ABSTRACT
A high-throughput and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been developed and validated for the determination of flunarizine in human plasma. Liquid-liquid extraction under acidic conditions was used to extract flunarizine and flunarizine-d8 from 100 µL human plasma. The mean extraction recovery obtained for flunarizine was 98.85% without compromising the sensitivity of the method. The chromatographic separation was performed on Hypersil Gold C18 (50 × 2.1 mm, 3 µm) column using methanol-10 mm ammonium formate, pH 3.0 (90:10, v/v) as the mobile phase. A tandem mass spectrometer (API-5500) equipped with an electrospray ionization source in the positive ion mode was used for detection of flunarizine. Multiple reaction monitoring was selected for quantitation using the transitions, m/z 405.2 â 203.2 for flunarizine and m/z 413.1 â 203.2 for flunarizine-d8. The validated concentration range was established from 0.10 to 100 ng/mL. The accuracy (96.1-103.1%), intra-batch and inter-batch precision (CV ≤ 5.2%) were satisfactory and the drug was stable in human plasma under all tested conditions. The method was used to evaluate the pharmacokinetics of 5 and 10 mg flunarizine tablet formulation in 24 healthy subjects. The pharmacokinetic parameters Cmax and AUC were dose-proportional.
Subject(s)
Chromatography, High Pressure Liquid/methods , Flunarizine/blood , Flunarizine/pharmacokinetics , Tandem Mass Spectrometry/methods , Flunarizine/chemistry , Flunarizine/isolation & purification , High-Throughput Screening Assays , Humans , Linear Models , Liquid-Liquid Extraction , Reproducibility of Results , Sensitivity and SpecificityABSTRACT
Five cyclodextrin derivatives, namely phosphate ester beta-CD, carboxymethyl-beta-CD(CM-beta-CD), bis-[6-oxygen-(beta-carboxymethyl-succinic acid-4-ester)] beta-CD(F-CM-beta-CD), beta-CD polymer(P-beta-CD), carboxymethyl-poly-beta-CD (CD-P-beta-CD), were used as chiral selector for separation of three basic drugs, lobeline, thiopendonesodium, flunarizine by capillary zone electrophoresis (CZE). All the five cyclodextrins have chiral separation ability to lobeline. P-beta-CD and CM-P-beta-CD have chiral recognition to thiopentonesodium and flunarizine. The results indicate that via optimizing separation conditions by varying pH and the concentration of chiral selectors the three racemic drugs could be baseline separated with 2% P-beta-CD or 0.5% CM-P-beta-CD in the buffer of 30 mmol/L Tris-H3PO4. And the best resolution ranging from 4 to 35 with CM-P-beta-CD as chiral additive was obtained within 10 min. The results were much better than those reported in other references.
