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

Abstract

Background: 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. Objectives: 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). Methods: Double-blind, randomized, placebo-controlled, crossover trial (n = 2 × 24) with 4 investigational medicinal products (IMP1-4). Results: 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. Limitations: Results of this trial cannot be generalized to other local anesthetics such as prilocaine, bupivacaine, or ropivacaine, which precipitate with NaHCO3 admixtures. Conclusions: 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.

Pharmacological and clinical implications of local anaesthetic mixtures: a narrative review

“…The risk of precipitation of levobupivacaine is also stated in the drug information leaflet and the medicolegal consequences should be considered [53]. Buffering of lidocaine results in less pain on infiltration [54] and is purported to prolong the duration of action. Buffered lidocaine solutions retained at least 94.7% of the initial concentration of lidocaine and remained clear, colourless and free of precipitate without changes in pH [55].…”

Dermatological Conditions Inducing Acute and Chronic Pain

“…Topical anaesthetics (54,57,85,86): Before using an injectable anaesthetic on the face or perineum Neurotoxins or filler injections Laser Ulcer detersion Music interventions (77,(87)(88)(89): During surgical procedures Lidocaine 5% patch (4,90): For localized neuropathic pain.…”

Spinal Injections

“…The acidic nature of lidocaine required for prolonged storage often causes burning and pain at the injection site during instillation that can be reduced when buffering the anesthetic with sodium bicarbonate. 12 Contrast material should be instilled after needle positioning to confirm needle tip placement and document epidural extension, as well as to exclude errant needle placement, such as within vasculature or the thecal sac. Patients who have sensitivities or allergies to iodinated contrast materials can undergo premedication treatment 13 or receive gadolinium-based contrast as an alternative.…”