Anesthesia · single question
What happens when a local anesthetic (LA) solution is buffered (pH adjusted)?
Show answer and explanation
Correct answer: B. Increases the pH of the LA solution
✓ B) Increases the pH of the LA solution is correct.
Commercial LA solutions are acidic (pH ~3.5–4) to preserve epinephrine and extend shelf life. Buffering (adding sodium bicarbonate) raises the pH toward physiologic levels (~7.4). This increases the proportion of the free base (uncharged) form of the anesthetic, which penetrates nerve membranes more readily, thereby DECREASING (not increasing) onset time and improving efficacy, especially in inflamed tissues.
Commercial LA solutions are acidic (pH ~3.5–4) to preserve epinephrine and extend shelf life. Buffering (adding sodium bicarbonate) raises the pH toward physiologic levels (~7.4). This increases the proportion of the free base (uncharged) form of the anesthetic, which penetrates nerve membranes more readily, thereby DECREASING (not increasing) onset time and improving efficacy, especially in inflamed tissues.