Enzyme-based microassay for accurate determination of soman in blood samples.

Successful medical therapy for nerve agent intoxication requires early diagnosis and treatment. Current clinical diagnostic methods do not permit early or definitive confirmation of intoxication. To improve the chances of successful medical therapy against nerve agent intoxication, a sensitive enzyme-based microassay for rapid and accurate quantification of residual soman levels in blood was developed. The new analytical technique is based on the linear correlation between residual eel acetylcholinesterase activities and the inhibitor concentration. Blood samples were deproteinized with perchloric acid, followed by immediate neutralization after deproteinization. The mixtures were centrifuged at 3000g and the supernatant was directly assayed for soman. The sensitivity of the technique (18-1820 pg/ml blood) is comparable to that attained by GC-FID analysis (250 pg/ml blood). To facilitate routine analysis, the linear range of the assay was optimized to span over a factor of 100 (0.1-10 nM), with a typical correlation factor of at least 0.999 (six standards). The assay accuracy, checked with four different concentrations of soman, was within +/- 10%. The assay capability in monitoring the pharmacokinetic of soman was validated using both in vitro and in vivo rat models.

Pharmacokinetics of HI-6 and atropine in anaesthetized pigs after administration by a new autoinjector.

A newly developed autoinjector (Astra Tech, Sweden) containing 500 mg HI-6 and 2 mg atropine sulphate was tested in anaesthetized normal pigs. The pharmacokinetics and pharmacodynamics of the drugs after administration by the autoinjector were compared with those after conventional needle and syringe delivery intramuscularly and intravenously. Cardiopulmonary parameters were monitored and serum concentrations of oxime, atropine, and acetylcholinesterase were determined in blood samples taken at intervals over a 6 h period postinjection. After injection in anaesthetized pigs, both HI-6 and atropine were absorbed rapidly and completely from the injection site. Therapeutic serum concentrations of HI-6, arbitrarily taken as 4 micrograms mL-1, were reached within 1 min of intravenous and autoinjector administration, and within 5 min of intramuscular injection. The concentrations remained above this level for 3-4 h. There were no significant changes in acetylcholinesterase activity, mean arterial blood pressure, or respiration frequency after injection of HI-6 and atropine sulphate. The heart rates increased significantly after administration of the two drugs (cardioacceleration defined as > or = 5% increase in heart rate), regardless of the technique employed. Our results show that HI-6 and atropine sulphate can be given intramuscularly by the new autoinjector with the same effectiveness and speed as when given intravenously. Irrespective of the injection technique, no overt signs of toxicity were observed at the drug concentrations used.