A Comparative Analysis of Local Anesthetics: Injection Associated Pain and Duration of Anesthesia

Local anesthesia administration is frequently the most painful step of dermatologic surgery. Identification of an anesthetic that minimizes infiltration pain and toxicity while maximizing duration of action would improve both patient satisfaction and procedural safety. This study compared eight local anesthetic solutions to identify the composition that minimizes infiltration pain, maximizes duration of effect, and minimizes amount of local anesthetic needed.

In a double-blinded study, thirty subjects were injected with eight local anesthetic solutions of varied concentrations of lidocaine, epinephrine, benzyl alcohol, and sodium bicarbonate. Infiltration pain was rated by subjects using a visual analog scale and duration of anesthesia was assessed by needle prick sensation every 15 minutes.

Solutions 2, 7, and 8, were significantly less painful (P<0.001), though not statistically different from each other. Two of the three solutions were buffered 10:1 with sodium bicarbonate. Additionally, two of the three contained notably decreased concentrations of lidocaine, 0.091% and 0.083%, than traditionally used in practice. The use of benzyl alcohol did not result in a reduction of reported pain. The duration of action was equal among the solutions regardless of anesthetic concentration.

A solution of 0.091% lidocaine with epinephrine 1:1,100,000 and 0.82% benzyl alcohol reduces medication dose while ensuring maximum patient comfort and, theoretically, increases shelf life. While considered off-label, clinically effective dermal anesthesia may be obtained at a lower concentration of lidocaine and epinephrine than is commonly used, aiding conservative use of local anesthetic, particularly during times of national shortage. J Drugs Dermatol. 2023;22(4): doi:10.36849/JDD.5183 Citation: Moses A, Klager S, Weinstein A, et al. A comparative analysis of local anesthetics: Injection associated pain and duration of anesthesia. J Drugs Dermatol. 2023;22(4):364-368. doi:10.36849/JDD.5183.