Digoxin

Interactions:

• • Erythromycin, tetracycline: ▲ digoxin levels by 10 - 40%

  • Quinidine, verapamil, flecainide, amiodarone: ▲ digoxin levels.

  • Digoxin toxicity is exacerbated by: ▼ K+, hypoxia, hypothyroidism, renal insufficiency, volume depletion.

If a loading dose is given: Digoxin serum concentration may be drawn within 12-24 hours after the initial loading dose administration. Concentrations drawn this early may confirm the relationship of digoxin plasma concentrations and response but are of little value in determining maintenance doses.

If a loading dose is not given: Digoxin serum concentration should be obtained after 3-5 days of therapy.