Enantiomeric screening of racemic citalopram and metabolites in human urine by entangled polymer solution capillary electrophoresis: an innovatory robustness/ruggedness study.

Several CE methods have been developed to achieve the chiral separation of citalopram (CIT) and its metabolites demethylcitalopram (DCIT), didemethylcitalopram (DDCIT), and citalopram N-oxide (CIT-NO). All of these compounds were present as racemic mixtures. The best method, which led to the first ever chiral screening of CIT, DCIT, DDCIT, and CIT-NO, involved the use of carboxymethyl-gamma-CD (CM-gamma-CD) and the entangled polymer hydroxypropylmethylcellulose (HPMC) as chiral and selectivity additives, respectively, in the buffer system. In an effort to improve the selectivity and sensitivity of the method, the chemical and instrumental parameters were optimized. The best conditions were short-end anodic hydrodynamic injection (6 s, 0.7 psi); as BGE pH 5, 20 mM phosphate buffer, 0.2% w/v CM-gamma-CD, 0.05% w/v HPMC; voltage of 28 kV with a ramp applied (0.4 s); cartridge temperature of 20 degrees C; detection at 205 nm. In addition, a simple and rapid achiral CE method for the determination of citalopram propionic acid (CIT-PA, the only anionic metabolite of CIT) is also reported for the first time. Prior to the electrophoretic procedure it was necessary to apply an extraction and preconcentration step to obtain analytes from the human urine samples. This was achieved using an optimized SPE process. Moreover, an innovatory experimental and statistical design approach, which involves the simultaneous evaluation of the global robustness and ruggedness effects, was applied. Both of the proposed methods proved to be very useful in the chiral pharmacokinetic screening of CIT and related metabolites in clinical human urine samples.

Sensitive capillary GC-MS-SIM determination of selective serotonin reuptake inhibitors: reliability evaluation by validation and robustness study.

A simple, fast, selective and very sensitive capillary GC-MS method for the simultaneous determination of five antidepressant drugs is described. Fluoxetine, fluvoxamine, citalopram, sertraline and paroxetine belong to the newest and most important drug group termed selective serotonin reuptake inhibitors. Imipramine was used in this method as an internal standard for quantification. Optimum parameters for GC separation were investigated, i.e., flow rate, column head pressure, injector temperature, injection splitless conditions and oven temperature program. MS detection was performed in SIM mode to increase the sensitivity. Stability of the solutions, linear concentration range, accuracy, precision, LOD, LOQ (3.6-41.5 mg/L) and specificity were examined in the presence of excipients for checking the reliability of this method. The robustness was evaluated with a matrix of 15 experiments (seven factors and three levels) using Plackett-Burman fractional factorial experimental design, and Youden and Steiner statistical treatment. The method was applied to the analysis of these antidepressants in nearly all their pharmaceutical formulations, obtaining recoveries between 98.1% and 102.7% with regard to the claimed values.

Enantiomeric determination, validation and robustness studies of racemic citalopram in pharmaceutical formulations by capillary electrophoresis.

A chiral capillary electrophoresis (CE) method has been developed allowing the enantiomeric separation of racemic citalopram (R-(-) and S-(+) citalopram) using as chiral selector carboxymethyl-gamma-cyclodrextrin (CM-gamma-CD). The influence of chemical and instrumental parameters on the separation such as cyclodextrin (CD) and buffer concentrations, buffer pH, voltage, injection pressure, ..., was investigated. Good chiral separation of the racemic mixture was achieved in less than 4 min using a fused-silica capillary and as background electrolyte (BGE) a phosphate buffer solution (20 mM, pH 7) containing 0.15% (w/v) of CM-gamma-CD as chiral selector. The separation was driven in normal polarity mode at 15 degrees C, 30 kV and hydrodynamic injection. In order to validate the method, the stability of the solutions, precision (repeatability, reproducibility and F-Snedecor test), linearity (Lack of Fit and ANOVA tests) accuracy (98-101%), detection and quantitation limits (0.06 and 0.2 mg L(-1), respectively), on a selected analytical placebo, were examined. Besides, a robustness test was performed using the Plackett-Burman fractional factorial experimental design using a matrix of 15 experiments for seven factors (internal parameters) with a statistical treatment suggested by Youden and Steinner. The proposed method is fast, sensitive, inexpensive and, besides, it has been evaluated by means of an extensive validation study and an exhaustive robustness test. The scope of this validated and robust method has been proved in the analysis of four pharmaceutical formulations; two of them (recently available in Spain), which just contained S-(+)-citalopram (escitalopram) as active principle. Recoveries between 101 and 103%, with regard to their nominal contents were obtained. In the other two pharmaceutical ones, the method provided the separation and quantification of both chiral isomers in the existing racemic mixture.