[The use of digitalis: a prospective study on the posology of digoxin with weekly interruption]

The dixogin dosage with an interruption of two consecutive days a week is frequently used in our country. We decided to compare this kind of digoxin dosage with an uninterrupted one by means of describing in each case the serum digoxin level, by determining whether it is in the so-called therapeutic range (0.8-2.0 ng/ml) or not, and by correlating the serum level to the clinical response (the control of heart rate in patients with atrial fibrillation). We designed a crossover clinical trial on 14 patients taking digoxin, having normal renal function and suffering from atrial fibrillation. The serum digoxin concentration found in the weekly interruption digoxin dosage (1.02 +/- 0.23 ng/ml before and 0.66 +/- 0.15 ng/ml after) was lower than one found in the continuous dosage (1.09 +/- 0.23 ng/ml). The 25% of the patients (before the interruption) and 75% (after the interruption) had plasma levels lower than 0.8 ng/ml, in opposition to the 8.3% found in the uninterrupted dosage. No patient on the continuous dosage showed clinical and/or electrocardiographic signs of digoxin toxicity. The mean heart rate was higher in the weekly interruption dosage (74.4 +/- 11.6 beats/min before and 83.9 +/- 6.4 beats/min after) than in the continuous dosage (72.9 +/- 10.5 beats/min). In terms of achieving serum digoxin levels within the so-called therapeutic range, the uninterrupted dosage proved to be better than the discontinuous one as well as to control the heart rate.