Dental Anesthetics
National Dental Month: Exotic compounds discovered by using high-throughput technology help take the pain out of dental work.
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A handful of related, very effective compounds continue to be the anesthetic mainstays of any dental practice, varying mostly in terms of how quickly they take effect and how quickly they wear off.
With names like benzocaine, lidocaine, articaine, and mepivacaine, it’s easy to guess that they’re all derivatives of the original naturally occurring local anesthetic, cocaine.
The analgesic properties of cocaine, an alkaloid found in coca leaves, have been known for centuries. It didn’t take long after cocaine was isolated in the 1800s for chemists to begin searching for less addictive alternatives for use as a local anesthetic.
The first such alternative was Novocaine, the trade name given to the compound procaine. Synthesized in the late 1800s, procaine could be injected, and patients couldn’t get hooked. For decades, it reigned as the archetypal dental anesthetic.
Procaine and “caine” successor molecules are amino compounds with a similar framework: a hydrophilic amine and a lipophilic aromatic group, connected by either an ester- or an amide-based linkage, explains Matthias C. Lu, a professor of medicinal chemistry and pharmacognosy at the University of Illinois, Chicago, and anesthetic chemistry expert. Long ago, these two classes were given the names “amino ester” and “amino amides,” and those labels have stuck, Lu says.
There’s some controversy over the molecules’ anesthetic mechanism. Lu has proposed that the molecules bind and interact with a specific receptor on the nerve cell membrane. Other pharmacologists believe that the molecules merely disturb the membrane structure and thus the receptor, albeit indirectly.
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Excerpted with permission, Chemical & Engineering News
Copyright © 2010 American Chemical Society