title: The lethality test used for estimating the potency of antivenoms against Bothrops asper snake venom: pathophysiological mechanisms, prophylactic analgesia, and a surrogate in vitro assay.
abstract: The potency of antivenoms is assessed by analyzing the neutralization of venom-induced lethality, and is expressed as the Median Effective Dose (ED50). The present study was designed to investigate the pathophysiological mechanisms responsible for lethality induced by the venom of Bothrops asper, in the experimental conditions used for the evaluation of the neutralizing potency of antivenoms. Mice injected with 4 LD50s of venom by the intraperitoneal route died within ∼25 min with drastic alterations in the abdominal organs, characterized by hemorrhage, increment in plasma extravasation, and hemoconcentration, thus leading to hypovolemia and cardiovascular collapse. Snake venom metalloproteinases (SVMPs) play a predominat role in lethality, as judged by partial inhibition by the chelating agent CaNa2EDTA. When venom was mixed with antivenom, there was a venom/antivenom ratio at which hemorrhage was significantly reduced, but mice died at later time intervals with evident hemoconcentration, indicating that other components in addition to SVMPs also contribute to plasma extravasation and lethality. Pretreatment with the analgesic tramadol did not affect the outcome of the neutralization test, thus suggesting that prophylactic (precautionary) analgesia can be introduced in this assay. Neutralization of lethality in mice correlated with neutralization of in vitro coagulant activity in human plasma.
authors.affiliation: Instituto Clodomiro Picado, Facultad de Microbiología, Universidad de Costa Rica, 1000 San José, Costa Rica.
authors.forename: Francisco
authors.initials: F
authors.lastname: Chacón
authors.affiliation: Instituto Clodomiro Picado, Facultad de Microbiología, Universidad de Costa Rica, 1000 San José, Costa Rica.
authors.forename: Andrea
authors.initials: A
authors.lastname: Oviedo
authors.affiliation: Instituto Clodomiro Picado, Facultad de Microbiología, Universidad de Costa Rica, 1000 San José, Costa Rica.
authors.forename: Teresa
authors.initials: T
authors.lastname: Escalante
authors.affiliation: Instituto Clodomiro Picado, Facultad de Microbiología, Universidad de Costa Rica, 1000 San José, Costa Rica.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Solano
authors.affiliation: Instituto Clodomiro Picado, Facultad de Microbiología, Universidad de Costa Rica, 1000 San José, Costa Rica.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Rucavado
authors.affiliation: Instituto Clodomiro Picado, Facultad de Microbiología, Universidad de Costa Rica, 1000 San José, Costa Rica. Electronic address: jose.gutierrez@ucr.ac.cr.
authors.forename: José María
authors.initials: JM
authors.lastname: Gutiérrez
mesh_terms: D000005:Abdomen / Q000473:pathology; D000700:Analgesics / Q000627:therapeutic use; D000818:Animals; D000997:Antivenins / Q000494:pharmacology*; D017837:Bothrops; D003435:Crotalid Venoms / Q000037:antagonists & inhibitors* / Q000633:toxicity*; D006470:Hemorrhage / Q000139:chemically induced; D006801:Humans; D066298:In Vitro Techniques; D045726:Metalloproteases / Q000378:metabolism; D051379:Mice; D009500:Neutralization Tests; D012769:Shock / Q000139:chemically induced; D012909:Snake Bites / Q000503:physiopathology*; D014147:Tramadol / Q000627:therapeutic use
chemical_list: D000700:Analgesics; D000997:Antivenins; D003435:Crotalid Venoms; D014147:Tramadol; D045726:Metalloproteases
keywords: Antivenom; Bothrops asper; Hemoconcentraton; Hemorrhage; Lethality; Neutralization