Quantification of 4 antidepressants and a metabolite by LC–MS for therapeutic drug monitoring

An in-depth analysis of four classes of antidepressants quantification from human serum using LC-MS/MS

Depression is a growing global crisis, with females at a higher rate of diagnosis than males. While the percentage of patients on prescribed antidepressants have tripled over the last two decades, we are still at a crossroad where the discrepancy lies between finding a drug to suit a patient and monitoring the abundance of it in the body to prevent unwanted side effects. Liquid Chromatography tandem mass spectrometry (LC-MS/MS) has garnered the attention of clinicians as a technique to accurately monitor therapeutic drugs in human serum with high specificity and accuracy. This may be a potential solution, but the challenge persists in the realm of sample preparation, where a method is automatable. We have developed and validated an LC-MS/MS-based assay for simultaneous quantification of 4 different classes of commonly prescribed antidepressants in women that is automated using a JANUS G3 Robotic Liquid Handler. Our method utilizes a simple sample preparation technique, utilizing only 20 μL of a serum sample, to accurately measure Bupropion, Citalopram, Desipramine, Imipramine, Olanzapine, Sertraline and Vilazodone across a range of 1.0 to 230 ng/mL. Our method exhibits a linearity of R2 ≥ 0.99 when detected in MRM mode and % CV of ≤ 20% for all analytes across the board. In addition, we have designed a prototype that can be utilized at a clinical mass spectrometry lab and assessed the long-term use of this prototype using an accelerated stability study. Overall, our developed method has the potential to be translated to clinical settings to monitor postpartum depression for a large number of patient samples using automation.

Determination of hydroxybupropion in human serum for routine therapeutic drug monitoring in psychiatry: A tool for dose-individualization in treatment with bupropion

Therapeutic drug monitoring (TDM) has become a clinical routine in psychiatry. Nevertheless, for bupropion there is only one method available that is suitable for routine use. However, it involves a complex sample clean-up. Owing to the instability of bupropion in serum, the main and active metabolite hydroxybupropion was chosen as the target substance. Therefore, a simple and robust high-performance liquid chromatography method for the quantification of hydroxybupropion in serum was developed and validated. A volume of 30 μL serum was used for easy sample clean-up, based on protein precipitation with acetonitrile followed by online solid-phase extraction. As hydroxybupropion was present in high serum concentrations, UV detection was possible. Owing to the commonly available instrumentation, the method could easily be integrated in routine TDM. The newly developed method was validated following the guidelines for bioanalytical method validation of the European Medicines Agency and US Food and Drug Administration. The lower limit of quantification was 100 ng/mL (0.391 μm) and linearity was shown between 100 and 2500 ng/mL. Intraday and interday precision ranged from 1.17 to 6.79% and from 6.07 to 9.41%, respectively. Intraday and interday accuracy ranged from 89.97 to 110.86% and from 95.05 to 101.2%. The method was shown to be selective, accurate and precise. Additionally, the method was successfully implemented in the therapeutic drug monitoring laboratory of the Department of Psychiatry, Psychosomatics and Psychotherapy at the University Hospital of Würzburg, Germany. Six months of routine analysis showed a rather low correlation between applied dose and serum concentration and therefore the necessity of TDM for dose-individualization in the treatment with bupropion.

Juvenile rat and pediatric trazodone studies: how to gain extra sensitivity to overcome bioanalytical challenges

AIM

Trazodone (TZD) is used for the treatment of depression in adults and, off-label, as a sleep medication in adult and pediatric populations. The off-label use is well documented, however further clinical studies are needed to confirm its efficacy and safety for the treatment of sleep disorders. In this scenario, we developed a bioanalytical method to quantify low TZD concentrations in samples collected by capillary microsampling (CMS) to support dose finding, Good Laboratory Practice juvenile rat toxicokinetic and upcoming pediatric studies.

METHODOLOGY

A method using only 8 μl of plasma was developed and successfully used for analyzing CMS samples from juvenile rats throughout toxicokinetic study.

CONCLUSION

By harmoniously maximizing each analytical step, we achieved a sensitive method to quantify TZD in CMS samples.

Use of high-pH (basic/alkaline) mobile phases for LC-MS or LC-MS/MS bioanalysis

High-pH or basic/alkaline mobile phases are not commonly used in LC-MS or LC-MS/MS bioanalysis because of the deeply rooted concern with column instability and reduced detection sensitivity for basic compounds in high-pH mobile phases owing to charge neutralization. With the advancement of LC column technology and the wide recognition of the "wrong-way-round" phenomena, high-pH mobile phases are more and more used in LC-MS or LC-MS/MS bioanalysis to improve chromatographic peak shape, retention, selectivity, resolution, and detection sensitivity, not only for basic compounds, but also for many other compounds. In this article, the benefits, practical considerations, application examples and cautions for using high-pH mobile phases in LC-MS or LC-MS/MS bioanalysis are reviewed, with a focus on quantification. Furthermore, the future trends in this field are also envisaged. A total of 84 references are cited in this review.

The Effect of Small Molecules on Sterol Homeostasis: Measuring 7-Dehydrocholesterol in Dhcr7-Deficient Neuro2a Cells and Human Fibroblasts

Well-established cell culture models were combined with new analytical methods to assess the effects of small molecules on the cholesterol biosynthesis pathway. The analytical protocol, which is based on sterol derivation with the dienolphile PTAD, was found to be reliable for the analysis of 7-DHC and desmosterol. The PTAD method was applied to the screening of a small library of pharmacologically active substances, and the effect of compounds on the cholesterol pathway was determined. Of some 727 compounds, over 30 compounds decreased 7-DHC in Dhcr7-deficient Neuro2a cells. The examination of chemical structures of active molecules in the screen grouped the compounds into distinct categories. In addition to statins, our screen found that SERMs, antifungals, and several antipsychotic medications reduced levels of 7-DHC. The activities of selected compounds were verified in human fibroblasts derived from Smith-Lemli-Opitz syndrome (SLOS) patients and linked to specific transformations in the cholesterol biosynthesis pathway.

Kinetic study and peak purity determination of bupropion hydrochloride using RRLC/DAD and HPLC/MWD methods: stability study and application in pharmaceutical preparation and in synthetic mixtures with nicotine

Two validated stability indicating chromatographic methods have been developed and used for the kinetic study and determination of bupropion HCl in presence of its degradation products and nicotine.

A validated, rapid UPLC-MS/MS method for simultaneous ivabradine, reboxetine, and metoprolol analysis in human plasma and its application to clinical trial samples

A recent clinical trial assessing human autonomic cardiovascular regulation applied pacemaker channel inhibition with ivabradine, norepinephrine transporter blockade with reboxetine, and beta-adrenoreceptor blockade with metoprolol. To verify patient adherence, we developed and validated a fast UPLC-MS/MS assay measuring all three compounds simultaneously. Deuterium-labeled drugs, d3-ivabradine, d5-reboxetine and d7-metoprolol, served as internal standards. Sample preparation of 200μL human plasma consisted of a single liquid-liquid extraction step by means of ethyl acetate. Chromatographic separation was performed on a 50-mm long BEH C18 column with gradient elution using a mixture of water and methanol each containing 2mM ammonium acetate over 4.5min. The mass spectrometer was operated in the positive electrospray ionization (ESI+) mode. Characteristic product ions resulting from collision-induced dissociation of unlabeled and deuterium-labeled drugs with argon were used for quantification in the selected-reaction monitoring mode. We validated the method according to the European Medicines Agency (EMA) guideline on bioanalytical method validation over the range from 1ng/mL to 500ng/mL for all three analytes. Linear responses with correlation coefficients>0.99 over that range were acquired. The LOQ value was 1ng/mL for each drug. Regulatory criteria for accuracy (80-120%) and precision (RSD<15%) were met for all drugs. The internal standard-normalized matrix factor was close to 1 for low and high analyte concentrations. We successfully measured ivabradine, reboxetine, and metoprolol concentrations in 107 human plasma samples from a clinical trial. Quality control samples processed in parallel confirmed the method's reliability in a clinical setting.

Determination of reboxetine in rat brain microdialysates and plasma samples using liquid chromatography coupled to fluorescence detection

A liquid chromatographic method with fluorescence detection was developed and validated for the quantification of the antidepressant reboxetine (RBX), a selective noradrenalin reuptake inhibitor, in rat brain microdialysates. After modification of the method in terms of sample preparation and sensitivity, it was also validated for the quantification of RBX in rat plasma samples. To enable fluorescence detection, a pre-column derivatization step with 9-fluorenylmethyl chloroformate was included. Separations were performed on a reversed phase C₁₈ column using gradient elution. The retention time for RBX was found to be 8.8 min. The assay of RBX in brain microdialysis samples showed a linear relationship in the calibration curve from 2 to 200 ng/mL, with a correlation coefficient ≥0.999. The limit of detection (LOD) and the lower limit of quantification (LLOQ) were 0.6 and 2.0 ng/mL respectively. The intra-day and the inter-day precision (RSD %) ranged between 1.5% and 11.7% with an average recovery of 101.2±8.2% (mean±SD, n=40). For the analysis of plasma samples, the calibration curve was linear between 20 and 700 ng/mL with a correlation coefficient ≥0.999. LOD and LLOQ were 6 and 20 ng/mL respectively. The intra-day and the inter-day precision (RSD %) ranged between 1.7% and 11.5% with an average recovery of 98.5±7.3% (mean±SD, n=40). We demonstrated the applicability of the method to determine the concentration-time profiles of RBX in brain and plasma following systemic administration.