Simultaneous analysis of olanzapine, fluoxetine, and norfluoxetine in human plasma using liquid chromatography-mass spectrometry and its application to a pharmacokinetic study.

Adjunctive therapy with olanzapine and fluoxetine has been shown to be beneficial in treatment-resistant depression and the depressive phase of bipolar disorder. Consensus guidelines issued by the Arbeitsgemeinschaft für Neuropsychopharmakologie und Pharmakopsychiatrie strongly recommend that patients taking olanzapine undergo therapeutic drug monitoring (TDM), and suggest that TDM is useful for patients taking fluoxetine. The aim of the current study was to develop and validate a sensitive, practical, and robust liquid chromatography-tandem mass spectrometry method (LC-MS/MS) for simultaneous determination of olanzapine, fluoxetine, and norfluoxetine in human plasma for routine TDM. Simple liquid-liquid extraction using ethyl acetate was used to extract olanzapine, fluoxetine, and norfluoxetine from 200 μL of pre-basified human plasma. Analytes were separated on an Agilent Eclipse Plus C18 column (4.6 × 100 mm, 5 μm) eluted with a mobile phase consisting of methanol:20 mM ammonium formate buffer (82.5:17.5, v/v), and then quantified using an electrospray ionization source operated in positive ion multiple reaction monitoring mode. The linear range for the analytes was 0.2-25 ng/mL, covering the vast majority of levels encountered in real-life samples. A weighting factor of 1/x2 best fit the calibration curves. The mean internal standard-normalized matrix effects for all analytes were 99.5%-110%. The extraction recoveries were 75%-85% for olanzapine and olanzapine‑d3, and 58%-69% for fluoxetine, norfluoxetine, and their deuterated internal standards. Accuracy and precision values also met the acceptance criteria. The stability assessments showed that QC samples containing the three analytes were stable for at least 1 d at room temperature, 21 d at -70 °C, and through three freeze-thaw cycles. Post-preparation storage for 2 d in the autosampler did not cause obvious degradation of the investigated compounds. This validated high performance LC-MS/MS method was successfully applied to a pharmacokinetic study in healthy male volunteers.

Ni XJ ，Wang ZZ ，Shang DW ，Lu HY ，Zhang M ，Wen YG ... -  《-》

Simultaneous determination of fluoxetine and its major active metabolite norfluoxetine in human plasma by LC-MS/MS using supported liquid extraction.

A rapid, sensitive and selective bioanalytical method was developed for the simultaneous determination of fluoxetine and its primary metabolite norfluoxetine in human plasma. Sample preparation was based on supported liquid extraction (SLE) using methyl tert-butyl ether to extract the analytes from human plasma. Chromatography was performed on a Synergi 4 μ polar-RP column using a fast gradient. The ionization was optimized using ESI (+) and selectivity was achieved by tandem mass spectrometric analysis using MRM functions, m/z 310 → 44 for fluoxetine, m/z 296 → 134 for norfluoxetine and m/z 315 → 44 for fluoxetine-d5 (internal standard). The method is linear over the range of 0.05-20 ng/mL (using a human plasma sample volume of 0.1 mL) with a coefficient determination of greater than 0.999. The method is accurate and precise with intra-batch and inter-batch accuracy (%bias) of < ± 15% and precision (%CV) of <15% for both analytes. A run time of 4 min means a high throughput of samples can be achieved. To our knowledge, this method appears to be the most sensitive one reported so far for the quantitation of fluoxetine and norfluoxetine and can be used for routine therapeutic drug monitoring or pharmacokinetic studies.

Li Y ，Emm T ，Yeleswaram S 《-》

A validated enantioselective assay for the simultaneous quantitation of (R)-, (S)-fluoxetine and (R)-, (S)-norfluoxetine in ovine plasma using liquid chromatography with tandem mass spectrometry (LC/MS/MS).

A liquid chromatography-tandem mass spectrometry (LC/MS/MS) method was developed and validated for the quantitation of (R)-, (S)-fluoxetine, and (R)-, (S)-norfluoxetine in ovine plasma. The analytes were extracted from ovine plasma at a basic pH using a single-step liquid-liquid extraction with methyl-tert-butyl ether. Chromatographic separation of all enantiomers was achieved using an AGP-chiral column with a run time of 10 min. (R)-, (S)-fluoxetine, and (R)-, (S)-norfluoxetine were quantitated at the total ion current (TIC) of multiple reaction monitoring (MRM) transitions of m/z 310.2→44.1, m/z 310.2→147.7 for (R)-, (S)-fluoxetine, and m/z 296.2→30.3, m/z 296.2→133.9 for (R)-, (S)-norfluoxetine. This method was validated for accuracy, precision, linearity, range, limit of quantitation (LOQ), selectivity, recovery, dilution integrity, matrix effect, and evaluation of carry-over. Observed accuracy ranges were as follows: (R)-fluoxetine -8.82 to 3.75%; (S)-fluoxetine -10.8 to 1.46%; (R)-norfluoxetine -7.50 to 0.37% and (S)-norfluoxetine -8.77% to -1.33%. Observed precision ranges were as follows: (R)-fluoxetine 5.29-11.5%; (S)-fluoxetine 3.91-11.1%; (R)-norfluoxetine 4.32-7.67% and (S)-norfluoxetine -8.77% to -1.33%. The calibration curves were weighted (1/X(2), n=4) and observed to be linear for all analytes with the following r(2) values: (R)-fluoxetine ≥ 0.997; (S)-fluoxetine ≥ 0.996; (R)-norfluoxetine ≥ 0.989 and (S)-norfluoxetine ≥ 0.994. The analytical range of the method was 1-500 ng/ml with an LOQ of 1 ng/ml for all analytes, using a sample volume of 300 μL.

Chow TW ，Szeitz A ，Rurak DW ，Riggs KW ... -  《-》

Simultaneous determination of Olanzapine and Fluoxetine in human plasma by LC-MS/MS: its pharmacokinetic application.

A simple and rapid liquid chromatography/tandem mass spectrometry (LC-MS/MS) method has been developed and validated for the simultaneous quantitation of Olanzapine and Fluoxetine in human plasma using Olanzapine-d3 and Fluoxetine-d5 HCl as internal standard (IS), respectively. After solid phase extraction of the plasma samples on Waters Oasis HLB Catridges, Olanzapine, Fluoxetine and IS were chromatographed on Thermo Hypersil Gold C18 (50 mm × 4.6 mmi.d., 5 μm) analytical column with isocratic elution using methanol: 2mM Ammonium acetate buffer (90:10). Quantitation was performed on a triple quadrupole mass spectrometer employing electrospray ionization technique and operating in multiple reaction monitoring (MRM) and positive ion mode with transitions at 313/256 for Olanzapine and 310/148 for Fluoxetine. The total chromatographic run time was 2.0 min and calibration curves were linear over the concentration range of 0.10-20.00 ng/mL for Olanzapine and 0.50-50.00 ng/mL for Fluoxetine. The method was validated for selectivity, sensitivity, recovery, linearity, accuracy and precision and stability studies. The recoveries obtained for the Olanzapine and its IS was ≥87% and Fluoxetine and its IS was ≥91%. Recoveries obtained were consistent and reproducible. Inter-batch and intra-batch coefficient of variation across three validation runs (LLOQ, LQC, MQC1, MQC and HQC) was less than 3.6 for Olanzapine and less than 5.2% for Fluoxetine. The method was successfully applied to a pharmacokinetic study of fixed dose combination of Olanzapine/Fluoxetine in healthy male volunteers.

Bonde SL ，Bhadane RP ，Gaikwad A ，Gavali SR ，Katale DU ，Narendiran AS ... -  《-》

Development of a rapid and sensitive SPE-LC-MS/MS method for the simultaneous estimation of fluoxetine and olanzapine in human plasma.

A high-performance liquid chromatographic assay with tandem mass spectrometric detection was developed to simultaneously quantify fluoxetine and olanzapine in human plasma. The analytes and the internal standard (IS) duloxetine were extracted from 500 μL aliquots of human plasma through solid-phase extraction. Chromatographic separation was achieved in a run time of 4.0 min on a Hypersil Gold C₁₈ column (50 × 4.6 mm, 5 µm) using isocratic mobile phase consisting of acetonitrile-water containing 2% formic acid (70:30, v/v), at a flow-rate of 0.5 mL/min. Detection of analytes and internal standard was performed by electrospray ionization tandem mass spectrometry, operating in positive-ion and multiple reaction monitoring acquisition mode. The protonated precursor to product ion transitions monitored for fluoxetine, olanzapine and IS were m/z 310.01 → 147.69, 313.15 → 256.14 and 298.1 → 153.97, respectively. The method was validated over the concentration range of 1.00-150.20 ng/mL for fluoxetine and 0.12-25.03 ng/mL for olanzapine in human plasma. The intra-batch and inter-batch precision (%CV) across four quality control levels was ≤ 6.28% for both the analytes. In conclusion, a simple and sensitive analytical method was developed and validated in human plasma. This method is suitable for measuring accurate plasma concentration in bioequivalence study and therapeutic drug monitoring as well, following combined administration.

Gopinath S ，Kumar RS ，Alexander S ，Danabal P ... -  《-》