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The scorpion Centruroides limpidus limpidus (C.l.l.) is endemic in México, producing hundreds of accidents in humans; children being one of the most susceptible targets. Few studies reported that severe envenoming by scorpion venom induces cardiac damage and electrolytes abnormalities in children, but the relationship of envenoming severity and toxic blood levels is unknown. The aim of this study was to determine the relationship among clinical status of envenoming, serum electrolyte, electrocardiographic abnormalities, and serum toxin levels in 44 children stung by scorpion over a period of 6 months in the State of Morelos, Mexico. The patients were said to be asymptomatic, when they presented just local symptoms, and were said to be symptomatic when showing local symptoms and at least one systemic symptom. The clinical status was evaluated at the admission at the emergency room of the Hospital, and 30 min after the administration of polyspecific F(ab')2 anti-scorpion therapy to symptomatic children. Forty-one percent of the children were asymptomatic and 59% symptomatic. Potassium and sodium imbalance and an elongation of the QT interval were detected; the rate of hypokalemia was higher in symptomatic than on asymptomatic children (50% and 6%, respectively). Hypokalemia persisted in 19% in symptomatic patients, whereas sodium reached normal levels 30 min after anti-venom therapy. The hypokalemia statistically correlated with elongation of the QT interval. The concentration of the toxic components of C.l.l in serum was significantly higher in symptomatic than asymptomatic children, and the serum levels of the toxic component significantly decreased to undetectable levels after the application of anti-venom therapy. Despite the small size of the sample, this study establishes that severity of envenoming was statistically related to potassium imbalance in serum, QT interval and the concentration of toxic components in serum, which decreased at undetectable levels after specific treatment with the anti-scorpion venom, correlating with clinical disappearance or greatly reduction of symptoms of envenomation., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Envenomations after scorpion stings are a major health problem throughout the world. Their specific treatment is immunotherapy which consists of the injection of specific antibody. In this article, we studied the pharmacokinetics of the toxic fraction of Centruroides limpidus limpidus venom (fraction II) in experimentally envenomed rabbits. After an intravenous injection, fraction II (FII) was rapidly distributed and eliminated from the body (terminal half-life of 1.9 h). When injected subcutaneously, high concentrations of FII were measured in the vascular space rapidly after the injection (Tmax = 1 h) and FII was eliminated with a terminal half-life of 1.8 h, close to that determined after intravenous injection. These observations go along with the rapid onset of clinical symptoms observed after accidental envenomations. To investigate the mechanism of action of antivenom, we examined the effects of the intravenous administration of antivenom (horse F(ab')2 directed against Centruroides venoms) on the pharmacokinetics of FII. Immunotherapy performed 2 h after the experimental envenomation largely increased the area under the concentration time curve of FII compared to that calculated in absence of immunotherapy (13,000 versus 170 ng h ml(-1), respectively). These observations agree with previous findings which showed that specific antibody fragments are able to remove drugs from their site of action and sequester them in the vascular space. These studies provide a powerful tool to determine an excellent procedure for further improvement of immunotherapy.