Decreasing the pain of local anesthesia: a prospective, double-blind comparison of buffered, premixed 1% lidocaine with epinephrine versus 1% lidocaine freshly mixed with epinephrine

Abstract

Background: Local anesthetics are acidic and cause pain on infiltration into the skin. Two methods are commonly used by dermatologists to raise the pH of lidocaine with epinephrine: buffering with sodium bicarbonate or freshly mixing lidocaine with epinephrine on the day of use.

Objective: Our purpose was to compare the pain induced by infiltration of the skin with 1% lidocaine with epinephrine 1:100,000 buffered with sodium bicarbonate (buffered) versus 1% lidocaine freshly mixed with epinephrine (fresh).

Methods: Sixty volunteers were recruited for this prospective, double-blind study. Each subject received an intradermal injection of the buffered solution and the fresh solution. Immediately after each injection subjects rated the pain of infiltration on a 100-mm visual analog scale. The pain scores for the anesthetic solutions were compared using the paired t test.

Results: The pain score for the buffered solution was 18.3 +/- 20.3, and the pain score for the fresh solution was 23.5 +/- 19.1 (P = .0543). Sixty-five percent of subjects felt the fresh solution was more painful than the buffered solution.

Limitations: The results did not reach statistical significance.

Conclusion: In this small study, buffered lidocaine with epinephrine caused less pain on infiltration into the skin than lidocaine freshly mixed with epinephrine, but the results were not statistically significant.