Poractant alfa and
Calsurf are two natural
surfactants widely used in China for the treatment of
neonatal respiratory distress syndrome, which are extracted from porcine and calf lungs, respectively. The purpose of this experimental study was to compare their in vitro characteristics and in vivo effects in the improvement of pulmonary function and protection of
lung injury. The biophysical properties, ultrastructure, and
lipid composition of both
surfactant preparations were respectively analysed in vitro by means of Langmuir-Blodgett trough (LBT), atomic force microscopy (AFM), and liquid-chromatography mass-spectrometry (LC-MS). Then, as core pharmacological activity, both head-to-head (100 and 200 mg/kg for both
surfactants) and licensed dose comparisons (70 mg/kg
Calsurf vs. 200 mg/kg
Poractant alfa) between the two
surfactants were conducted as prophylaxis in preterm rabbits with primary
surfactant deficiency, assessing survival time and rate and dynamic compliance of the respiratory system (Cdyn). Intrapulmonary
surfactant pools, morphometric volume density as alveolar expansion (Vv), and
lung injury scores were determined post mortem. AFM and LC-MS analysis revealed qualitative differences in the ultrastructure as well as in the
lipid composition of both preparations.
Calsurf showed a longer plateau region of the LBT isotherm and lower film compressibility. In vivo, both
surfactant preparations improved Cdyn at any dose, although maximum benefits in terms of Vv and intrapulmonary
surfactant pools were seen with the 200 mg/kg dose in both
surfactants. The group of animals treated with 200 mg/kg of
Poractant alfa showed a prolonged survival time and rate compared to untreated but ventilated controls, and significantly ameliorated
lung injury compared to
Calsurf at any dose, including 200 mg/kg. The overall outcomes suggest the pulmonary effects to be dose dependent for both preparations. The group of animals treated with 200 mg/kg of
Poractant alfa showed a significant reduction of mortality. Compared to
Calsurf,
Poractant alfa exerted better effects if licensed doses were compared, which requires further investigation.