Buffered lidocaine 1%/epinephrine 1:100,000 with sodium bicarbonate (sodium hydrogen carbonate) in a 3:1 ratio is less painful than a 9:1 ratio: A double-blind, randomized, placebo-controlled, crossover trial

• Published in: Journal of the American Academy of Dermatology 2020-07, Vol.83 (1), p.159-165
• Main Authors: Vent, Alexandra, Surber, Christian, Graf Johansen, Nicole Tracy, Figueiredo, Verena, Schönbächler, Georg, Imhof, Laurence, Buset, Caroline, Hafner, Jürg
• Format: Article
• Language: English
• Subjects: 3:1; admixture; Adult; Anesthesia, Local - adverse effects; Anesthetics, Local - administration & dosage; bicarbonate; Buffers; burning sensation; controlled; Cross-Over Studies; double-blind; Double-Blind Method; epinephrine; Epinephrine - administration & dosage; Female; Humans; lidocaine; Lidocaine - administration & dosage; local anesthesia; Male; Middle Aged; Pain, Procedural - etiology; Pain, Procedural - prevention & control; placebo; randomized; ratio; Sodium Bicarbonate - administration & dosage; sodium hydrogen carbonate; trial; unbuffered; Vasoconstrictor Agents - administration & dosage; Young Adult
• ISSN: 0190-9622; 1097-6787
• DOI: 10.1016/j.jaad.2019.09.088

Neutralizing (buffering) lidocaine 1%/epinephrine 1:100,000 solution (Lido/Epi) with sodium hydrogen carbonate (NaHCO3) (also called sodium bicarbonate) is widely used to reduce burning sensations during infiltration of Lido/Epi. Optimal mixing ratios have not been systematically investigated. To determine whether a Lido/Epi:NaHCO3 mixing ratio of 3:1 (investigational medicinal product 1) causes less pain during infiltration than a mixing ratio of 9:1 (IMP2) or unbuffered Lido/Epi (IMP3). Double-blind, randomized, placebo-controlled, crossover trial (n = 2 × 24) with 4 investigational medicinal products (IMP1-4). The 3:1 mixing ratio was significantly less painful than the 9:1 ratio (P = .044). Unbuffered Lido/Epi was more painful than the buffered Lido/Epi (P = .001 vs IMP1; P = .033 vs IMP2). IMP4 (NaCl 0.9% [placebo]) was more painful than any of the anesthetic solutions (P = .001 vs IMP1; P = .001 vs IMP2; P = .016 vs IMP3). In all cases, the anesthesia was effective for at least 3 hours. Results of this trial cannot be generalized to other local anesthetics such as prilocaine, bupivacaine, or ropivacaine, which precipitate with NaHCO3 admixtures. Lido/Epi-NaHCO3 mixtures effectively reduce burning pain during infiltration. The 3:1 mixing ratio is significantly less painful than the 9:1 ratio. Reported findings are of high practical relevance, given the extensive use of local anesthesia today.