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, 1–15 mg in divided doses over 24 hours; less urgent digitalization, 250–500 micrograms daily (higher dose may be divided), Maintenance, 625–500 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, 075–1 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: 05---2 ng/mL