Development and validation of a high-performance liquid chromatography-tandem mass spectrometric method for simultaneous determination of bupropion, quetiapine and escitalopram in human plasma

Determination of atomoxetine or escitalopram in human plasma by HPLC: Applications in neuroscience research studies

BACKGROUND

Atomoxetine and escitalopram are potent and selective drugs approved for noradrenergic or serotonergic modulation of neuronal networks in attention-deficit hyperactivity disorder (ADHD) or depression, respectively. High-performance liquid chromatography (HPLC) methods still play an important role in the therapeutic drug monitoring (TDM) of psychopharmacological drugs, and coupled with tandem mass spectrometry are the gold standard for the quantification of drugs in biological matrices, but not available everywhere. The aim of this work was to develop and validate a HPLC method for neuroscientific studies using atomoxetine or escitalopram as a test drug.

MATERIALS AND METHODS

A HPLC method from routine TDM determination of atomoxetine or citalopram in plasma was adapted and validated for use in neuroscientific research. Using photo diode array detection with UV absorption at 205 nm, the variation of internal standard within one chromatographic method enables separate drug monitoring for concentration-controlled explorative studies in healthy humans and patients with Parkinson's disease.

RESULTS

The method described here was found to be linear in the range of 0.002 - 1.4 mg/L for atomoxetine and 0.0012 - 0.197 mg/L for escitalopram, with overall mean intra-day and inter-day imprecision and accuracy bias < 10% for both drugs. The method was successfully applied in concentration-controlled neuroimaging studies in populations of healthy humans and patients with Parkinson's disease.

CONCLUSION

A simple, sensitive, robust HPLC method capable of monitoring escitalopram and atomoxetine is presented and validated, as a useful tool for drug monitoring and the study of pharmacokinetics in neuroscientific study applications.

Simultaneous Quantification of Methotrexate and Its Metabolite 7-Hydroxy-Methotrexate in Human Plasma for Therapeutic Drug Monitoring

Objective

To establish and validate a simple, sensitive, and rapid liquid chromatography tandem mass spectrometry (LC-MS/MS) method for the determination of methotrexate (MTX) and its major metabolite 7-hydroxy-methotrexate (7-OH-MTX) in human plasma.

Method

The chromatographic separation was achieved on a Zorbax C₁₈ column (3.5 μm, 2.1 × 100 mm) using a gradient elution with methanol (phase B) and 0.2% formic acid aqueous solution (phase A). The flow rate was 0.3 mL/min with analytical time of 3.5 min. Mass spectrometry detection was performed in a triple-quadruple tandem mass spectrometer under positive ion mode with the following mass transitions: m/z 455.1/308.1 for MTX, 471.0/324.1 for 7-OH-MTX, and 458.2/311.1 for internal standard. The pretreatment procedure was optimized with dilution after one-step protein precipitation.

Results

The calibration range of methotrexate and 7-OH-MTX was 5.0-10000.0 ng/mL. The intraday and interday precision and accuracy were less than 15% and within ±15% for both analytes. The recovery for MTX and 7-OH-MTX was more than 90% and the matrix effect ranged from 97.90% to 117.60%.

Conclusion

The method was successfully developed and applied to the routine therapeutic drug monitoring of MTX and 7-OH-MTX in human plasma.

Bioequivalence of two quetiapine extended release tablets in Chinese healthy volunteers under fasting and fed conditions and effects of food on pharmacokinetic profiles

Objective

The objectives of this study were to evaluate the bioequivalence of Quesero extended release (Quesero XR) tablets and Seroquel extended release (Seroquel XR) tablets under fasting and fed conditions and to determine the effect of food on the pharmacokinetic (PK) properties of Quesero XR or Seroquel XR in Chinese healthy volunteers.

Methods

A single-site, randomized, open-label, two-period crossover design with a 10-day washout period was conducted in 20 subjects under the fed and fasting studies. A single oral dose of 200 mg Quesero XR or Seroquel XR was given to the subjects after an overnight fast of 10 hours. Blood samples were taken at scheduled time spots from 0 hour pre dose to 36 hours post dose. Plasma concentrations of quetiapine were measured by a validated ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method. The PK parameters were calculated by non-compartment analysis using Phoenix WinNonlin software.

Results

On both conditions, no significant differences were found among the main PK parameters of the two preparations by analysis of variance (P>0.05); the Wilcoxon test of maximum peak plasma concentration (T_max) showed no significant differences (P>0.05); the 90% confidence limit (CL) of lnC_max, lnAUC_0→36, and lnAUC_0→∞ fell within the acceptable range of 80%–125%. As compared with the fasting state, the T_max was advanced and the mean maximum plasma concentration (C_max), AUC_0→36, and AUC_0→∞ were also increased in the fed state; the geometric mean ratio and 90% CI of the main PK parameters fell outside the range of the CIs; analysis of variance showed significant differences in the other PK parameters except for apparent total clearance after oral administration (clearance rate; P<0.05).

Conclusion

The two formulations of Quesero XR and Seroquel XR are bioequivalent under both fasting and fed conditions, and food may affect the PK profiles by increasing the rate and extent of absorption of Quesero XR or Seroquel XR in Chinese healthy volunteers.

Development and validation of a gas chromatography/tandem mass spectrometry method for simultaneous quantitation of several antipsychotics in human plasma and oral fluid

RATIONALE

Antipsychotic drugs are prescription medications used to treat psychotic disorders, such as schizophrenia, schizoaffective disorder, or psychotic depression. With several antipsychotic drugs currently available all over the world, this class of drugs has quickly gained importance in both the clinical and forensic context. This work describes the development and validation of a methodology for the determination of seven antipsychotic drugs in plasma and oral fluid samples.

METHODS

The antipsychotic drugs (chlorpromazine, clozapine, haloperidol, olanzapine, quetiapine, cyamemazine and, levomepromazine) were isolated from 0.2 mL of oral fluid and 0.5 mL of plasma using solid-phase extraction (SPE) following analysis by gas chromatography/tandem mass spectrometry (GC/MS/MS). The method was validated according to the international guidelines in terms of selectivity, linearity, accuracy, precision and recovery.

RESULTS

The procedure was linear within 2-600 ng/mL (plasma) and 2-400 ng/mL (oral fluid), the intervals varying according to the compound; a mean R² value of 0.99 was obtained and the calibrator's accuracy (mean relative error) was within a ±15 % interval for all concentrations. The limits of detection ranged from 1 to 10 ng/mL. Within- and between-run precision and accuracy were acceptable for all studied compounds. The extraction efficiency of the process ranged from 79% to 95%. The method was applied to authentic specimens.

CONCLUSIONS

The described method was proven selective and sensitive for the determination of antipsychotics in low sample volumes using SPE and GC/MS/MS. This method was considered suitable not only for routine analysis of patients undergoing antipsychotic treatment (to evaluate compliance), but also in forensic scenarios where the studied compounds may be involved. To the best of our knowledge, this is the first work that reports the determination of antipsychotic drugs in oral fluid using MS/MS.

Optimized bio-analytical methods development and comparative pharmacokinetic studies of four antidepressants in Egyptian population based on gender difference

The pharmacokinetics (PK) and pharmacodynamics of many oral antidepressants (OADs) vary substantially among different genders and ethnicities. Likewise is their therapeutic effectiveness, time to response and the incidence of adverse drug events. The aim of this study is to compare the PK of four OADs (desvenlafaxine; DSV, venlafaxine; VLX, escitalopram; ESP, and agomelatine; AGT) among Egyptian males and females. In this study, LC-MS/MS methods were developed and validated for determining the four OADs in human plasma. Samples were prepared by liquid-liquid extraction. Chromatographic separation was performed on reversed-phase C₁₈ columns followed by positive-ion electrospray ionization and MS/MS detection. The assays were applied for the assessment of PK parameters in human volunteers (n = 95). The developed methods were linear, accurate, and precise for the determination of DSV, VLX, ESP and AGT with extraction recovery of 90 ± 2.0, 98 ± 1.0, 90 ± 1.3 and 87 ± 4.3%, respectively. OADs levels were successfully measured in subjects' plasma and PK parameters were calculated. A prevalent inter-individual variation in PK of the studied OAD was observed. The PK profile of DSV, VLX or ESP did not vary significantly between male and female subjects (p = 0.07-0.98; confidence level (CL) = 95) while the PK of AGT exhibited a significant gender-based variation in both the C_max and the AUC_∞ (p = 0.047 and 0.0015; CL = 95). Our results highlight the significance of therapeutic drug monitoring of OADs. Further, it indicates the dose adjustment based on gender difference may not be relevant for DSV, VLX and ESP while it may be considered for AGT.