Buffered local anesthetics reduce injection pain and provide anesthesia for up to 5 hours

Local anesthetics are manufactured as acidic solutions to increase their stability and shelf life [1]. The pH of lidocaine in preparations used for local anesthesia varies between 3.5 and 7.0 [2]. However, physiological pH lies between 7.35 and 7.45. The difference in pH in the tissue and the more acidic local anesthesia increases the number of hydrogen ions upon infiltration. Hydrogen ions activate nociceptors, which is thought be the reason why these agents cause pain on infiltration. The time taken for the tissue to transform the solution from the ionized to the unionized form could also delay the onset of anesthesia [1-3].

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