Inhibition of the myotoxic activities of three African Bitis venoms (B. rhinoceros, B. arietans and B. nasicornis) by a polyvalent antivenom

A murine model of venom-induced myotoxicity was used to assess the antimyotoxic capacity of a polyvalent antivenom (PAV), rich in F(ab')2 fragments, obtained from horses immunized with Bitis venoms. Intramuscular (i.m.) injection of Bitis rhinoceros, Bitis arietans or Bitis nasicornis into mice induced a time- and dose-dependent increase in plasma CK activity. The area under the plasma CK activity vs. time curve (AUC) between 0 and 48 h was used to quantify the data. Pre-incubation with PAV neutralized the venoms' myotoxicity, in a concentration-dependent manner: 80–100% neutralization occurred when the ratio of the PAV volume to the venom mass was 3-fold that recommended for use in human envenomation. Intravenous administration of PAV 1 h before the i.m. venom injection, afforded significant protection against myotoxicity, especially in the case of B. arietans. An antimyotoxic effect was also observed, albeit reduced, when the PAV treatment was applied 1 h after the venom injection. These data indicate that a PAV developed and manufactured in Brazil protects against the myotoxicity of the venoms of B. rhinoceros, B. arietans or B. nasicornis, which account for a large number of snakebite accidents in the African continent.