Comparison of Infasurf (Calfactant) and Survanta (Beractant) in the Prevention and Treatment of Respiratory Distress Syndrome

Abstract

Background. In biophysical and animal testing, Infasurf develops lower surface tension and restores total surfactant activity better than Survanta. Methods. We performed 2 prospective, randomized, masked clinical trials; 1 trial used a prophylactic strategy aimed at prevention of respiratory distress syndrome (prophylaxis trial) for infants who were born between 23 weeks, 0 days and 29 weeks, 6 days of gestation, and the second trial used a treatment strategy (treatment trial) for intubated infants with a birth weight of 401 to 2000 g who required fractional inspired oxygen of >0.4 to maintain an arterial oxygen saturation of >90% (or an arterial/alveolar oxygen ratio of <0.2) at any time before 36 hours of age. Our purpose was to determine if Infasurf (calfactant) was more effective than Survanta (beractant) at increasing the proportion of patients alive and not receiving supplemental oxygen at 36 weeks' postmenstrual age. Informed, written, parental consent was required, and protocols were approved by the institutional review boards of all participating institutions. The dose of surfactant was 4 mL/kg (100 mg/kg) for Survanta and 3 mL/kg (105 mg/kg) for Infasurf for both trials. The assigned drug was drawn into 2 masked syringes and administered by a health care professional who, in most cases, was not directly responsible for caring for the patient. A maximum of 3 repeat treatments, at least 6 hours apart, were permitted if the neonate required fractional inspired oxygen of >0.30 to maintain an arterial oxygen saturation of >90% (or an arterial/alveolar oxygen ratio of 0.33) and the infant remained intubated for respiratory distress syndrome. Results. Both trials were halted for not meeting enrollment targets after a 32-month recruitment period. The decision to end recruitment was made after the interim analysis of the treatment trial. We enrolled 749 infants in the prophylaxis trial and 1361 infants in the treatment trial. The primary outcome (alive and not receiving supplemental oxygen at 36 weeks' postmenstrual age) rate in the prophylaxis trial was 52.1% for group 1 and 52.4% for group 2. In the treatment trial, the primary outcome rate was 58.7% in group 1 and 56.8% in group 2. Based on sample-size requirements for a conclusion of similarity, and the lack of statistical significance to the differences noted in the primary outcome, we have chosen not to break the investigator blind but to report the results as groups 1 and 2. Conclusion. Early trial closure prevents us from either accepting or rejecting our null hypothesis.