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Optimal Mixing Ratio Reduces Pain During Lido/Epi Injection

While mixing lidocaine 1% and epinephrine 1:100,000 (Lido/Epi) solutions with sodium hydrogen carbonate (NaHCO3) reduces burning pain during infiltration, findings from a recent study suggested a 3:1 mixing ratio was associated with significantly less pain.

In the randomized, placebo-controlled study, the researchers compared pain during injection between 4 medicinal products (IMP1-4), which included a 3:1 mixing ratio of Lido/Epi-NaHCO3 (IMP1), a 9:1 mixing ratio (IMP2), unbuffered Lido/Epi (IMP3), or placebo (NaCl 0.9% [IMP4]).
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The researchers found the 3:1 mixing ratio was significantly less painful compared with the 9:1 ratio. Unbuffered Lido/Epi was more painful compared with buffered Lido/Epi, but IMP4 was more painful compared with any of the anesthetic solutions, they added. In all cases, the anesthesia was effective for at least 3 hours, the researchers said.

“Reported findings are of high practical relevance given the extensive use of local anesthesia today,” they concluded. However, the “results of this trial cannot be transferred to other local anesthetics such as prilocaine, bupivacaine, or ropivacaine which precipitate with NaHCO3 admixtures.”


Vent A, Surber C, Graf Johansen NT, et al. Buffered lidocaine 1%, epinephrine 1:100'000 with sodium bicarbonate (hydrogen carbonate) in a 3:1 ratio is less painful than a 9:1 ratio: A double-blind, randomized, placebo-controlled, crossover trial [published online January 17, 2020]. J Am Acad Dermatol. doi:10.1016/j.jaad.2019.09.088



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