Efficacy of lidocaine 7 %, tetracaine 7 % self-occlusive cream in reducing MAL-cPDT-associated pain in subjects with actinic keratosis: A randomized, single-blind, vehicle-controlled trial (The "3P-Trial")

Abstract

Introduction: Conventional photodynamic therapy (cPDT) is considered a very effective treatment of actinic keratosis (AK) lesions. However, its use is limited by the fact that this procedure could be very painful. The use of topical anesthetics such as tetracaine or lignocaine/prilocaine has shown disappointing results in term of pain reduction. A self-occlusive topical 7% lidocaine/7% tetracaine anesthetic cream (LT-C) approved by the FDA to provide local topical anesthesia in adults undergoing superficial dermatological procedures is available. There are no data regarding its pain reducing effect during cPDT. We perform a prospective, randomized, single-blind, two-center trial (The 3P-Trial) to assess the pain reduction effect of LT-C versus vehicle in subjects with AK undergoing cPDT.

Material and methods: Fifty AK subjects (74 ± 10 years, 32 men, 18 women) with on average 17 lesions were enrolled after their written informed consent. Eight subjects presented also a total of 16 basal cell carcinoma lesions. Twenty-five were randomized to LT-cream, applied 1 h before the Methyl amino levulinate (MAL)-cPDT session and 25 to cream vehicle. The main outcome was the patient-assessed evaluation of pain score during and just after the conclusion of cPDT session (mean of the two values) using a 10-point visual analog scale (VAS). The cPDT session (LED Red light 630 nm) was performed with a duration of 6 ± 2 min with a standard fluence of 37 J/cm2. All treated lesions were prepared by gentle superficial curettage.

Results: All the randomized subjects concluded the trial. The mean ± SD of VAS score in vehicle group was 6.2 ± 2.7 (95 % CI of the mean: 5.0-7.5). In the group treated with LT-cream the VAS score was 3.3 ± 1.9 (95 % CI of the mean: 2.5-4.1). The active cream reduced the VAS score by 47 %. Median values of pain VAS score in the active group was reduced by 60 % in comparison with vehicle group (3.0 vs 7.5). The difference between the two groups was statistically significant (p = 0.0009; Mann-Whitney test).

Discussion: The 3P-trial has demonstrated that the preventive application of the self-occlusive lidocaine 7%-tetracaine 7% cream is very effective in reducing the procedure-associated pain during MAL-cPDT for the treatment of AK lesions.

Keywords: Actinic keratosis; Lidocaine; Photodynamic therapy; Randomized trial; Tetracaine.