Pharmacokinetic studies of scorpion venom before and after antivenom immunotherapy.

The improvement of the immunotherapeutic treatment of envenomations requires a better knowledge of the pharmacological actions of the scorpion venom and of the mechanism of its in vivo neutralization by antivenom. In the present work, we determined the toxicokinetic parameters of the toxic fraction of Androctonus australis garzonii venom in the absence and after antivenom immunotherapy, in experimentally envenomed rabbits. After subcutaneous injection of the scorpion venom, toxins showed a fast and complete resorption from the site of injection associated with a simultaneous distribution in a large extracellular compartment and with an important body clearance. The precocious intravenous injection of an appropriate antivenom dose was shown to induce an immediate, complete and durable neutralization of toxins, as well as their rapid redistribution from the peripheric compartment to the vascular one. On the contrary, the intramuscular injection of the same antivenom dose produced a slower and partial redistribution of toxins, leading to a delayed neutralization of the venom. The intravenous injection of smaller antivenom doses induced transient decreases of circulating toxins, indicating that a minimal antivenom dose has to be administered to allow an efficient and durable neutralization of the venom. We concluded also that this minimal effective dose of antivenom has to be injected precociously, by intravenous route, to achieve an efficient immunotherapy.

1H NMR spectroscopy and GC-MS analysis of alpha-chloralose. Application to two poisoning cases.

Alpha-chloralose, a compound widely used as a rodenticide and in the control of bird pests, is readily available. Two cases of intentional poisoning are reported. Both patients became comatose and presented hypersialorrhea and myoclonal crises in the legs. They were discharged from hospital after several days. As clinical signs of alpha-chloralose poisoning lack specificity, anamnesis might be difficult, particularly in the case of delayed diagnosis. Toxicological analysis is therefore critical, and this article reports the investigation of serum and urine samples by gas chromatography-mass spectrometry (GC-MS) in the electron-impact mode, and by 1H nuclear magnetic resonance (1H NMR) spectroscopy. Non-hydrolyzed urinary samples and those hydrolyzed by beta-glucuronidase were taken into consideration. After acetylation, GC-MS analysis was based on characteristic mass-to-charge ratio values of 272 for alpha-chloralose and 206 for beta-hydroxyethyltheophylline, which was used as internal standard. Characterization of alpha-chloralose species by 1H NMR spectroscopy was performed taking two parameters into account: chemical shift and coupling-constant values. Without any pretreatment, 1H NMR spectroscopy revealed the presence of free (5.50 and 6.15 ppm) and conjugated forms of alpha-chloralose by characteristic resonances of H1 and chloral-type protons, respectively. Quantitative analysis was performed by relative integration of peak areas. Serum alpha-chloralose showed concentrations below the quantitation limit of both methods. In urine samples, the free chemical species rapidly decreased. GC-MS analysis revealed the predominence of conjugation after a beta-glucuronidase hydrolysis step. 1H NMR analysis directly showed that on admission of the first patient, average urinary concentrations were 1.73 mmol/L (535 mg/L) for the free form and 13.72 and 6.25 mmol/L for the two conjugated forms. A later enzymatic treatment confirmed the total concentration of alpha-chloralose chemical species. Analysis of alpha-chloralose in urine by either GC-MS or 1H NMR spectroscopy methods proved to be comparable.