A comparison of the reactivating efficacy of a novel bispyridinium oxime K203 with currently available oximes in VX agent-poisoned rats

Figures & data

Figure 1.  Chemical structure of oximes.

Table 1.  LD50 values of oximes following i.m. administration in rats.

Oximes	LD50 (mg/kg) ± 95% confidence limit
K203	326.4 (285.4−373.2)
HI-6	781.3 (738.4−826.6)*
Obidoxime	240.7 (180.5−267.2)
Trimedoxime	258.2 (220.4−267.2)
Methoxime	442.2 (421.2−477.8)*

*Significantly different from K203, obidoxime and trimedoxime at a level of p < 0.05 as determined by one-way ANOVA test.

Table 2.  Percentage of reactivation of VX agent-inhibited ChE by oximes in rat blood and diaphragm in vivo.

Treatment	ChE activity (µkat/L or µkat/kg)
	Blood	Diaphragm
Atropine	6.49 ± 0.73^a	8.97 ± 0.46^a
Atropine + HI-6(% reactivation^b)	15.02 ± 0.99(74.2*^,x)	13.71 ± 3.34(45.4*^,x)
Atropine + obidoxime(% reactivation)	13.70 ± 1.26(62.8*)	10.09 ± 2.10(10.7)
Atropine + trimedoxime(% reactivation)	11.20 ± 0.97(41.1*)	9.17 ± 1.26(1.9)
Atropine + methoxime(% reactivation)	12.17 ± 0.76(49.5*)	9.04 ± 1.79(0.6)
Atropine + K203(% reactivation)	11.77 ± 1.62(46.0*)	9.11 ± 0.38(1.2)

^aMeans ± SD, N = 8. The untreated control value for rat blood ChE activity was 17.99 ± 1.52 µkat/L and for diaphragm ChE activity 19.42 ± 3.62 µkat/kg, ^bPercent reactivation was determined using the ChE activity values: {1– [((saline) – (oxime + atropine))/((saline) – (atropine control))]} × 100.

*Significantly different from the atropine group at a level of p < 0.05, ^xsignificantly different from atropine + K203 group at the level of p < 0.05 as determined by one-way ANOVA test.