A simplified procedure for the analysis of formoterol in human urine by liquid chromatography–electrospray tandem mass spectrometry: Application to the characterization of the metabolic profile and stability of formoterol in urine

Development of a multi‐functional concurrent assay using weak cation‐exchange solid‐phase extraction (WCX‐SPE) and reconstitution with a diluted sample aliquot for anti‐doping analysis

“…Meldonium is known to reduce lactic acid levels, thus enhancing both the energy storage and the endurance of elite athletes . Furthermore, to evaluate the exact concentration of drugs in urine, the conjugated metabolites, such as glucuronides, sulfates, or cysteinyl conjugates, have to be de‐conjugated in order to use the multiclass doping analysis method …”

“…18 Furthermore, to evaluate the exact concentration of drugs in urine, the conjugated metabolites, such as glucuronides, sulfates, or cysteinyl conjugates, have to be de-conjugated in order to use the multiclass doping analysis method. [19][20][21][22][23][24] Ethyl glucuronide (EtG) is considered to be a biomarker for ethanol consumption since high levels of EtG are often correlated with abnormal steroid profiles. In particular, consumption of ethanol is assumed to cause an elevation of the testosterone/epitestosterone ratio and a decrease in the androsterone/testosterone ratio.…”

Effect of non‐prohibited drugs on the phase II metabolic profile of morphine. An in vitro investigation for doping control purposes

“…Different mobile phase composition (ultrapurified water/methanol and ultrapurified water/acetonitrile), pHs (formic acid, acetic acid, ammonium formate and ammonium acetate) and stationary phases (C8, C18, C6‐phenyl, and HILIC) were evaluated in order to obtain a good separation between the 2 glucuronidated metabolites (M3G and M6G) of morphine. Satisfactory separation was obtained using the analytical column type and the LC solvents are those currently used by our laboratory to perform the routine analyses, so method switching is limited only to mobile phase composition stabilization. No significant improvements in both, chromatographic separation and sensitivity, were obtained using more polar stationary phases such as C8 and C6‐phenyl.…”

Enantioselective disposition of (R,R)‐formoterol, (S,S)‐formoterol and their respective glucuronides in urine following single inhaled dosing and application to doping control

“…In terms of mass balance, around half of administered formoterol is recovered in urine as both free drug and metabolites . Following inhaled delivery, formoterol recovered from the urine is mostly in the form of unchanged free drug (40%–60%), as well as an O‐demethylated metabolite (5%–25%), and glucuronide conjugate (25%–40%), the proportion of which may vary significantly between individuals . Glucuronidation occurs at the phenolic position as well as the formation of a benzyl glucuronide .…”

“…5,6 Following inhaled delivery, formoterol recovered from the urine is mostly in the form of unchanged free drug (40%-60%), as well as an Odemethylated metabolite (5%-25%), and glucuronide conjugate (25%-40%), the proportion of which may vary significantly between individuals. 7 Glucuronidation occurs at the phenolic position as well as the formation of a benzyl glucuronide. 6 This glucuronidation metabolism is enantioselective, 8 and is generally susceptible to considerable pharmacogenetic variability.…”