NEONATAL RESPIRATORY DISTRESS SYNDROME: Pharmacology

Question 1

what is the pathophysiology of NRDS ?

Answer 1

Pulmonary surfactant is responsible for reducing surface tension at the air–liquid interface in the alveoli, preventing lung collapse at resting lung pressures.
The surfactants are macromolecular complex consisting of phospholipids (80-85%), neutral lipids( 5-10%) and surfactant-specific proteins A–D (5%–10%). Surfactant proteins B and C are hydrophobic and involved in spreading of the surfactant layer at the air–liquid interface. The hydrophilic surfactant proteins A and D are involved in surfactant metabolism and in host defence by enhancing phagocytosis of pathogens.
Surfactant is synthesised by type II alveolar epithelial cells and is normally present in substantial amounts in the lungs at full-term delivery. However, preterm infants (especially those born at or before 28 weeks’ gestation) have immature lungs which may produce too little surfactant. These infants develop difficulty breathing within minutes or hours of delivery, a condition called neonatal respiratory distress syndrome.

Question 2

How to treat NRDS?

Answer 2

• Give inhaled corticosteroid such as betamethasone to at risk mothers 48hrs before delivery or at least before 12 hrs.
  *Surfactant is given as soon as possible after delivery to infants with neonatal respiratory distress syndrome, or to those considered to be at high risk of developing it. Surfactant combined with noninvasive ventilation reduces the risk of death by 40%.

Question 3

What are the two natural surfactants currently available ?

Answer 3

There are two natural therapeutic surfactants: beractant (bovine lung extract) and poractant alfa (porcine lung phospholipid fraction).