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

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