Autocatalytic Degradation and Stability of Obidoxime

Rubnov, Shai; Shats, Igor; Lévy, Daniel; Amisar, Shai; Schneider, Hava

doi:10.1211/0022357991772024

Cited by 10 publications

(5 citation statements)

References 2 publications

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“…We were able to describe the turnover of MDO by hydrolysis X MDO versus time t in all cases well by X normalM normalD normalO = a ( e c 0 k H t − 1 ) a normale c 0 k normalH t + 1 where a represents the quotient of 4-HBA to MDO, c 0 represents the starting concentration of MDO, and k H represents the rate coefficient of hydrolysis. The formula is a logistic function and describes a limited growth; corresponding expressions have been used in the literature to describe autocatalytic reactions. , …”

Section: Resultsmentioning

confidence: 99%

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Competition between Hydrolysis and Radical Ring-Opening Polymerization of MDO in Water. Who Makes the Race?

et al. 2023

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A major challenge in modern society is the reduction of microplastics created by polymers having stable C–C backbones. The chemistry of radical ring-opening copolymerization of cyclic ketene acetals (CKAs) with vinyl monomers in introducing degradable ester units into the C–C backbone is highly promising. Although the corresponding reaction in an aqueous medium should provide biodegradable primary dispersions, the bottleneck is the hydrolytic instability of CKAs. Therefore, in-depth hydrolysis kinetics of CKA (2-methylene-1,3-dioxepane, MDO) at different pH values and temperatures under homogenous and heterogenous conditions are studied to get a “sweet spot” under which emulsion polymerization of MDO might be possible. Depending on the pH, the hydrolysis of MDO undergoes three different mechanisms with slowed hydrolysis kinetics under alkaline conditions. Besides 4-hydroxy-1-butylacetate (4-HBA), other co-hydrolysis products were detected, leading to the autocatalysis effect. The fast MDO hydrolysis during emulsion copolymerization with vinyl acetate led to the formation of polymers with extremely less incorporation of ring-opened MDO units. Degradation tests of the corresponding emulsion copolymers compared with copolymers prepared in solution confirmed the low incorporation ratio of MDO. The results and discussion presented in this work will be a strong guideline for future emulsion copolymerizations of CKAs.

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Section: Resultsmentioning

confidence: 99%

“…The formula is a logistic function and describes a limited growth; corresponding expressions have been used in the literature to describe autocatalytic reactions. 17,20 With 2 we can calculate the corresponding reaction coefficients (Table 1).…”

mentioning

confidence: 99%

Competition between Hydrolysis and Radical Ring-Opening Polymerization of MDO in Water. Who Makes the Race?

et al. 2023

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“…3.58). Obidoxime (3.253), one such agent, undergoes acid-catalyzed hydrolysis to the mono-and dialdehyde plus hydroxylamine [172]. Because the reaction is a reversible one, it can go to completion in very dilute solutions only.…”

Section: Fig 332 Thismentioning

confidence: 99%

The Biochemistry of Drug Metabolism — An Introduction. Part 3. Reactions of Hydrolysis and Their Enzymes

Testa

Kraemer

2007

ChemInform

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“…Although the chemical stability of monocomponent parenteral formulations containing pralidoxime [ 9 , 10 ], obidoxime [ 11 ], atropine [ 12 ], and midazolam [ 13 , 14 ] has been reported as stable, the combination of many of them in the same autoinjector formulation has never been explored and may lead to physicochemical interactions and a loss of stability. Apart from drug chemical stability in solution, another crucial point to identify is the drug adsorption within the elastomeric gasket materials used to manufacture the autoinjectors.…”

Section: Introductionmentioning

confidence: 99%

Stability of Multicomponent Antidote Parenteral Formulations for Autoinjectors against Chemical War Agents (Neurotoxics)

Rodríguez Fernández,

Hernández,

Anaya

et al. 2024

Pharmaceutics

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Combinations of different drugs are formulated in autoinjectors for parenteral administration against neurotoxic war agents. In this work, the effects on the chemical stability of the following three variables were studied: (i) type of drug combination (pralidoxime, atropine, and midazolam versus obidoxime, atropine, and midazolam); (ii) pH (3 versus 4); and (iii) type of elastomeric sealing material (PH 701/50 C BLACK versus 4023/50 GRAY). Syringes were stored at three different temperatures: 4, 25, and 40 °C. Samples were assayed at different time points to study the physical appearance, drug sorption on the sealing elastomeric materials, and drug content in solution. Midazolam was unstable in all tested experimental conditions. Drug adsorption was observed in both types of sealing elastomeric materials and was significantly (p < 0.01) dependent on the lipophilicity of the drug. The most stable formulation was the combination of pralidoxime and atropine at pH 4 with the elastomeric sealing material 4023/50 GRAY.

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Autocatalytic Degradation and Stability of Obidoxime

Cited by 10 publications

References 2 publications

Competition between Hydrolysis and Radical Ring-Opening Polymerization of MDO in Water. Who Makes the Race?

Competition between Hydrolysis and Radical Ring-Opening Polymerization of MDO in Water. Who Makes the Race?

The Biochemistry of Drug Metabolism — An Introduction. Part 3. Reactions of Hydrolysis and Their Enzymes

Stability of Multicomponent Antidote Parenteral Formulations for Autoinjectors against Chemical War Agents (Neurotoxics)

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