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.

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.