Pharmacokinetics of digoxin-specific Fab: effects of decreased renal function and age.

Aims To study the influence of age and renal function on digoxin-specific Fab (DS-Fab) pharmacokinetics. Methods Sixteen patients (35–91 years) with creatinine clearance ranging from 10.6 to 122.1 ml min−1 who had been admitted to hospital with severe digoxin or digitoxin self-poisoning were treated with DS-Fab (80 to 800 mg). Plasma DS-Fab concentrations were determined by radioimmunoassay. Results The mean (±s.d.) distribution and elimination half-lives, apparent volume of distribution and total body clearance were 1.1±0.4 h, 20.2±7.3 h, 13.1±5.8 l, and 17.6±10.8 ml min−1, respectively. Interindividual variability of DS-Fab total body clearance was linked linearly with the decrease in creatinine clearance or with the increase in age and DS-Fab distribution volume was not dependent on creatinine clearance or age. Conclusions The data suggest that DS-Fab should be given to elderly and renal-impaired patients at doses similar to those given to younger or normal renal function patients.