LC-MS/MS identification of trimetazidine metabolites in human urine

Application of liquid chromatography-tandem mass spectrometry (LC-MS/MS) to identify trimetazidine (TMZ) metabolites in human urine has allowed to study known and unknown metabolites [1]. TMZ is predominantly eliminated in the urine with elimination half‐life of 6.5 hours, without cumulative dose effect [2]. Due to its physicochemical properties TMZ and its metabolites can be retained and separated in a C18 stationary phase by reversed phase chromatography [3]. In the presented study, urine samples of one healthy volunteer have been collected after a single dose of TMZ at the baseline and at the following intervals:  0–4h, 4–8h, 8–12h, 12–24h after administration. Chromatographic separation was carried out using UHPLC C18 column combined with a mobile phase gradient starting at 100% aqueous conditions. Accurate mass of possible protonated/ deprotonated ions of TMZ metabolites from the created database was used to look for possible candidates in the full-scan data of the post-administration samples that were not present in the basal samples using TraceFinder software. Full-scan spectra and product ion scan spectra at low and high collision energies (CE 15 eV, 45 eV) of detected possible metabolites were acquired and as a major metabolite was observed intact TMZ with maximum concentration (11,4 μg/ml) in time interval 4-8 h after the administration. Moreover, five minor metabolites have been observed, namely Trimetazidine-N-oxide (M1), N-formyl trimetazidine (M2), Desmethyl-trimetazidine O-sulphate (M3), Desmethyl-trimetazidine O-glucuronide (M4) and Desmethyl-trimetazidine-N-oxide-O-glucuronide (M5), which was the only one up to now unreported . In addition, renal excretion profiles of detected TMZ metabolites have been proposed.