Estimation of Digoxin Dosage in VLBW Infants Using Serum Creatinine Concentrations

Abstract

Digoxin steady state plasma concentrations (Css) and the corresponding serum creatinine concentrations were studied in 17 VLBW infants. Birth weight was in the range of 760-1 500 g (mean 1 068 g), gestational age ranged from 26 to 32 weeks (mean 28.7 weeks). Digoxin steady state plasma concentrations were found in the range of 0.5-6.5 ng/ml (mean 1.88 ng/ml) during maintenance therapy with 1.6-8.4 micrograms/kg BW/24 h (mean 4.4 micrograms/kg BW/24 h) given in two divided doses intravenously. No digoxin-like immunoreactive substance could be detected in the plasma of 18 infants (10 patients with a birth weight less than or equal to 1 500 g, 8 patients with a birth weight of 2 100-4 730 g) that were not treated with digoxin. The calculated digoxin clearance ranged from 0.38-4.03 ml/min/kg BW. Serum creatinine concentrations were found in the range of 35-274 mumol/l (0.4-3.1 mg/100 ml). A hyperbolic correlation may be derived from the digoxin clearance and the corresponding serum creatinine concentration. A linear relationship was observed between the dose normalized digoxin concentrations (y = Css/dose in 24 h) and the respective creatinine concentrations x (y = 0.52x-0.05; n = 17; s = 0.24; r = 0.86; p less than 0.01). According to this equation we suggest a dosing schedule for digoxin in VLBW infants with impaired renal function. Digoxin maintenance dose is derived from the digoxin target and the creatinine serum concentration. This dose recommendation proved reliable on four VLBW infants (birth weight 770-1 260 g) with decreased renal function.

Permanently oriented antibody immobilization for digoxin determination with a flow-through fluoroimmunosensor

“…Different and very sensitive radioimmunoassays exist for the measurement of digoxin in serum [7]. However, radioisotopes are now being replaced by fluorescent labels, such as fluorescent labeled antibodies, which allow simple, rapid techniques that can be automated.…”