19 November 2010
Photo: AP
Delivering TB drugs directly to the lungs by inhaling a fine powder, can be more effective, faster and require lower doses.
A new way of taking tuberculosis drugs shows promise in laboratory tests. Instead of taking a pill or getting a shot, patients would inhale their medicine to get the drug deep into the lungs.
Tuberculosis is one of the world's most serious health challenges. The World Health Organization says one-third of the world's population is infected - that's two billion people. The vast majority of them never get sick, but last year alone more than nine million did, and an estimated 1.7 million died from TB.
Treating tuberculosis has never been easy. Drugs must be taken for months, and too often patients stop taking the pills, which opens the way for resistant forms of the disease to develop. So the search is on for better ways to treat TB.
A PhD student at the University of Colorado has been exploring using existing drugs in a new form - a very fine powder that is inhaled, instead of a pill. J'aime Manion says most tuberculosis bacteria cluster in the lungs, so delivering drugs directly to the lungs can be more effective, faster, and require lower doses.
"Over and over again we see that when you treat with inhalation, you see a faster clearance of the bacteria," she said. "And this is so important because the treatment times for tuberculosis are from three to six months, with tons of antibiotics, with terrible side effects."
Manion has been working with inhalable particles that are about three microns in diameter - three one-thousandths of a millimeter across.
Creating the inhalant from an established drug that's manufactured in pill form isn't simply a matter of grinding it up into a fine powder. Manion says she and her team found that adding an amino acid called leucine gave the powdered medicine some useful properties, such as keeping the individual particles from sticking together.
"And when they're less sticky, they're able to blow apart and disperse better. And that's a really big, important thing for inhalable antibiotics because we want them to not go in as a clump, but to go in as individual particles and to make the most of their small size, so that they get where they're going and they get to the deepest, smallest parts of the lungs," Manion explained.
By inhaling the drug, the patient gets the medicine directly into the lungs, where most of the target tuberculosis bacteria are.
"The point of the inhalable antibiotics is, we can concentrate a dose in this area, and then maybe get more effect out of a lower dose because it's concentrated into a smaller area and it's hitting the affected site," she said. "And after it hits its target, it then is absorbed by the bloodstream and does further good in the body."
Inhaled drugs are already being used to treat other diseases, including asthma and cystic fibrosis. The challenges have mainly been in manufacturing the drug in such a way that the ultra-small particles actually get into the tiny passageways deep in the lungs. But scientists are overcoming some of those challenges.
At the same joint meeting of the International Pharmaceutical Federation and the American Association of Pharmaceutical Scientists where J'aime Manion presented her research, others were sharing their findings on inhalable drug delivery for conditions ranging from human papillomavirus to lung cancer.
Manion's work so far has focused on developing an inhalable form of tuberculosis antibiotics. Now that she has, she hopes other researchers will be able to continue the process with tests on laboratory animals.