Calfactant - Drug Monograph

Introduction

Calfactant is a natural pulmonary surfactant derived from calf lungs that is used for the prevention and treatment of respiratory distress syndrome (RDS) in premature infants. It is a sterile, non-pyrogenic suspension containing phospholipids, neutral lipids, and hydrophobic surfactant-associated proteins B and C (SP-B and SP-C). Calfactant represents a significant advancement in neonatal care, dramatically improving survival and reducing complications associated with surfactant deficiency in premature infants.

Mechanism of Action

Calfactant functions by replacing deficient or dysfunctional endogenous surfactant in premature infants. It lowers surface tension at the air-liquid interface of the alveoli, preventing alveolar collapse at end-expiration. The phospholipid components (primarily dipalmitoylphosphatidylcholine) form a monolayer at the alveolar surface, while the surfactant proteins (SP-B and SP-C) facilitate adsorption and spreading of the phospholipid film. This mechanism improves lung compliance, maintains functional residual capacity, and facilitates gas exchange across the alveolar-capillary membrane.

Indications

Calfactant is FDA-approved for:

• Prevention of respiratory distress syndrome (RDS) in premature infants at high risk for RDS
• Treatment ("rescue") of premature infants who develop RDS

The drug is typically administered to infants with birth weights less than 1350 grams or gestational age less than 32 weeks who are at significant risk for developing RDS or have evidence of RDS requiring mechanical ventilation.

Dosage and Administration

• Administer through an endotracheal tube adapter
• Instill slowly over 20-30 seconds for each aliquot
• Gently reposition infant (supine then prone or right side then left side) between aliquots
• Ventilate for at least 30 seconds after each aliquot
• Monitor for desaturation or bradycardia during administration

• Prevention: May administer up to 3 doses every 12 hours
• Treatment: May readminister every 12 hours (maximum 4 total doses)

Pharmacokinetics

Contraindications

• Hypersensitivity to any component of calfactant
• Infants with congenital anomalies incompatible with life beyond the neonatal period
• Infants who have not been intubated or are not receiving mechanical ventilation

Warnings and Precautions

• Acute administration effects: May cause transient bradycardia, oxygen desaturation, or airway obstruction during instillation
• Reflux into endotracheal tube: May occur if administered too rapidly
• Requires specialized training: Should only be administered by healthcare providers experienced in neonatal intubation and resuscitation
• Monitoring essential: Continuous monitoring of oxygen saturation, heart rate, and endotracheal tube patency required during administration
• Pulmonary hemorrhage: Has been reported following surfactant administration (incidence approximately 1-2%)

Drug Interactions

No clinically significant drug interactions have been documented with calfactant due to its local pulmonary administration and lack of systemic absorption. However, concurrent administration with other intratracheal medications should be avoided unless specifically indicated and separated by appropriate time intervals.

Adverse Effects

• Transient bradycardia during administration
• Oxygen desaturation during administration
• Endotracheal tube reflux or blockage
• Cyanosis

• Pulmonary hemorrhage (1-2%)
• Apnea
• Patent ductus arteriosus (associated with prematurity rather than drug)
• Intraventricular hemorrhage (associated with prematurity rather than drug)

Monitoring Parameters

• During administration: Continuous cardiorespiratory monitoring (heart rate, oxygen saturation, respiratory rate)
• Post-administration: Frequent assessment of ventilatory settings (peak inspiratory pressure, FiO₂ requirements)
• Serial blood gases: Monitor for improvement in oxygenation and ventilation parameters
• Chest radiographs: Assess for improvement in lung expansion and development of complications
• Signs of adverse effects: Monitor for pulmonary hemorrhage, airway obstruction, or equipment malfunction

Patient Education

• Calfactant is a natural substance that helps premature babies breathe more easily
• The medication is administered directly into the breathing tube by specially trained medical staff
• During administration, temporary changes in heart rate or oxygen levels may occur but are closely monitored
• Multiple doses may be needed depending on the baby's response
• Treatment significantly improves outcomes for premature infants with breathing difficulties
• The healthcare team will explain the benefits and risks specific to your infant's condition

References

1. FDA Prescribing Information: Calfactant (Infasurf®) 2. American Academy of Pediatrics Committee on Fetus and Newborn. Surfactant replacement therapy for preterm and term neonates with respiratory distress. Pediatrics. 2014;133(1):156-163. 3. Polin RA, Carlo WA, Committee on Fetus and Newborn. Surfactant replacement therapy for preterm and term neonates with respiratory distress. Pediatrics. 2014;133(1):156-163. 4. Soll R, Özek E. Prophylactic protein free synthetic surfactant for preventing morbidity and mortality in preterm infants. Cochrane Database Syst Rev. 2010;(1):CD001079. 5. Engle WA, Committee on Fetus and Newborn. Surfactant-replacement therapy for respiratory distress in the preterm and term neonate. Pediatrics. 2008;121(2):419-432. 6. Speer CP, Sweet DG, Halliday HL. Surfactant therapy: past, present and future. Early Hum Dev. 2013;89 Suppl 1:S22-S24.