FDA approves Surfaxin for respiratory distress syndrome
Respiratory distress syndrome (RDS) is a common complication of premature infants. The lungs of premature infants are not able to make enough surfactant, which is a liquid that coats the alveoli (breathing sacs) inside the lungs and helps to keep them open. Without enough surfactant, the lungs collapse and the infant has difficulty breathing. Some infants with this condition do not survive; others who do survive may suffer permanent damage to their lungs. On March 6, 2012, the U.S. Food and Drug Administration (FDA) approved Surfaxin (lucinactant) for treatment of RDS.
The approval took a long time coming for Surfaxin’s manufacture, Discovery Laboratories Inc., based in Warrington, Pennsylvania. The drug joins four other FDA-approved drugs for RDS treatment: Curosurf (poractant alpha), Exosurf (colfosceril palmitate), Survanta (beractant), and Infasurf (calfactant; no longer marketed). Discovery Laboratories had made four previous attempts to obtain FDA approval for the product; the first attempt was made in 2004. In February 2005, the FDA issued an “approvable” letter, which requested the resolution of some manufacturing issues before approval could be granted.
However, the FDA rejected Surfaxin three more times; the last turndown occurred in 2009.
The approval was finally granted after review of a randomized, controlled, multi-dose study, which was comprised of 1,294 premature infants. The study demonstrated that the drug was both safe and effective. The infants in the study received Surfaxin, Exosurf or Survanta within 30 minutes of birth. A comparison between Surfaxin and Exosurf was conducted and another comparison was made between Surfaxin and Survanta. The study revealed that Surfaxin demonstrated significant improvement in both RDS at 24 hours after birth and RDS-related mortality through two weeks, when compared with Exosurf (the primary comparison for the study).
The most common side effects of Surfaxin were not related to the drug itself; rather, they were associated with its administration via an endotracheal tube (a tube inserted into the infant’s airway to administer the medication); the side effects included endotracheal tube reflux (expulsion of the medication from the lungs), skin paleness, endotracheal tube obstruction, and a need for dose interruption.
The earlier an infant is born, the less developed the lungs are and the higher the risk of RDS. Most cases are seen in infants born before 28 weeks. It is very uncommon in infants born full-term (at 40 weeks).
Despite greatly improved RDS treatment in recent years, significant controversy still exists. Delivering artificial surfactant directly to the infant's lungs can significantly improve the condition; however, how much should be given, which infants should receive it, and when is still under investigation. Infants suffering from RDS will receive warm, moist oxygen. This is critically important; however, it needs to be given carefully to reduce the side effects associated with too much oxygen. A respirator (breathing machine) can be lifesaving, especially for infants with the following: high levels of carbon dioxide in the arteries; low blood oxygen in the arteries; and low blood pH (acidity). The device can also be lifesaving for infants with repeated breathing pauses (apnea). There are a number of different types of breathing machines available; however, the devices can damage fragile lung tissues; thus, their use should be avoided or limited when possible.
A treatment called continuous positive airway pressure (CPAP) that delivers slightly pressurized air through the nose can help keep the airways open and may prevent the need for a respirator machine for many infantss. Even with CPAP, oxygen and pressure will be reduced as soon as possible to prevent side effects associated with excessive oxygen or pressure. Other respiratory aids include extracorporeal membrane oxygenation (ECMO) to directly infuse oxygen into the blood stream and inhaled nitric oxide to improve oxygen levels
In addition to prematurity, the following increase the risk of neonatal RDS:
- A brother or sister who had RDS
- Maternal diabetes
- Cesarean delivery
- Delivery complications that lead to acidosis (acidic blood) in the newborn at birth
- Multiple gestation (twins or more)
- Rapid labor
The risk of RDS may be decreased if the pregnant mother has chronic, pregnancy-related high blood pressure or prolonged rupture of membranes; the stress from these situations may cause the infant's lungs to mature earlier.