Pharmacokinetics of
antivenoms has been mainly studied in normal animals, whereas very little is known on pharmacokinetics in envenomed animals. The aim of this study was to compare pharmacokinetic parameters of whole
IgG equine
antivenom in normal rabbits and in rabbits suffering a moderate envenoming by
intramuscular injection of the
venom of the viperid snake Bothriechis lateralis, which induces drastic microvascular alterations. Anti-Micrurus nigrocinctus
antivenom was used, instead of polyvalent (Crotalinae)
antivenom, to avoid the formation of toxin-antibody complexes which may alter
antivenom pharmacokinetics. It was thus possible to study the effect of vascular alterations, i.e.,
edema and
hemorrhage, induced by the
venom on
IgG antivenom distribution and elimination. An ELISA was utilized to quantify equine
IgG antivenom concentration in rabbit serum. In addition, the amount of
IgG antivenom extravasated in injected muscles was also determined. Results indicate that there were no significant differences, between control and envenomed rabbits, in any of the pharmacokinetic parameters investigated, thus suggesting that a moderate envenoming by this viperid species does not alter the pharmacokinetics of
IgG antivenom. A significantly higher amount of
antivenom IgG was observed in muscle from envenomed rabbits than in muscle from control animals. However, this corresponds to a low percentage of the administered
antivenom and, therefore, this increased local extravasation does not have a significant impact in the overall
antivenom pharmacokinetics.