You probably know that sildenafil (commonly known as Viagra) is a popular drug for men with erectile dysfunction (ED). But what you may not know is that it is being investigated as a possible treatment for people with chronic obstructive pulmonary disease (COPD) as well. This use for sildenafil is just one of a host of new treatments for COPD now under investigation.
Sildenafil belongs to a class of drugs known as phosphodiesterase- 5 (PDE-5) inhibitors. The medication is effective for ED because it relaxes blood vessels in the penis, which permits more blood to flow, a requirement for producing and maintaining an erection. Sildenafil also relaxes and widens blood vessels in the lungs, making it easier for the heart to pump blood through them. This lowers high blood pressure in the lungs -- a condition known as pulmonary arterial hypertension, or PAH.
Researchers are now studying whether sildenafil (sold under the brand name Revatio for PAH) will improve exercise capacity, quality of life, and shortness of breath in people with COPD who do not have PAH. Results from this phase II are due shortly.
Airway Bypass for COPD
Every time a healthy person breathes in, air sacs (alveoli) at the end of the airways fill up with air like small balloons. When the person breathes out, the air sacs deflate, and the air goes out. However, if you have emphysema (a type of COPD), the walls between many of the air sacs are destroyed. The airways and air sacs lose their elasticity and become floppy.
The loss of stable air sac walls, which normally hold airways open when you breathe out, causes small airways to collapse when you exhale, so air has difficulty escaping and becomes trapped in your lungs. This trapped air leads to over expanded lungs and changes the shape of the diaphragm, which results in the need to expend more effort to breathe in.
One experimental treatment for advanced emphysema (COPD) helps relieve this shortness of breath by creating holes between medium-sized airways and the alveoli to allow the trapped air to escape from the lungs. In this minimally invasive procedure, called an airway bypass, a bronchoscope (a long thin tube with a light and lens that is used to look at the airways) is inserted through the mouth, into the windpipe, and down into smaller airways, or bronchi.
To get trapped air around these blocked airways (bronchioles), the doctor inserts a very small needle through the bronchoscope and uses it to create tiny holes through the airway wall and into surrounding alveoli. Up to six holes may be created in each lobe to connect the damaged collapsed airways with the larger healthier airways, allowing the air to escape. These new passages are kept open with stents that are similar to the wire mesh tubes used to keep clogged arteries open in people with heart disease. The stents -- which are smaller than the eraser on the end of a pencil -- are chemically treated to reduce the growth of scar tissue, which helps prevent the new passageway from closing.
It's not clear yet how well the airway bypass procedure works or if there are safety concerns, but investigators are conducting a multicenter, randomized, double-blind, sham-controlled study to answer those questions. The study, dubbed EASE (Exhale Airway Stents for Emphysema), is expected to conclude in 2012. If successful, it will open the door to a much-needed alternative for people facing lung volume reduction surgery (LVRS) or lung transplantation. Both of these procedures pose substantial risks and benefit only a select group of individuals with emphysema.
What Can You Do?
These are just a few of the promising new COPD treatments currently in development. If you have COPD, you can ask your doctor if there are any potential new therapies being studied nearby. You can also check out the National Institutes of Health's website at www.clinicaltrials.gov. The site lists criteria for participation in a given clinical trial as well as who to contact for more information.
