Applied topically or taken orally, acyclovir is one of the most commonly-used herpes-treatment drugs. It can also damage the kidneys over time, however, so the less of it that's used, the better. According to a new study, combining the drug with activated carbon helps make it more effective, so a smaller amount of it is required.

Even on its own, activated carbon is known for its ability to absorb toxins within its porous structure – that's why it's used in water filters. The carbon itself is non-toxic, and safe to ingest.

With that in mind, a University of Illinois at Chicago-led team started by applying dilutions of the material to cells in the lab, and then exposing those cells to both types of the herpes virus – simplex 1 and simplex 2. As compared to cells that received no carbon, the treated cells were 40 to 60 percent less likely to become infected.

Next, the researchers mixed acyclovir with activated carbon, then applied the solution to the afflicted eyes or genitals of mice infected with either type of the virus. It was found that the drug/carbon combo reduced inflammation and viral load much quicker and more effectively than acyclovir alone, meaning that the same beneficial effect could be achieved using fewer doses.

"We think that the charcoal releases particles of acyclovir slowly over time because the herpes virus, as well as other organic molecules and particles, are more attracted to the charcoal than the drug, and as these particles interact with the charcoal they displace and release the drug," says post-doctoral fellow Tejabhiram Yadavalli, who led the research along with Prof. Deepak Shukla. "The activated carbon acts like a slow-release drug capsule. Because it likes to bind with the virus, this gives it additional anti-viral properties."

The low-cost technology has been named DECON, for Drug Encapsulated Carbon. It is described in a paper that was published this week in the journal Science Advances.