Research carried out at Royal Brompton Hospital indicates that the size of inhaled medicine particles has a direct impact on how well treatment for patients with chronic obstructive pulmonary disease (COPD) works.
The study found that smaller particles of medicine could reach a larger area of patients’ lungs when inhaled, and were more evenly dispersed throughout their lungs than coarse, larger particles. This was the first time that research has showed that the lungs of patients with COPD are less able to receive larger particles of drugs than healthy lungs.
Lead researcher Dr Omar Usmani, consultant physician and reader in respiratory medicine, previously carried out a study which found that larger drug particles were more effective for patients with asthma, which suggests that there are key differences between the lungs of patients with the two respiratory conditions.
The new findings, presented at the European Respiratory Society congress in London, were based on a clinical trial which involved 18 patients with COPD and 18 healthy controls. Dr Usmani received a career development fellowship to undertake the research that was funded by the National Institute for Health Research (NIHR) and sponsored by Imperial College London.
COPD is an umbrella term for a collection of conditions causing lung damage, including chronic bronchitis and emphysema, and affects around three million people in the UK. Symptoms include coughing, wheezing, breathlessness and a tight chest.
Often patients with COPD have significant damage deep down in the narrow airways in the lungs because the disease is usually caused by smoking and cigarette smoke contains very small particles, which affect the small airways. Inhalers, which are commonly prescribed for the condition, contain reliever drugs that widen the narrowed airways. However, inhalers cannot always target drugs to reach the very deep areas inside the lungs.
For the study, particles of the drug Salbutamol Sulphate – which is used in inhalers - were scientifically engineered into different sizes and tagged with a radioactive tracer to show up on a nuclear medicine scan. Patients were given an inhaler without knowing if it contained small or large particles of medicine.
The scans illustrated that the smaller particles reached the damaged deeper parts of the lungs when inhaled and had a better distribution than the larger particles, which did not reach the outer areas of the lungs. This was the case regardless of how quickly patients inhaled the particles, although inhaling small particles slowly was found to be the optimal technique to disperse the drug throughout the lungs.
Commenting on the findings, Dr Omar Usmani said:
“The key to successful management of the symptoms of COPD is to accurately target the damaged areas in the airways. Our research shows that smaller particles of inhaled medicine were better at ending up in the areas of the lungs where they were needed, compared with large particles. This was of particular interest considering that the lungs of patients with COPD were less able to receive larger particles of drugs than healthy lungs.
“Larger-scale research and further analysis is needed, but we believe that these findings could help to develop a new generation of inhalers for COPD patients containing smaller particles of medicine, which will hopefully benefit millions of patients around the world.”
Participants undertook a number of advanced breathing tests during a four-hour period after taking the inhalers. These looked at deep lung function in the narrow airway and measured if participants could breathe more easily after taking the inhalers.
Analysis of this data is now being undertaken to ultimately establish whether or not inhaling smaller particles can improve patient outcomes. The research team will also assess whether patients experience any side-effects from inhaling smaller particles of medicine. This further research is expected to be completed by early next year.
Find out more about other research into COPD taking place at the Trust