Identification of the precipitate in alkalinized solutions of mepivacaine and bupivacaine at 37 degrees C.
Commercial and control solutions of bupivacaine (0(.)75%) and mepivacaine (1(.)5%) were alkalinized with bicarbonate until cloudy at room temperature. The solutions were heated to 37 degrees C for 2(.)5 h. The precipitates were filtered, lyophylized and analysed by fast atom bombardment mass spectrometry. Analysis showed the precipitates to be predominantly the free base of the local anaesthetic. The precipitate of the commercial bupivacaine solution also contained a small amount of the hydrochloride salt. The mepivacaine control crystals contained an unknown at molecular weight 528, which may represent a dimer of the free base and hydrochloride salt.
Bigeleisen
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Division of Regional Anaesthesia, University of Rochester School of Medicine & Dentistry, Strong Memorial Hospital, 601 Elmwood Avenue, Box 604, Rochester, NY 14642, U.S.A. Paul_Bigeleisen@urmc.rochester.edu
Wempe
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D000779:Anesthetics, Local / Q000737:chemistry*; D002045:Bupivacaine / Q000737:chemistry*; D011232:Chemical Precipitation; D006863:Hydrogen-Ion Concentration; D013058:Mass Spectrometry; D008619:Mepivacaine / Q000737:chemistry*; D008970:Molecular Weight; D017693:Sodium Bicarbonate / Q000737:chemistry
D000779:Anesthetics, Local; D017693:Sodium Bicarbonate; D008619:Mepivacaine; D002045:Bupivacaine