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At least 109 records · Page 6Linked to original sources
PubMed1993

[Characterization of the biological activities of the 'yellow' and 'white' venoms from Crotalus durissus ruruima compared with the Crotalus durissus terrificus venom. Neutralizing activity of Crotalus durissus ruruima antivenins].

The biological activities of 'yellow' and 'white' venom of a rattlesnake Crotalus durissus ruruima Hoge, 1965, found in the savanna-like vegetation (cerrado) of northern Brazil (Roraima) and Venezuela have been studied, and compared to the reference Crotalus durissus terrificus venom. The lethal activity of venoms depended on the inoculation route. The most toxic venom was the white one. The venoms of C. d. terrificus and the yellow of C. d. ruruima had similar lethalities. The yellow venom of C. d. ruruima showed a caseinolytic activity three times higher than that obtained with either the venom of C. d. terrificus or the white one of the C. d. ruruima. Hemorrhagic and necrotic activities were found only in the yellow venom. White and yellow venoms from C. d. ruruima showed a similar action on fibrinogen; this thrombin-like action was greater with C. d. terrificus venom. On histopathological sections local and pulmonary hemorrhage was found only with the yellow venom, but myonecrotic activity was observed with both venoms of C. d. ruruima. Among all antivenoms studied, the anti-bothropic-crotalic was the best at neutralizing hemorrhagic and hemolytic activities. These results suggest that antivenom bothropic-crotalic should be used in the treatment of patients with snakebite by C. d. ruruima: besides its neutralization on lethal activity, it also neutralizes the hemorrhagic activity present in some venoms.

Animals↗
PubMed1998

Pharmacokinetics of 125I-labelled Walterinnesia aegyptia venom and its distribution of the venom and its toxin versus slow absorption and distribution of IGG, F(AB')2 and F(AB) of the antivenin.

A three-compartment open pharmacokinetic model best fitted the data obtained following the i.v. injection of the venom, toxin and the immunoglobulin fractions into either rabbits or mice. The venom and toxin, however, possessed pharmacokinetic characteristics that were significantly different from the immunoglobulin fractions. The venom and toxin had very highly significantly greater disposition rate constants to the shallow and deep tissue compartments and overall elimination rate constant from the central compartment than any of the immunoglobulin fractions. This was reflected in other pharmacokinetic parameters, including highly significantly smaller areas under the curve (AUC) and highly significantly greater volumes of the central compartment (Vc), shallow tissue compartment (Vt shallow), deep tissue compartment (Vt deep) and total body clearance (TBC). In rabbits, F(ab')2 possessed the fastest disposition rate constants and the shortest distribution half-lives, while Fab showed the slowest disposition rate constants and the longest distribution half-lives. The same picture occurred in mice except that the values for Fab were between those of F(ab')2 and IgG. The time needed by the venom and toxin to reach maximum tissue concentration (tmax) ranged between 7 and 15 min and 60 and 180 min for the shallow and deep tissue compartments, respectively. The immunoglobulin fractions required 8-26-fold these times to attain tmax; F(ab')2 was the fastest to achieve its maximal concentration. Following i.m. injection, very fast absorption of venom and toxin took place, with the toxin reaching tmax within 5-20 min and 90% of the injected dose absorbed within 60 min. The bioavailability factor (F) was 0.82 and 0.88 for the venom and toxin, respectively. Fab had an F-value of 0.36 and required 4.3 and 47.4-fold the time taken by the venom and toxin to achieve tmax. The calculated values of F for F(ab')2 and IgG were 0.25 and 0.26, respectively. In the physiologically based pharmacokinetics (PBPK), the venom and toxin reached tmax in the different organs studied very rapidly while the immunoglobulin fractions required several-fold this time to attain tmax. F(ab')2 possessed the highest CPmax, the smallest AUC and the shortest t1/2 beta in the different tissues; Fab had values between F(ab)2 and IgG. It is concluded that F(ab')2 possesses pharmacokinetic characteristics that render it most suitable for use in serotherapy of snake and scorpion envenoming. It should be injected i.v. in doses higher than calculated neutralizing doses to compensate for the slow rate of distribution. Because of slow and incomplete absorption, the i.m. injection of the immunoglobulin fractions would be of little value in serotherapy.

Absorption↗
PubMed1998

Pharmacokinetics of 125I-labelled IgG, F(ab')2 and Fab fractions of scorpion and snake antivenins: merits and potential for therapeutic use.

The immunoglobulin fractions IgG, F(ab')2 and Fab of scorpion and snake antivenoms possess pharmacokinetic characteristics that are significantly different from their respective venoms. The venoms (and their toxins) are several fold faster in their distribution into the tissues than any of the immunoglobulin fraction. In rabbits, F(ab')2 possessed the fastest disposition rate constants and the longest distribution half lives. In the physiologically based pharmacokinetic experiments carried out in mice F(ab')2 possessed the highest Cp(max), smallest AUC and the shortest t1/2beta in the different tissues while Fab had values in between IgG and F(ab')2. Rescue experiments in anaesthetized rats challenged with lethal doses of venoms or toxins and infused with border-line neutralizing doses of antivenoms, showed that rats infused with F(ab')2 completely recovered, those infused with IgG partially rescued and none of the rats infused with Fab survived. It is concluded that F(ab')2 of scorpion and snake antivenoms possess pharmacokinetic characteristics that render it the most suitable for use in serotherapy of scorpion and snake envenoming.

Animals↗