Lidocaine as antagonist of scorpion poison toxicity from Centruroides limpidus limpidus

BACKGROUND: In Mexico, scorpion poisoning is a health problem because the poison has beta toxins that affect sodium channel activation. Lidocaine decreases ion permeability across the sodium channel acting in the opposite manner. The aim of this work is to determine whether lidocaine antagonized the toxic effect of the crude poison of Centruroides limpidus limpidus. METHODS: One half the lethal dose of the crude poison was determined alone and in the presence of different doses of lidocaine. Experiments with crude poison at LD(50) and crude poison plus lidocaine were carried out after 30, 90, and 180 min of poison inoculation; lung, heart, and brain were obtained for histopathologic analysis. RESULTS: Lidocaine (7 mg/kg dose) increased LD(50) of crude poison (2.95 +/- 0.22 to 6.68 +/- 0.25, p <0.001). Intraalveolar hemorrhage at 30, 90, and 180 min, myocardial edema, and brain congestion at 90 min were significantly reduced (p <0.05). CONCLUSIONS: Lidocaine exerts a protective effect against toxicity of the crude poison of Centruroides limpidus limpidus, probably by its antagonist activity on the sodium channel.