Judith E. Soberman, MD

For more than 30 years, serumdigoxin concentrations (SDCs)have been monitored toensure safe, effective therapy.1,2Although the therapeuticrange for SDCs is often listed as either0.8 to 2.0 ng/mL or 0.5 to 2.0ng/mL, the results of clinical trials inthe 1990s suggest an upper limit of1.0 ng/mL for treatment of heart failure.3-11 An upper limit for the SDC of1.0 ng/mL is also recommendedfor patients who have heart failureand atrial fibrillation with rapid ventricularresponse.