ANTITHROMBIN-III AND ANTIVENOM REVERSAL OF COAGULOPATHY IN RATS ENVENOMATED WITH MALAYAN PIT VIPER VENOM

The therapeutic effects of antithrombin III (AT-III) and unrefined equ ine antivenom in the treatment of coagulopathy induced by Malayan pit viper (Calloselasma rhodostoma) venom were assessed in 42 adult Wistar rats. Following intramuscular venom injection (2 mu g/g body weight), serial blood samples were taken from the femoral vein for measurement of whole blood clotting time and AT-III activity. There was progressi ve depletion of AT-III and blood ceased to clot a mean (S.E.) of 164 ( 8.3) min after venom injection. Coagulopathy was reversed by a high do se antivenom (10 mu g/g) or a lower dose of antivenom (5 mu g/g) in co mbination with AT-III (greater than or equal to 0.1 U/g; P < 0.01) but not 5 mu g/g antivenom or AT-III alone. Following successful treatmen t, the mean plasma AT-III activity remained above 90%. In this animal model, systemic envenomation by the Malayan pit viper causes uncoagula ble blood associated with AT-III consumption. The dose of antivenom re quired to reverse this coagulopathy can be reduced by half by the addi tion of AT-III sufficient to maintain blood concentrations within the normal range.