Abstract
Antivenomous immunotherapy is still used empirically. To improve the efficacy and safety of immunotherapy, we studied the effects of administering antivenom antibodies (F(ab′)2) on the pharmacokinetics of the Vipera aspis venom in rabbits. Free venom levels were measured by enzyme-linked immunosorbent assay and total concentrations were quantified by measuring the radioactivity of trichloroacetic acid-precipitable radioiodinated venom. The intravenous infusion of 125 mg of antivenom 7 h after intramuscular injection with 700 μg·kg−1 of V. aspis venom produced a redistribution of the venom antigens from the extravascular to the vascular space. Moreover, antivenom antibodies were able to neutralize the totality of venom antigens in the vascular space, because no free plasma venom was detectable by enzyme-linked immunosorbent assay within 15 min after antivenom injection. Similar effects were obtained after injection of 25 mg of antivenom; however, the venom was only partially neutralized with lower doses (5 and 2.5 mg). We further established that intravenous injection is the most efficient route for antivenom administration, and we examined the effects of early and late immunotherapy. Finally, the efficacy of Fab antibodies was compared with that of F(ab′)2; the plasma redistribution and the immunoneutralization of the venom were lower than those induced after injection of the same dose of F(ab′)2. The difference between the effects of F(ab′)2 and Fab could be explained by the differential pharmacokinetics of the two fragments.
Footnotes
-
Send reprint requests to: Dr. Cassian Bon, Unité des Venins, Institut Pasteur, 25 rue du Dr Roux, 75724 Paris, France.
- Abbreviations:
- AUC
- area under the curve
- AUMC
- area under the mean curve
- BSA
- bovine serum albumin
- ELISA
- enzyme-linked immunosorbent assay
- HMWP
- high molecular weight protein
- LMWP
- low molecular weight polypeptide
- PBS
- phosphate buffer saline
- TCA
- trichloroacetic acid
- Vdss
- volume of distribution at steady state
- Received July 8, 1996.
- Accepted December 9, 1996.
- The American Society for Pharmacology and Experimental Therapeutics
JPET articles become freely available 12 months after publication, and remain freely available for 5 years.Non-open access articles that fall outside this five year window are available only to institutional subscribers and current ASPET members, or through the article purchase feature at the bottom of the page.
|