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Document Type

Dissertation - University Access Only

Award Date

2015

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry and Biochemistry

First Advisor

Brian A. Logue

Abstract

Although the current suite of FDA approved antidotes (i.e., sodium nitrite, sodium thiosulfate, and hydroxocobalamin) are effective for treating cyanide poisoning, each antidote individually has major limitations (e.g., large effective dosage or delayed onset of action). To mitigate these current limitations, next-generation cyanide antidotes are being investigated, including sulfanegen and cobinamide (Cbi). Analytical methods capable of detecting these therapeutics individually and simultaneously (for combination therapy) are essential for the development of sulfanegen and Cbi as potential antidotes. Therefore, two liquid chromatography-tandem mass-spectrometry (LC-MS-MS) methods were developed for 1) the analysis of 3-MP (i.e., sulfanegen converts to the active sulfur donor, 3-MP, upon administration into the blood) individually, and 2) the simultaneous analysis of 3-MP and Cbi. Sample preparation of 3-MP for both methods consisted of spiking plasma with an internal standard (13C3-3-MP), precipitation of plasma proteins, and derivatizing with monobromobimane to produce 3-mercaptopyruvate-bimane (3-MPB). Preparation of Cbi involved denaturation of plasma proteins and addition of excess cyanide to produce dicyanocobinamide (Cbi(CN)2) from each Cbi species. The LOD for the 3-MP method was 0.1 μM and the LODs for the 3-MP/Cbi method were 0.5 μM for 3-MP and 0.2 μM for Cbi(CN)2. For the analysis of 3-MP alone, the linear range was 0.5-100 μM. Linear ranges for the simultaneous method were 2-500 μM for 3-MP and 0.5-50 μM for Cbi. Accuracy and precision for the 3-MP method was 100 ± 9% and <7% relative standard deviation (RSD), respectively. The accuracy and precision for the 3-MP with Cbi(CN)2 method were 100 ± 9% and <5.5% RSD for 3-MP. For Cbi(CN)2, the accuracy was 100 ± 13% and <9.5% RSD, respectively. The methods were able to detect 3-MP in rabbits treated with sulfanegen and rats treated with cobinamide. The development of the validated analytical methods for detection of next generation antidotes will facilitate potential FDA approval, and ultimately, use of the therapeutics for cyanide poisoning. To further determine the effectiveness of 3-MP as a cyanide antidote, its pharmacokinetic properties were evaluated in rabbits. Plasma 3-MP concentrations were monitored using liquid chromatography-tandem mass spectrometry following IV administration of sulfanegen to rabbits. Concentrations of 3-MP rapidly increased during sulfanegen administration, indicating rapid absorption and distribution of 3-MP throughout the body. Elimination of 3-MP was also relatively rapid; the calculated halflife of sulfanegen was ~262 mins, which is comparable to current FDA approved cyanide antidotes. A one-compartment model with first-order elimination was used to describe the pharmacokinetic behavior of 3-MP. The results of this study indicate that sulfanegen may be useful to rapidly combat the effects of cyanide poisoning.

Library of Congress Subject Headings

Cyanides Antidotes Liquid chromatography Tandem mass spectrometry

Description

Includes bibliographical references

Format

application/pdf

Number of Pages

109

Publisher

South Dakota State University

Rights

In Copyright - Educational Use Permitted
http://rightsstatements.org/vocab/InC-EDU/1.0/

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