digoxin (Lanoxin)

Heart failure. Atrial fibrillation and atrial flutter (slows ventricular rate). Paroxysmal atrial tachycardia. High Alert Medication: This medication bears a heightened risk of causing significant patient harm when it is used in error.
Therapeutic: antiarrhythmics, inotropics
Pharmacologic: digitalis glycosides
Increases the force of myocardial contraction. Prolongs refractory period of the AV node. Decreases conduction through the SA and AV nodes. Therapeutic Effects: Increased cardiac output (positive inotropic effect) and slowing of the heart rate (negative chronotropic effect).
Contraindications/Precautions Uncontrolled
ventricular arrhythmias; AV block : in absence
of pacemaker Idiopathic hypertrophic
subaortic stenosis; Constrictive pericarditis;
Hypokalemia greatly increase risk of digoxin toxicity Hypercalcemia increase risk of toxicity, especially with mild hypokalemia); Hypomagnesemia may increaserisk of digoxin toxicity
Adverse Reactions/Side Effects: yelloow green vision-digoxin
CNS: fatigue, headache, weakness. EENT: blurred vision, yellow or green vision. CV: ARRHYTHMIAS, bradycardia, ECG changes, AV block, SA block. GI: anorexia, *nausea, vomiting, diarrhea. Hemat: thrombocytopenia. Metab: electrolyte imbalances with acute digoxin toxicity.
Drug-Drug: Thiazide and loop diuretics, antibiotic end with cillin B, excessive use of laxatives may cause hypokalemia which may increase risk of toxicity.
Drug-Natural: Licorice and stimulant natural products -aloe increase risk of potassium depletion. St. John's wort may decrease levels and effect. Drug-Food:high-fiber meal decrease absorption. Administer digoxin 1 hour before or 2 hours after such a meal.
For rapid effect, a larger initial loading/digitalizing dose should be given in several divided doses over 12-24 hr. Maintenance doses are determined for digoxin by renal function. doses required for atrial arrhythmias are higher than for inotropic effect.
• IV (Adults): Digitalizing dose—0.5-1 mg . PO (Adults): Digitalizing dose—0.75-1.5 mg given as 50% of the dose initially and one quarter of the initial dose in each of 2 doses at 6-12 hr intervals.
Maintenance dose—0.125-0.5 mg/day depending on pts lean body weight, renal function, serum level..
Assessment: Monitor apical pulse .Withhold dose and notify professional if pulse rate is <60 bpm in an adult, <70 bpm in a child, or <90 bpm in an infant. Also notify professional of any significant changes in rate, rhythm, or quality of pulse. Monitor BP in pt receiving IV digoxin.
• Monitor ECG during IV administration. Notify professional if bradycardia or new arrhythmias occur. Monitor intake and output ratios and daily weights. Assess for peripheral edema, and auscultate lungs for rales or crackles throughout therapy.. Digoxin increased risk of falls in the elderly.
Lab Test Considerations: • Evaluate serum electrolyte levels: potassium, magnesium, and calcium and renal and hepatic functions. Notify professional if patient is hypokalemic. Hypokalemia, hypomagnesemia, or hypercalcemia may make the patient more susceptible to digitalis toxicity.
Neonates may have falsely elevated serum digoxin concentrations due to a naturally occurring substance chemically similar to digoxin..Older adults may be toxic even when serum concentrations are within normal range; assess for clinical symptoms of toxicity even when serum levels are normal.
Therapeutic serum digoxin levels range from 0.5-2ng/mL. Bacteria in the GI tract can metabolize some digoxin before it is absorbed. Pt receie erythromycin or tetracycline, which kill gut bacteria can develop toxicity on their usual doses of digoxin
Older are at risk for digoxin toxicity due to decreased renal clearance, which can exist when serum creatinine levels are normal. Digoxin requirements in the older adult may change and a formerly therapeutic dose can become toxic. Treatment of arrhythmias include digoxin immune Fab-Digibinds.
Implementation: High Alert: Digoxin has a narrow therapeutic range. • For rapid digitalization, the initial dose is higher than the maintenance dose; 50% of the total digitalizing dose is given initially. The remainder of the dose will be administered in 25% increments at 4-8 hr intervals.
• IM: Administer deep into gluteal muscle and massage well to reduce painful local reactions. Do not administer more than 2 mL of digoxin in each IM site. IM administration is not generally recommended.
IV Adminstration
• pH: 6.8-7.2.
• Direct IV:
Diluent: May be administered undiluted. May also dilute 1 mL of digoxin in 4 mL of sterile water for injection, D5W, or 0.9% NaCl. Less diluent will cause precipitation. Use diluted solution immediately.
• Rate: Administer over at least 5 min.
Patient/Family Teaching: Teach parents or caregivers that changes in heart rate, especially bradycardia, are among the first signs of digoxin toxicity in infants and children
Take missed doses within 12 hr of scheduled dose or omit. Do not discontinue medication without consulting health care professional.
• Teach patient to take pulse and to contact health care professional before taking medication if pulse rate is <60 or >100.
Evaluation/Desired Outcomes
• Decrease in severity of HF.
• Increase in cardiac output.
• Decrease in ventricular response in atrial tachyarrhythmias.
• Termination of paroxysmal atrial tachycardia.