Effects of Commercial (pH ˜ 3.5) and Freshly Prepared (pH ˜ 6.5) Lidocaine‐Adrenaline Solutions on Tissue pH

Abstract

Differences in the effects of commercially available, sodium bisulfite-containing (pH 3.5-4), and freshly prepared (pH 6.5) lidocaine-adrenaline solutions on tissue pH and tissue oxygenation were studied experimentally. In rabbits, a 5 x 5 cm area under the panniculum was infiltrated with 0.9% NaCl, plain lidocaine, plain adrenaline or one of the two lidocaine-adrenaline solutions. Tissue pH was measured continuously as well as intermittently in the infiltrated area with monocrystalline antimony needle electrodes. Infiltration of the tissue with the 4 ml volume of a test solution did not seem to induce any significant tissue injury. Tissue pH was decreased for 30 min following plain lidocaine and for 90 min or more following lidocaine-adrenaline infiltration. With the exception of the first few minutes, no significant differences in the effects on tissue pH between commercial and freshly prepared lidocaine-adrenaline solutions could be seen. Tissue hypoxia occurred only following infiltration with plain adrenaline. It may thus be concluded that in spite of the low pH and the O2-reducing properties of commercial lidocaine-adrenaline solutions, a rapid buffering occurs in the tissues. The use of commercial lidocaine-adrenaline solution for local infiltration thus seems as safe as that of freshly prepared lidocaine-adrenaline solutions.

Buffered 4% Articaine as a Primary Buccal Infiltration of the Mandibular First Molar: A Prospective, Randomized, Double-blind Study

“…However, the body intrinsically has an efficient buffering system that maintains tissues at a physiologic pH. The pH conversion buffering process, as reported by Wennberg et al (32), could occur within several minutes. Punnia-Moorthy (33) reported a freshly prepared 2% lignocaine with adrenaline formulation (pH = 5.25) being converted to a pH of 7.17 within 3 minutes after an intradermal injection.…”

Interaction of local anaesthetics with lipid membranes under inflammatory acidic conditions

“…The drug and nerve cell membrane interaction causable under inflammatory conditions does not support the consideration that the acidification is an important factor for the failure of local anaesthesia in inflamed tissues. Rabbit tissues rapidly buffer the excess acidity after infiltration with acidic lidocaine solutions (Wennberg et al, 1982) and such pH buffering capacity increases in the inflamed tissues of rats (Punnia-Moorthy, 1988). These pathophysiological facts may be also disadvantageous for the mechanistic hypothesis based on tissue acidification.…”

“…Normal and inflamed tissues show pH 5.9-7.5 for 3 and 5 min after injection or infiltration of local anaesthetic solutions (Wennberg et al, 1982;Punnia-Moorthy, 1988). Therefore, all the following experiments on pH-dependent membrane interaction were performed in the reaction media of pH 5.9-7.4.…”

Intra-arterial Injection of Metoclopramide, Midazolam, Propofol and Pethidine

“…The "Maxolon" (DermaTech) preparation of metoclopramide used in this case also contains the preservative sodium metabisulfite. This substance has been shown to cause reversible vasoconstriction in humans 24 , but tissue infiltration at the usual concentrations has not reliably been shown to cause tissue damage in animal studies, despite a pH lowering effect 25,26 .…”