It is also thought to be involved in the effectiveness of naltrexone in alcohol dependence by reducing the euphoric effects of alcohol. The role of KOR modulation by naltrexone in its effectiveness for alcohol dependence is unclear but this action may also be involved based on theory and animal studies. Other activities
In addition to the opioid receptors, naltrexone binds to and acts as an antagonist of the opioid growth factor receptor (OGFR) and toll-like receptor 4 (TLR4) and interacts with high- and low-affinity binding sites in filamin-A (FLNA). It is said that very low doses of naltrexone (<0.001–1 mg/day) interact with FLNA, low doses (1 to 5 mg/day) produce TLR4 antagonism, and standard clinical doses (50 to 100 mg/day) exert opioid receptor and OGFR antagonism. The interactions of naltrexone with FLNA and TLR4 are claimed to be involved in the therapeutic effects of low-dose naltrexone. Pharmacokinetics
The absorption of naltrexone with oral administration is rapid and nearly complete (96%). The bioavailability of naltrexone with oral administration is 5 to 60% due to extensive first-pass metabolism. Peak concentrations of naltrexone are 19 to 44 μg/L after a single 100 mg oral dose and time to peak concentrations of naltrexone and 6β-naltrexol (metabolite) is within 1 hour.
Tracheomalacia is a condition or incident where the cartilage that keeps the airway (trachea) open is soft such that the trachea partly collapses especially during increased airflow. This condition is most commonly seen in infants and young children. The usual symptom is stridor when a person breathes out. This is usually known as a collapsed windpipe. The trachea normally opens slightly during breathing in and narrows slightly during breathing out. These processes are exaggerated in tracheomalacia, leading to airway collapse on breathing out. If the condition extends further to the large airways (bronchi) (if there is also bronchomalacia), it is termed tracheobronchomalacia. The same condition can also affect the larynx, which is called laryngomalacia. The term is from trachea and the Greek μαλακία, softening

Signs and symptoms
Tracheomalacia occurs when the walls of the trachea collapse. This can happen because the walls of the windpipe are weak, or it can happen because something is pressing on it. This may include hypotonia of the trachealis muscle. The whole windpipe can be affected, or only a short piece of it. If the collapsed part of the windpipe goes past the area where the windpipe branches off into the two lungs, it is called bronchomalacia.This problem causes noisy or difficult breathing in the first 1 to 2 months after birth. This is called congenital tracheomalacia (it was present at birth). It is not very common. Babies born with tracheomalacia may have other health issues like a heart defect, reflux or developmental delay.