Neutralization of rattlesnake venom toxicites by various compounds

Neutralization of edema, hemorrhage and myonecrosis induced by North American crotalid venoms in simulated first-aid treatments

Venoms of the broad-banded copperhead (Agkistrodon contortrix laticinctus, ACL) and the prairie rattlesnake (Crotalus viridis viridis, CVV), like other crotalid venoms, cause severe local tissue damage such as edema, hemorrhage and myonecrosis. Antivenom therapy is not very effective in neutralizing this local tissue damage, and such observations support the need for an effective first-aid regimen aimed at minimizing local tissue reactions. Some of the local tissue damage induced by these venoms is due to phospholipase A2 myotoxins, and since para-bromophenacyl bromide (p-BPB), an inhibitor of PLA2 catalytic activity, has been shown to inhibit the myotoxic action of two PLA2 myotoxins, we hypothesized that this compound would inhibit part of the myotoxic activity of these crude venoms. For in vitro neutralization experiments, venoms were mixed with combinations of either p-BPB, antivenom or both prior to injection into the muscles of the lower hindlimb of mice. For in vivo neutralization experiments, mice were injected with venom followed by either topical DMSO containing p-BPB or intramuscular injection with saline containing p-BPB. A final set of mice received these same injections followed by i.p. infusions of antivenom to simulate experimental first-aid followed by hospital treatment. In the in vitro neutralization tests, edema was significantly reduced when both antagonists were used together, and there was a highly significant neutralization of ACL- and CVV-generated myonecrosis. In the in vivo neutralization experiments, hemorrhage was significantly reduced when injection of ACL venom was followed by topical DMSO-p-BPB, and myonecrosis was reduced when injection of ACL venom was followed by intramuscular injection of saline-p-BPB. Antivenom significantly reduced edema, hemorrhage and myonecrosis induced by CVV venom, but reduced only myonecrosis induced by ACL venom. Taken together, these results suggest a role for pBPB in the first-aid treatment of snakebite especially when followed by hospital treatment with antivenom.

Effect of diethylenetriaminepentaacetic acid and procaine on hemorrhage induced by rattlesnake venom

Nineteen compounds and seven combinations of compounds were tested for their ability to neutralize the hemorrhagic activity of Crotalus atrox venom in vitro and in vivo. Two compounds and four combinations were effective in reducing hemorrhage in an in vivo test in which the venom was injected before injection of compounds. DTPA plus procaine HCl was the most effective combination and reduced hemorrhage when injected 1, 5, or 15 minutes after injection of venom. DTPA-procaine reduced hemorrhage induced by injection of C. atrox venom into dogs as well as mice. DTPA in combination with procaine did not reduce myonecrosis or lethality resulting from injection of venom into mice, but it could be used in conjunction with antivenin to treat local tissue damage resulting from rattlesnake venom poisoning.