Do changes in body temperature following envenomation by the scorpion Leiurus quinquestriatus influence the course of toxicity?
Four fatal cases following scorpion sting in children are presented. Two victims had rectal temperature above 41 degrees C, the third exhibited a temperature of 40.9 degrees C from the combined effects of scorpion sting and heat stroke, while the fourth was hypothermic. All victims developed hypothermia 48 hr following the sting. The hyperthermia was effectively treated by acetaminophen suppositories, ice packs and water sponges. All victims showed late hypotension that was refractory to dopamine infusion. This was explained by bradykinin released by the venom blocking the dopaminergic receptors. Deterioration of the cortical activity of the victims maintained on mechanical ventilation before the incidence of asystole suggests a central component in the cardiovascular manifestations of envenomation. A. amoreuxi venom was selected as a model for the pharmacokinetic and quantitative toxicological studies since it has no effect on body temperature. In hyperthermic rabbits injected with labelled lethal fraction of A. amoreuxi venom, there was a significant decrease in the elimination half-life, t1/2 beta, the apparent volume of the tissue compartment, Vt, the apparent volume of distribution, Vdss, and the intercompartmental rate constant, kCT. Hypothermic rabbits showed a significant decrease in the apparent first-order elimination rate constant, kd, and a significant increase in the elimination half-life. In both states a higher concentration of the lethal fraction in the blood was calculated. This would explain the rapidity of onset of the electrocardiographic effects and the decreased survival time in both the hyperthermic and hypothermic rabbits injected with venom when compared to normothermic animals. The s.c. LD50 in mice and the i.v. MLD in rats were significantly reduced in the hypothermic mice and hypothermic and hyperthermic rats.
Ismail
M
M
Department of Pharmacology, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia.
Abd-Elsalam
M A
MA
Morad
A M
AM
D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D001831:Body Temperature; D002648:Child; D002675:Child, Preschool; D004562:Electrocardiography; D005260:Female; D006207:Half-Life; D006359:Heat Exhaustion / Q000150:complications; D006801:Humans; D007223:Infant; D008297:Male; D051379:Mice; D011817:Rabbits; D051381:Rats; D012189:Retrospective Studies; D065008:Scorpion Stings / Q000150:complications / Q000378:metabolism*; D012604:Scorpion Venoms / Q000493:pharmacokinetics / Q000506:poisoning* / Q000633:toxicity; D012605:Scorpions
D001786:Blood Glucose; D012604:Scorpion Venoms