CLINICAL PHARMACOLOGY
Mechanism Of Action
Endogenous pulmonary surfactant reduces surface tension at the air-liquid interface of the alveoli during ventilation and stabilizes the alveoli against collapse at resting transpulmonary pressures. A deficiency of pulmonary surfactant in preterm infants results in Respiratory Distress Syndrome (RDS) characterized by poor lung expansion, inadequate gas exchange, and a gradual collapse of the lungs (atelectasis).
CUROSURF compensates for the deficiency of surfactant and restores surface activity to the lungs of these infants.
Pharmacodynamics
In vitro -CUROSURF lowers minimum surface tension to ≤ 4mN/m as measured by the Wilhelmy Balance System.
Pharmacokinetics
CUROSURF is administered directly to the lung, where biophysical effects occur at the alveolar surface. No human pharmacokinetic studies have been performed to characterize the absorption, biotransformation, or elimination of CUROSURF.
Clinical Studies
Rescue Treatment Of Respiratory Distress Syndrome
The clinical efficacy of CUROSURF in the treatment of established Respiratory Distress Syndrome (RDS) in premature infants was demonstrated in one single-dose study (Study 1) and one multiple-dose study (Study 2) involving approximately 500 infants. Each study was randomized, multicenter, and controlled.
In study 1, premature infants 700 to 2000 grams birth weight with RDS requiring mechanical ventilation and a FiO2 ≥ 0.60 were enrolled. CUROSURF 2.5 mL/kg single dose (200 mg/kg) or control (disconnection from the ventilator and manual ventilation for 2 minutes) was administered after RDS developed and before 15 hours of age. The results from Study 1 are shown below in Table 2.
Table 2: Study 1 Results in Premature Infants with Respiratory Distress Syndrome
Efficacy Parameter | Single Dose CUROSURF n=78 | Control n=67 | p-Value |
Mortality at 28 Days (All Causes) | 31% | 48% | ≤0.05 |
Bronchopulmonary Dysplasia* | 18% | 22% | N.S. |
Pneumothorax | 21% | 36% | ≤0.05 |
Pulmonary Interstitial Emphysema | 21% | 38% | ≤0.05 |
*Bronchopulmonary dysplasia (BPD) diagnosed by positive x-ray and supplemental oxygen dependence at 28 days of life. N.S.: not statistically significant |
In Study 2, premature infants 700 to 2000 g birth weight with RDS requiring mechanical ventilation and a FiO2 ≥ 0.60 were enrolled. In this two-arm trial, CUROSURF was administered after RDS developed and before 15 hours of age, as a single-dose or as multiple doses. In the single-dose arm, infants received CUROSURF 2.5 mL/kg (200 mg/kg). In the multiple-dose arm, the initial dose of CUROSURF was 2.5 mL/kg followed by up to two 1.25 mL/kg (100 mg/kg) doses of CUROSURF. The results from Study 2 are shown below in Table 3.
Table 3: Study 2 Results in Premature Infants with Respiratory Distress Syndrome
Efficacy Parameter | Single Dose CUROSURF n=184 Rate (%) | Multiple Dose CUROSURF n=173 Rate (%) | p-Value |
Mortality at 28 Days (All Causes) | 21 | 13 | 0.048 |
Bronchopulmonary Dysplasia* | 18 | 18 | N.S. |
Pneumothorax | 17 | 9 | 0.03 |
Pulmonary Interstitial Emphysema | 27 | 22 | N.S |
*Bronchopulmonary dysplasia (BPD) diagnosed by positive x-ray and supplemental oxygen dependence at 28 days of life. N.S.: not statistically significant |
There is no controlled experience on the effects of administering initial doses of CUROSURF other than 2.5 mL/kg (200 mg/kg), subsequent doses other than 1.25 mL/kg (100 mg/kg), administration of more than three total doses, dosing more frequently than every 12 hours, or initiating therapy with CUROSURF more than 15 hours after diagnosing RDS. Adequate data are not available on the use of CUROSURF in conjunction with experimental therapies of RDS, e.g., high-frequency ventilation or extracorporeal membrane oxygenation.