Comparative Kinetics of Digoxin in Serum and Vitreous Humor in a Guinea Pig Model. II. Single Oral Dose Administration

In a continuation of work previously reported involving the comparative kinetics of digoxin in vitreous humor and serum after an intravenous dose, the present report describes the pharmacokinetics of digoxin in this model following the administration of a single oral dose. Serum and vitreous humor concentrations of digoxin were monitored by radioimmunoassay for 720 min after a single oral dose of 0.1 mg digoxin/kg. Serum concentrations peaked by 60 min and declined over the remaining observation period with a half-life of 360 min. Vitreous humor concentrations lagged behind the serum concentrations, peaked between 60 and 120 min, and then declined at a rate less than that of serum with convergence of concentration occurring in the 720-min samples. The vitreous humor-serum ratios ranged from a low of 0.003 (15 min) to a high of 0.98 at convergence. The impact of these findings upon forensic toxicologic practice is reviewed.