Determination of 21-hydroxydeflazacort in human plasma by high-performance liquid chromatography/atmospheric pressure chemical ionization tandem mass spectrometry. Application to bioequivalence study.
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 C18 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 < or =5.5% (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 Cmax. Since both the 90% CI for AUC(0-24 h) and Cmax 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.
Ifa
D R
DR
Department of Pharmacology, ICB-University of São Paulo, Brazil. ifa@usp.br
Moraes
M E
ME
Moraes
M O
MO
Santagada
V
V
Caliendo
G
G
de Nucci
G
G
D000293:Adolescent; D000328:Adult; D001274:Atmospheric Pressure; D001774:Blood Chemical Analysis / Q000379:methods* / Q000592:standards; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D005260:Female; D006801:Humans; D007166:Immunosuppressive Agents / Q000097:blood* / Q000493:pharmacokinetics / Q000592:standards; D008297:Male; D013058:Mass Spectrometry / Q000379:methods* / Q000592:standards; D011282:Pregnenediones / Q000097:blood* / Q000493:pharmacokinetics / Q000592:standards; D011786:Quality Control; D012015:Reference Standards; D013810:Therapeutic Equivalency
D007166:Immunosuppressive Agents; D011282:Pregnenediones; C048465:21-deacetyldeflazacort