Quantification of pralidoxime (2-PAM) in urine by ion pair chromatography-diode array detection: application to in vivo samples from minipig.

Abstract

Pralidoxime (2-PAM) is a monopyridinium oxime used as an antidote for the treatment of poisoning with organophosphorus (OP) compounds, for example, pesticides and nerve agents, reactivating OP-inhibited acetylcholinesterase. However, appropriate dosing and efficacy remains a matter of discussion requiring experimental data. Therefore, we developed and validated an ion pair chromatography-diode array detection (IPC-DAD) method suitable for quantitative analysis of 2-PAM in human and porcine urine. Before injection of 20 µl, urine was acidified with trichloroacetic acid, mixed with internal standard (pyridine-4-aldoxime, 4-PAO), and diluted with IPC solvent yielding a total dilution of 1:49.5 and a 100% recovery. Isocratic separation was carried out at 25 °C on a LiChrospher 60 RP-select B column (125 x 4.0 mm I.D.) using phosphate buffer (7.5 mM Na(2) HPO(4) , 7.5 mM KH(2) PO(4) , pH 2.6) mixed with octanesulfonate (2.5 mM) as ion pair reagent and acetonitrile (6% v/v) as organic modifier (1 ml/min). 2-PAM was detected at 293 nm and 4-PAO at 275 nm. The method is rugged, selective, and characterized by good intra-day and inter-day precision (RSD, 1.3-6.0%) and accuracy (88-100%) with a limit of detection at 4.9 µg/ml, a limit of quantification at 9.8 µg/ml, and a broad calibration range from 4.9-2500 µg/ml. The procedure was applied to urine samples obtained from dimethoate poisoned minipigs receiving 2-PAM therapy (intravenous bolus injection and infusion). Results indicate that 60-80% of infused 2-PAM is rapidly (within 1-2 h) excreted in the urine.

• Authors: Harald John, Michael Eddleston, R Eddie Clutton, Franz Worek, Horst Thiermann
• Journal: Drug testing and analysis (Drug Test Anal) 2012 Mar-Apr Vol. 4 Issue 3-4 Pg. 169-78 ISSN: 1942-7611 [Electronic] England
• PMID: 22102522 (Publication Type: Journal Article, Validation Study)
• Copyright: Copyright © 2011 John Wiley & Sons, Ltd.

Chemical References

• Antidotes
• Cholinesterase Inhibitors
• Cholinesterase Reactivators
• Pralidoxime Compounds
• pralidoxime
• Dimethoate

Topics

• Animals
• Antidotes (analysis)
• Calibration
• Cholinesterase Inhibitors (poisoning)
• Cholinesterase Reactivators (urine)
• Chromatography, High Pressure Liquid (methods)
• Dimethoate (poisoning)
• Humans
• Limit of Detection
• Pralidoxime Compounds (urine)
• Swine