How Do Lung Surfactants Work?

Lung surfactants are medications used in the prevention and treatment of respiratory distress syndrome (RDS) in premature infants. RDS is a condition in which fluid fills up in the lungs of preterm babies because they are born before the lung surfactant system is fully developed. 

Lung surfactant medications are sterile extracts from the lungs of animals such as cows, calves, and pigs. Lung surfactant is a complex substance naturally secreted by the lungs, composed of proteins and phospholipids, which are fat molecules that contain phosphate.

The main functions of lung surfactants include:

• Reducing the surface tension in the liquid/air interface in the lungs’ air sacs (alveoli), which prevents the alveoli from filling with fluid or collapsing with the expulsion of air during exhalation.
• Killing inhaled germs and prevented them from spreading.
• Modulating the immune response.

The development of the lung surfactant system starts at 24 weeks of gestation in a fetus and adequate surfactant amounts are produced only by 32 weeks. Premature babies born earlier than 32 weeks of gestation have a deficiency of lung surfactants and are at high risk for developing respiratory distress syndrome.

Lung surfactants compensate for the surfactant deficiency till a premature baby’s lungs develop and produce sufficient amounts on their own. Lung surfactant therapy may not be effective for babies who have dysfunctional lung surfactants because of inherited gene mutations.

Currently, all available FDA-approved lung surfactants are animal-derived biological products that require invasive administration through an endotracheal tube. Biological products also have limited availability and do not meet the needs of all preterm babies that require treatment with lung surfactants.

Intensive research and clinical trials are ongoing to develop synthetic lung surfactants that can be administered non-invasively as aerosols through nasal continuous positive airway pressure (nCPAP) machines. The development of synthetic lung surfactants can facilitate adequate production and improve cost efficiency.

Lung surfactants are suspensions instilled through the endotracheal tube inserted into the airway to assist breathing in preterm newborns. Lung surfactants are used for the prevention and treatment of respiratory distress syndrome in premature infants.

Lung surfactants also have an orphan designation for the treatment of full-term newborns with respiratory failure caused by meconium aspiration syndrome (a condition in which the baby aspirates their first stool), persistent pulmonary hypertension of the newborn, or pneumonia and sepsis.

Researchers suggest that infants born earlier than 28 weeks of gestation should receive lung surfactant within the first few minutes of life and infants born after 30 weeks of gestation should receive the therapy if they show signs of respiratory distress syndrome.

Side effects of lung surfactants may include the following:

• Cyanosis (bluish skin coloration due to low oxygen)
• Airway obstruction
• Bradycardia (slow heartbeat)
• Endotracheal tube reflux
• Endotracheal tube blockage
• Oxygen desaturation
• Requirement for manual ventilation
• Reintubation
• Patent ductus arteriosus (failure of fetal connection between the aorta and pulmonary artery to close, which normally closes at birth)
• Intracranial hemorrhage
• Pneumothorax (lung collapse)
• Pulmonary interstitial emphysema (a condition in which air gets trapped in the tissue outside the alveoli)
• Bronchopulmonary dysplasia (impaired lung development that causes chronic lung disease due to injury/irritation from oxygen exposure and positive pressure ventilation in preterm babies)
• Acquired pneumonia
• Sepsis
• Acquired septicemia
• Pulmonary hemorrhage
• Hypotension (low blood pressure)
• Hypertension (high blood pressure)
• Hypercarbia (elevated carbon dioxide levels in the blood)
• Vasoconstriction

Information contained herein is not intended to cover all possible side effects, precautions, warnings, drug interactions, allergic reactions, or adverse effects. Check with your doctor or pharmacist to make sure these drugs do not cause any harm when you take them along with other medicines. Never stop taking your medication and never change your dose or frequency without consulting your doctor.

Generic and brand names of lung surfactant drugs include:

• beractant
• calfactant
• Curosurf
• Infasurf
• poractant alfa
• Survanta