You get a call from the minor surgery clinic for a vial of buffered lidocaine. Since it's not commercially available and would need to be compounded, you contact the provider for details. The provider states he wants buffered lidocaine is less painful on injection and works just as well as the non-buffered lidocaine.

Do you proceed or not? Why or why not?

SELECT  here for discussion

Maybe and maybe not. The subject of buffered lidocaine is somewhat controversial on a number of different issues. Since it's a medication use issue, you may decide to run it through the local Pharmacy and Therapeutics committee (the committee of the medical staff charged with reviewing
medication use issues) for review and comment. I'll try to hit the big issues and point out the plusses and minuses.

Buffering may decrease the pain on injection - Non-buffered lidocaine is somewhat acidic with a pH of 5-6. Lidocaine with epinephrine has an even lower pH (3-4). The buffering to an acidic pH is done by the manufacturer to increase shelf life and solubility but this acidic pH may cause pain on injection. In vivo, upon injection or infiltration of lidocaine (body pH ~7.4) the lidocaine molecule loses it's charge and become neutral, allowing it to penetrate the nerve membrane where it causes it pharmacological effect
of blocking sodium channels and inhibiting the conduction of pain impulses. Buffering probably decreases the pain on injection.  Some small studies seem to validate this theory as measured by patient preference. Another study showed lower pH products do not necessarily cause more pain. A slower rate of injection of non-buffered lidocaine (ex. ~ 30 seconds vice 2-5 seconds). Warming the non-buffered lidocaine solution to ~ 40 degrees C may also reduce pain on injection/infiltration.

One study showed similar infection rates between patients who used buffered lidocaine vs. non-buffered lidocaine.

Solution stability is probably shorter when buffered with sodium bicarbonate. Lidocaine without epinephrine MAY be stable for 1-2 weeks if refrigerated and prepared aseptically (within a laminar flow hood). Lidocaine with epinephrine degrades much more rapidly when buffered. If desired, this should be made immediately before use and discarded afterwards.

REFERENCES (per MICROmedex)

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Bartfield JM, Homer PJ, Ford DT et al: Buffered lidocaine as a local anesthetic: an investigation of shelf life. Ann Am Med 1992; 21:16-19.

Capogna G, Cellano D, Varrassi G et al: Epidural mepivacaine for cesarean section: effect of a pH-adjusted solution. J Clin Anesth 1991; 3:211-215.

Cheney PR, Molzen G & Tandberg D: The effect of pH buffering on reducing the pain associated with subcutaneous infiltration of bupivacaine. Am J Emerg Med 1991; 9:147-148.

Christoph RA, Buchanan L, Begalia K et al: Pain reduction in local anesthetic administration through pH buffering. Ann Emerg Med 1988; 17:117-120.

DiFazio CA, Carron H, Grosslight KR et al: Comparison of pH- adjusted lidocaine solutions for epidural anesthesia. Anesth Analg 1986; 65:760-764.

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Gaggero G, Meyer O, Van Gessel E et al: Alkalinization of lidocaine 2% doses not influence the quality of epidural anaesthesia for elective cesarean section. Can J Anaesth 1995; 42:1080-1084.

Gosteli P, Van Gessel E & Gamulin Z: Effects of pH adjustment and carbonation of lidocaine during epidural anesthesia for foot or ankle surgery. Anesth Analg 1995; 81:104-109.

Holmes HS: Options for painless local anesthesia. Postgrad Med J 1991;89:71-72.

Larson PO, Ragi G, Swanby M et al: Stability of buffered lidocaine and epinephrine used for local anesthesia. J Dermatol Surg Oncol 1991; 17:411-414.

Mader TJ, Playe SJ & Garb JL: Reducing the pain of local anesthetic infiltration: warming and buffering have a synergistic effect. Ann Emerg Med 1994; 23:550-554.

McKay W, Morris R & Mushlin P: Sodium bicarbonate attenuates pain on skin infiltration with lidocaine, with or without epinephrine. Anesth Analg 1987; 66:572-574.

Morris R, McKay W & Mushlin P: Comparison of pain with intradermal and subcutaneous infiltration with various local anesthetic solutions. Anesth Analg 1987; 66:1180-1182.

Murakami CS, Odland PB & Ross BK: buffered local anesthetics and epinephrine degradation. J Dermatol Surg Oncol 1994; 20:192-195.

Orlinsky M, Hudson C, Chan L et al: Pain comparison of unbuffered versus buffered lidocaine in local wound infiltration. J Emerg Med 1992; 10:441-415.

Scarfone RJ, Jasani M & Gracely EJ: Pain of local anesthetics: rate of administration and buffering. Ann Emerg Med 1998; 31:36-40.

Stewart JH, Cole GW & Klein JA: Neutralized lidocaine with epinephrine for local anesthesia. J Dermatol Surg Oncol 1989; 15:1081-1083.