Acetaminophen Metabolism in Man, as Determined by High-Resolution Liquid Chromatography

Abstract

Acetaminophen is a commonly used analgesic, available without prescription. Several of its metabolites have heretofore been isolated from physiologic fluids and analytically characterized. In general, the separation methods are complicated, usually requiring extensive sample pretreatment, and do not measure the individual conjugated metabolites. High-resolution anionexchange separation of urinary samples from subjects receiving acetaminophen reveals eight chromatographic peaks, representing seven metabolites and the free drug itself. Metabolites separated include 2-methoxyacetaminophen, its glucuronide and sulfate conjugates, the sulfate conjugate of 2-hydroxyacetaminophen, the glucuronide and sulfate conjugates of acetaminophen, S-(5-acetamido-2-hydroxyphenyl)cysteine, and S-(5-acetamido-2-glucuronosidophenyl)cysteine. Urinary and serum concentrations of the drug and its seven metabolites were determined by high-resolution liquid chromatography as a function of time after two clinically normal men ingested 1950 mg of the drug. Concentrations in urine and serum are compared, and estimated urinary excretion rates are reported for all metabolites except S-(5-acetamido-2-hydroxyphenyl)cysteine. Serum concentrations of the glucuronide were higher than concentrations of the free drug 2 h after the drug was ingested, indicating that solvent-extraction procedures for serum will yield low estimates of total drug unless hydrolysis precedes the extraction step.

Ratios of Acetaminophen Metabolites Identify New Loci of Pharmacogenetic Relevance in a Genome-Wide Association Study

“…Our association of rs165722 (LD r 2 = 0.98 with rs4680) with the ratio of 2-methoxyacetaminophen sulfate and 2-hydroxyacetaminophen sulfate and the biochemical function of COMT as a catechol-O-methyltransferase suggests that the hydroxy-and methoxy-groups are therefore on the three-position, and not in the two-position. Interestingly, there is literature precedence for both structures [18,30], but this GWAS analysis supports the identification as the three-form rather than the two-form. A genetic association of rs1531022 in UGT2B15 with vanillyl mandelate (VMA) has been reported previously [31].…”

“…[17]. Indeed, as we argue in this paper, the position of the hydroxy-and methoxy-groups of hydroxyacetaminophen and methoxyacetaminophen containing molecules is likely to be in the 3-position rather than in the 2-position as initially postulated based on literature precedence [18], i.e., 3-hydroxyacetaminophen sulfate (CAS 1702376-36-0), 3-methoxyacetaminophen sulfate (CAS 60603-12-5), and 3-methoxyacetaminophen glucuronide (52092-55-4), respectively. However, to avoid confusion please note that we did not rename these molecules in the Supplementary Tables and Figures.…”

Assessing Causal Relationship Between Human Blood Metabolites and Five Neurodegenerative Diseases With GWAS Summary Statistics

“…As a result, it is shown that the four associations are still significant, with consistent effects in direction magnitude ( Supplementary Table 4 ). 2-methoxyacetaminophen sulfate, also known as 4-(acetylamino)-3-methoxyphenyl hydrogen sulfate, is a member of the acetamide class and has a role as a drug metabolite ( Mrochek et al, 1974 ; Bozzoni et al, 2016 ). Acetamides have long been recognized to be related to levels of glutathione and N-acetylcysteine, which are known biomarkers for ALS ( Przedborski et al, 1996 ) and other NDDs such as AD ( Saharan and Mandal, 2014 ).…”

Identifying serum metabolite biomarkers for autoimmune diseases: a two-sample mendelian randomization and meta-analysis

“…Exogenous metabolism, as a crucial pathway in the body, plays a vital role in regulating and detoxifying such chemicals to prevent potential harm caused by environmental substances. Specifically, 2-methoxyacetaminophen belongs to the class of acetamides and is a paracetamol sulfate derivative with a methoxy group substitution at position 3 ( 60 ). On the other hand, glycerol 2-phosphate is a bacterial metabolite produced during a metabolic reaction within Escherichia coli ( 61 ).…”