Vipera ammodites bites treated with antivenom ViperaTAb®: a case series and pharmacokinetic evaluation

In the southeastern parts of Europe Vipera a. ammodytes and Vipera berus are the only medically important poisonous snakes. Differentiation of their bites based on clinical presentation is very difficult and unreliable. In the past this was not a concern, since snakebites were successfully treated with Viperfav™ (Aventis Pasteur, France) or European viper venom antiserum (Zagreb antivenom) (Institute of Immunology, Croatia) as formulations containing equine F(ab’)2 fragments that are either specific for both venoms, either clinically proved to be safe and effective for the treatment of V. a. ammodytes and V. berus envenomings. However, due to current shortage in ViperfavTM and Zagreb antivenom availability, V. a. ammodytes and V. berus bites have recently been treated with ViperaTAb® (MicroPharm Limited, United Kingdom) composed of ovine Fab fragments as active principle against the venom of V. berus only. Its therapeutical convenience for use against V. a. ammodytes venom-induced toxicity in human has not been described yet, although neutralisation efficacy has been proved preclinically. In view of this for the first time we present cases of several V. a. ammodytes snakebites treated with ViperaTAb® whose pharmacokinetics has been measured and correlated with clinical picture.