Determination of 21-hydroxydeflazacort in human plasma by high-performance liquid chromatography/atmospheric pressure chemical ionization tandem mass spectrometry. Application to bioequivalence study

✍ Scribed by Ifa, Demian R.; Moraes, Maria E.; Moraes, Manuel O.; Santagada, Vincenzo; Caliendo, Giuseppe; Nucci, Gilberto de

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 85 KB
• Volume: 35
• Category: Article
• ISSN: 1076-5174
• DOI: 10.1002/(sici)1096-9888(200003)35:3<440::aid-jms955>3.0.co;2-8

✦ Synopsis

A liquid chromatographic atmospheric pressure chemical ionization tandem mass spectrometric method is described for the determination of 21-hydroxydeflazacort in human plasma using dexamethasone 21-acetate as an internal standard. The procedure requires a single diethyl ether extraction. After evaporation of the solvent under a nitrogen flow, the analytes are reconstituted in the mobile phase, chromatographed on a C 18 reversed-phase column and analyzed by mass spectrometry via a heated nebulizer interface where they are detected by multiple reaction monitoring. The method has a chromatographic run time of less than 5 min and a linear calibration curve with a range of 1-400 ng ml -1 (r > 0.999). The between-run precision, based on the relative standard deviation for replicate quality controls, was Ä5.5% (10 ng ml -1 ), 1.0% (50 ng ml -1 ) and 2.7% (200 ng ml -1 ). The between-run accuracy was ±7.1, 3.8 and 4.8% for the above concentrations, respectively. This method was employed in a bioequivalence study of two DFZ tablet formulations (Denacen from Marjan Industria e Comercio, Brazil, as a test formulation, and Calcort from Merrell Lepetit, Brazil, as a reference formulation) in 24 healthy volunteers of both sexes who received a single 30 mg dose of each formulation. The study was conducted using an open, randomized, two-period crossover design with a 7-day washout interval. The 90% confidence interval (CI) of the individual geometric mean ratio for Denacen/Calcort was 89.8-109.5% for area under the curve AUC (0 -24 h) and 80.7-98.5% for C max . Since both the 90% CI for AUC (0 -24 h) and C max were included in the 80-125% interval proposed by the US Food and Drug Administration, Denacen was considered bioequivalent to Calcort according to both the rate and extent of absorption.