Use of Human Microsomes and Deuterated Substrates: An Alternative Approach for the Identification of Novel Metabolites of Ketamine by Mass Spectrometry
In vitro biosynthesis using pooled human liver microsomes was applied to help identify in vivo metabolites of ketamine by liquid chromatography (LC)-tandem mass spectrometry. Microsomal synthesis produced dehydronorketamine, seven structural isomers of hydroxynorketamine, and at least five structural isomers of hydroxyketamine. To aid identification, stable isotopes of the metabolites were also produced from tetra-deuterated isotopes of ketamine or norketamine as substrates. Five metabolites (three hydroxynorketamine and two hydroxyketamine isomers) gave chromatographically resolved components with product ion spectra indicating the presence of a phenolic group, with phenolic metabolites being further substantiated by selective liquid-liquid extraction after adjustments to the pH. Two glucuronide conjugates of hydroxynorketamine were also identified. Analysis by LC-coupled ion cyclotron resonance mass spectrometry gave unique masses in accordance with the predicted elemental composition. The metabolites, including the phenols, were subsequently confirmed to be present in urine of subjects after oral ketamine administration, as facilitated by the addition of deuterated metabolites generated from the in vitro biosynthesis. To our knowledge, phenolic metabolites of ketamine, including an intact glucuronide conjugate, are here reported for the first time. The use of biologically synthesized deuterated material as an internal chromatographic and mass spectrometric marker is a viable approach to aid in the identification of metabolites. Metabolites that have particular diagnostic value can be selected as candidates for chemical synthesis of standards.
Pharmacology, Toxicology and Pharmaceutical Science
4
6%
Other
12
18%
Unknown
12
18%
Attention Score in Context
Attention Score in Context
This research output has an Altmetric Attention Score of 9. This is our high-level measure of the quality and quantity of online attention that it has received. This Attention Score, as well as the ranking and number of research outputs shown below, was calculated when the research output was last mentioned on 11 January 2022.
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#4,015,788
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Outputs from Drug Metabolism and Disposition
#175
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Outputs of similar age
#13,144
of 102,902 outputs
Outputs of similar age from Drug Metabolism and Disposition
#6
of 22 outputs
Altmetric has tracked 26,434,713 research outputs across all sources so far. Compared to these this one has done well and is in the 83rd percentile: it's in the top 25% of all research outputs ever tracked by Altmetric.
So far Altmetric has tracked 2,523 research outputs from this source. They receive a mean Attention Score of 4.2. This one has done particularly well, scoring higher than 90% of its peers.
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