No abstract

Benzocaine (BNZ) and lidocaine (LC) are commonly used topical (spray) anesthetics approved for use in humans. Benzocaine has structural similarities to methemoglobin (MHb)-forming drugs that are current candidates for cyanide prophylaxis, while LC has been reported to increase MHb in man. In this study, we compared MHb and sulfhemoglobin (SHb) production in three groups of Macaques (Chinese rhesus and Indian rhesus (Macaca mulatta) and pig-tailed macaques (Macaca nemestrina)) after exposure to BNZ and LC. Formation of SHb, unlike MHb, is not thought to be reversible and therefore is considered to be of greater toxic significance. Both MHb and SHb levels were measured periodically on a CO-Oximeter. All rhesus macaques (n = 8) were administered an intratracheal/intranasal) dose of 56 mg (low dose) or 280 mg (high dose) of BNZ or 40 mg of LC in a randomized cross-over design (all animals received all three treatments). Pig-tailed macaques (n = 6) were given an intranasal dose of 56 mg of BNZ and 40 mg of LC. As no differences in the peak MHb or time to peak (mean +/- SD) were observed among the three macaque subspecies, the data were pooled. Lidocaine did not cause MHb or SHb formation above baseline in any monkey. In contrast, all monkeys (n = 14) had a significant elevation in peak MHb formation after 56 mg of BNZ, which ranged from 4.0% to 19.4% with an average of 8.6 +/- 4.0% (mean +/- SD), with peak MHb levels reached at 30 min.(ABSTRACT TRUNCATED AT 250 WORDS)

Sulfur mustard (HD) is a potent vesicating agent of military importance, with known radiomimetic properties. The euthymic hairless guinea pig (EHGP) (Cavia porcellus) is emerging as the animal model of choice for cutaneous HD study. With elucidation of the systemic effects, we may better utilize this animal for all HD toxicity work. To this end, studies were conducted to determine the definitive median lethal dose (MLD) of subcutaneously applied sulfur mustard (HD) in the EHGP, and to correlate the induced hematological changes. Eight groups of two animals each were dosed at 0.3 log intervals from an extrapolated expected dose, deriving a tentative mean around which five groups of six animals each were dosed at 0.1 log intervals, resulting in a definitive MLD of 48.17 mg kg(-1). Sulfur mustard was then administered to seven groups of six animals each at a dose of 30 mg kg(-1) and hematology performed. Significant leukocyte count suppression was found to occur on days 4, 5 and 6, following a leukocyte elevation on day 1 after exposure. Serum potassium levels were found to be elevated all 7 days after HD exposure. Establishing the MLD for subcutaneously applied HD and the pattern of induced leukocyte suppression allows for more definitive evaluation of successful toxicity counter-measures.

Hypochliorie soilutions are thought to be efficacious when used to topi.cally dft-ontaminaise intact skin. However, lb~w -studios havo exarn-ined the efficacy of decontarninatiOn of chrmacally contamninated wounds. Therefore, we cornpafed the decontamination efficacy of sodium hypochlcinte (0 5% and 2 5% solutions), calcium hyoochlonle (0 5% and 2 5% soluttions) and Stente water to untreated controls in wounds exposed to sultur mustard (HO). Anesthetized euthymic hairles guinea pigs (EHGP) (n--6) were exposed tn 0 4 LD50 HO in a hA-thickntss 8 mm surgical bmop~sy skin deflect (ioe wound) Each animal was subsequenstfy ocantamtnoted, after a twO-minuto intra-wound4 exposure to iqjuid HD, with~ Oon Ot the dtecontamrination solutions Oirontamination etficacy was determiined by the visual grad-mg of the HOtraumatized wound lesion and by comparison of !he exoected HO1-induced leukocyte supprssionLeikcicyte supprwgoon wmev iricrnsisteril in alt animnals, theOreor, the visual grading was the only v~iable evaluation method No signiticant dfl"jri'ncos were rAbsonipj amrong wouinds decontaiminated w~1h any of tho noilutons However. the Okn surrounding undecontamiruited ibul sexposed) control animails .khowed the 'esil-votual ;:-.vhotoqy The lesions induced follonwing decontamsinaton are preisume.,d to be due to the mpc~onv-cAl flushing of HO oo-to the peni-lestioiial ikin, or bry chemical damAqe induced by the %Lcution, or H0t-solution intetraction Further studies are requireod to bast deineatte the optimal deconlaminnatiton procosi for HO cor'taminittad wounds 94-07965CC0VENT PART NOTICE

Introduction: Many substances that form methemoglobin (MHb) effectively counter cyanide (CN) toxicity. Although MHb formers are generally applied as treatments for CN poisoning, it has been proposed that a stable, long-acting MHb former could serve as a CN pretreatment. Using this rationale, the 8-aminoquinoline WR242511, a potent long-lasting MHb former in rodents and beagle dogs, was studied in the rhesus monkey for advanced development as a potential CN pretreatment.Methods: In this study, WR242511 was administered intravenously (IV) in 2 female and 4 male rhesus monkeys in doses of 3.5 and/or 7.0 mg/kg; a single male also received WR242511 orally (PO) at 7.0 mg/kg. Health status and MHb levels were monitored following exposure.Results: The selected doses of WR242511, which produced significant methemoglobinemia in beagle dogs in earlier studies conducted elsewhere, produced very little MHb (mean Ͻ2.0%) in the rhesus monkey. Furthermore, transient hemoglobinuria was noted approximately 60 minutes postinjection of WR242511 (3.5 or 7.0 mg/kg), and 2 lethalities occurred (one IV and one PO) following the 7.0 mg/kg dose. Myoglobinuria was also observed following the 7.0 mg/kg dose. Histopathology analyses in the 2 animals that died revealed liver and kidney toxicity, with greater severity in the orally-treated animal.Conclusions: These data demonstrate direct and/or indirect drug-induced toxicity. It is concluded that WR242511 should not be pursued as a pretreatment for CN poisoning unless the anti-CN characteristics of this compound can be successfully dissociated from those producing undesirable toxicity.