Evaluating a filter device used for intermittent intravenous drug delivery to newborn infants

Injection of aminoglycosides into a filter chamber was compared with retrograde injection into i.v. tubing for delivery of intermittent drug dosages at low infusion rates in neonates. In 50 infants receiving gentamicin sulfate and 21 receiving amikacin sulfate for at least two days by retrograde i.v. infusion, peak and trough concentrations of the drugs were obtained. A subsequent dose was administered using the filter device, and peak and trough concentrations were obtained. For each infant, the difference between trough and peak concentration (ΔC) was compared for the two methods. In vitro teting for gentamicin concentration was performed using the same infusion systems (10 trials for each system). For both in vivo and in vitro testing, the infusion flow rate was 10 mL/hr. For infants receiving gentamicin, ΔC was greater for the filter device in 32, greater for retrograde infusion in 13, and equal in 5. The mean gentamicin ΔC was significantly greater for the filter chamber method than for retrograde infusion. The in vitro studies showed significantly better gentamicin recovery with the filter than with retrograde infusion. For amikacin, ΔC was greater for the filter device in 15 infants, but the mean amikacin ΔC was not significantly different for the two methods. At low flow rates commonly used in infants, the infusion system using the filter device was equal to or superior to retrograde infusion for ensuring complete delivery of intermittent drug doses.