Pharmacokinetics of Total and Free Digoxin and Fab Fragments in 5 Intoxicated Patients after Administration of Specific Anti-Digoxin Fab Fragments

Life-threatening digitalis overdose can now be safely and rapidly reversed by administration of specific anti-digoxin Fab fragments (Antman et al 1990). The aim of the therapy is to lower the intravascular free drug concentration by changing the equilibrium of the free drug between the intravascular and intracellular body water compartments (Hursting et al 1987). Thus, a toxin concentration gradient from intracellular to intravascular space is created (Scherrmann et al 1989). Fab fragment administration has been shown to alter digoxin disposition (Schaumann et al 1986). To monitor the efficacy of Fab fragments, both free and total digoxin concentrations have to be determined. This paper reports the pharmacokinetics of free and total digoxin concentrations in five patients poisoned by digoxin and of Fab fragments for two of them.