Delivering drugs into the lungs with inhalable nanoparticles can help treat chronic obstructive pulmonary disease (COPD). In mice showing signs of the disease, the treatment improved lung function and reduced inflammation.
COPD makes the airways in the lungs progressively narrower and stiffer, obstructing airflow and preventing the elimination of mucus. As a result, mucus builds up in the lungs, attracting pathogenic bacteria which further aggravates the disease.
This thick layer of mucus also traps medications, making it difficult to treat infections. SO, Jun Liang Zhu at Soochow University in China and colleagues developed inhalable nanoparticles that can penetrate mucus to deliver drugs deep into the lungs.
The researchers constructed the hollow nanoparticles from porous silica, which they filled with an antibiotic called ceftazidime. A shell of negatively charged compounds surrounding the nanoparticles blocked the pores, preventing antibiotic leakage. This negative charge also helps the nanoparticles penetrate mucus. Then the slight acidity of the mucus changes the charge of the shells from negative to positive, opening the pores and releasing the medicine.
Researchers used an inhalable spray containing nanoparticles to treat a bacterial lung infection in six mice showing signs of COPD. An equal number of animals received only the antibiotic.
On average, mice treated with the nanoparticles had about 98% fewer pathogenic bacteria in their lungs than those given the antibiotic alone. They also had fewer inflammatory molecules in their lungs and less carbon dioxide in their blood, indicating better lung function.
These results suggest that nanoparticles could improve drug delivery in people with COPD or other lung conditions like cystic fibrosis, where thick mucus makes it difficult to treat infections, says Vincent Rotello at the University of Massachusetts Amherst, who was not involved in the study. However, it is not known whether these nanoparticles are eliminated through the lungs. “If you have a delivery system that develops over time, that would be a problem,” he says.