Clinical Pharmacology for Infasurf
Mechanism Of Action
Endogenous lung surfactant is essential for effective ventilation because it modifies alveolar surface tension thereby stabilizing the alveoli. Lung surfactant deficiency is the cause of Respiratory Distress Syndrome (RDS) in preterm neonates. INFASURF is a lung surfactant that restores lung surface activity in preterm neonates with RDS by adsorbing to the surface of the air:liquid interface and modifying surface tension similarly to natural lung surfactant.
Pharmacodynamics:
Calfactant dose-response relationships and the time course of pharmacodynamic response are unknown. In vitro, INFASURF lowered minimum surface tension to ≤ 3 mN/m as measured on a pulsating bubble surfactometer. Ex vivo, INFASURF restored the pressure volume mechanics and compliance of surfactant-deficient rat lungs. In vivo, INFASURF improved lung compliance, respiratory gas exchange, and survival in preterm lambs with profound surfactant deficiency.
Pharmacokinetics
The absorption, distribution, metabolism, and excretion of calfactant in humans following intratracheal administration of INFASURF is unknown.
Immunogenicity
The immunogenicity of INFASURF is unknown.
Clinical Studies
Overview Of Clinical Trials
The efficacy of INFASURF to reduce the risk of respiratory distress syndrome (RDS) in preterm neonates <29 weeks of gestational age at risk for RDS and for the rescue treatment of RDS in preterm neonates ≤72 hours of age with RDS who required endotracheal intubation was based on three randomized, active-controlled clinical trials that enrolled 3,098 neonates:
- INFASURF vs colfosceril palmitate to reduce the risk of RDS in preterm neonates (Trial 1)
- INFASURF vs beractant to reduce the risk of RDS and treatment of RDS in preterm neonates (Trial 2)
- INFASURF vs colfosceril palmitate for treatment of RDS in preterm neonates (Trial 3)
INFASURF vs beractant trial (Trial 2) was one trial that included two cohorts that assessed the efficacy of INFASURF to reduce the risk of RDS (cohort #1) and for the rescue treatment of RDS (cohort #2).
While efficacy cannot be established from uncontrolled trials, there were four uncontrolled trials that included 15,500 preterm neonates who were treated with INFASURF. However, efficacy results are presented only for the three controlled trials described below.
Reduction Of Risk For Neonatal Respiratory Distress Syndrome
INFASURF vs Colfosceril Palmitate Trial to Reduce the Risk of Respiratory Distress Syndrome
A total of 853 neonates <29 weeks gestation were enrolled in a randomized, double-blind, active-controlled, parallel group trial (Trial 1) that compared INFASURF (3 mL/kg) to colfosceril palmitate (5 mL/kg). The initial dose was administered within 30 minutes of birth. If the patient remained intubated, repeat doses were administered every 12 hours (for up to a total of 3 doses). Each dose was divided in 2 equal aliquots and administered intratracheally in small bursts over 20 to 30 inspiratory cycles through a side port adapter into the proximal end of the endotracheal tube. After each aliquot was instilled, the neonate was positioned with either the right or the left side dependent.
The primary efficacy endpoints for this trial were incidence of RDS, incidence of bronchopulmonary dysplasia (BPD) at day 28, and death due to RDS evaluated at 14 days for all treated patients. Select secondary endpoints included death at 28 days or prior to discharge, incidence of air leaks due to RDS, and the cross over to other surfactant treatment. Table 3 displays the efficacy results in this trial.
Table 3 : Efficacy Results in Preterm Neonates (< 29 weeks of gestational age) (Trial 1)
|
INFASURF
(N=431) % |
Colfosceril palmitate
(N=422) % |
p- Value |
| Primary Endpoints |
| Incidence of RDS |
15 |
47 |
<0.001 |
| Bronchopulmonary dysplasiaa |
16 |
17 |
0.60 |
| Death due to RDS |
2 |
5 |
<0.01 |
| Secondary Endpoints |
| Any death to 28 days |
12 |
16 |
0.10 |
| Any death before discharge |
18 |
19 |
0.56 |
| Incidence of air leaksb |
10 |
15 |
0.01 |
| Crossover to other surfactantc |
0.2 |
3 |
<0.001 |
aBronchopulmonary dysplasia, diagnosed by positive X-ray and oxygen dependence at 28 days.
b Pneumothorax and/or pulmonary interstitial emphysema.
c If the neonate failed to respond to the three doses of the initial randomized surfactant, was <72 hours of age, and had an a/A PO2 ratio <0.1, the neonate was permitted to receive the comparator surfactant. |
INFASURF vs. Beractant Trial To Reduce The Risk Of Respiratory Distress Syndrome
A total of 1,119 neonates were enrolled in the INFASURF vs beractant trial (Trial 2) which included two cohorts that evaluated INFASURF to reduce the risk of RDS (cohort #1) and for the rescue treatment of RDS (cohort #2) [see Clinical Studies]. Cohort #1 was a randomized, double-blind, active-controlled, trial in 457 neonates ≤ 30 weeks gestation and ≤ 1,250 grams birth weight that compared the 4 mL/kg (100 mg phospholipids/kg) dose of INFASURF to the 4 mL/kg dose of beractant. Note that the INFASURF formulation and dose used in this trial were different from the marketed INFASURF formulation and the recommended dose of 3 mL/kg (105 mg phospholipid/kg). The initial dose was administered intratracheally within 15 minutes of birth and if the patient required ≥30% oxygen repeat doses were administered intratracheally at ≥6 hours following the previous INFASURF dose (for a total of 3 repeat doses before 96 hours of age (a total of 4 doses including the initial dose and the repeat doses)); the recommended frequency of INFASURF repeat dosing is every 12 hours and the maximum number of doses including the initial and repeat doses is three [see DOSAGE AND ADMINISTRATION]. The surfactant treatments were administered through a 5-French feeding catheter inserted into the endotracheal tube. Each dose was instilled in four equal aliquots (between each of the instillations, the catheter was removed and mechanical ventilation resumed for 0.5 to 2 minutes). Each of the aliquots was administered with the patient in one of four different positions (prone, supine, right, and left lateral).
There was increased mortality from any cause at 28 days (p=0.03) and in death due to respiratory causes (p=0.005) in INFASURF-treated neonates compared to beractant-treated neonates. For evaluable patients (patients who met the protocol-defined entry criteria), mortality from any cause and mortality due to respiratory causes were also higher in the INFASURF group (p = 0.07 and 0.03, respectively). However, these observations have not been replicated in other adequate and well-controlled trials and their relevance to the intended population is unknown. There was no significant difference in the incidence of RDS, air leaks, BPD, and treatment failure between INFASURF and beractant groups.
Rescue Treatment Of Neonatal Respiratory Distress Syndrome
INFASURF vs Colfosceril Palmitate Trial For The Rescue Treatment Of Respiratory Distress Syndrome
A total of 1,126 neonates ≤72 hours of age with RDS who required endotracheal intubation and had an arterial/Alveolar oxygen ratio (a/A) PO2 < 0.22 were enrolled into a randomized, double-blind, active-control, parallel group trial (Trial 3) that compared INFASURF (3 mL/kg) and colfosceril palmitate (5 mL/kg). Patients received an initial dose, and if intubation was still required, patients received one repeat dose 12 hours later (total of 2 doses). Each dose was instilled intratracheally in small bursts over 20 to 30 inspiratory cycles in two aliquots through a side-port adapter into the proximal end of the endotracheal tube. After each aliquot was instilled, the neonate was positioned with either the right or the left side dependent.
The primary efficacy endpoints for this trial were the incidence of RDS-related air leaks, incidence of BPD at 28 days, and mortality secondary to RDS. Select secondary endpoints included any death at day 28 or prior to hospital discharge and crossover to other surfactant. Table 4 describes the efficacy results of this trial.
Table 4 : Efficacy Results in Neonates ≤72 Hours of Age (Trial 3)
|
INFASURF
(N=570) % |
colfosceril palmitate
(N=556) % |
p-Value |
| Primary Endpoints |
| Air leaks a |
11 |
22 |
<0.001 |
| BPD b |
5 |
6 |
0.41 |
| Death due to RDS |
4 |
4 |
0.95 |
| Secondary Endpoints |
| Any death to 28 days |
8 |
10 |
0.21 |
| Any death before discharge |
9 |
12 |
0.07 |
| Crossover to other surfactant c |
4 |
4 |
1 |
a Pneumothorax and/or pulmonary interstitial emphysema.
b BPD is bronchopulmonary dysplasia, diagnosed by positive X-ray and oxygen dependence at 28 days.
c If the neonate failed to respond to the two doses of the initial randomized surfactant, was <96 hours of age, and had an a/A PO2 ratio <0.1, the neonate was permitted to receive the comparator surfactant. |
INFASURF Versus Beractant Trial For The Rescue Treatment Of Respiratory Distress Syndrome
A total of 1,119 neonates were enrolled in the INFASURF vs. beractant trial (Trial 2) which included two cohorts that evaluated INFASURF to reduce risk of RDS (cohort #1) [see Clinical Studies] and for rescue treatment of RDS (cohort #2). Cohort #2 was a randomized, double-blind, active-controlled trial in 662 neonates with RDS who required endotracheal intubation and had an a/A PO2 <0.22 that compared the 4 mL/kg (100 mg phospholipids/kg) dose of INFASURF to the 4 mL/kg dose of beractant. Note that the INFASURF formulation and dose used in this trial were different from the marketed INFASURF formulation and the recommended dose of 3 mL/kg (105 mg phospholipids/kg). If the neonate required ≥30% oxygen, repeat doses were administered at ≥6 hours following the previous treatment (for a total of four doses before 96 hours of age). Note that the recommended frequency of INFASURF repeat dosing is every 12 hours and the maximum number of doses including the initial and repeat doses is three [see DOSAGE AND ADMINISTRATION]. The surfactant was administered intratracheally through a 5-French feeding catheter inserted into the endotracheal tube. Each dose was instilled in four equal aliquots (the catheter was removed between each of the instillations and mechanical ventilation resumed for 0.5 to 2 minutes). Each of the aliquots was administered with the patient in one of four different positions (prone, supine, right, and left lateral) to facilitate even distribution of the surfactant.
The primary efficacy endpoints were the incidence of air leaks, death due to respiratory causes or to any cause, BPD, or treatment failure evaluated at 28 days or to discharge. There was no significant difference between the INFASURF and beractant groups in these efficacy endpoints.