[Gycoside serum concentrations under maintenance therapy with Lanicor, Card-Lamuran, MF708d, and Lanitop (author's transl)].

The biological availability of digitoxin from Lanicor was compared with that from two different galenical preparations of Card-Lamuran (Card-Lamuran and MF708d both containing equal amounts of active ingredients: 0,125 mg digitoxin and 10 mg raubasine). The patients who were kept on their individually adjusted oral digitoxin maintenance dosage received the three preparations in a randomised order. Additionally, the equivalent dosages of Lanicor and Lanitop were determined from the data on their biological availability. In 24 patients with heart failure (mean age 70.5 years), radioimmunoassay of the glycoside concentration in the serum was performed. The patients were cardially well compensated with Lanicor and it could be assumed that there would be no change in the daily maintenance dosage for the entire period of the study (42 days). Our results show that digitoxin had the same bio-availability from Lanicor and the two different galenical preparations of Card-Lamuran and MF708d. Patients can therefore safely be switched from one of these preparations to the other. On average, doses of Lanicor 1.55 times higher than those of Lanitop must be given to obtain the same serum glycoside concentrations. The variation of this factor was no greater than the variation in serum concentrations of digitoxin during continued maintenance therapy with Lanicor. The mean serum concentrations of digitoxin under maintenance therapy in our geriatric patients (mean value 2.1 mg/ml) were higher than the digitoxin concentrations published in the literature for younger patients (average 1.4 ng/ml). The calculated daily maintenance doses providing a digitoxin concentration of 1.4 mg/ml were ca. 0.3 mg Lanicor and ca. 0.2 mg Lanitop. This is somewhat less than generally assumed. This agrees with the clinical experience that the glycoside maintenance dosage in elderly patients is generally less than in middle-aged patients.