- Number 373 |
- October 8, 2012
Abracadabra: Sound levitates pharmaceutical droplets
These drops of solution remain suspended
for a long period of time, thanks to the
vibrational force of sound waves that keep
them stationary in an air column.
(Photo by Dan Harris)
It’s not a magic trick and it’s not sleight of hand – scientists really are using levitation to improve the drug development process, eventually yielding more effective pharmaceuticals with fewer side effects.
Scientists at DOE's Argonne National Laboratory have discovered a way to use sound waves to levitate individual droplets of solutions containing different pharmaceuticals. While the connection between levitation and drug development may not be immediately apparent, a special relationship emerges at the molecular level.
At the molecular level, pharmaceutical structures fall into one of two categories: amorphous or crystalline. Amorphous drugs typically are more efficiently taken up by the body than their crystalline cousins; this is because amorphous drugs are both more highly soluble and have a higher bioavailability, suggesting that a lower dose can produce the desired effect.
“One of the biggest challenges when it comes to drug development is in reducing the amount of the drug needed to attain the therapeutic benefit, whatever it is,” said Argonne X-ray physicist Chris Benmore, who led the study.
Argonne scientist Chris Benmore
demonstrates his acoustic levitator, which
could help to improve the efficiency and
quality of pharmaceutical development.
(Photo by Dan Harris)
Getting pharmaceuticals from solution into an amorphous state, however, is no easy task. If the solution evaporates while it is in contact with part of a vessel, it is far more likely to solidify in its crystalline form. “It’s almost as if these substances want to find a way to become crystalline,” Benmore said.
In order to avoid this problem, Benmore needed to find a way to evaporate a solution without it touching anything. Because liquids conform to the shape of their containers, this was a nearly impossible requirement – so difficult, in fact, that Benmore had to turn to an acoustic levitator, a piece of equipment originally developed for NASA to simulate microgravity conditions.
Although only small quantities of a drug can currently be “amorphized” using this technique, it remains a powerful analytical tool for understanding the conditions that make for the best amorphous preparation, Benmore explained.[Kristin Manke, 509.372.6011,
kristin.manke@pnnl.gov]
