Oxomemazine: A minor metabolite of alimemazine?
Abstract
Oxomemazine and trimeprazine are two structurally related sedative phenothiazines. In cases of trimeprazine intoxication, the concomitant detection of low concentrations of oxomemazine raises the question of co-administration versus a metabolic origin. The aim of this study was to assess whether oxomemazine could be a metabolite of trimeprazine in humans. Trimeprazine metabolism was investigated following a single oral administration of 20 mg in a healthy volunteer, with plasma and urine analyses performed by LC-HRMS. Metabolites were generated in silico and identified based on accurate mass and fragmentation spectra. Pharmaceutical formulations containing trimeprazine were analyzed to exclude a drug-related impurity origin. In addition, clinical and forensic samples in which trimeprazine had been detected were retrospectively reprocessed to search for oxomemazine. Oxomemazine was detected at very low concentrations after trimeprazine administration, accounting for approximately 0.1% of plasma trimeprazine concentrations and up to 2–3% in urine. The main metabolites identified were N-desmethyl-trimeprazine, hydroxylated derivatives, and trimeprazine sulfoxide. Oxomemazine was not detected in the analyzed pharmaceutical products. In clinical and post-mortem cases, oxomemazine was inconsistently detected and always at low proportions relative to trimeprazine. Oxomemazine is a very minor metabolite of trimeprazine in humans. Its detection at low concentrations should not systematically be interpreted as evidence of co-administration, an important consideration for clinical and forensic toxicological interpretation.
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BibTeX
@article{fabresse2026oxomemazine,
title = {{Oxomemazine: A minor metabolite of alimemazine?}},
author = {Nicolas Fabresse and Thomas Gicquel and Marie Carles and Carole Pourriere-Fabiani and Caroline Solas-Chesneau and Anne-Laure Pélissier-Alicot},
journal = {Annales de Toxicologie Analytique},
year = {2026},
month = oct,
doi = {10.1016/j.toxac.2026.03.110},
url = {https://hal.science/hal-05679126v1},
note = {CC BY-NC 4.0},
}
RIS
TY - JOUR
TI - Oxomemazine: A minor metabolite of alimemazine?
AU - Nicolas Fabresse
AU - Thomas Gicquel
AU - Marie Carles
AU - Carole Pourriere-Fabiani
AU - Caroline Solas-Chesneau
AU - Anne-Laure Pélissier-Alicot
PY - 2026
DA - 2026/10/30
JO - Annales de Toxicologie Analytique
DO - 10.1016/j.toxac.2026.03.110
UR - https://hal.science/hal-05679126v1
AB - Oxomemazine and trimeprazine are two structurally related sedative phenothiazines. In cases of trimeprazine intoxication, the concomitant detection of low concentrations of oxomemazine raises the question of co-administration versus a metabolic origin. The aim of this study was to assess whether oxomemazine could be a metabolite of trimeprazine in humans. Trimeprazine metabolism was investigated following a single oral administration of 20 mg in a healthy volunteer, with plasma and urine analyses performed by LC-HRMS. Metabolites were generated in silico and identified based on accurate mass and fragmentation spectra. Pharmaceutical formulations containing trimeprazine were analyzed to exclude a drug-related impurity origin. In addition, clinical and forensic samples in which trimeprazine had been detected were retrospectively reprocessed to search for oxomemazine. Oxomemazine was detected at very low concentrations after trimeprazine administration, accounting for approximately 0.1% of plasma trimeprazine concentrations and up to 2–3% in urine. The main metabolites identified were N-desmethyl-trimeprazine, hydroxylated derivatives, and trimeprazine sulfoxide. Oxomemazine was not detected in the analyzed pharmaceutical products. In clinical and post-mortem cases, oxomemazine was inconsistently detected and always at low proportions relative to trimeprazine. Oxomemazine is a very minor metabolite of trimeprazine in humans. Its detection at low concentrations should not systematically be interpreted as evidence of co-administration, an important consideration for clinical and forensic toxicological interpretation.
SN - 0768-598X
SN - 1961-9480
ER -