Serum digitoxin

Smith, T. W., Radioimmunoassay for serum digitoxin Concentration. Methodology and clinical experience. J. Pharmacol. Exp. Ther. 175, 352-360 (1970). 

Acute delirium occurred in a 61-year-old man whose serum digitoxin concentration was 44 ng/ml (129). 

The metabolism of digitoxin can be increased, with resulting increasing dosage requirements, by enzyme-inducing drugs (200). For example, phenobarbital 100 mg daily reduces steady-state serum digitoxin concentrations by 50%. 

In five healthy adults quinidine prolonged the half-hfe of a single dose of digitoxin from 174 to 261 hours and reduced its total body clearance from 1.54 to 1.09 ml/hour/kg and renal clearance from 0.65 to 0.46 ml/hour/kg. Digitoxin volume of distribution and protein binding were unaffected. Quinidine caused a rise in serum digitoxin concentrations (284). 

A study in 10 patients with heart failure showed that their steady-state serum digitoxin levels were slightly, but not significantly raised (from 13.6 to 15.1 nanograms/mL) while taking 20 mL of aluminium/magnesi-um hydroxide gel three or four times daily, separated from the digitoxin... 

Serum digoxin ieveis are reported to be unchanged by diltiazem in a number of studies but others describe increases ranging from 20 to 8S%. Serum digitoxin levels have also been reported to rise in some patients, but only by about 20%. There is a risk of additive bradycardia when cardiac glycosides are given with diltiazem. 

Quinidine 750 mg daily increased the steady-state serum digitoxin levels of 8 healthy subjects by 45%, from 13.6 to 19.7 nanograms/mL, over 32 days. Another study found a 31% increase in serum digitoxin levels over 10 days, whereas yet another found all 5% increase after 70 days of treatment with 360 mg quinidine three times dailyA study in 5 healthy subjects found that quinidine reduced the total body clearance of digitoxin by 63%, resulting in raised serum digitoxin levels. ... 

Intestinal absorption of digoxin is less complete compared to digitoxin. In order to improve absorption, acetylated- and methylated-digoxin derivates were developed. Digitoxin is metabolised in hepatic microsomal enzymes and can be cleared independently from renal function. The therapeutical serum level of digoxin is 0.5-2.0 ng/ml and 10-35 ng/ml of digitoxin. Steady state plateau of therapeutic plasma concentrations is reached after 4-5 half-life-times using standard daily doses [5]. 

This technique has also been employed for the preparation of a catalytic imprinted membrane by coating a cellulose membrane with a polymer incorporating particles imprinted with the transition-state analogue of a dehydrofluorination reaction [264]. The application of such an MIP composite membrane as the recognition element in an optical sensor has been reported for digitoxin analysis in serum samples by embedding digitoxin-MIP particles in polyvinyl chloride film in presence of plasticizer by the dry inversion process [265],... 

Digitoxin plasma concentrations can be reduced by rifampicin, and the dosage should be adjusted according to the serum concentration (SEDA-10, 272). 

GC Oliver, BM Parker, DL Brasfield, CW Parker. The measurement of digitoxin in human serum by radioimmunoassay. J Clin Invest 47 1035, 1968. 

Plasma albumin has binding sites for various natural metabolic substances (e.g., glucose, fatty acids, bilirubin) as well as xenobiotics and drugs (e.g., digitoxin, Warfarin). While chromatographic and solubility differences from pure human serum albumin occur in some glycosylated albumins, there does... 

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