A Sensitive Microscale HPLC-UV Method for the Determination of Doxofylline and its Metabolites in Plasma: An Adapted Method for Therapeutic Drug Monitoring in Children

2019 ◽  
Vol 16 (1) ◽  
pp. 47-54
Author(s):  
Yue-E Wu ◽  
Xiu-Fu Wu ◽  
Min Kan ◽  
Hai-Yan Shi ◽  
Meng-Jie Liu ◽  
...  
Keyword(s):  
Therapeutic Drug Monitoring ◽  
Drug Monitoring ◽  
Pure Water ◽  
Internal Standard ◽  
Mean Value ◽  
Hplc Method ◽  
Individual Variability ◽  
Small Sample ◽  
Therapeutic Drug ◽  
Chronic Obstructive

Background: Doxofylline (DXE) is a novel methylxanthine derivative used in the treatment of asthma and Chronic Obstructive Pulmonary Diseases (COPD). Therapeutic Drug Monitoring (TDM) has been proposed in adults, while the adapted analytical method and TDM data are still missing in children. Methods: A highly sensitive and stability indicating High-Performance Liquid Chromatography (HPLC) method of DXE with caffeine as the internal standard, was developed and validated by separating its metabolites, β-Hydroxyethyltheophylline (HPE) and Theophylline (TPE). HPLC separation is achieved on C18 column connected to an ultraviolet detector (276 nm), using acetonitrile and ultra-pure water in a gradient mode of elution at a flow rate of 0.9 mL/min at 25°C. A liquid-liquid extraction method using ethyl acetate was developed with a small sample volume of plasma of 50 μL. Trough concentration was monitored in children receiving DXE therapy. Results: The method was linear over the concentration ranges from 0.4-20 µg/mL for DXE, HPE and TPE, respectively, in plasma. The limits of quantification were 0.4 µg/mL. Intra- and interday coefficients of variation did not exceed 6.5%, and the accuracy ranged from 94.9% to 112.5%. A total of 39 children (mean age of 1.8 years, range: 0.3-5.7 years) were included. The pediatric patients had detectable DXE concentrations with a mean value of 1.78 µg/mL (range from 0.49 to 6.36 µg/mL), and HPE measurable concentrations with a mean value of 0.52 µg/mL (range from 0.40 to 0.82 µg/mL), while the TPE could not be measured in any patient. Conclusion: A sensitive, reliable, and adapted HPLC method has been developed for the simultaneous analysis of DXE and its metabolites in children. The DXE and its metabolites trough concentrations showed large inter-individual variability.

scholarly journals Sensitive and Rapid Quantification of Busulfan in Small Plasma Volumes by Liquid Chromatography–Electrospray Mass Spectrometry

2001 ◽  
Vol 47 (8) ◽  
pp. 1437-1442 ◽  
Author(s):  
Thomas E Mürdter ◽  
Janet Coller ◽  
Alexander Claviez ◽  
Frank Schönberger ◽  
Ute Hofmann ◽  
...  
Keyword(s):  
Liquid Chromatography ◽  
Therapeutic Drug Monitoring ◽  
Drug Monitoring ◽  
Internal Standard ◽  
Therapeutic Drug ◽  
High Dose ◽  
Selected Ion Monitoring ◽  
Hematopoietic Stem ◽  
Adults And Children ◽  
Liquid Chromatographic

Abstract Background: High-dose busulfan is widely used in conditioning regimens before hematopoietic stem cell transplantation in both adults and children. Large interindividual variability in pharmacokinetics after oral administration has been reported; therefore, therapeutic drug monitoring of busulfan may decrease the incidence of drug-related toxicity (for example, hepatic venoocclusive disease) and may also improve therapeutic efficacy. Methods: Busulfan concentrations were quantified using 200 μL of plasma and liquid–liquid extraction with diethyl ether after the addition of [2H8]busulfan as the internal standard. Separation and detection of busulfan and [2H8]busulfan were achieved with a LUNA C8 column (5 μm; 150 × 2 mm i.d.) at 30 °C, a HP 1100 liquid chromatography system, and a HP 1100 single-quadrupole mass spectrometer. Busulfan and [2H8]busulfan were detected as ammonium adducts in selected-ion monitoring mode at m/z 264.2 and 272.2, respectively. Results: The calibration curve was linear at 5–2000 μg/L busulfan. Intra- and interassay imprecision (CV) and bias were both <11%. The limits of detection and quantification were 2 and 5 μg/L, respectively. Extraction recovery of busulfan was >87%. Analysis of pharmacokinetics in four patients receiving high-dose busulfan indicated that minimum busulfan concentrations before the next dose were 405–603 μg/L, with no interference observed. Conclusions: The new rapid and sensitive liquid chromatographic–mass spectrometric assay is an appropriate method for quantification of busulfan in human plasma, making therapeutic drug monitoring of busulfan faster and easier in clinical practice.

Management of Chronic Myelogenous Leukemia Using Therapeutic Drug Monitoring of Imatinib: The French Experience of a Centralized Laboratory

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 3222-3222
Author(s):  
Mathieu Molimard ◽  
Stephane Bouchet ◽  
Gabriel Etienne ◽  
Laurence Legros ◽  
Delphine Rea ◽  
...  
Keyword(s):  
Plasma Concentration ◽  
Therapeutic Drug Monitoring ◽  
Sex Ratio ◽  
Chronic Myelogenous Leukemia ◽  
Drug Monitoring ◽  
Individual Variability ◽  
Myelogenous Leukemia ◽  
Therapeutic Drug ◽  
Efficient Treatment ◽  
Trough Plasma

Abstract Pharmacokinetic monitoring is widely used in different medical specialities, but it has been rarely applied in clinical oncology practice. The current gold standard treatment of chronic myelogenous leukemia (CML) is imatinib, a tyrosine kinase inhibitor. We have previously shown the necessity to obtain a trough plasma threshold of 1000 ng/mL for efficient treatment with imatinib. We routinely perform centralized quantification for patients in France and this has allowed the assessment of imatinib therapeutic monitoring and its use in a real-life setting. After 16 months of data collection, we had gathered 1607 samples for 1044 CML patients (mean age 55 years, F/M sex ratio 0.67) treated with imatinib 400 mg (median) range (100–800mg). We received only one sample for 739 patients and more than one sample for 305 patients. The mean trough plasma concentration of imatinib (Cmin) was 1043 ng/mL (median: 876 ng/mL) and 596 of the 1044 CML patients (57%) had a Cmin <1000ng/ml at first determination. Plasma concentration increased with dose, but there was a large inter-individual variability (64%) and intra-individual variability was twice as small. For plasma concentrations < 1000 ng/mL, mean dose was 420 mg and for those ≥ 1000 ng/mL, this was 510 mg. For the 189 patients having had at least 2 correct Cmin determination, 70% had initial Cmin< 1000 ng/mL (mean concentration of 1st determination: 583 ng/mL). Among the 62 patients who initially had a Cmin below 1000 ng/mL that subsequently rose above this threshold, 63% had their imatinib dose increased; the rest did not have a dose modification. For the latter, it is probable in view of low intra-individual variability that this was due to enhanced compliance. For the 32 patients with a first Cmin <1000 and no CCyR, none of those with Cmin remaining below 1000 ng/mL achieved CCyR, wheras 5 (28%) achieved CCyR when Cmin rose above 1000 ng/mL. In cases where there was suspicion of a drug–drug interaction, the most frequently combined drugs were proton pump inhibitors (such as omeprazole), diuretics, allopurinol and NSAIDs. The most recurrent adverse effects were digestive, hematological and muscular. Although the studied population had characteristics generally described for this pathology (age, sex ratio), there was probably selection bias at the beginning of study: we received first and foremost the patients having an insufficient response, and therefore low plasma concentration. Therapeutic drug monitoring of imatinib appears to be helpful for the management of CML patients and the resulting database allows a better understanding and use of this treatment.

scholarly journals Development and validation of a new HPLC method for valproic acid determination in human plasma and its application to a therapeutic drug monitoring study

2020 ◽  
Vol 66 (1) ◽  
Author(s):  
Emrah Dural ◽  
Seniha Çelebi ◽  
Aslı Bolayır ◽  
Burhanettin Çiğdem
Keyword(s):  
Valproic Acid ◽  
Therapeutic Drug Monitoring ◽  
Human Plasma ◽  
Drug Monitoring ◽  
High Performance ◽  
High Standard ◽  
Hplc Method ◽  
Therapeutic Drug ◽  
Recommended Treatment ◽  
Monitoring Study

The aim of this study was to develop a new, simple and reliable high performance liquid chromatography (HPLC) method for analysis of valproic acid (VPA) in human plasma and apply to it to a therapeutic drug monitoring study. Also, the relationship between plasma-VPA concentrations and the amount of VPA used by patients was aimed to be evaluated. Plasma samples (0.25 mL) were precipitated with the same volume of acetonitrile and after centrifugation, aliquots were applied to a C18 column (250 mm x 4.6 mm). Mobile phase was prepared with phosphate buffer and acetonitrile (47.5:52.5, v/v). The flow-rate was 1.2 mL/min. Accuracy was between -2.9 and 3.2% and precision was ≤6.6%. Method was specific and sensitive with a detection limit of 2.2 µg/mL and the average recovery was 94.3%. Calibration curve was linear (r2>0.9968) from 10 to 150 µg/mL. Plasma-VPA levels of the epileptic patient population (n=33) treated with VPA between 0.5 and 1.5 g/day were also determined. Patient plasma-VPA concentrations ranged from 2.9 to 166.4 µg/g/mL (56.3±38.8). High RSD% (68.8%) was observed in dose-rated plasma-VPA results. Moreover, VPA plasma levels were found to be outside the recommended treatment range in 30.3% of the patients examined. The procedure described was found to be relatively simple, precise, and applicable for routine therapeutic drug monitoring (TDM) especially in neurology clinics or in toxicology reference laboratories. The high standard deviation (SD) observed in the dose depended plasma-VPA values of the volunteers proved the importance of TDM during the use of this drug. The results showed that for rational drug use, it is important to identify individual polymorphisms in the CYP2C9, CYP2A6 and CYP2B6 subtypes responsible for VPA metabolism, and to rearrange drug doses taking these enzyme activities into account.

Intra-individual variability in lopinavir plasma trough concentrations supports therapeutic drug monitoring

AIDS ◽  
2003 ◽  
Vol 17 (7) ◽  
pp. 1107-1108 ◽  
Author(s):  
Marta Boffito ◽  
David J Back ◽  
Patrick G Hoggard ◽  
Annamaria Caci ◽  
Stefano Bonora ◽  
...  
Keyword(s):  
Therapeutic Drug Monitoring ◽  
Drug Monitoring ◽  
Individual Variability ◽  
Therapeutic Drug ◽  
Trough Concentrations

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

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Xinxin Ren ◽  
Zhipeng Wang ◽  
Yunlei Yun ◽  
Guangyi Meng ◽  
Xialan Zhang ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Therapeutic Drug Monitoring ◽  
Human Plasma ◽  
Drug Monitoring ◽  
Internal Standard ◽  
Gradient Elution ◽  
Therapeutic Drug ◽  
Tandem Mass ◽  
The Matrix ◽  
Analytical Time

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.

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