A Pilot Study To Assess the Suitability of Riboflavin As a Surrogate Marker of Breast Cancer Resistance Protein in Healthy Participants.

We recently showed that riboflavin is a selected substrate of breast cancer resistance protein (BCRP) over P-glycoprotein (P-gp) and demonstrated its prediction performance in preclinical drug-drug interaction (DDI) studies. The aim of this study was to investigate the suitability of riboflavin to assess BCRP inhibition in humans. First, we assessed the substrate potential of riboflavin toward other major drug transporters using established transfected cell systems. Riboflavin is a substrate for organic anion transporter (OAT)1, OAT3, and multidrug and toxin extrusion protein (MATE)2-K, with uptake ratios ranging from 2.69 to 11.6, but riboflavin is not a substrate of organic anion-transporting polypeptide (OATP)1B1, OATP1B3, organic cation transporter (OCT)2, and MATE1. The effects of BMS-986371, a potent in vitro inhibitor of BCRP (IC 50 0.40 µM), on the pharmacokinetics of riboflavin, isobutyryl carnitine, and arginine were then examined in healthy male adults (N = 14 or 16) after oral administration of methotrexate (MTX) (7.5 mg) and enteric-coated (EC) sulfasalazine (SSZ) (1000 mg) alone or in combination with BMS-986371 (150 mg). Oral administration of BMS-986371 increased the area under the plasma concentration-time curves (AUCs) of rosuvastatin and immediate-release (IR) SSZ to 1.38- and 1.51-fold, respectively, and significantly increased AUC(0-4h), AUC(0-24h), and C max of riboflavin by 1.25-, 1.14-, and 1.11-fold (P-values of 0.003, 0.009, and 0.025, respectively) compared with the MTX/SSZ EC alone group. In contrast, BMS-986371 did not significantly influence the AUC(0-24h) and C max values of isobutyryl carnitine and arginine (0.96- to 1.07-fold, respectively; P > 0.05). Overall, these data indicate that plasma riboflavin is a promising biomarker of BCRP that may offer a possibility to assess drug candidate as a BCRP modulator in early drug development. SIGNIFICANCE STATEMENT: Endogenous compounds that serve as biomarkers for clinical inhibition of breast cancer resistance protein (BCRP) are not currently available. This study provides the initial evidence that riboflavin is a promising BCRP biomarker in humans. For the first time, the value of leveraging the substrate of BCRP with acceptable prediction performance in clinical studies is shown. Additional clinical investigations with known BCRP inhibitors are needed to fully validate and showcase the utility of this biomarker.

New Therapeutic Approach to Reduce Methotrexate Toxicity after High-Dose Chemotherapy in a Child with Acute Lymphocytic Leukemia: Efficacy and Safety of Hemoadsorption with HA-230 Adsorber.

BACKGROUND: High-dose methotrexate (HDMTX) is likely to cause a number of side effects and manifest itself as hepatotoxicity, nephrotoxicity, mucositis, and neurotoxicity. A several studies demonstrated the efficacy of extracorporeal detoxification methods such as plasma exchange, hemodialysis (HD), HD filtration, and hemoperfusion for the treatment of MTX delayed clearance. However, none of the existing methods as effective as expected and limited for general implementation due to a procedure-related complication. CASE REPORT: Here, we report a successful implementation of HA-230 hemoadsorption procedure to remove cumulated MTX from the body and reduce its toxicity in a child with ALL after high-dose chemotherapy. RESULTS AND CONCLUSION: Based on our results, single-hemoadsorption procedure with the HA-230 adsorber in case of delayed methotrexate clearance was safe and well-tolerated in a pediatric patient with ALL and would significantly improve the patient's condition. Further studies need to demonstrate its safety and efficacy in a large number of pediatric patients.

Optimization and validation of an analytical method for the estimation of methotrexate in rabbit plasma.

Methotrexate (MTX) is an anticancer drug used for the treatment of various cancers and autoimmune diseases. In this study, High Performance Liquid Chromatography (HPLC) method was developed and validated for the estimation of MTX in rabbit plasma with high estimation rate and recovery. Various validation parameters like, sensitivity, sample recovery, accuracy and precision analysis were studied. The pre-saturated reversed C18 end capped HPLC column was used to separate MTX present in rabbit plasma. A solvent mixture of 100mM phosphate buffer pH 7.4 and acetonitrile (92:8 percent v/v) was employed as the mobile phase. Analysis was carried out at ʎ max 303 nm and retention time of MTX was found 5.32 min. During the method development and validation ICHQ2 (R1) guidelines were strictly followed. Developed method was found excellent in terms of recovery of MTX from plasma samples (98.6%). It is obvious from the current study that the developed HPLC method can be utilized to analyze the level of MTX in patients. Furthermore, the cost of the developed method for the determination of MTX would be very low as compared to the previously reported methods.

Comparison of two dose escalation strategies of methotrexate in active rheumatoid arthritis: a multicentre, parallel group, randomised controlled trial.

OBJECTIVES: There are no head-to-head trials of different dose escalation strategies of methotrexate (MTX) in RA. We compared the efficacy, safety and tolerability of 'usual' (5 mg every 4 weeks) versus 'fast' (5 mg every 2 weeks) escalation of oral MTX. METHODS: This multicentre, open-label (assessor blinded) RCT included patients 18-55 years of age having active RA with disease duration <5 years, and not on DMARDs. Patients were randomized 1:1 into usual or fast escalation groups, both groups starting MTX at 15 mg/week till a maximum of 25 mg/week. Primary outcome was EULAR good response at 16 weeks, secondary outcomes were ΔDAS28 and adverse effects (AE). Analyses were intention-to-treat. RESULTS: 178 patients with mean DAS28-CRP of 5.4(1.1) were randomized to usual (n=89) or fast escalation groups (n=89). At 16 weeks, there was no difference in good EULAR response in the usual (28.1%) or fast escalation (22.5%) groups (p=0.8). There was no difference in mean ΔDAS28-CRP at 8 weeks (-0.9, -0.8, p=0.72) or 16 weeks (-1.3, -1.3, p=0.98). Even at 24 weeks (extended follow-up), responses were similar. There were no inter-group differences in ΔHAQ, or MTX-polyglutamates 1-3 levels at 8 or 16 weeks. Gastrointestinal AE were higher in the fast escalation group over initial 8 weeks (27%, 40%, p=0.048), but not over 16 weeks. There was no difference in cytopenias, transaminitis, or drug discontinuation/dose reduction between the groups. No serious AE were seen. CONCLUSION: A faster MTX escalation strategy in RA was not more efficacious over 16-24 weeks, and did not significantly increase AE, except higher gastrointestinal AE initially. TRIAL REGISTRATION NUMBER: CTRI/2018/12/016549.

Translating research into clinical practice: quality improvement to halve non-adherence to methotrexate.

OBJECTIVE: MTX remains the cornerstone for therapy for RA, yet research shows that non-adherence is significant and correlates with response to therapy. This study aimed to halve self-reported non-adherence to MTX at the Kellgren Centre for Rheumatology. METHODS: An anonymous self-report adherence questionnaire was developed and data collected for 3 months prior to the introduction of interventions, and then regularly for the subsequent 2.5 years. A series of interventions were implemented, including motivational interviewing training, consistent information about MTX and development of a summary bookmark. Information on clinic times was collected for consultations with and without motivational interviewing. Surveys were conducted to ascertain consistency of messages about MTX. A biochemical assay was used to test MTX serum levels in patients at two time points: before and 2.8 years following introduction of the changes. Remission rates at 6 and 12 months post-MTX initiation were retrieved from patient notes and cost savings estimated by comparing actual numbers of new biologic starters compared with expected numbers based on the numbers of consultants employed at the two time points. RESULTS: Between June and August 2016, self-reported non-adherence to MTX was 24.7%. Following introduction of the interventions, self-reported non-adherence rates reduced to an average of 7.4% between April 2018 and August 2019. Clinic times were not significantly increased when motivational interviewing was employed. Consistency of messages by staff across three key areas (benefits of MTX, alcohol guidance and importance of adherence) improved from 64% in September 2016 to 94% in January 2018. Biochemical non-adherence reduced from 56% (September 2016) to 17% (June 2019), whilst remission rates 6 months post-initiation of MTX improved from 13% in 2014/15 to 37% in 2017/18, resulting is estimated cost savings of £30 000 per year. CONCLUSION: Non-adherence to MTX can be improved using simple measures including focussing on the adherence and the benefits of treatment, and providing consistent information across departments.

Evaluation of time to clearance of high-dose methotrexate using the ARK immunoassay in pediatric hematology/oncology patients: A single-center experience.

A retrospective, single-center, observational study evaluated the difference in time to clearance of high-dose methotrexate between the fluorescence polarization immunoassay (FPIA) and ARK methotrexate assay in pediatric hematology/oncology patients. The post-ARK immunoassay group had an increase in clearance time of 33 h/cycle and 31% increase in cycles with delayed clearance. On posthoc analysis, use of an adjusted clearance threshold of <0.15 µmol/L post-ARK immunoassay, as opposed to the traditional <0.1 µmol/L threshold, would have similar incidence of delayed clearance. The ARK immunoassay demonstrated a positive bias compared to the FPIA in clinical practice, which led to an institutional policy change.

Studies on the intracellular accumulation process of methotrexate and its correlation with the key protein using an LC-MS/MS method: a novel way to realize prospective individualized medication.

High-dose methotrexate (HDMTX) combined with leucovorin (LV) is the first-line drug therapy for many kinds of malignant tumors. However, the specific treatment plans, such as dosage and duration of administration, are usually formulated according to the clinician's experience and therapeutic drug monitoring (TDM) of methotrexate in patients' plasma, which are responsible for strong individual differences of drug usage. A large number of studies have shown that methotrexate targets the inside of the cell. The key cytotoxic component is the methotrexate polyglutamates (MTXPGs) in the cell. The concentration of methotrexate in plasma does not reflect the efficacy and side effects well. Based on mass spectrometry technology, we developed and validated an accurate, sensitive, and stable method to quantify the intracellular MTX (MTXPG1) and its metabolites MTXPG2-7 simultaneously. The lower limit of quantification was 0.100 ng/ml, and the run time was only 3 min. Moreover, our team has already developed two LC-MS/MS-based methods to respectively quantify methotrexate in plasma samples and two key proteins (γ-glutamyl hydrolase [GGH] and folylpolyglutamate synthetase [FPGS]) in peripheral blood mononuclear cells (PBMC). Through these highly sensitive and accurate approaches, we have gained a deep understanding of the whole pharmacokinetic process of MTX and explored the key factors affecting the accumulation process of intracellular active components (MTXPGs). Based on this research, it is possible to find a more effective way to provide an accurate reference for clinical drug use than traditional therapeutic drug monitoring (TDM).

A simple and accurate HFCF-UF method for the analysis of homocysteine, cysteine, cysteinyl-glycine, and glutathione in human blood.

The presence of reduced aminothiols, including homocysteine (Hcy), cysteine (Cys), cysteinyl-glycine (CG), and glutathione (GSH), is significantly increased in the pathological state. However, there have been no reports on the relationship between reduced aminothiols (Hcy, Cys, CG, and GSH) and different genders, ages, and drug combinations in human blood. The accurate quantification of these reduced thiols in biological fluids is important for monitoring some special pathological conditions of humans. However, the published methods typically not only require cumbersome and technically challenging processing procedures to ensure reliable measurements, but are also laborious and time-consuming, which may disturb the initial physiological balance and lead to inaccurate results. We developed a hollow fiber centrifugal ultrafiltration (HFCF-UF) method for sample preparation coupled with a high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method and used it to determine four reduced aminothiols (Hcy, Cys, CG, and GSH) in human blood for the first time. A total of 96 clinical patients were enrolled in our study. The influence of different genders, ages, and drug combinations on the levels of four reduced thiols in human blood was also discussed by SPSS 24.0. The sample preparation was simplified to a single 5 min centrifugation step in a sealed system that did not disturb the physiological environment. The validation parameters for the methodological results were excellent. The procedure was successfully applied to monitoring the concentrations of four reduced aminothiols (Hcy, Cys, CG, and GSH) in 96 clinical blood samples. There were no significant differences in Hcy, Cys, CG, or GSH for the different genders, ages, or combinations with methotrexate or vancomycin (P > 0.05). However, there was a significant increase in Hcy concentration in patients treated with valproic acid who were diagnosed with epilepsy (p=0.0007). It is advisable to measure reduced Hcy level in patients taking valproic acid. The developed HFCF-UF method was simple and accurate. It can be easily applied in clinical research to evaluate oxidative stress in further study.

Delayed methotrexate elimination in a patient with primary central nervous system lymphoma: A case report.

WHAT IS KNOWN AND OBJECTIVE: Methotrexate (MTX) is an important agent for the treatment of primary central nervous system lymphomas (PCNSL) but needs to be given in big doses by intravenous infusions to achieve therapeutic concentrations in the cerebrospinal fluid. However, co-administration with many drugs may delay the excretion of MTX which may cause serious adverse effects if the serum concentration exceeds 0.1 µmol/L 72 h after an intravenous infusion. CASE SUMMARY: A 67-year-old Japanese female with PCNSL was treated with high-dose MTX-based chemotherapy. The serum MTX concentration 72 h post-infusion was 0.153 µmol/L when she was taking levofloxacin (LVFX) but <0.1 µmol/L 72 h after 4 subsequent infusions when she was not taking LVFX. She was given many other drugs but the timing of the short course of LVFX and the fact that ciprofloxacin also delays MTX excretion suggests that LVFX was the cause. WHAT IS NEW AND CONCLUSION: Co-administration of LVFX may delay the excretion of MTX. Therefore, serum concentrations of MTX should be monitored to help prevent and improve the management of potentially serious MTX drug-drug interaction.

A single assessment of methotrexate levels at 42 hours permits safe administration and early discharge in children with lymphoblastic lymphoma and leukemia receiving high-dose methotrexate.

High-dose methotrexate (HDMTX) is an important component of treatment in pediatric acute lymphoblastic leukemia (ALL) and lymphoblastic lymphoma (LL). Optimal rescue therapy is essential for the safe administration of HDMTX. A cost-effective strategy that does not compromise safety is necessary for low- and middle-income countries. Consecutive admissions for HDMTX in children with ALL and LL over 12 months were analyzed. The dose of HDMTX was 3 g/m2 in B-ALL and B-LL and 5 g/m2 in T-ALL and T-LL. A methotrexate level was measured at 42 hours of starting HDMTX infusion (T42-MTX). Three doses of folinic acid at T42, T48, and T54 and alkalinized hydration till T54 were administered if T42-MTX <1 µM. A total of 282 cycles of HDMTX that were administered in 71 patients were analyzed. T42-MTX was <1 µM in 266 (94.3%) cycles. T42-MTX was ≥1 µM in 12% and 3% of cycles of HDMTX administered at a dose of 5 g/m2 and 3 g/m2, respectively (p = .074). The median duration of hospitalization for HDM was three days and did not differ with the dose of HDMTX administered (p = .427). Mucositis, delayed recovery of blood counts, and hospitalization for reversible toxicity occurred after 21 (7.4%), 28 (9.9%), and 19 (6.7%) cycles of HDMTX, respectively. Mucositis was greater following the administration of 5 g/m2 of HDMTX. A single T42-MTX measurement permits the safe administration of HDMTX and an expedited discharge from the hospital within three days in more than 90% of children with ALL/LL.

Calibrating from Within: Multipoint Internal Calibration of a Quantitative Mass Spectrometric Assay of Serum Methotrexate.

BACKGROUND: Clinical LC-MS/MS assays traditionally require that samples be run in batches with calibration curves in each batch. This approach is inefficient and presents a barrier to random access analysis. We developed an alternative approach called multipoint internal calibration (MPIC) that eliminated the need for batch-mode analysis. METHODS: The new approach used 4 variants of 13C-labeled methotrexate (0.026-10.3 µM) as an internal calibration curve within each sample. One site carried out a comprehensive validation, which included an evaluation of interferences and matrix effects, lower limit of quantification (LLOQ), and 20-day precision. Three sites evaluated assay precision and linearity. MPIC was also compared with traditional LC-MS/MS and an immunoassay. RESULTS: Recovery of spiked analyte was 93%-102%. The LLOQ was validated to be 0.017 µM. Total variability, determined in a 20-day experiment, was 11.5%CV. In a 5-day variability study performed at each site, total imprecision was 3.4 to 16.8%CV. Linearity was validated throughout the calibrator range (r2 > 0.995, slopes = 0.996-1.01). In comparing 40 samples run in each laboratory, the median interlaboratory imprecision was 6.55%CV. MPIC quantification was comparable to both traditional LC-MS/MS and immunoassay (r2 = 0.96-0.98, slopes = 1.04-1.06). Bland-Altman analysis of all comparisons showed biases rarely exceeding 20% when MTX concentrations were >0.4 µM. CONCLUSION: The MPIC method for serum methotrexate quantification was validated in a multisite proof-of-concept study and represents a big step toward random-access LC-MS/MS analysis, which could change the paradigm of mass spectrometry in the clinical laboratory.

The evaluation of red blood cell folate and methotrexate levels during protocol M in childhood acute lymphoblastic leukemia.

BACKGROUND: After High-Dose Methotrexate (HD-MTX), folinic acid rescue therapy (Leucovorin) is administered to reduce side effects in pediatric acute lymphoblastic leukemia (ALL) patients. Leucovorin and MTX are structural analogues, possibly competing for cellular transport and intracellular metabolism. We hypothesize that Leucovorin accumulates during consecutive courses, which might result in a lower MTX uptake. METHODS: We prospectively measured red blood cell (RBC) folate and MTX levels during four HD-MTX and Leucovorin courses in 43 patients treated according the DCOG ALL-11 protocol with 2-weekly HD-MTX (5 g/m2/dose) and Leucovorin (15 mg/m2/dose) using LC-MS/MS. We estimated a linear mixed model to assess the relationship between these variables over time. RESULTS: Both RBC MTX-PG and folate levels increased significantly during protocol M. MTX-PG2-5 levels increased most substantially after the first two HD-MTX courses (until median 113.0 nmol/L, IQR 76.8-165.2) after which levels plateaued during the 3d and 4th course (until median 141.3 nmol/L, IQR 100.2-190.2). In parallel, folate levels increased most substantially after the first two HD-MTX courses (until median 401.6 nmol/L, IQR 163.3-594.2) after which levels plateaued during the 3d and 4th course (until median 411.5 nmol/L, IQR 240.3-665.6). The ratio folate/MTX-PG decreased significantly over time, which was mostly due to the relatively higher increase (delta) of MTX-PG. CONCLUSION: These results suggest that the increase in RBC folate levels does not seem to have a large effect on RBC MTX levels. Future studies, assessing competition of Leucovorin and MTX on other cellular mechanisms which might negatively affect treatment efficacy, are necessary.

Risk factors associated with delayed methotrexate clearance and increased toxicity in pediatric patients with osteosarcoma.

High-dose methotrexate (HD-MTX; 12 g/m2 ) is part of standard therapy for pediatric osteosarcoma (OS). Risk factors associated with MTX toxicity in children with OS are not well defined. We investigated the association between peak MTX levels (four-hour) and delayed MTX clearance or treatment toxicity. Information was retrieved from electronic medical records of 33 OS patients treated with HD-MTX at Texas Children's Hospital from 2008 to 2015. We found that the four-hour MTX level did not contribute to toxicity or delayed MTX clearance. We demonstrated that certain demographic characteristics are associated with delayed clearance and increased toxicity.

Solitary serum methotrexate level 36 hours post high-dose methotrexate: A safe, efficacious, and cost-effective strategy to monitor methotrexate toxicities in childhood leukemia in resource-limited centers.

BACKGROUND: The standard practice during high-dose methotrexate (HD-MTX) in acute lymphoblastic leukemia (ALL) to mitigate toxicity is to serially monitor levels till serum MTX < 0.01 µmol/L. Most resource-limited centers lack in-house access to MTX levels, and therefore repeated monitoring is costly and cumbersome. We studied the efficacy and safety of "solitary 36 hours post HD-MTX levels (MTX36 )." PROCEDURE: This prospective observational study consecutively enrolled children with ALL receiving HD-MTX. Cycles with unavailable MTX36 and MTX36  > 10 µmol/L were excluded. HD-MTX was administered over 24 hours (BFM-2009 protocol) with 12 hours of prehydration. MTX36 were performed at other centers. Leucovorin was given in six hourly doses 36 hours post HD-MTX. Hydration was continued until the last dose of leucovorin. MTX toxicities, including change of creatinine from baseline at 36 hours (∆Cr36 ), were noted. Two groups depending on MTX36 (≤1 µmol/L vs > 1 µmol/L) received six versus eight doses of leucovorin, and toxicities were compared. RESULTS: Twenty-nine children with median age five years (1-11) who received 100 HD-MTX cycles with a median MTX dose of 3 g/m2 (2-5) were analyzed. The median MTX36 level was 1.165 µmol/L (0.1-7.32). Toxicities of HD-MTX (CTCAE-4.0): transaminitis-22%; creatinine elevation ≥ 1.25 times baseline-24%; cytopenias-16%; mucositis-17%; acute kidney injury (AKI)-6%. All toxicities were ≤CTCAE grade 3. Creatinine elevation, AKI, and mucositis were significantly higher in the group with higher MTX36 . There was no correlation (r = 0.3) between ∆Cr36 and MTX36 . MTX36 was thrice more economical than the standard protocol. CONCLUSION: MTX36 is a potential cost-effective, efficacious, and safe limited sample strategy to monitor HD-MTX, particularly in centers where in-house MTX levels are unavailable.

A Previously Unknown Drug-Drug Interaction Is Suspected in Delayed Elimination of Plasma Methotrexate in High-Dose Methotrexate Therapy.

Background: High-dose methotrexate (HD-MTX) therapy is widely implemented for leukemia, osteosarcoma, and lymphoma. Although various measures have been taken to avoid toxicity from high serum MTX concentrations, there are many cases of delayed elimination of MTX. Objective: We suspected that delayed elimination of serum MTX was caused by unknown interactions between MTX and concomitant drugs. Methods: Concerning concomitant drugs in the case of delayed elimination of MTX, we performed screening tests in 35 patients who had undergone HD-MTX therapy. We then investigated the risk factors for delayed MTX elimination in 94 patients with leukemia, lymphoma, or osteosarcoma retrospectively. Results: The percentages of concomitant use of Stronger Neo-Minophagen C (SNMC), a glycyrrhizin preparation, and vincristine were higher in the delayed group. The percentage of delayed MTX elimination in patients receiving HD-MTX therapy was 41%. Multiple logistic regression analysis revealed that the concomitant use of SNMC solely was a significant risk factor for delayed MTX (odds ratio = 12.20; 95% CI = 1.06-139.84). Conclusion and Relevance: Concomitant use of SNMC was shown to be related to delayed elimination of serum MTX, and our results suggested a previously unknown drug-drug interaction between MTX and SNMC.

A novel three-dimensional network of CuCr2O4/CuO nanofibers for voltammetric determination of anticancer drug methotrexate.

Considering the importance of measuring anticancer drugs, a carbon paste electrode (CPE) modified with CuCr2O4/CuO nanofibers in the presence of hydrophobic ionic liquid (IL) was fabricated for methotrexate (MTX) sensing. CuCr2O4/CuO nanofibers were prepared by electrospinning method. Then, the morphology and structure of the nanofibers were studied by scanning electron microscopy, thermal analysis, X-ray diffraction, energy-dispersive X-ray, map analysis, and FT-IR spectroscopy. The electrochemical behavior of MTX at CuCr2O4/CuO/IL/CPE surface was studied using cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy. After optimization of the experimental parameters, the prepared sensor showed a low detection limit of 25 nM MTX, based on signal-to-noise (S/N = 3), and it can determine in a wide range of 0.1-300 µM in Britton-Robinson buffer solution at pH 2.5. The modified electrode was used to determine MTX concentration in blood and urine samples with good recoveries of 94.1-104.3. This sensor has several advantages such as low cost, easy preparation, high-performance speed and high sensitivity, selectivity, stability, and repeatability. Graphical abstract Scheme of preparation of CuCr2O4/CuO nanofibers by electrospinning method and design of a carbon past electrode using prepared nanofibers (CuCr2O4/CuO/IL/CPE). This electrode was used for methotrexate determination in plasma and urine samples using differential pulse voltammetry.

Synthesis of bifunctional cabbage flower-like Ho3+/NiO nanostructures as a modifier for simultaneous determination of methotrexate and carbamazepine.

Cabbage flower-like Ho3+/NiO nanostructure (CFL-Ho3+/NiO NSs) with significant electrocatalytic oxidation has been published for the first time. First, structure and morphology of CFL-Ho3+/NiO-NSs have been described by XRD, SEM, and EDX methods. Then, CFL-Ho3+/NiO-NSs have been applied as a modifier for simultaneous electrochemical detection of methotrexate (MTX) and carbamazepine (CBZ). Functions of the modified electrode have been dealt with through electrochemical impedance spectroscopy (EIS). It has been demonstrated that the electrode response has been linear from 0.001-310.0 µM with a limit of detection of 5.2 nM and 4.5 nM (3 s/m) through DPV for MTX and CBZ. Diffusion coefficient (D) and heterogeneous rate constant (kh) have been detected for MTX and CBZ oxidation at the surface of the modified electrode. Moreover, CFL-Ho3+/NiO-NS/GCE has been employed for determining MTX and CBZ in urine and drug specimens. Outputs showed the analyte acceptable recovery. Therefore, the electrode could be applied to analyze both analytes in drug prescription and clinical laboratories. Graphical abstract Electrochemical sensor based on bifunctional cabbage flower-like Ho3+/NiO nanostructures modified glassy carbon electrode for simultaneous detecting methotrexate and carbamazepine was fabricated.

Methotrexate pharmacokinetic is influenced by co-administration of cyclosporin in rheumatoid arthritis patients. Results from a randomized clinical trial.

The aim was to investigate if the pharmacokinetics of methotrexate (MTX) are affected by the addition of cyclosporin (CsA). Forty patients diagnosed with early rheumatoid arthritis (RA) were included in this open prospective study: 20 patients were treated with a dose of 7.5 mg MTX and a dose of 2.5 mg/kg CsA, 20 patients were treated with a dose of 7.5 mg MTX and placebo. Baseline measurements of plasma MTX and erythrocyte MTX were made. Area under the plasma concentration versus time curve (AUC) and other pharmacokinetic variables were estimated by means of a population based software model. Clinical improvement of 20-50-70% according to the American College of Rheumatology (ACR) and adverse events were evaluated ongoing for 52 weeks. We found that mean peak plasma MTX concentration was significantly higher in the MTX + CsA combination treatment group (p = .003). No differences in AUC, erythrocyte MTX or other pharmacokinetic parameters were found between the two treatment groups. Estimated Glomerular Filtration Rate (eGFR) decreased significantly in the MTX + CsA treatment group (p < .001), but no serious adverse events occurred in either of the two groups. In conclusion, CsA added to methotrexate treatment in early RA significantly increased peak-plasma MTX concentration, but other pharmacokinetic parameters and measurements of MTX were unchanged.

Delayed Methotrexate Elimination after Administration of a Medium Dose of Methotrexate in a Patient with Genetic Variants Associated with Methotrexate Clearance.

Polymorphisms in methotrexate transporter pathways have been associated with methotrexate toxicities and clearance. Recent genome-wide association studies have revealed that the SLCO1B1 T521C variant is associated with methotrexate elimination. We present a case of a pediatric patient with acute lymphoblastic leukemia who suffered from persistently high plasma methotrexate concentrations and acute kidney injuries after the admin-istration of a medium dose of methotrexate. Subsequent genetic analysis showed that he was a carrier of dys-functional genetic variants associated with methotrexate clearance. This case highlights that polymorphisms of methotrexate transporter pathways can adversely affect methotrexate elimination in a clinically significant manner.

Population pharmacokinetics of high-dose methotrexate in Chinese pediatric patients with medulloblastoma.

Methotrexate (MTX) pharmacokinetics has substantial inter-individual variability and toxicity. In children with medulloblastoma treated with high-dose methotrexate (HD-MTX), the pharmacokinetic properties of methotrexate have not been established. A total of 660 serum samples from 105 pediatric patients with medulloblastoma were included in a population pharmacokinetic (PPK) analysis of methotrexate by using the nonlinear mixed-effects modeling method. The basic one-compartment population pharmacokinetic model was established by NONMEM software and the first-order conditional estimation (FOCE) method, and the final covariate model was obtained by the stepwise regression method. Weight (WT), creatinine clearance (CrCL), and whether the treatment was combined with dexamethasone (DEX) were covariates that had significant effects on the clearance rate (CL) of the model. The pharmacokinetic equation of CL in the final covariate model was as follows: CLi = 9.23× (1 + 0.0005× (θCrCL -105.78)) × (1 + 0.0017× (θWT -16)) × eηcl,i (L/h), IF (θDEX ) CLi = 1.19× CLi (L/h). The estimation accuracy of all pharmacokinetic parameters were acceptable (relative standard error < 14.74%). The goodness-of-fit diagram and bootstrap tests indicated that the final PPK model was stable with acceptable predictive ability. The PPK model may be useful for determining personalized medication levels in pediatric medulloblastoma patients undergoing HD-MTX therapy.