Kinetics of envenomation with Russell's viper (Vipera russelli) venom and of antivenom use in mice.

The kinetics of I125-labelled venom and antivenom of Russell's viper (Vipera russelli) were determined following i.v. administration in mice. The kinetic profiles follow a two-compartment open model with mean distribution half-lives of 15.93 and 15.36 min, and mean elimination half-lives of 8.88 and 5.37 hr for venom and antivenom, respectively. Antivenom follows closely that of venom in its mode of distribution while its elimination is almost twice as fast as that of venom. The steady-state distribution ratio between blood and tissue indicates a greater affinity of the venom to the tissues as compared to antivenom. The primary route of elimination of venom and antivenom or their degraded products was via the urine. Small amounts of trichloroacetic acid-precipitable radioactivity and radioimmunoassayable venom and antivenom recovered in the urine suggest that very little intact venom or antivenom was excreted in the urine. Kinetic studies using unlabelled venom produced values comparable to those obtained with the labelled venom. The results emphasize the importance of maintaining optimal serum antivenom levels, by timely and repeated administration instead of a single bolus dose, in the management of snake envenoming.