Comparison of the onset, depth, and duration of cutaneous anesthesia between topical 10% lidocaine and EMLA creams: a randomized, intraindividual, comparative trial

Abstract

Background

The eutectic mixture of local anesthetics (EMLA) is an effective cutaneous anesthetic, although its application is time consuming and poses a risk of methemoglobinemia. Currently, the efficacy of topical 10% lidocaine cream is unclear.

Objective

To compare the onset, anesthesia depth, and duration of topical 10% lidocaine and EMLA cream.

Methods

The randomized, split-body, comparative trial performed on 40 participants who received a topical 10% lidocaine cream or EMLA on forearms for 15–150 min. Pain was stimulated using a 21-gauge needle insertion and evaluated with the Verbal Pain Score. Adverse effects were recorded.

Results

EMLA conferred significantly better efficacy than 10% lidocaine (p < .001). For acceptable pain at 4-mm depth, the minimal application times were 40.88 and 45.38 min of EMLA and 10% lidocaine creams, respectively. With 60/120-min application, the maximal needle-insertion depths with acceptable pain were 6.61/9.47 mm (EMLA) and 6.01/8.94 mm (10% lidocaine). EMLA’s anesthetic effect showed an early increase after removal which was sustained for 60–90 min. Both creams caused adverse effects, with EMLA showing higher proportions, although the differences were statistically insignificant.

Conclusion

The efficacy of EMLA was superior to 10% lidocaine cream, especially regarding anesthesia onset and duration.

Keywords:

• Topical lidocaine
• eutectic mixture of local anesthetics
• EMLA
• cutaneous anesthesia
• local anesthesia

Acknowledgments

The authors thank Dr Kunlawat Thadanipon for valuable advice. Also, thanks to the study participants and site personnel who helped in the study.

Ethics approval

Reviewed and approved by Srinakharinwirot University IRB; approval SWUEC-517/2563F.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Faculty of Medicine, Srinakharinwirot University under grant number 160/2564