A correlative study of serum digoxin levels with clinical tolerance.

In a series of 102 digitalised patients serum digoxin levels (SDL) were determined by radioimmunoassay (RIA). Age categorisation included juveniles (15%), adults (67%) and geriatrics (18%). Clinical categorisation included loading, adequate, inadequate, toxic, and borderline digitalisation groups. The mean SDL in the toxic-group was 3 .93 ng/ml (S.D. 1.40), and in the nontoxic group 1.27 ng/ml (S.D. 0.84). In the toxic group with high SDL, palpitations (39.3%), vomiting (35.7%), nausea (21.5%), anorexia (17.8%) and hiccough (10.7%) were the commonest manifestations of digoxin intolerance (JPMA 31:161, 1981). Digoxin is the most widely used cardiac glycoside for patients with cardiac decompensation. Varying incidence of digoxin intolerance has been reported but with careful dose adjustment the frequency of its toxic effects can be reduced (Doherty, 1973; Storestein et al., 1977; Takahashi et al., 1979). Despite extensive clinical use the critical evaluation of its side effects remains a diagnostic problem mainly because of the narrow margin between therapeutic and toxic doses, and also because of nonspecificity of gastrointestinal side effects. Different methods for estimation of serum digoxin concentration have been used including erythrocyte rubibium 86 method (Lowenstein and Corrill, 1966), double isotope dilution assay and gas liquid chromatography (Watson and Haber, 1971). Radioimmunoassay (RIA) for digoxin has been the most recommended procedure (Smith et al., 1969). Serum digoxin levels estimated by RIA are reported in this study. Material and Methods The series consists of 102 consecutive patients taking digoxin (70 males and 32 females). Their ages ranged from 8 to 95 years (mean 50-3 years). Age subcategorisation included: Adults: 69 (67%): 21-69 years old (mean 48.5 years) Juvenile:15 (15%): 8-20 years old (mean 14 years) Geriatrics. 18 (18%): 70-93 years old (mean 77.2 years). Out-patients and in-patients receiving digoxin for cardiac failure associated with coronary, hypertensive or rheumatic heart disease were included in the study. History of heart disease and digoxin intake was obtained and a twelve lead electrocardiogram was taken. Clinical criteria of digoxin toxicity included nausea, vomiting, anorexia, weakness, yellow vision, slow pulse, palpitations and electrocardiographic evidence of ectopic beats, tachycardia or conduction disturbances. Serum digoxin estimation was carried out by the radioimmunosassay (Smith et al., 1969), using digoxin RIA Kit (Radiochemical Centre, Amersham, England), and serum digoxin level (SDL) was expressed as millimicrogram per-milliter (ng/ml).