BACKGROUND: Animal-derived, protein-containing surfactants seem to be superior 
to protein-free surfactants. Lucinactant, a synthetic surfactant containing a 
surfactant protein-B peptide analog, has been shown to be effective in animal 
models and phase II clinical trials. To date, lucinactant has not been compared 
with an animal-derived surfactant in a premature animal model.
OBJECTIVE: The objective was to compare the acute and sustained effects of 
lucinactant among premature lambs with respiratory distress syndrome (RDS) with 
the effects of a natural porcine surfactant (poractant-alpha).
METHODS: After 5 minutes of mechanical ventilation twin premature lambs were 
assigned randomly to the lucinactant group (30 mg/mL, 5.8 mL/kg) or the 
poractant-alpha group (80 mg/mL, 2.2 mL/kg). Heart rate, systemic arterial 
pressure, arterial pH, blood gas values, and lung mechanics were recorded for 12 
hours.
RESULTS: Baseline fetal pH values were similar for the 2 groups (pH 7.27). After 
5 minutes of mechanical ventilation, severe RDS developed (pH: <7.08; Paco2: >80 
mm Hg; Pao2: <40 mm Hg; dynamic compliance: <0.08 mL/cm H2O per kg). After 
surfactant instillation, similar improvements in gas exchange and lung mechanics 
were observed for the lucinactant and poractant-alpha groups at 1 hour (pH: 7.3 
+/- 0.1 vs 7.4 +/- 0.1; Paco2: 8 +/- 18 mm Hg vs 40 +/- 8 mm Hg; Pao2: 167 +/- 
52 mm Hg vs 259 +/- 51 mm Hg; dynamic compliance: 0.3 +/- 0.1 mL/cm H2O per kg 
vs 0.3 +/- 0.1 mL/cm H2O per kg). The improvements in lung function were 
sustained, with no differences between groups. Cardiovascular profiles remained 
stable in both groups.
CONCLUSIONS: Among preterm lambs with severe RDS, lucinactant produced 
improvements in gas exchange and lung mechanics similar to those observed with a 
porcine-derived surfactant.