True or false, adding sodium bicarbonate to increase the pH of a local anesthetic produces a "carbonated local anesthetic?"

Answer: False

Adding sodium bicarbonate to a local anesthetic does not produce a carbonated local anesthetic.  Adding sodium bicarbonate increases the pH of the local anesthetic, making the pH closer to the pKa of the local anesthetic, in turn causing more of the local anesthetic to exist as a base (uncharged moiety) which diffuses across membranes more quickly than charged molecules and therefore speeds the onset of action of the local anesthetic.

Carbonated local anesthetics are not available in the USA but are available in Canada.  Carbonated local anesthetics are produced by bubbling CO2 through a local anesthetic under pressure and in a nitrogen atmosphere.  This produces LA~carbonate v. LA~HCl (that are used in the USA).

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