What is the significance of using a "buffered" local anesthetic?

Using a buffered local anesthetic primarily enhances the unionized fraction of the drug, which leads to a faster onset of action. In the body, local anesthetics exist in both ionized and unionized states, with the unionized form being able to more readily cross the nerve membrane to exert its effect. By buffering the local anesthetic, the pH of the solution is adjusted, typically making it less acidic. This adjustment increases the proportion of the unionized fraction, allowing the anesthetic to penetrate nerve membranes more efficiently and resulting in quicker pain relief.

The other options do not accurately capture the primary significance of buffering. While buffering can have some effects on the duration of action, the principal benefit is seen in the onset speed. Allergic reactions are primarily linked to the anesthetic itself, rather than the pH adjustment from buffering. Additionally, reducing the pH is counterintuitive to the purpose of buffering, which is to create a more neutral environment conducive to the anesthetic's effectiveness.