The ability of sheep
antivenoms, consisting of whole
IgG molecules or
Fab fragments, to neutralize local
hemorrhage,
edema and myonecrosis induced by Bothrops asper
venom was comparatively studied in mice. The two
antivenoms were produced from the same batch of hyperimmune plasma and were adjusted to the same neutralizing potency against these effects in assays where
venom and
antivenoms were incubated prior to injection. Thus, if differences are observed in experiments involving independent injection of
venom and
antivenoms, they would depend on the pharmacokinetic profiles of the products. Despite the observation that both
antivenoms neutralized the three effects if preincubated with
venom, neutralization was only partial when
antivenoms were administered i.v. at various time intervals after envenomation. No significant differences were observed between
IgG and Fab
antivenoms concerning neutralization of hemorrhagic and
edema-forming activities, whereas
IgG antivenom was slightly more effective in neutralizing myotoxic activity in experiments involving independent injection of
venom and
antivenom. These results do not support the hypothesis that
Fab fragments are more effective than whole
IgG molecules in the neutralization of locally-acting toxins from B. asper
venom.