[Preoperative digitalization. Measurement of digoxin plasma levels (author's transl)]

In a study of 233 patients from the department of surgery and anesthesiology taking digoxin preparations 64, per cent exhibit digoxin levels in the therapeutic range (0.6--1.5 ng/ml), 19 per cent had subtoxic concentrations ranged from 1.6--2.0 ng/ml and 7 per cent were in the toxic range (greater than 2 ng/ml). In patients treated with digoxin before admission to hospital subtherapeutic levels were most frequent. An average loading dose of digoxin 1 mg or more on one day may result in subtoxic and toxic digoxin levels on the second day, in patients receiving less than 1 mg digoxin daily an increasing frequency of plasma digoxin concentrations of 1.5 ng/ml or higher values was present on the third day. Averaged plasma digoxin concentrations were correlated with daily maintenance dose. There was, however, a wide individual variation in digoxin plasma concentrations. A low incidence of toxic digoxin plasma levels was observed in patients receiving a daily oral maintenance dose of 0.375 mg digoxin (Lanicor). For prophylactic digitalization of patients with normal renal and thyroid function the following schedules or statistical guidlines are proposed: Lanicor (bioavailability 60%): oral loading dose of 0.75 mg over two days, and then daily oral maintenance dose of 0.375 mg; Novodigal (bioavailability 80%): oral loading dose of 0.6 mg over two days and then daily oral maintenance dose of 0.3 mg; Digoxin i.v.: intravenous loading dose of 0.5 (0.4) mg over two days and then 0.25 (0.2) mg daily intravenous maintenance dose. For any patient needing treatment with digitalis glycosides therapy must be individual and dynamic. The reasons for toxic concentrations were frequently attributed to wrong dosage.