Researchers are reporting progress in the quest for a drug that can regrow hair.
In a study published Friday in the journal Science Advances, Dr. Angela Chistiano and colleagues at Columbia University Medical Center said they were able to grow hair in laboratory mice using two drugs already approved by the FDA.
One of the drugs, tofacitinib (Xeljanz), is used to treat rheumatoid arthritis, and the other is a blood cancer treatment called ruxolitinib (Jakafi). They're part of a class drugs known as JAK inhibitors.
Researchers discovered that when JAK inhibitors were applied as a topical solution directly to the skin, instead of taken orally, they triggered hair growth by activating cells in hair follicles.
"JAK inhibitors seem to be among the very few number of compounds that produce hair growth very soon after their application," Christiano said.
In the study, mice treated for five days with JAK inhibitors sprouted new hair within 10 days.
That could be an appealing prospect for millions of men, since about half of those over age 50 experience some degree of hair loss.
However, the treatment has not yet been tested on humans, and results that seem promising in lab animals don't always turn out to work in people. It's too early to know how the treatment would be formulated, how much a person would need to use, or what it would cost.
"What we've found is promising, though we haven't yet shown it is effective for male pattern baldness," Christiano said in a statement. "More work needs to be done to test formulations of JAK inhibitors specially made for the scalp to determine whether they can induce hair growth in humans."