By Pat Anson, Editor

A fast acting pain reliever widely used to treat everything from itching to dental pain could be developed into a new medication that offers longer lasting pain relief.

"Because of its versatility and effectiveness at quickly numbing pain in targeted areas, lidocaine has been the gold standard in local anesthetics for more than 50 years," said George Kracke, PhD, an associate professor of anesthesiology and perioperative medicine at the University of Missouri (MU) School of Medicine.

"While lidocaine is effective as a short-term painkiller, its effects wear off quickly. We developed a new compound that can quickly provide longer lasting relief. This type of painkiller could be beneficial in treating sports injuries or in joint replacement procedures."

Lidocaine is used as an injectable pain reliever for minor surgical or dental procedures, and as an over-the-counter ointment or spray to relieve itching, burning and pain from shingles, sunburns, and insect bites.

The new compound -- called boronicaine -- could potentially serve many of those same functions as an injectable or topical painkiller.  

MU researchers synthesized boronicaine as a derivative of lidocaine by changing its chemical structure. They found that boronicaine provided pain relief that lasted five times longer than lidocaine. In pre-clinical, early stage studies, boronicaine provided about 25 minutes of relief, compared to about five minutes of pain relief with lidocaine.

"Although some conditions may warrant the use of a short-lasting painkiller, in many cases a longer lasting anesthetic is a better option," said Kracke, who is lead author of a study published in the chemistry journal ChemMedChem . "Having a longer lasting anesthetic reduces the dosage or number of doses needed, limiting the potential for adverse side effects."

Other types of short term analgesics provide longer pain relief than lidocaine, but they also have side effects they can cause heart toxicity and gastrointestinal problems. Preliminary findings show no toxicity in single-dose studies of boronicaine, though more studies are needed.

"Boronicaine could have distinct advantages over existing painkilling medications," said M. Frederick Hawthorne, PhD, director of MU's International Institute of Nano and Molecular Medicine and a pioneer in the field of boron chemistry. "We're conducting more research into the side effects of the compound, but in time it could very well become a useful material to use as an anesthetic."