COLUMBUS, Ohio -- An Ohio State University researcher has patented a dental anesthetic formula that's considerably more effective than any currently available.
The composition is a mix of a local anesthetic agent and a sugar alcohol. The alcohol opens the protective covering of sensory nerves, allowing the anesthetic agent to enter the innermost parts of the nerves it is meant to numb.
Researchers found that the new composition could completely numb the anesthetized region in about 90 percent of cases, as opposed to about 50 percent of cases using only the local anesthesia in the standard dosage.
"Using the sugar alcohol makes local anesthesia more effective," said Al Reader, inventor of the composition, a professor of dentistry and director of Ohio State's Advanced Endodontics Program.
Reader believes the principle behind his new formulation could be applied to improve anesthesia for a range of surgeries.
Reader tested different versions of his formulation - a mixof lidocaine (a local anesthetic) and mannitol (the sugar alcohol) in different proportions - on more than 200 people. The best results came from a concoction of mannitol and about 64 milligrams of lidocaine - roughly double the amount currently used by dental anesthetists. With that combination, about 90 percent of patients were able to achieve complete numbness.
Reader and his colleagues studied the efficacy of the composition on study participants by delivering mild shocks to the base of the tooth - the region that had been numbed - and evaluating the patient's response. If the patient did not feel anything up to a certain voltage, the case was recorded as total anesthesia. "This would mean the patient will not feel a thing during a dental procedure such as drilling," Reader explained.
When Reader increased the mannitol's concentration in the composition beyond a certain limit, some of the anesthetized subjects felt sore in the jaw. "Although mannitol is inert and does not interact chemically with either the anesthetic agent or body fluids, high concentrations of it tend to remove water from the surrounding tissue. That causes an irritation," he said. "That's how we arrived at the upper limit."
The idea that mannitol could help increase the efficacy of local anesthetics came to Reader several years ago when he learned that doctors were using the compound to get chemotherapeutic agents across the blood-brain barrier in patients with brain tumors. Since the barrier is nature's mechanism to prevent toxins in the blood from crossing into the brain, it does not allow drug molecules to reach either.
"Dental surgeons are taught that if patients have not been effectively numbed, it's because of an inaccurate injection - which, in turn, is because the anesthetist hasn't understood the patient's anatomy," Reader said. "So I studied the anatomy. But it didn't help. We gave more anesthetic, but that didn't help either." Reader also tried numbing additional nerves at the base of the tooth to increase the numbing effect. "Nothing worked," he said. "That's when I decided to try mannitol."
Reader is discussing commercialization plans with private companies. The composition will have to undergo further clinical trials for FDA approval, but mannitol is routinely used in medicine, so he expects speedy approval.
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