scholarly journals Validated Simple HPLC-UV Method for Mycophenolic Acid (MPA) Monitoring in Human Plasma. Internal Standardization: Is It Necessary?

Molecules ◽  
2021 ◽  
Vol 26 (23) ◽  
pp. 7252
Author(s):  
Paweł K. Kunicki ◽  
Aleksandra Wróbel
Keyword(s):  
Mycophenolic Acid ◽  
Internal Standard ◽  
Therapeutic Drug ◽  
Stability Parameters ◽  
High Agreement ◽  
Routine Monitoring ◽  
Accuracy Of Measurements ◽  
Internal Standardization ◽  
Routine Therapeutic Drug Monitoring ◽  
Trough Plasma

The aim of the work was to prepare a simple but reliable HPLC-UV method for the routine monitoring of mycophenolic acid (MPA). Sample preparation was based on plasma protein precipitation with acetonitrile. The isocratic separation of MPA and internal standard (IS) fenbufen was made on Supelcosil LC-CN column (150 × 4.6 mm, 5 µm) using a mobile phase: CH3CN:H2O:0.5M KH2PO4:H3PO4 (260:700:40:0.4, v/v). UV detection was set at 305 nm. The calibration covered the MPA concentration range: 0.1–40 µg/mL. The precision was satisfactory with RSD of 0.97–7.06% for intra-assay and of 1.92–5.15% for inter-assay. The inaccuracy was found between −5.72% and +2.96% (+15.40% at LLOQ) and between −8.82% and +5.31% (+19.00% at LLOQ) for intra- and inter-assay, respectively, fulfilling acceptance criteria. After a two-year period of successful application, the presented method has been retrospectively calibrated using the raw data disregarding the IS in the calculations. The validation and stability parameters were similar for both calculation methods. MPA concentrations were recalculated and compared in 1187 consecutive routine therapeutic drug monitoring (TDM) trough plasma samples from mycophenolate-treated patients. A high agreement (r2 = 0.9931, p < 0.0001) of the results was found. A Bland–Altman test revealed a mean bias of −0.011 μg/mL (95% CI: −0.017; −0.005) comprising −0.14% (95% Cl: −0.39; +0.11), whereas the Passing–Bablok regression was y = 0.986x + 0.014. The presented method can be recommended as an attractive analytical tool for medical (hospital) laboratories equipped with solely basic HPLC apparatus. The procedure can be further simplified by disapplying an internal standard while maintaining appropriate precision and accuracy of measurements.

scholarly journals Routine clozapine assay monitoring to improve the management of treatment-resistant schizophrenia

2021 ◽  
pp. 1-4
Author(s):  
David Kitchen ◽  
Alex Till ◽  
Panchu Xavier
Keyword(s):  
High Risk ◽  
Clinical Utility ◽  
Target Range ◽  
Therapeutic Drug ◽  
Treatment Resistant ◽  
Clozapine Therapy ◽  
Routine Monitoring ◽  
Number Of Patients ◽  
Routine Therapeutic Drug Monitoring ◽  
Health Trust

Aims and method Routine therapeutic drug monitoring in clozapine therapy has previously not been considered justifiable. Using observational data, the clinical utility of annual clozapine assay monitoring is explored within a large mental health trust. Results After the introduction of routine monitoring, the rate of clozapine assays rose to 2.3 per patient per year, with a consistent reduction in high-risk clozapine assays (<0.1 mg/L or >1.0 mg/L or any result more than 24 months old). High-risk assays are associated with a mortality rate of 31.6 deaths per 1000 patients, more than twice that of those within the target range (0.35–0.60 mg/L and conducted within the past 12 months) (P = 0.048). Clinical implications Routine clozapine assay monitoring has significant clinical utility. Our simple but targeted approach can be readily implemented to reduce the number of patients with high-risk clozapine assay levels, potentially reduce all-cause mortality and provide optimal treatment for those with treatment-resistant schizophrenia.

scholarly journals Analysis of Pembrolizumab in Human Plasma by LC-MS/HRMS. Method Validation and Comparison with Elisa

Biomedicines ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 621
Author(s):  
Aurélien Millet ◽  
Nihel Khoudour ◽  
Jérôme Guitton ◽  
Dorothée Lebert ◽  
François Goldwasser ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Human Plasma ◽  
High Resolution Mass Spectrometry ◽  
Internal Standard ◽  
Therapeutic Drug ◽  
Limit Of Quantification ◽  
Immunoglobulin G4 ◽  
Positive Mode ◽  
Surrogate Peptide ◽  
First Time

Pembrolizumab is a humanized immunoglobulin G4-kappa anti-PD1 antibody used in the treatment of different solid tumors or haematological malignancies. A liquid chromatography coupled with a high resolution mass spectrometry (orbitrap technology) method was fully developed, optimized, and validated for quantitative analysis of pembrolizumab in human plasma. A mass spectrometry assay was used for the first time a full-length stable isotope-labelled pembrolizumab-like (Arginine 13C6-15N4 and Lysine 13C6-15N2) as an internal standard; the sample preparation was based on albumin depletion and trypsin digestion and, finally, one surrogate peptide was quantified in positive mode. The assay showed good linearity over the range of 1–100 μg/mL, a limit of quantification at 1 μg/mL, excellent accuracy from 4.4% to 5.1%, and also a between-day precision below 20% at the limit of quantification. In parallel, an in-house ELISA was developed with a linearity range from 2.5 to 50 µg/mL. Then, results were obtained from 70 plasma samples of cancer patients that were treated with pembrolizumab and quantified with both methods were compared using the Passing-Bablok regression analysis and Bland-Altman plotting. The LC-MS/HRMS method is easy to implement in the laboratory for use in the context of PK/PD studies, clinical trials, or therapeutic drug monitoring.

scholarly journals Quantification of plasma remdesivir and its metabolite GS-441524 using liquid chromatography coupled to tandem mass spectrometry. Application to a Covid-19 treated patient

2020 ◽  
Vol 58 (9) ◽  
pp. 1461-1468 ◽  
Author(s):  
Jean-Claude Alvarez ◽  
Pierre Moine ◽  
Isabelle Etting ◽  
Djillali Annane ◽  
Islam Amine Larabi
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Half Life ◽  
Limit Of Detection ◽  
Treated Patient ◽  
Internal Standard ◽  
Therapeutic Drug ◽  
Active Metabolites ◽  
Limit Of Quantification ◽  
Positive Mode

AbstractObjectivesA method based on liquid chromatography coupled to triple quadrupole mass spectrometry detection using 50 µL of plasma was developed and fully validated for quantification of remdesivir and its active metabolites GS-441524.MethodsA simple protein precipitation was carried out using 75 µL of methanol containing the internal standard (IS) remdesivir-13C6 and 5 µL ZnSO4 1 M. After separation on Kinetex® 2.6 µm Polar C18 100A LC column (100 × 2.1 mm i.d.), both compounds were detected by a mass spectrometer with electrospray ionization in positive mode. The ion transitions used were m/z 603.3 → m/z 200.0 and m/z 229.0 for remdesivir, m/z 292.2 → m/z 173.1 and m/z 147.1 for GS-441524 and m/z 609.3 → m/z 206.0 for remdesivir-13C6.ResultsCalibration curves were linear in the 1–5000 μg/L range for remdesivir and 5–2500 for GS-441524, with limit of detection set at 0.5 and 2 μg/L and limit of quantification at 1 and 5 μg/L, respectively. Precisions evaluated at 2.5, 400 and 4000 μg/L for remdesivir and 12.5, 125, 2000 μg/L for GS-441524 were lower than 14.7% and accuracy was in the [89.6–110.2%] range. A slight matrix effect was observed, compensated by IS. Higher stability of remdesivir and metabolite was observed on NaF-plasma. After 200 mg IV single administration, remdesivir concentration decrease rapidly with a half-life less than 1 h while GS-441524 appeared rapidly and decreased slowly until H24 with a half-life around 12 h.ConclusionsThis method would be useful for therapeutic drug monitoring of these compounds in Covid-19 pandemic.

scholarly journals Development and Validation of an Up-to-Date Highly Sensitive UHPLC-MS/MS Method for the Simultaneous Quantification of Current Anti-HIV Nucleoside Analogues in Human Plasma

2021 ◽  
Vol 14 (5) ◽  
pp. 460
Author(s):  
Amedeo De Nicolò ◽  
Alessandra Manca ◽  
Alice Ianniello ◽  
Alice Palermiti ◽  
Andrea Calcagno ◽  
...  
Keyword(s):  
Human Plasma ◽  
Multiple Reaction Monitoring ◽  
Internal Standard ◽  
Reversed Phase ◽  
Therapeutic Drug ◽  
People Living With Hiv ◽  
Simultaneous Quantification ◽  
Working Solution ◽  
Tenofovir Alafenamide ◽  
Combination Regimens

Therapeutic options to treat HIV infection have widened in the past years, improving both effectiveness and tolerability, but nucleoside reverse transcriptase inhibitors (NRTIs) are still considered the standard backbone of the combination regimens. Therapeutic drug monitoring (TDM) can be useful for these drugs, due to concentration–effect relationship, with risk of ineffectiveness, toxicity or adherence concerns: in this scenario, robust and multiplexed methods are needed for an effective TDM activity. In this work, the first validated ultra-high spectrometry liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS) method is described for the high-sensitive simultaneous quantification of all the currently used NRTIs in human plasma, including tenofovir alafenamide (TAF), following FDA and EMA guidelines. The automated sample preparation consisted in the addition of an internal standard (IS) working solution, containing stable-isotope-linked drugs, protein precipitation and drying. Dry extracts were reconstituted with water, then, these underwent reversed phase chromatographic separation: compounds were detected through electrospray ionization and multiple reaction monitoring. Accuracy, precision, recovery and IS-normalized matrix effect fulfilled guidelines’ requirements. The application of this method on samples from people living with HIV (PLWH) showed satisfactory performance, being capable of quantifying the very low concentrations of tenofovir (TFV) in patients treated with TAF.

Generation of Pharmacokinetic Data During Routine Therapeutic Drug Monitoring

1993 ◽  
Vol 15 (4) ◽  
pp. 281-288 ◽  
Author(s):  
E. El Desoky ◽  
J. Meinshausen ◽  
K. Bühl ◽  
G. Engel ◽  
A. Harings-Kaim ◽  
...  
Keyword(s):  
Therapeutic Drug Monitoring ◽  
Drug Monitoring ◽  
Therapeutic Drug ◽  
Pharmacokinetic Data ◽  
Routine Therapeutic Drug Monitoring

High-Performance Liquid Chromatographic Determination of Memantine in Human Urine Following Solid-Phase Extraction and Precolumn Derivatization

2013 ◽  
Vol 96 (6) ◽  
pp. 1302-1307 ◽  
Author(s):  
Karim Michail ◽  
Hoda Daabees ◽  
Youssef Beltagy ◽  
Magdy Abd Elkhalek ◽  
Mona Khamis
Keyword(s):  
Human Urine ◽  
High Performance ◽  
Solid Phase ◽  
Internal Standard ◽  
Chromatographic Determination ◽  
Therapeutic Drug ◽  
Time Interval ◽  
Precolumn Derivatization ◽  
Uv Detector

Abstract A validated HPLC-UV method is presented for the quantification of urinary memantine hydrochloride, a novel medication approved to treat moderate and advanced cases of Alzheimer's disease. The drug and amantadine hydrochloride, the internal standard, were extracted from human urine using SPE. The extract was then buffered and derivatized at room temperature using o-phthalaldehyde in the presence of N-acetyl-L-cyteine. Chromatographic separation of the formed derivatives was achieved on a C18 column using methanol–water mobile phase adjusted to pH 7 and pumped isocratically at 1 mL/min. The UV detector was set at 340 nm. The chromatographic run time did not exceed 10 min. The LOD and LOQ were 8 and 20 ng/mL, respectively. The RSDs for intraday and interday precisions did not exceed 5.5%. The method was used to monitor memantine hydrochloride in human urine in order to determine an appropriate sampling interval for future noninvasive therapeutic drug monitoring. The assay could also be applied to the determination of amantadine. The described assay showed that a postdosing time interval of 25–75 h seems adequate for sampling and monitoring memantine in urine.

scholarly journals Recent Advances in Therapeutic Drug Monitoring of Voriconazole, Mycophenolic Acid, and Vancomycin: A Literature Review of Pediatric Studies

Pharmaceutics ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1991
Author(s):  
Matylda Resztak ◽  
Joanna Sobiak ◽  
Andrzej Czyrski
Keyword(s):  
Therapeutic Drug Monitoring ◽  
Mycophenolic Acid ◽  
Drug Monitoring ◽  
Pediatric Patients ◽  
Fungal Infections ◽  
Cord Blood Transplantation ◽  
Active Form ◽  
Therapeutic Drug ◽  
Hematopoietic Stem ◽  
Acute Kidney Disease

The review includes studies dated 2011–2021 presenting the newest information on voriconazole (VCZ), mycophenolic acid (MPA), and vancomycin (VAN) therapeutic drug monitoring (TDM) in children. The need of TDM in pediatric patients has been emphasized by providing the information on the differences in the drugs pharmacokinetics. TDM of VCZ should be mandatory for all pediatric patients with invasive fungal infections (IFIs). Wide inter- and intrapatient variability in VCZ pharmacokinetics cause achieving and maintaining therapeutic concentration during therapy challenging in this population. Demonstrated studies showed, in most cases, VCZ plasma concentrations to be subtherapeutic, despite the updated dosages recommendations. Only repeated TDM can predict drug exposure and individualizing dosing in antifungal therapy in children. In children treated with mycophenolate mofetil (MMF), similarly as in adult patients, the role of TDM for MMF active form, MPA, has not been well established and is undergoing continued debate. Studies on the MPA TDM have been carried out in children after renal transplantation, other organ transplantation such as heart, liver, or intestine, in children after hematopoietic stem cell transplantation or cord blood transplantation, and in children with lupus, nephrotic syndrome, Henoch-Schönlein purpura, and other autoimmune diseases. MPA TDM is based on the area under the concentration–time curve; however, the proposed values differ according to the treatment indication, and other approaches such as pharmacodynamic and pharmacogenetic biomarkers have been proposed. VAN is a bactericidal agent that requires TDM to prevent an acute kidney disease. The particular group of patients is the pediatric one. For this group, the general recommendations of the dosing may not be valid due to the change of the elimination rate and volume of distribution between the subjects. The other factor is the variability among patients that concerns the free fraction of the drug. It may be caused by both the patients’ population and sample preconditioning. Although VCZ, MMF, and VAN have been applied in pediatric patients for many years, there are still few issues to be solve regarding TDM of these drugs to ensure safe and effective treatment. Except for pharmacokinetic approach, pharmacodynamics and pharmacogenetics have been more often proposed for TDM.

scholarly journals Influence of CYP3A Metabolizer Status on the Pharmacokinetics and Pharmacodynamics of Amiodarone

2000 ◽  
Vol 43 (3) ◽  
pp. 95-101
Author(s):  
Stanislav Mičuda ◽  
Martin Hodač ◽  
Petr Pařízek ◽  
Miloslav Pleskot ◽  
Luděk Šišpera ◽  
...  
Keyword(s):  
Plasma Concentrations ◽  
Inverse Correlation ◽  
Urinary Free Cortisol ◽  
Information Value ◽  
Therapeutic Drug ◽  
Amiodarone Therapy ◽  
Pharmacokinetics And Pharmacodynamics ◽  
Electrophysiologic Study ◽  
Free Cortisol ◽  
Trough Plasma

The present work was designed to determine whether the individual differences in pharmacokinetics and pharmacodynamics of amiodarone and its N-desethyl metabolite are related to cytochrome CYP3A metabolizer status. Methods: 12 cardiac patients with inducible ventricular tachyarrhythmias during the baseline electrophysiologic study were enrolled in this study. Urinary 24-hour excretion of 6β-hydroxycortisol (6β-OHC and the ratio of 6β-hydroxycortisol to urinary free cortisol (6β-OHC/UFC) were measured before the first amiodarone administration. Trough plasma concentrations of amiodarone and N-desethylamiodarone (N-DEA) were measured after 79 ± 11 days (2nd period) and after 182 ± 25 days (3rd period). Electrophysiologic effects of amiodarone therapy were established with serial electrophysiologic studies in 9 of these patients at the baseline and after 79 ± 11 days (during the second period). Results: Both the 6β-OHC excretion and 6β-OHC/UFC ratio varied approximately 6-fold between the patients. We found significant inverse correlation between the 6β-OHC excretion and the trough plasma concentrations of amiodarone at the time of the 3rd period (rs = -0.58, p < 0.05). Similarly, there was correlation between the 24-hour urinary 6β-OHC excretion and trough plasma concentrations of amiodarone during the 3rd period (rs = -0.64, p < 0.025). We were unable to detect any association between CYP3A activity and amiodarone pharmacodynamics. Conclusion: This study points toward important information value of CYP3A metabolizer status in the context of therapeutic drug monitoring of amiodarone.

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