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Acetylcholinesterase reactivators (oximes) are highly hydrophilic compounds. This factor is considered to limit their distribution through the human body, especially into the central nervous system. However, some results contradict this hypothesis and confirm low concentrations of oximes inside the CNS. This study aims to verify oxime penetration through the blood-brain barrier, and into different brain regions. It has been confirmed that oximes can penetrate the BBB after therapeutic dose administration (0.73%, 0.69%, and 0.52% corresponding to obidoxime, HI-6, and new oxime K027). Although the whole brain level of K027 seems to be lower compared with other oximes we have to keep in mind that these numbers represent only a percentage of the concentration found in plasma. So, for more adequate comparison it is essential to have a look at the actual concentration of oximes in the wet brain tissue: 106.6 ± 19.87 ng/g (K027), 49.88 ± 10.21 ng/g (obidoxime) and 86.51 ± 42.37 ng/g (HI-6), where concentration of K027 was one order of magnitude higher than obidoxime and HI-6. In spite of the fact that the distribution of oximes into the CNS is minimal and concentrations differ from section to section, reasonable reactivation should still occur. [ABSTRACT FROM AUTHOR]

Oxime K203 is a new compound designed to be used as an acetylcholinesterase reactivator for the treatment of intoxication following exposure to tabun and certain pesticides. After intramuscular administration of a therapeutic (23 mg/kg) dose, the time-course of plasma concentrations of K203 in rats was determined by HPLC. Maximum concentrations were reached between 4.0 and 60 rain (16.5±2.1 µg/ml in 40 min and 16.6±2.0 in 60 min, respectively) with the concentration being relatively constant during this period. There was no significant effect on the plasma concentration of thiobarbituric acid reactive substances (TBARS) during the administration of K203, indicating an absence of oxidative stress. Indeed, administration of K203 led to a significant increase in low molecular weight antioxidants which could tentatively be interpreted as representing a beneficial effect. [ABSTRACT FROM AUTHOR]

The bimolecular rate constants (ka) of inhibition were determined for cholinesterase in rat blood in vivo and three nerve agents in vitro. They were in the range of 105-106 M·min-1 with the highest value for VX (ka = 8.92 x 106), the next highest for soman (ka = 3.22 x 106) and the lowest for sarin (ka = 0.39 x 106), respectively. The inhibition rate is the same in vitro and in vivo; when the real inhibition in vivo and in vitro is compared, it is possible to assess the concentration of the nerve agent present in the blood stream. When administered intramuscularly it is about 70% of the dose administered. [ABSTRACT FROM AUTHOR]

The hydrolytic efficacy of foam-making blends on the basis of cationic and nonionic surfactants and hydrogen peroxide was tested against the organophosphate Fenitrothion. The length of alkyl chains in both classes of surfactants and their mutual ratios are not parameters which significantly influenced the reactivity of blends. On the other hand, an increase in the hydrogen peroxide concentration induced a significant increase in the velocity of hydrolysis of Fenitrothion. [ABSTRACT FROM AUTHOR]