Pharmacokinetics of Digoxin in Low-Birth-Weight Infants

Abstract

Digoxin pharmacokinetics were studied in 13 low-birth-weight infants requiring digoxin therapy. Their weights ranged from 820 to 2,710 g (x̄ = 1,440 g) and gestational ages ranged from 26 to 38 weeks (x̄ = 30.9 weeks). The distribution and elimination of digoxin can be described by an open two-compartment model. Poor correlation between volume of distribution Vdβ (5.7 ± 1.0 liters/kg) and gestational age (GA) or weight (Wt) was observed. Digoxin half-life (47 ± 21 h) was inversely related to GA and Wt (r = 0.69 and 0.66, respectively), but total body digoxin clearance (29.8 ± 14.7 ml/min/1.73 m^2) was found to be highly dependent on these two variables (r = 0.87 and 0.88, respectively). According to the results of this study and our previous investigation, digitalizing and maintenance dosages of digoxin were recommended.

Estimation of Digoxin Dosage in VLBW Infants Using Serum Creatinine Concentrations

“…Furthermore the reported incidence of cardiac toxicity has been in the range up to 30% (2). During the last few years therefore dose recommendations given by several authors tended towards a "low dose" digoxin therapy (7)(8)(9)(10). Following these guide-lines our very small premature infants with congestive heart failure were treated with digoxin.…”

“…For adults with impaired renal function similar schedules have been established during the recent years (37)(38)(39). For VLBW infants with age-dependent normal renal function proved dose recommendations given in the past should be used (8,9).…”

“…This is in part due to its narrow therapeutic range and the resulting risk of toxic side effects (5)(6)(7). "Low dose" digoxin therapy has therefore been recommended previously by various authors (8)(9)(10).…”