The Science

While our motivation is simple, the science that goes into creating a lung surfactant that resembles the real thing is a little more complicated.

Highest level of SP-B to phospholipid ratio makes Infasurf® (calfactant) less affected by inhibitory proteins.

Plasma proteins can leak into alveolar space and inhibit surfactant function. Infasurf® (calfactant) was the most resistant to the three surfactant-inhibiting proteins studied.1

Comparison of SP-B in Exogenous Surfactants* SP-B Content as a % of Phospholipids

Native Lung Surfactant (calf)Infasurf® (calfactant)Curosurf® (poractant alfa)Survanta® (beractant)
  • Infasurf® (calfactant) contains the highest levels of SP-B as a percentage of total phospholipids, same as native calf lung surfactant (0.74%)1,2,5
  • Lab bench testing has shown surfactant films high in SP-B may be less susceptible to inhibitory proteins1

Protein Inhibition Profile for Surfactants1 Adsorption and Surface Tension Lowering

Surfactant vs. Inhibitory Protein (8 mg/mL concentration)
Infasurf® (calfactant)UnaffectedUnaffectedModerately Affected
Curosurf® (poractant alfa)Severely AffectedSeverely AffectedSeverely Affected
Survanta® (beractant)Severely AffectedSeverely AffectedSeverely Affected
  • Even when exposed to high levels of inhibitory proteins, Infasurf® (calfactant) still rapidly adsorbs and lowers surface tension to near zero
  • Adsorption and surface tension lowering properties of the other surfactants are inhibited by plasma proteins at low concentrations

* Chart does not imply clinical superiority of Infasurf® (calfactant).
While clinical studies have demonstrated that SP-B is an essential element, they have not determined the minimum SP-B to phospholipid ratio required for optimal surfactant efficacy.
There are no prospective, randomized clinical trials comparing Infasurf® and Curosurf® with respect to safety or efficacy.