The serum therapeutic level of digoxin is widely variable and the determination of digitalization and maintenance doses is more or less empirical. Author intended to study the range of therapeutic level of digoxin and its relation to the doses of digoxin as well as factors controlling the serum level of digoxin.
The subjects to study were 65 cases including 6 normal adults and 59 cases of heart diseases with congestive heart failure. 33 cases were male and 32 cases were female with mean age of 56.2 years and serum digoxin levels were measured 83 times by radioimmunoassay method. Normal 6 adults were given daily 0. 75mg of digoxin for 3 days and followed by daily 0.25mg of digoxin for 3 days. The serum digoxin levels were measured on next morning of each last medication of digitalization and maintenance. The serum digoxin level of 9 patients with heart failure who were not responded to digoxin were measured more than twice. The serum digoxin levels were also measured in 40 patients with heart failure with serum creatinine less than 2mg% and with good response to digoxin and in 9 patients with heart failure and with serum creatinine more than 2mg%. The correlation between serum digoxin levels and factors such as body weight, height, cardiothoracic ratio, R in Vs, serum calcium, potassium, total serum protein and albumin were also examined.
Following results were obtained;
1. In 6 normal adults, the mean serum digoxin level was 1. 440. 574(ranging 0.722.25) ng/ml after daily digoxin 0. 75mg for 3 days and was 0.890.454(ranging 0.491.50) ng/ ml after daily digoxin 0.25mg for 3days. These data showed that the serum digoxin level varied depending on doses of medication and also there was considerable individual variation of serum digoxin level with same doses of digoxin.
2. In 9 patients with heart failure and refractory response to digoxin, the serum digoxin increased by continuing medication.
3. In 40 patients with serum creatinine less than 2mgo and heart fa.ilure with good therapeutic response to digoxin, the mean serum digoxin level was 1.05-0..461 ng/ml ranging 0.252.18ng/ml and the serum therapeutic digoxin level of most patients was in range of 0. 5 2.Ong/m1.
4. In 10 patients with serum creatinine more than 2mg% and heart failure, various dose., of digoxin were given and the mean serum digoxin level was 2.40-1.276ng/ml.. There were cases of which serum digoxin were 3.20 and 4.21ng/ml with daily digoxin only 0..125mg respectively. These data showed that the digoxin was accumulated in patients with deteriorated renal function.
5. There appeared to be some mild negative correlation between body weight and serum digoxin and positive correlation between cardio-thoracic ratio, serum calcium and serum digoxin.
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