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.

Validation of UV-Vis spectrophotometric and colorimetric methods to quantify methotrexate in plasma and rat skin tissue: Application to in vitro release, ex vivo and in vivo studies from dissolving microarray patch loaded pH-sensitive nanoparticle.

This research transformed MTX into smart nanoparticles that respond to the acidic conditions present in inflammation. These nanoparticles were then incorporated into a patch that dissolves over time, aiding their penetration. A method using UV-Vis spectrophotometry was validated to support the development of this new delivery system. This method was used to measure the quantity of MTX in the prepared patches in various scenarios: in laboratory solutions with pH 7.4 and pH 5.0, in skin tissue, and plasma. This validation was conducted in laboratory studies, tissue samples, and live subjects, adhering to established guidelines. The resulting calibration curve displayed a linear relationship (correlation coefficient 0.999) across these scenarios. The lowest quantity of MTX that could be accurately detected was 0.6 µg/mL in pH 7.4 solutions, 1.46 µg/mL in pH 5.0 solutions, 1.11 µg/mL in skin tissue, and 1.48 µg/mL in plasma. This validated method exhibited precision and accuracy and was not influenced by dilution effects. The method was effectively used to measure MTX levels in the developed patch in controlled lab settings and biological systems (in vitro, ex vivo, and in vivo). This showed consistent drug content in the patches, controlled release patterns over 24 h, and pharmacokinetic profiles spanning 48 h. However, additional analytical approaches were necessary for quantifying MTX in studies focused on the drug's effects on the body's functions.

Adherence to low-dose methotrexate in children with juvenile idiopathic arthritis using a sensitive methotrexate assay.

BACKGROUND: Low-dose weekly methotrexate (MTX) is the mainstay of treatment in juvenile idiopathic arthritis. Unfortunately, a substantial part of patients has insufficient efficacy of MTX. A potential cause of this inadequate response is suboptimal drug adherence. The aim of this study was to assess MTX adherence in juvenile idiopathic arthritis patients by quantification of MTX concentrations in plasma. Secondly, the association between MTX concentrations and either self-reported adherence issues, or concomitant use of biologics was examined. METHODS: This was a retrospective, observational study using plasma samples from juvenile idiopathic arthritis patients. An ultrasensitive liquid chromatography-tandem mass spectrometry method was developed for quantification of MTX and its metabolite 7-hydroxy-MTX in plasma. The determined MTX plasma concentrations in juvenile idiopathic arthritis patients were compared with corresponding adherence limits, categorising them as either adherent or possibly non-adherent to MTX therapy. RESULTS: Plasma samples of 43 patients with juvenile idiopathic arthritis were analysed. Adherence to MTX in this population was 88% shortly after initiation of MTX therapy and decreased to 77% after one year of treatment. Teenagers were more at risk for non-adherence (p = 0.002). We could not find an association between MTX adherence with either self-reported adherence issues, nor with the use of concomitant biological treatment (p = 1.00 and p = 0.27, respectively; Fisher's Exact). CONCLUSIONS: Quantification of MTX in plasma is a feasible and objective method to assess adherence in patients using low-dose weekly MTX. In clinical practice, the use of this method could be a helpful tool for physicians to refute or support suspicion of non-adherence to MTX therapy.

Successful multiple-exchange peritoneal dialysis in a patient with severe hematological toxicity by methotrexate: case report and literature review / Diálise peritoneal com múltiplas trocas bem-sucedida em paciente com grave toxicidade hematológica por metotrexato: relato de caso e revisão de literatura

Abstract Methotrexate is an effective medication to control several diseases; however, it can be very toxic, being myelosuppression one of its main adverse effects, which increases in severity and frequency in patients with renal failure. We present the case of a 68-year-old man with chronic, end-stage renal disease associated with ANCA vasculitis, under treatment with peritoneal dialysis, who received the medication at a low dose, indicated by disease activity, which presented as a complication with severe pancytopenia with mucositis that improved with support measures and multiple-exchange peritoneal dialysis. We reviewed 20 cases published to date of pancytopenia associated with methotrexate in patients on dialysis and found high morbidity and mortality, which is why its use in this type of patient is not recommended. However, when this complication occurs, a therapeutic option could be the use of multiple-exchange peritoneal dialysis in addition to supportive therapy for drug-related toxicity, although it is recognized that studies are required to show the role of multiple-exchange peritoneal dialysis in the removal of this medication.

Resumo Apesar de sua toxicidade, o metotrexato é um medicamento eficaz no controle de várias doenças. A mielossupressão, um de seus principais efeitos adversos, aumenta em gravidade e frequência nos pacientes com insuficiência renal. Apresentamos o caso de um homem de 68 anos de idade com doença renal terminal relacionada à vasculite associada ao ANCA em diálise peritoneal, que recebeu a medicação em dose baixa em função da atividade da doença e que teve como complicação pancitopenia grave com mucosite, tratada com medidas de suporte e diálise peritoneal com múltiplas trocas. Revisamos 20 casos publicados até o presente momento sobre pancitopenia associada a metotrexato em pacientes em diálise. Foi identificada alta morbidade e mortalidade, razão pela qual seu uso nesse tipo de paciente não é recomendado. No entanto, quando esta complicação ocorre, uma opção terapêutica pode ser o uso de diálise peritoneal com múltiplas trocas, além da terapia de suporte para toxicidade medicamentosa. Maiores estudos são necessários para demonstrar o papel da diálise peritoneal com múltiplas trocas na remoção desse medicamento.

The effect of methotrexate and azathioprine on the serum levels of IgA-alfa1-antitrypsin complex in juvenile chronic arthritis

In the present study we investigated the influence of methotrexate (MTX) and azathioprine (AZA) on the serum levels of the IgA-alpha1-antitypsin (IgA-AT) complex in patients with the systemic form of juvenile chronic arthritis (JCA). Fifty-six JCA patients (22 treated with MTX, 18 treated with AZA, and 16 not treated with any immuno-suppressive agent) were enrolled in the study. MTX dosage ranged from 0.3 to 0.5 mg kg(-1) week(-1) while AZA was given daily at an average dose of 1 mg/kg. MTX was given for 13 months (SD = 7 months) whereas AZA for 11 months (SD = 6 months). The average value of the complex was higher in JCA patients than in both control groups (0.74 + 0.73 U vs 0.37 + 0.13 U (control children), P<0.001 and vs 0.23 + 0.12 U (control adults), P<0.001). Values exceeding the normal range were found in twenty-two JCA patients (39.4 percent). Serum IgA-AT level was lowest in the MTX group compared to AZA and non-treated patients (0.56 + 0.24 U, 0.76 + 0.43 U, 0.95 + 0.52 U, respectively, P<0.05). IgA values exceeding normal levels for age were found in 14 percent of the patients. A correlation between the levels of the IgA-AT complex and C-reactive protein (r = 0.43, P<0.01), alpha1-acid-glycoprotein (r = 0.45, P<0.01), alpha1-antichymotrypsin (r = 0.52, P<0.01), alpha1-antitrypsin (r = 0.40, P<0.01) and IgA (r = 0.56, P<0.01) was established.

Predicción del retraso en la eliminación de metotrexato mediante métodos bayesianos / Predicting delayed methotrexte elimination using Bayesian methods

Introducción: El objetivo de este estudio fue comprobar la capacidad de los métodos bayesianos para predecir adecuadamente la evolución temporal de las concentraciones plasmáticas de metotrexato (MTX) en los pacientes monitorizados en el departamento de Oncología Pediátrica. Material y métodos: Como fase previa, se procedió a la estimación de los parámetros farmacocinéticos poblacionales del MTX a partir de los datos de 56 pacientes que recibieron 310 ciclos de tratamiento con MTX. Los parámetros farmacocinéticos del MTX fueron estimados mediante IT2B y NPEM. Se estimaron los tiempos óptimos de muestreo del MTX mediante D-optimalidad. Resultados y conclusión: En dos pacientes, las concentraciones extraídas a las 0 y 10 horas detectaron pacientes con futuras concentraciones tóxicas a las 24 horas, lo que permitió tomar medidas preventivas y de intensa vigilancia en los pacientes. Las concentraciones reales extraídas a las 24 horas postinfusión coincidieron exactamente con las predichas por metodología bayesiana, validando esta sistemática de trabajo (AU)