Digoxin

dr.joan

Digoxin :
Trade name: Lanoxicaps, Lanoxin, Novo-Digoxin (CAN)
Drug classes:

• Cardiac glycoside
• Cardiotonic agent

Pregnancy: (Category C)
Therapeutic actions
Increases intracellular calcium and allows more calcium to enter the myocardial cell during depolarization via a sodium---potassium pump mechanism; this increases force of contraction (positive inotropic effect), increases renal perfusion (seen as diuretic effect in patients with CHF), decreases heart rate (negative chronotropic effect), and decreases AV node conduction velocity.
Indications
· CHF
· Atrial fibrillation
· Atrial flutter
· Paroxysmal atrial tachycardia

Dose
by mouth, rapid digitalization, 1–1.5 mg in divided doses over 24 hours; less urgent digitalization, 250–500 micrograms daily (higher dose may be divided), Maintenance, 62.5–500 micrograms daily (higher dose may be divided) according to renal function and, in atrial fibrillation, on heart-rate response; usual range, 125–250 micrograms daily (lower dose may be appropriate in elderly)
Emergency loading dose by intravenous infusion, 0.75–1 mg over at least 2 hours then maintenance dose by mouth on the following day
Contraindications:

• Contraindications: allergy to digitalis preparations, ventricular tachycardia, ventricular fibrillation, heart block, sick sinus syndrome, IHSS, acute MI, renal insufficiency and electrolyte abnormalities (decreased K+, decreased Mg++, increased Ca++).
• Use cautiously with pregnancy and lactation.

Side effects:

• CNS: Headache, weakness, drowsiness, visual disturbances
• GI: GI upset, anorexia
• CV: Arrhythmias

Nursing Considerations

• Monitor apical pulse for 1 min before administering; hold dose if pulse <60 in adult or <90 in infant, retake pulse in 1 h. If adult pulse remains <60 or infant <90, hold drug and notify prescriber. Note any change from baseline rhythm or rate.
• Check dosage and preparation carefully.
• Avoid IM injections, which may be very painful.
• Follow diluting instructions carefully, and use diluted solution promptly.
• Avoid giving with meals; this will delay absorption.
• Have emergency equipment ready; have K+ salts, lidocaine, phenytoin, atropine, and cardiac monitor on standby in case toxicity develops.

Monitor for therapeutic drug levels: 0.5---2 ng/mL.