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Digoxin is a cardiac glycoside which is indicated for the treatement of CHF, AF, etc. Absorption of digoxin is incomplete when administered orally and bioavailability of digoxin varies from manufactuer to manufactuer. A loading dose of digoxin 8∼12㎍/㎏ Ⅳ is necessary because of its long elimination half-life and then a maintenance dose, usually 0.25㎎/day, is administered orally. Therapeutic Drug Monitoring is mandatory for this drug because of the narrow therapeutic index. Recently, there have been many reports on the relationship between the occurrence of clinical toxic symptoms and the digoxin blood concentration. Namely there aren´t toxic symtoms in the 90％ of patients with digoxin blood concentrations below 2.0ng/㎖, while toxic symptom appears in 87％ of patients with digoxin blood concentration above 2.0ng/㎖. For the majority of patients, it would behoove the physician to keep the digoxin level within normal therapeutic range(0.9∼2.0ng/㎖) to avoid toxic symptoms and to give the patient therapeutic benefit of digoxin therapy. It is a well-established fact that dosage adjustment is required when switching from parenteral to oral therapy. Also dosage adjustment is necessary when an interaction disease state is present(ie, CHF, renal failure, abnormal thyroid function, etc.) or when concomitant drug therapy of an interacting drug(ie, quinidine, antacid etc.). We have classified all the TDM consults of digoxin at Wallace Memorial Baptist Hospital.
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