ABSTRACT
Digitalis therapy in cardiac failure is used by physicians according to conventional dosages; we call this type of digitalization "empiric". With this method digitalis intoxication in hospitalized patients is likely to occur in 8 to 20% of the cases. Another method of digitalization which we call "rational" is based upon an initial dosage of 0.015 mg per Kilo of digoxin, followed by a maintenance dosage determined by the relationship between initial dosage and daily rate of elimination. The latter depends upon the individual value of endogenous creatinine clearance (determined by age, weight and sex). Blood level of digoxin during steady state was measured in 454 patients divided randomly in four groups, each of whom following a different protocol of digitalization: 31 patients were treated with the rapid "empiric" digitalization (group I), 249 patients with the slow "empiric" digitalization (group II), 81 patients with the "rational" digitalization (group III), and 93 patients after a initial "empiric" dosage were treated with a maintenance dosage calculated by the "rational" method. An excessive initial dosage (blood level of digoxin > 2 ng/ml) was observed in 47.9% of patients of group I, in 15.9% of patients in group II, in 9.8% of patients of group III and in 14.7% of patients of group IV. manifestations of digitalis intoxication occurred in 30% patients of group I, in 10% of patients of group II, in 4.9% of patients of group III, and in 2.1% of group IV. Blood value of digoxin below therapeutic levels (under 0.5 ng/ml) was observed in only 13.1% of patients of group II, in 8.6% of patients of group III, and in 8% of patients of group IV. The lower percentage of digitalis intoxication observed in patients treated with "rational" method of digitalization is highly significant if compared with that observed in patients treated with empiric digitalization. The use of the "Lanoxin-rulex" makes the rational digitalization easier to handle, and gives the physicians the habit of considering the more important determinants of digoxin blood level. Conditions more likely to determine a wrong digitalis dosage are discussed in detail.
