A randomized controlled trial comparing Ametop™ with placebo for reducing pain associated with local anesthetic skin infiltration before neuraxial anesthesia in parturients

• We performed a prospective randomized double blind placebo controlled study.
• Ametop gel reduces pain of local anesthetic infiltration by 33% compared to placebo.
• Ametop gel is a potentially useful adjunct for needle phobic parturients undergoing neuraxial block.

BackgroundBetween 10–22% of the general population experience needle phobia. Needle phobic parturients are at increased risk of adverse outcomes. We assessed the efficacy of topical Ametop™ (tetracaine 4%) gel in reducing the pain associated with local anesthetic skin infiltration before neuraxial block in non-laboring women.MethodsThis was a prospective, randomized, double-blind, placebo-controlled study. Ametop™ or placebo was applied to the skin of the lower back at least 20 min before neuraxial block using a standardized technique with 1% lidocaine skin infiltration. The primary outcome was numeric pain score (0–10) 30 s after lidocaine infiltration. Groups were compared using Welch’s t-test.ResultsThirty-six subjects in each group were analyzed. There was a statistically significant difference in the mean (standard deviation) pain score between the Ametop™ and the placebo groups: 2.36 ± 1.80 and 3.51 ± 2.22, respectively (P=0.019). There were no significant adverse events.ConclusionThe mean numeric pain score in the Ametop™ group was 33% lower compared to the placebo group. Topical Ametop™ gel applied at least 20 min before local anesthetic infiltration of the skin prior to neuraxial block in elective cesarean delivery may be a useful adjunct in needle phobic women.