Detection of new urinary exemestane metabolites by gas chromatography coupled to mass spectrometry

Cavalcanti, Gustavo de Albuquerque; Garrido, Bruno Carius; Leal, Felipe Dias; Padilha, Marina; Torre, Xavier de la; Neto, Francisco Radler de Aquino

doi:10.1016/j.steroids.2011.04.001

Cited by 12 publications

(3 citation statements)

References 14 publications

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“…Phase I metabolites of EXE have been identified in vivo. In addition to the major active phase I metabolite 17 β -dihydro-EXE (17 β -DHE), several minor metabolites with much lower activities are formed, including 6 ξ -hydroxy-6 ξ -hydroxymethylandrosta-1,4-diene-3,17-dione; 6 ξ -hydroxyandrosta-1,4-diene-3,17-dione; 3 ξ -hydroxy-5 ξ -androst-1-ene-6-methylene-17-one; 6 ξ -17 β -dihydroxy-6 ξ -hydroxymethylandrosta-1,4-diene-3-one; and 6 ξ -17 β -dihydroxyandrosta-1,4-diene-3-one ( Evans et al, 1992 ; Cavalcanti Gde et al, 2011 ; de Albuquerque Cavalcanti et al, 2011 ). Cytosolic aldo-keto reductase 1Cs and carbonyl reductase 1 are highly active in EXE reduction to 17 β -DHE in vitro, and several common variants in the cytosolic keto steroid reductases have been associated with altered enzymatic activity in vitro ( Platt et al, 2016 ; Peterson et al, 2017 ).…”

Section: Introductionmentioning

confidence: 99%

Identification and Quantification of Novel Major Metabolites of the Steroidal Aromatase Inhibitor, Exemestane

et al. 2018

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Exemestane (EXE) is an aromatase inhibitor used for the prevention and treatment of estrogen receptor-positive breast cancer. Although the known major metabolic pathway for EXE is reduction to form the active 17b-dihydro-EXE (17b-DHE) and subsequent glucuronidation to 17b-hydroxy-EXE-17-O-b-D-glucuronide (17b-DHE-Gluc), previous studies have suggested that other major metabolites exist for exemestane. In the present study, a liquid chromatography-mass spectrometry (LC-MS) approach was used to acquire accurate mass data in MS E mode, in which precursor ion and fragment ion data were obtained simultaneously to screen novel phase II EXE metabolites in urine specimens from women taking EXE. Two major metabolites predicted to be cysteine conjugates of EXE and 17b-DHE by elemental composition were identified. The structures of the two metabolites were confirmed to be 6-methylcysteinylandrosta-1,4-diene-3,17-dione (6-EXE-cys) and 6-methylcysteinylandrosta-1,4-diene-17b-hydroxy-3-one (6-17b-DHE-cys) after comparison with their chemically synthesized counterparts. Both underwent biosynthesis in vitro in three stepwise enzymatic reactions, with the first involving glutathione conjugation. The cysteine conjugates of EXE and 17b-DHE were subsequently quantified by liquid chromatography-mass spectrometry in the urine and matched plasma samples of 132 subjects taking EXE. The combined 6-EXE-cys plus 6-17b-DHE-cys made up 77% of total EXE metabolites in urine (vs. 1.7%, 0.14%, and 21% for EXE, 17b-DHE, and 17b-DHE-Gluc, respectively) and 35% in plasma (vs. 17%, 12%, and 36% for EXE, 17b-DHE, and 17b-DHE-Gluc, respectively).

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Section: Introductionmentioning

confidence: 99%

Identification and Quantification of Novel Major Metabolites of the Steroidal Aromatase Inhibitor, Exemestane

et al. 2018

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“…[ 9 – 13 ] Recently, the major metabolic pathway of Exe has been delineated; as a reduction of double bond in 17 keto group via aldo-keto reductase (AKR) to form 17β-dihydroexemestane (17DhExe) is a major pathway for exemestane phase I metabolism. [ 14 ] In addition, 17DhExe has been reported to be an active metabolite which is subsequently inactivated by glucuronidation to 17β-dihydroexemestane-17-O-β-D-glucuronide (Exe17Oglu). [ 15 , 16 ] Inactivation of 17DhExe is catalysed by the enzyme UDP-gluconoryltransferase 2B17 (UGT2B17).…”

Section: Introductionmentioning

confidence: 99%

Validation of a Rapid and Sensitive LC-MS/MS Method for Determination of Exemestane and Its Metabolites, 17β-Hydroxyexemestane and 17β-Hydroxyexemestane-17-O-β-D-Glucuronide: Application to Human Pharmacokinetics Study

et al. 2015

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A novel, rapid and sensitive liquid chromatography-tandem mass spectrometric (LC-MS/MS) method was developed and validated for the evaluation of exemestane pharmacokinetics and its metabolites, 17β-dihydroexemestane (active metabolite) and 17β-dihydroexemestane-17-O-β-D-glucuronide (inactive metabolite) in human plasma. Their respective D3 isotopes were used as internal standards. Chromatographic separation of analytes was achieved using Thermo Fisher BDS Hypersil C18 analytic HPLC column (100 × 2.1 mm, 5 μm). The mobile phase was delivered at a rate of 0.5 mL/min by gradient elution with 0.1 % aqueous formic acid and acetonitrile. The column effluents were detected by API 4000 triple quadrupole mass spectrometer using electrospray ionisation (ESI) and monitored by multiple reaction monitoring (MRM) in positive mode. Mass transitions 297 > 121 m/z, 300 > 121 m/z, 299 > 135 m/z, 302 > 135 m/z, 475 > 281 m/z, and 478 > 284 m/z were monitored for exemestane, exemestane-d3, 17β-dihydroexemestane, 17β-dihydroexemestane-d3, 17β-dihydroexemestane-17-O-β-D-glucuronide, and 17β-dihydroexemestane-17-O-β-D-glucuronide-d3 respectively. The assay demonstrated linear ranges of 0.4 – 40.0 ng/mL, for exemestane; and 0.2 – 15.0 ng/mL, for 17β-dihydroexemestane and 17β-dihydroexemestane-17-O-β-D-glucuronide, with coefficient of determination (r2) of > 0.998. The precision (coefficient of variation) were ≤10.7%, 7.7% and 9.5% and the accuracies ranged from 88.8 to 103.1% for exemestane, 98.5 to 106.1% for 17β-dihydroexemestane and 92.0 to 103.2% for 17β-dihydroexemestane-17-O-β-D-glucuronide. The method was successfully applied to a pharmacokinetics/dynamics study in breast cancer patients receiving exemestane 25mg daily orally. For a representative patient, 20.7% of exemestane in plasma was converted into 17β-dihydroexemestane and 29.0% of 17β-dihydroexemestane was inactivated as 17β-dihydroexemestane-17-O-β-D-glucuronide 24 hours after ingestion of exemestane, suggesting that altered 17-dihydroexemestane glucuronidation may play an important role in determining effect of exemestane against breast cancer cells.

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“…Exemestane has been determined by different analytical techniques such as LC-MS [5][6][7][8][9], GC-MS [10], LC-radio immunoassay [11], UVspectrophotometry [12], HPTLC [13] and UPLC [14].…”

Section: Introductionmentioning

confidence: 99%

A Novel Validated Stability-Indicating RP-HPLC Method for the Determination of Exemestane (Steroidal Aromatase Inhibitor)

Mukthinuthalapati¹,

Venkatesh²

2015

J Bioequiv Availab

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Background: Exemestane is an active irreversible lipophilic steroidal aromatase inhibitor used to treat breast cancer in addition to surgery and/or radiation in post-menopausal women. It is a white to slightly yellow crystalline powder with a molecular weight of 296.41. Exemestane is freely soluble in N, N-dimethyl formamide, soluble in methanol, and practically insoluble in water. The present robust RP-HPLC method supports the quantitative analysis of Exemestane in pharmaceutical formulations and for carrying out the forced degradation studies.Methods: A novel stability indicating liquid chromatographic method was developed for the determination of Exemestane using HPLC system of Shimadzu Model CBM-20A/20 Alite, equipped with SPD M20A prominence PDA and Zorbax SB C18 (150 mm × 4.6 mm i.d., 3.5 µm particle size) column. A mixture of sodium acetate buffer and acetonitrile (30:70, v/v) was used as a mobile phase with 1.0 ml/min flow rate and the method was validated as per ICH guidelines. Forced degradation studies were performed in different stress conditions such as acidic, basic, oxidation and thermal degradations. Results:The proposed liquid chromatographic method has shown linearity over a concentration range 0.1-200 μg/ml with regression equation y = 59411x -7316 with correlation coefficient 0.999. During the validation process i.e. the intra-day and inter-day precision studies, accuracy and robustness studies the method has shown an RSD of less than 2.0 %. Exemestane is found to be more stable during all the degradation studies because the percentage of degradation was reported to be less than 10. Conclusions:The proposed method was found to be precise, accurate and robust and it can be applied for the determination of Exemestane in any formulations.

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Detection of new urinary exemestane metabolites by gas chromatography coupled to mass spectrometry

Cited by 12 publications

References 14 publications

Identification and Quantification of Novel Major Metabolites of the Steroidal Aromatase Inhibitor, Exemestane

Identification and Quantification of Novel Major Metabolites of the Steroidal Aromatase Inhibitor, Exemestane

Validation of a Rapid and Sensitive LC-MS/MS Method for Determination of Exemestane and Its Metabolites, 17β-Hydroxyexemestane and 17β-Hydroxyexemestane-17-O-β-D-Glucuronide: Application to Human Pharmacokinetics Study

A Novel Validated Stability-Indicating RP-HPLC Method for the Determination of Exemestane (Steroidal Aromatase Inhibitor)

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