Plasma cocaine and tetracaine levels following application of topical anesthesia in a swine laceration model.
Standard TAC (0.5% tetracaine, 0.05% epinephrine, and 11.8% cocaine) solution is finding increased use as a topical anesthetic for lacerations. The extent of systemic absorption of TAC components and their resultant physiologic effects are unclear. Absorption of cocaine or tetracaine may result in serious toxicity. The investigators hypothesized that there are no measurable plasma cocaine or tetracaine levels after application of TAC in a swine laceration model. After an overnight fast 10 domestic swine underwent tracheostomy, mechanical ventilation, femoral venous, and arterial cannulation. Maintenance anesthesia with intermittent thiopental and pancuronium was provided to maintain stage III anesthesia. Heart rate (HR), arterial pressure (BP), plasma cocaine, and tetracaine levels were measured at intervals for 180 minutes. Five milliliters of TAC was applied for 15 minutes to a standardized facial laceration in experimental swine (n = 5). Randomly labeled plasma samples were placed in vials containing 2% sodium fluoride and 1% potassium oxalate, immediately refrigerated, and analyzed for cocaine and tetracaine using gas chromatography and mass spectroscopy. Significant changes in HR and mean BP, compared with baseline values, were analyzed using Dunnett's multiple range test. Plasma cocaine levels were measurable in all experimental swine after 10 minutes, while no tetracaine was detectable. No significant differences in HR or BP changes were observed between experimental and control subjects. Application of standard TAC solution results in measurable plasma cocaine levels, but not tetracaine. Further studies into anesthetic formulation, as well as timing and technique of application, are required before consensus on optimal emergency departmental use of topical anesthesia can be achieved.
Terndrup
T E
TE
Department of Emergency Medicine, State University of New York Health Science Center, Syracuse 13210.
Mariani
P J
PJ
Walls
H C
HC
Spear
R M
RM
Karatay
C M
CM
D000287:Administration, Topical; D000779:Anesthetics, Local / Q000378:metabolism / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D003042:Cocaine / Q000097:blood* / Q000378:metabolism / Q000494:pharmacology*; D004338:Drug Combinations; D004837:Epinephrine / Q000378:metabolism / Q000494:pharmacology*; D008401:Gas Chromatography-Mass Spectrometry; D006339:Heart Rate / Q000187:drug effects; D012869:Skin Absorption; D013552:Swine; D013748:Tetracaine / Q000097:blood* / Q000378:metabolism / Q000494:pharmacology*; D014947:Wounds and Injuries / Q000378:metabolism
D000779:Anesthetics, Local; D004338:Drug Combinations; D013748:Tetracaine; C034627:TEC solution; D003042:Cocaine; D004837:Epinephrine