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Tetracaine protects against cocaine lethality in mice
S A Grant1, R S Hoffman, L R Goldfrank
1Department of Emergency Medicine, Long Island Jewish Medical Center, New Hyde Park, New York.
Study Hypothesis:
Tetracaine will enhance cocaine toxicity.
Study Population:
Two hundred forty female Swiss albino mice weighing 27 to 45 g.
Methods:
Intraperitoneal injections of tetracaine and cocaine were given to groups of ten mice each in a controlled, blinded fashion. Either tetracaine or an equal volume of normal saline was given five minutes before one of six incremental doses of cocaine, ranging from 60 to 110 mg/kg. The experiment was repeated twice using two different doses of tetracaine: either an LD10 (40 mg/kg determined from preliminary studies), or one-twentieth of the dose of cocaine (which approximates the ratio used in tetracaine, epinephrine, and cocaine). Lethality was recorded at 24 hours. Lethality between groups was compared with a Wilcoxon sign-rank test.
Results:
Tetracaine reduced cocaine lethality at all doses. This reduction in lethality was statistically significant at both tetracaine doses (P < .05).
Conclusion:
In the mouse, pretreatment with tetracaine significantly decreases cocaine lethality.