Automated determination of venlafaxine in human plasma by on-line SPE-LC-MS/MS. Application to a bioequivalence study.
A new automated SPE-LC-ESI-MS/MS method was developed and validated to quantify venlafaxine in human plasma using fluoxetine as an internal standard. The analytes were automatically extracted from plasma by C18 SPE cartridges, separated on a C8 RP column and analyzed by MS in the multiple reaction-monitoring (MRM) mode. The method has a chromatographic run time of 4.0 min and a linear calibration curve over the range of 0.25-200 ng/mL (r >0.997). The between-run precisions, based on the percent RSD for replicate quality controls (0.75; 80, and 200 ng/mL), were < 8.5% for all concentrations. The between-run accuracies, based on the percent relative error, were < 4.0%. This method was successfully employed in a bioequivalence study of two venlafaxine capsule formulations (test formulation from Eurofarma (Brazil) and Efexor XR, reference formulation, from Wyeth-Whitehall, Brazil) in 48 healthy volunteers of both sexes who received a single 150 mg dose of each formulation. More than 3000 samples were analyzed eliminating the analyst's exposure to hazardous organic solvents normally employed in off-line liquid-liquid extractions. The 90% confidence interval (CI) of the individual ratio geometric mean for Test/Reference was 91.6-103.4% for AUC(0-48 h) and 102.2-112.6% for C(max). Since both 90% CI for AUC(0-48 h) and C(max) were included in the 80-125% interval proposed by the US Food and Drug Administration (FDA) and the Brazilian National Health Surveillance Agency (ANVISA), the test formulation was considered bioequivalent to Efexor XR according to both the rate and extent of absorption.
Suenaga
Eunice Mayumi
EM
Núcleo de Bioequivalência e Ensaios Clínicos (NuBEC-SPDM), Universidade Federal de São Paulo, UNIFESP, Brazil.
Ifa
Demian R
DR
Cruz
Alessandro Carvalho
AC
Pereira
Renata
R
Abib
Eduardo
E
Tominga
Mineko
M
Nakaie
Clovis Ryuichi
CR
D002138:Calibration; D003511:Cyclohexanols / Q000097:blood* / Q000737:chemistry*; D006801:Humans; D015394:Molecular Structure; D052616:Solid Phase Extraction / Q000295:instrumentation* / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000295:instrumentation* / Q000379:methods*; D000069470:Venlafaxine Hydrochloride
D003511:Cyclohexanols; D000069470:Venlafaxine Hydrochloride