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- Bernard G Krohn, MD, FACC* ()
In a recent issue of the Journal, Adams, et al. (1) correctly stated that: “Patients taking digoxin did significantly better than those not taking the drug, but the serum concentration did not correlate with outcome.” Nevertheless, they concluded: “These results support the possibility that a lower therapeutic goal for serum digoxin concentration is warranted in patients with heart failure.”
This conclusion is flawed because in individual patients the concentration of digoxin in the serum does not accurately represent the amount of digoxin in the tissues where it works. The digoxin in the serum is only a tiny fraction of the total amount of digoxin in the body. The total amount of digoxin in the body is easy to calculate from the doses administered, and it does correlate with outcome (2–4). Guiding dosage this way allowed high doses of digoxin (15 to 19 μg/kg of lean body weight) to be given to patients after cardiac operations, and the patients recovered rapidly (5,6).
Because serum digoxin concentrations poorly guide dosage and results, contradictions between serum levels and results have been seen by many doctors. Low serum concentrations of digoxin appeared in patients who received therapeutic benefits. In contrast, high serum concentrations of 2.5 ng/ml have been seen in patients who had no signs or symptoms of toxicity.
Dr. Jelliffe published a method for calculating the milligrams of digoxin needed to produce a specific peak total body load of digoxin and to engender a desired therapeutic result (2–4). A safe, effective amount of peak total body digoxin to treat heart failure is 8 to 10 μg/kg of lean body weight. This program is used at the University of Southern California/Los Angeles County Medical Center and at several other hospitals.
Studying the effects of digoxin requires knowing the total amount of digoxin in the body, which controls the amount of digoxin in the tissues where digoxin works.
- American College of Cardiology Foundation
- Adams K.F. Jr.,
- Gheorghiade M.,
- Uretsky B.F.,
- Patterson J.H.,
- Schwartz T.A.,
- Young J.B.
- Jelliffe R.W.