Antivenom injection time related effects of Hemiscorpius lepturus scorpion envenomation in rabbits

Hemiscorpius lepturus is the most dangerous scorpion species, endemic in Khuzestan province and other southwestern areas of Iran, causing morbidity and mortality in children and adults. The efficacy of the antivenom for reversal of manifestation caused by venom of this scorpion is a controversial issue. In the present work, H. lepturus venom (1500 µg/kg) was subcutaneously injected into two separate groups of rabbits. Groups 1 and 2 of rabbits received antivenom through i. v route, at 1 and 3 hours after venom injection respectively. Electrocardiograms of all the rabbits recorded during the experiment. In group 1 rabbits blood collection carried out, before and 1 hr after venom injection as well as 3 and 24 hours after antivenom injection. In group2 animals, blood collection was carried out before and 3 hours after venom injection as well as 3 and 24 hours after antivenom injection. Separated serum used for determination of alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), creatine phosphokinase (CPK), creatine kinase isoenzyme, MB (CK-MB), urea، creatinine and Blood Urea Nitrogen (BUN). In group 1 rabbits highly significant (P<0. 01) increase in level of CPK, CK-MB and significant (P<0. 05) increase in level of urea, creatinine and BUN within 3 and 24 hours after antivenom injection was observed. In group 2, highly significant (P<0. 01) elevated level of CPK, CK-MB and significant (P<0. 05) elevated level of urea and creatinine within 3 hours after antivenom injection was observed. Moreover, highly significant (P<0. 01) elevated level of CPK, CKMB and AST and significant (P<0. 05) elevated level of rest of the biochemical parameters within 24 hours after antivenom injection was observed. On the other hand, in these groups, electrocardiogram abnormalities such as ST elevation and sinus bradycardia in limb lead II, were indicator of a mild cardiac injury. In conclusion, results obtained in this study indicate that the efficacy of antivenom for reversal of cytotoxic manifestations occurring after envenomation is time limited. Therefore, it is recommended to use antivenom as early as possible before the occurrence of serious cytotoxic effect on various organs.