile or hypermetabolism-induced atrial arrhythmias may be resistant to digoxin, predisposing to toxicity
|
| Drug Interactions: |
- beta blockers + digoxin = increased digoxin toxicity, decreased inotropic effect
- calcium + digoxin = increased risk of arrhythmias
- verapamil + digoxin = increased digoxin level
- propafenone + digoxin = decreased inotropic effect
- quinidine + digoxin = increased digoxin level
- rifampin + digoxin = decreased digoxin level
- sympathomimetics + digoxin = increased risk of arrhythmias
- drugs which cause hypokalemia = increased risk of digoxin toxicity
|
| Monitoring Therapy: |
- heart rate
- PR interval
- ECG
- potassium, magnesium and calcium levels
- BUN, creatinine
- cardiac indices
- routine levels not indicated; dosage adjustments should be based on symptomatology
|
| CCTC Protocol: |
- May be administered by intermittent IV infusion by an RN.
- May be given IV direct by an approved nurse in the CCTC.
|
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