Fractional CO2 laser assisted delivery of topical anesthetics: A randomized controlled pilot study

Many dermatological procedures are performed under local anesthesia. Topical anesthesia requires prolonged occlusion and is often insufficient. Infiltration anesthesia is associated with discomfort. Pretreatment with an ablative fractional laser (AFXL) may enhance penetration of topical drugs, including lidocaine. Primary aim of this study was to assess whether AFXL pretreatment enhances the efficacy of two regularly used anesthetics: (i) articain hydrochloride 40 mg/ml + epinephrine 10 μg/ml solution (AHES); (ii) lidocaine 25 mg/g + prilocaine 25 mg/g cream (EMLA cream). Secondary aim was to assess which anesthetic is superior on AFXL pretreated skin.

In 10 healthy subjects, four 1 cm(2) test regions on the back were randomized to [A] AFXL pretreatment (fractional CO2 laser, 5% density, 2.5 mJ/microbeam) + topical application of AHES, [B] AFXL pretreatment + EMLA cream, [C] sham AFXL + AHES, and [D] sham AFXL + EMLA cream. After ten minutes, an AFXL pass (35 mJ/microbeam) was given as pain stimulus at each test region. Pain was scored on a 0-10 visual analogue scale (VAS) after each stimulus.

AFXL pretreatment was not considered painful. Median VAS scores for the pain stimulus were [A] 2.35, [B] 3.15, [C] 4.55, and [D] 4.35. VAS scores were significantly lower for region [A] (AFXL + AHES) versus region [B] (AFXL + EMLA; P < 0.01) and versus region [C] (sham AFXL + AHES; P < 0.01). VAS scores were not significantly different for region [B] (AFXL + EMLA) versus region [D] (sham AFXL + EMLA, P = 0.15).

AFXL pretreatment at very low settings gives significant pain reduction already within ten minutes when AHES is used as topical anesthetic. AHES is clearly superior to EMLA cream on AFXL pretreated skin. Possibly, a liquid solution penetrates more easily into the AFXL channels than a cream. Further research should determine the clinical efficacy of laser assisted topical anesthesia and the exact role of the type of anesthetic, its vehicle and the laser settings.