Determination Of Drug Concentrations Research Articles

Development of SIMPATEC-USP: An abbreviated impactor for rapid testing of inhalation devices

Cascade impactors like the Andersen Cascade Impactor (ACI) and Next Generation Impactor (NGI) are complex and costly due to multiple stages. This study introduces SIMPATEC-USP (Simplified Impactor Developed at the University of São Paulo), a low-cost, single-stage alternative meeting US Pharmacopeia standards for testing dry powder inhalers (DPIs). SIMPATEC-USP simplifies particle retention into a single Petri dish stage, eliminating multi-stage complexity. Its design includes a straightforward closure system for easy assembly/disassembly. A collection chamber holds a glass Petri dish with filter paper for final filtration, ensuring efficient aerosol product collection. SIMPATEC-USP also offers potential use with culture media for applications like antibacterial screening. Operating at 30 L/min, SIMPATEC-USP consists of three parts: a single-stage chamber, an L-shaped tube mimicking the trachea, and a vacuum pump. Aerosol particles are deposited onto the Petri dish via a nozzle, and the collected sample is weighed to determine drug concentration. Tested with inhalation-grade lactose, SIMPATEC-USP effectively collects and analyzes particles, allowing for rapid aerodynamic comparison of formulations, capsule retention assessment, and sample collection for drug release studies. The results demonstrate that it is possible to evaluate the performance of three inhalation devices regarding the mass migrating to the collection plate and that retained within the device itself. In conclusion, SIMPATEC-USP is highly suitable for exploratory studies and educational activities in pharmaceutical technology and pulmonary drug delivery systems.

Ocular Surface Fluid: More than a Matrix.

Although the eye can be subjected to therapeutic manipulation, some of its structures are highly inaccessible. Thus, conventional therapeutic administration pathways, such as topical or systemic routes, usually show significant limitations in the form of low ocular penetration or the appearance of side effects linked to physiology, among others. The critical feature of many xenobiotics is the drug gradient from the concentrated tear reservoir to the relatively barren corneal and conjunctival epithelia, which forces a passive route of absorption. The same is true in the opposite direction, towards the ocular surface (OS). With the premise that tears can be regarded as equivalent to or a substitute for plasma, researchers may determine drug concentrations in the OS fluid. Within this framework, a survey of scholarly sources on the topic was conducted. It provided an overview of current knowledge, allowing the identification of relevant theories, methods, and gaps in the existing research that can be employed in subsequent research. OS fluid (tears particularly) has enormous potential as a source of biological material for external drug screening and as a biomarker of various systemic diseases. Given the numerous alternate matrices, knowledge of their properties is very important in selecting the most appropriate specimens in toxicological analyses.

A developed and validated centrifugal ultrafiltration coupled with high performance liquid chromatography-tandem mass spectrometry method for rapid quantification of unbound lenvatinib in human plasma

In clinical practice, the determination of unbound drug concentration is very important for dose adjustment and toxicity prediction because only the unbound fraction can achieve a pharmacological effect. A fast, sensitive and accurate analytical method of centrifugal ultrafiltration coupled with high performance liquid chromatography-tandem mass spectrometry method was developed and applied to allow the quantification of unbound lenvatinib concentration. The application of linear regression analysis was used to examine the effects of centrifugal force, centrifugal time, and protein content on ultrafiltrate volume (Vu). The results indicated that the centrifugal force and centrifugal time have an influence on Vu that is significantly positive (P < 0.05). This developed method with good linearity (r2 = 0.9996), good accuracy (bias % ≤ 2.24 %), good precision (CV % ≤ 7.10 %), and good recovery (95.46 %−106.46 %) was suitable for routine clinical practice and studies. Particularly, the ultrafiltration membrane had no non-specific binding to lenvatinib. The unbound fractions can be separated in just 15 min. This method was applied to quantify clinical samples and to determine the plasma protein binding and unbound fraction of lenvatinib. This study provides a more effective and promising method for determination of unbound lenvatinib. It could be beneficial to measure the unbound concentration of lenvatinib in personalized medicine and therapeutic drug monitoring in routine clinical practice.

Association of CYP3A4*1B, CYP3A4*22 and CYP3A5*3 polymorphisms carriage with efficacy and safety of tamsulosin in patients with benign prostatic hyperplasia

Tamsulosin is a first-line drug in the treatment of lower urinary tract symptoms (LUTS) in benign prostatic hyperplasia (BPH). Despite high estimates of its efficacy and safety, it rates may vary due to genetic polymorphisms of genes for the enzymes involved in the drugs metabolism.The aim of the work was to evaluate the carriage influence of genes polymorphisms of the CYP3A enzymes group of tamsulosin metabolizers on the efficacy and safety of therapy in patients with LUTS in BPH.Materials and methods. A total of 142 patients with LUTS, with an established BPH diagnosis (N40 according to ICD-10) were included in the study and underwent all stages. All patients received monotherapy with tamsulosin 0.4 mg/day for at least 8 weeks. An IPSS questionnaire with the definition of quality of life, a prostate ultrasound with the determination of the prostate volume and residual urine, as well as uroflowmetry, were used to evaluate the results of the treatment. Controls were performed at 2, 4 and 8 weeks from the start of the therapy. The carriage of polymorphic markers CYP3A4 (*1B, *22) and CYP3A5*3 was determined in patients; HPLC was used to determine drug concentrations in blood plasma and levels of cortisol and its metabolite 6-beta-hydroxycortisol in urine to assess the phenotypic activity of CYP3A.Results. No statistically significant associations between CYP3A phenotype (defined by CYP3A4 and CYP3A5 genotypes) and clinical parameters of the tamsulosin therapy efficacy and the safety assessment in the studied sample of patients were found (p &gt;0.05). Similar data were obtained for individual variants of CYP3A4*1B, CYP3A4*22, CYP3A5*3 (p &gt;0.05). The comparison of the tamsulosin residual equilibrium concentration values in patients in the study sample with respect to the carriers of CYP3A4 and CYP3A5 gene variants did not reveal the presence of significant differences in either CYP3A phenotypes and carriers and non-carriers of individual CYP3A4*1B (p=0.57), CYP3A4*22 (p=0.37) and CYP3A5*3 (p=0.76) variants. No association was found between the metabolic ratio of 6-beta-hydroxycortisol / cortisol in urine and the CYP3A phenotype encoded by a combination of genotypes of CYP3A4 and CYP3A5 gene variants (p &gt;0.05).Conclusion. A possible association between the carriage of CYP3A4*1B, CYP3A4*22, CYP3A5*3 variants, a CYP3A activity assessed by the content of an endogenous substrate of this isoenzyme and its metabolite in urine, the level of plasma concentration of the drug, and the efficacy and safety of tamsulosin, has not been confirmed. The contribution of CYP3A4 and CYP3A5 genetic polymorphisms to clinical parameters of the tamsulosin therapy requires a further study.

Human β-defensin-1 affects the mammalian target of rapamycin pathway and autophagy in colon cancer cells through long non-coding RNA TCONS_00014506.

Colorectal cancer has a low 5-year survival rate and high mortality. Human β-defensin-1 (hBD-1) may play an integral function in the innate immune system, contributing to the recognition and destruction of cancer cells. Long non-coding RNAs (lncRNAs) are involved in the process of cell differentiation and growth. To investigate the effect of hBD-1 on the mammalian target of rapamycin (mTOR) pathway and autophagy in human colon cancer SW620 cells. CCK8 assay was utilized for the detection of cell proliferation and determination of the optimal drug concentration. Colony formation assay was employed to assess the effect of hBD-1 on SW620 cell proliferation. Bioinformatics was used to screen potentially biologically significant lncRNAs related to the mTOR pathway. Additionally, p-mTOR (Ser2448), Beclin1, and LC3II/I expression levels in SW620 cells were assessed through Western blot analysis. hBD-1 inhibited the proliferative ability of SW620 cells, as evidenced by the reduction in the colony formation capacity of SW620 cells upon exposure to hBD-1. hBD-1 decreased the expression of p-mTOR (Ser2448) protein and increased the expression of Beclin1 and LC3II/I protein. Furthermore, bioinformatics analysis identified seven lncRNAs (2 upregulated and 5 downregulated) related to the mTOR pathway. The lncRNA TCONS_00014506 was ultimately selected. Following the inhibition of the lncRNA TCONS_00014506, exposure to hBD-1 inhibited p-mTOR (Ser2448) and promoted Beclin1 and LC3II/I protein expression. hBD-1 inhibits the mTOR pathway and promotes autophagy by upregulating the expression of the lncRNA TCONS_00014506 in SW620 cells.

Simulated drug disposition in critically ill patients to evaluate effective PK/PD targets for combating Pseudomonas aeruginosa resistance to meropenem.

Bacterial infections, including those caused by Pseudomonas aeruginosa, often lead to sepsis, necessitating effective antibiotic treatment like carbapenems. The key pharmacokinetic/pharmacodynamic (PK/PD) index correlated to carbapenem efficacy is the fraction time of unbound plasma concentration above the minimum inhibitory concentration (MIC) of the pathogen (%fT > MIC). While multiple targets exist, determining the most effective one for critically ill patients remains a matter of debate. This study evaluated meropenem's bactericidal potency and its ability to combat drug resistance in Pseudomonas aeruginosa under three representative PK/PD targets: 40% fT > MIC, 100% fT > MIC, and 100% fT > 4× MIC. The hollow fiber infection model (HFIM) was constructed, validated, and subsequently inoculated with a substantial Pseudomonas aeruginosa load (1 × 108 CFU/mL). Different meropenem regimens were administered to achieve the specified PK/PD targets. At specified intervals, samples were collected from the HFIM system and subjected to centrifugation. The resulting supernatant was utilized to determine drug concentrations, while the precipitates were used to track changes in both total and drug-resistant bacterial populations over time by the spread plate method. The HFIM accurately reproduced meropenem's pharmacokinetics in critically ill patients. All three PK/PD target groups exhibited a rapid bactericidal response within 6 h of the initial treatment. However, the 40% fT > MIC and 100% fT > MIC groups subsequently showed bacterial resurgence and resistance, whereas the 100% fT > 4× MIC group displayed sustained bactericidal activity with no evidence of drug resistance. The HFIM system revealed that maintaining 100% fT > 4× MIC offers a desirable microbiological response for critically ill patients, demonstrating strong bactericidal capacity and effective prevention of drug resistance.

Hollow-fiber liquid phase microextraction for determination of fluoxetine in human serum by nano-liquid chromatography coupled to high resolution mass spectrometry

Therapeutic drug monitoring (TDM) is a personalized care tool based on the determination of a target drug concentration in human serum. An antidepressant drug of interest for such investigations is fluoxetine (FXT), due to a severe impact of genetic polymorphisms on its metabolism. A bioanalytical method employed for TDM purposes must exhibit satisfactory selectivity and detectability, which becomes more difficult due to highly complex biological matrices. In this study, a highly selective bioanalytical method for the determination of FXT in human serum is proposed, which provides excellent clean-up efficiency based on a low cost hollow fiber liquid-phase microextraction (HF-LPME) sample preparation step and nano-liquid chromatography coupled to high-resolution mass spectrometry (nano-LC-HRMS). HF-LPME was performed using a two-phase “U” configuration, with 6 cm fiber, 20 µL of 1-octanol acting as supported liquid membrane, and ammonium hydroxide (pH 10) as the donor phase with NaCl (10 % m/v) and methanol (5 % v/v) as additives, requiring only 250 µL of the sample. The procedure was conducted for 30 min under a 750 rpm stirring rate. Gradient elution was carried out employing an acetonitrile–water as mobile phase, the composition of 30:70 to 100:00 (v/v) for 15 min, using formic acid 0.1 % (v/v) as an additive. MS1 was acquired in an Orbitrap mass analyzer, while MS2 was acquired in a linear trap quadrupole. Satisfactory linearity (Pearson’s r = 0.99709) was obtained for a concentration range of 0.02 to 2.5 µg mL−1, which is compatible with the therapeutic and toxic range for FXT. The developed method presents adequate precision (1.61 to 7.45 %) and accuracy (95 to 114 %) and allows the dilution of high concentration samples in a 1:4 ratio (v/v), enabling its application for forensic serum samples. To our knowledge, this is the first study reporting a method based on HF-LPME and nano-LC-HRMS with any analytical purpose, especially with a TDM focus.

DNA hybrid florescent chrominance sensor: Drug sensing through direct gradient florescent color transformation of hybrid DNA crystals loaded lanthanide (Eu3+/Tb3+) complexes

In this study, a highly sensitive anticancer drug sensor was synthesized using DNA crystals loaded with luminescent Ln3+(Eu3+/Tb3+) complexes. The sensors exhibited a pronounced color transformation property due to the differential quenching of Eu3+ and Tb3+ emissions upon drug interactions. These luminescent hybrid DNA crystals present a significant advancement in sensing anticancer drugs like curcumin, transitioning from monitoring fluorescence intensity changes to a visually discernable color change. This new approach eliminates the need for specialized instrumentation. Owing to the intrinsic biocompatibility of materials composed of DNA, this hybrid sensor has the potential to sense drugs within the human body. Hybrid crystals loaded with a single complex will lose their fluorescence properties due to drug quenching; however, crystals loaded with mixed complexes emit distinct fluorescent colors, such as yellow-green and orange-red, at different drug concentrations. This color transformation allows for the direct determination of drug concentration based on crystal color, making the sensing process more simple and easily observable.

Salt-assisted liquid–liquid microextraction for determination of haloperidol in human plasma by LC-MS/MS

Haloperidol is an antipsychotic used in the treatment of schizophrenia. Compared to other antipsychotics, it is widely used in developing countries due to its affordable price. Haloperidol has a narrow therapeutic range and variable pharmacokinetics; therefore, therapeutic drug monitoring (TDM) is recommended. For this reason, in this study, an easily applicable, fast, selective, accurate, reliable, and economical LC-MS/MS method was developed for the determination of haloperidol in human plasma for use in TDM and also method was validated according to European Medicines Agency (EMA) Bioanalytical method validation guidelines. In the developed method, analyte and internal standard were extracted from plasma by salt-assisted liquid-liquid microextraction (SALLME) technique and after that injected to the LC system. The limit of quantification of haloperidol was determined as 1 ng/ml. The calibration curve was validated between 1-15 ng/ml, with correlation coefficients &gt;0.99. In addition, the developed method was used to determine drug concentration levels in the plasma of real patients.

Label-free mapping of cetuximab in multi-layered tumor oral mucosa models by atomic force-microscopy-based infrared spectroscopy.

Sensitive mapping of drugs and drug delivery systems is pivotal for the understanding and improvement of treatment options. Since labeling alters the physicochemical and potentially the pharmacological properties of the molecule of interest, its label-free detection by photothermal expansion is investigated. We report on a proof-of-concept study to map the cetuximab distribution by atomic-force microscopy-based infrared spectroscopy (AFM-IR). The monoclonal antibody cetuximab was applied to a human tumor oral mucosa model, consisting of a tumor epithelium on a lamina propria equivalent. Hyperspectral imaging in the wavenumber regime between 903 cm-1 and 1312 cm-1 and a probing distance between the data points down to 10 × 10 nm are used for determining the local drug distribution. The local distinction of cetuximab from the tissue background is gained by linear combination modeling making use of reference spectra of the drug and untreated models. The results from this approach are compared to principal component analyses, yielding comparable results. Even single molecule detection appears feasible. The results indicate that cetuximab penetrates the cytosol of tumor cells but does not bind to structures in the cell membrane. In conclusion, AFM-IR mapping of cetuximab proved to sensitively determine drug concentrations at an unprecedented spatial resolution without the need for drug labeling.

Comparative Analysis of Sibutramine Concentration Determination

This paper underscores the practical implications of employing FTIR RMSE analysis in pharmaceutical research. It highlights the method's rapid and non-destructive nature for quantifying drug concentration in complex formulations, emphasizing its significance in pharmaceutical quality assurance. The study advocates for integrating FTIR RMSE with conventional gravimetric and volumetric methods to enhance the analytical toolkit for pharmaceutical compound analysis. Furthermore, it elucidates the potential of FTIR RMSE in expediting analytical processes and improving estimation accuracy. The paper accentuates the synergy between classical gravimetric techniques and modern spectroscopic methods, providing valuable insights into pharmaceutical compound analysis within heterogeneous formulations. In terms of contributions, this paper advances analytical methods in pharmaceutical research by comprehensively exploring traditional gravimetric/volumetric techniques alongside Fourier Transform Infrared Spectroscopy (FTIR) coupled with Root Mean Square Error (RMSE) analysis. It assesses their effectiveness in determining drug concentrations, mainly focusing on sibutramine quantification, a complex active pharmaceutical ingredient. The results indicate a strong correlation (R² = 0.987) between the two methodologies, with FTIR RMSE consistently yielding slightly higher results due to its sensitivity to molecular structural fluctuations and component interactions. In conclusion, this study advocates for integrating FTIR RMSE into pharmaceutical research practices. It emphasizes the need for calibration and refinement of this technique to further enhance estimation accuracy and analytical precision. It underscores the pivotal role of advanced analytical methods in various applications, including pharmaceutical and biomedical fields.

Developing an in vitro lipolysis model for real-time analysis of drug concentrations during digestion of lipid-based formulations

Understanding the effect of digestion on oral lipid-based drug formulations is a critical step in assessing the impact of the digestive process in the intestine on intraluminal drug concentrations. The classical pH-stat in vitro lipolysis technique has traditionally been applied, however, there is a need to explore the establishment of higher throughput small-scale methods. This study explores the use of alternative lipases with the aim of selecting digestion conditions that permit in-line UV detection for the determination of real-time drug concentrations. A range of immobilised and pre-dissolved lipases were assessed for digestion of lipid-based formulations and compared to digestion with the classical source of lipase, porcine pancreatin. Palatase® 20000 L, a purified liquid lipase, displayed comparable digestion kinetics to porcine pancreatin and drug concentration determined during digestion of a fenofibrate lipid-based formulation were similar between methods. In-line UV analysis using the MicroDISS ProfilerTM demonstrated that drug concentration could be monitored during one hour of dispersion and three hours of digestion for both a medium- and long-chain lipid-based formulations with corresponding results to that obtained from the classical lipolysis method. This method offers opportunities exploring the real-time dynamic drug concentration during dispersion and digestion of lipid-based formulations in a small-scale setup avoiding artifacts as a result of extensive sample preparation.

Electrochemical sensor based on polypyrrole/triiron tetraoxide (PPY/Fe3O4) nanocomposite deposited from a deep eutectic solvent for voltammetric determination of procaine hydrochloride in pharmaceutical formulations

This investigation reports the electrochemical preparation of a polypyrrole/triiron tetraoxide (PPY/Fe3O4) nanocomposite from deep eutectic solvents (DESs), and their application as novel sensor electrodes to determine certain pharmaceutical formulations using cyclic voltammetry (CV). The modified polypyrrole/Fe3O4 nanocomposite was characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), X-ray diffraction (XRD), and Fourier-transform infrared (FTIR) spectroscopy. These techniques confirmed the incorporation of Fe3O4 into the polypyrrole composite. Cyclic voltammetry and electrochemical impedance spectroscopy (EIS) indicated that PPY/Fe3O4 shows higher redox currents and greater electrical conductivity with procaine hydrochloride than other pharmaceutical formulations (ascorbic acid, diclofenac, losartan potassium, adiphenine hydrochloride, and metformin hydrochloride). Factors that could influence the determination of procaine hydrochloride, including pH, temperature, scan rate, concentration of drug, stability, and reproducibility, have all been optimized. Under optimal conditions, the calibration curve shows a linear relationship between oxidation peak current and procaine hydrochloride concentrations (between 0.005 and 0.3 mol/L), with an R2 of 0.9943. The limit of detection (LOD) was 0.0024 mol/L and the limit of quantification (LOQ) was 0.0079 mol/L. The modified sensor (PPY/Fe3O4) constructed in this study was successfully used for the determination of procaine hydrochloride drug concentrations in a procaine-penicillin pharmaceutical product.

Serum levels of infliximab and adalimumab are associated with deep remission in inflammatory bowel disease

ObjectiveDeep remission defined by clinical-biomarker remission and mucosal healing has emerged as a new therapeutic target in inflammatory bowel disease. The aim of this study was to define an optimal cut-off concentration for infliximab and adalimumab during maintenance therapy associated with deep remission. The secondary objective, was to evaluate the influence of variables on anti tumor necrosis factor-alpha concentrations and deep remission. MethodRetrospective study including 120 and 122 patients inflammatory bowel disease diagnosed who received maintenance therapy with infliximab and adalimumab. Biomarker remission was considered by C-reactive protein < 5 mg/L and fecal calprotectin < 100 µg/g. Crohn's disease clinical remission was defined by a Harvey Bradshaw score < 5 and mucosal healing by a simple endoscopic score for Crohn's disease< 3. In ulcerative colitis, it was defined as a Mayo total score < 3 and Mayo endoscopic subscore < 2. Receiver operating characteristic test was performed to determine drug concentration thresholds associated with deep remission. Anti tumor necrosis factor-alpha concentrations were classified into quartiles. X2 and Kruskal-Wallis test were used to compare discrete and continuous variables between quartile groups. Multivariate logistic regression was performed to identify patient characteristics and serological facto C-reactive protein rs associated with deep remission. ResultsAnti tumor necrosis factor-alpha concentrations were higher in patients with deep remission, in infliximab (4.4, interquartile range: 3.3-6.5 vs 2.3, interquartile range: 1.1-4.2 µg/mL, P < 0.005) and adalimumab (6.3, interquartile range: 4.2-8.2 vs 3.9, interquartile range: 2.4-5.5 µg/mL, P < 0.005). A Receiver operating characteristic test identified a concentration threshold of 3.1 µg/mL in infliximab (area under the Receiver operating characteristic test curve, 0.72) and 6.3 µg/mL in adalimumab (area under receiver operating characteristic test curve, 0.75) associated with deep remission. Factors associated with the highest quartiles of serum infliximab concentration were: elevated body mass index, absence of previous inflammatory bowel disease-surgery, C-reactive protein < 5 mg/L, and fecal calprotectin < 100 µg/g. In adalimumab, higher quartiles were related to concomitant immunosuppressants, low body mass index, absence of previous inflammatory bowel disease-surgery, and C-reactive protein < 5 mg/L and fecal calprotectin < 100 µg/g. Multivariate regression identified fecal calprotectin < 100 µg/g, C-reactive protein < 5 mg/L, infliximab > 3.1 µg/mL and adalimumab concentrations > 6.3 µg/mL as factors significantly associated with deep remission. ConclusionsTrough infliximab and adalimumab concentrations, C-reactive protein < 5 mg/L and fecal calprotectin < 100 µg/g are associated with deep remission during maintenance therapy. Cutoff point of 3.1 and 6.3 g/mL for infliximab and adalimumab respectively, were identified as deep remission predictors.

Protein binding investigation of first-line and second-line antituberculosis drugs

Data about antituberculosis drugs binding are incomplete for first-line drugs and lacking for second-line drugs that are used extensively for multi-drug resistant tuberculosis (levofloxacin, linezolid and moxifloxacin). Thus, the main purposes of this study were first to investigate thoroughly the relation between the carrier-proteins level and the drug binding and second to investigate the feasibility of predicting the free drug concentrations by the means of in vitro and in vivo results. In vitro experiments mimicked real-case samples by spiking drugs combinations from the clinical practice. We measured a median in vivo protein binding of 1.5% for ethambutol, 9.7% for isoniazid, 0.7% for pyrazinamide and 88.2% for rifampicin; and a median in vitro protein binding of 26.2% for levofloxacin, 12.8% for linezolid and 46.3% for moxifloxacin. The albumin concentration had a moderate impact on the moxifloxacin binding and a strong impact on the levofloxacin, linezolid and rifampicin binding (below values of 30 g/L). The determination of the free drug concentration seems to have few interests for ethambutol, isoniazid, moxifloxacin and pyrazinamide, a limited interest for linezolid because of its low binding and a major interest for rifampicin in hypoalbuminemia TB patients and for levofloxacin because their total concentration was an inaccurate reflection of the free concentration. The free concentration predicted by mathematical model was suitable for levofloxacin and linezolid, unlike for rifampicin, where the real free concentration should be measured. Further investigations should be carried out to investigate the benefit of the free concentration for levofloxacin, linezolid and rifampicin mainly in the critical period of active tuberculosis associated to hypoalbuminemia.

B-341 Analytical Performances of Homogeneous Mobility Shift Assay for Infliximab and Biosimilars and Resulting Exposure Assessments in Large Cohort of Patients With Inflammatory Bowel Diseases

Abstract Background Biosimilar for infliximab (IFX) are currently available for the treatment of various immune mediated inflammatory diseases including inflammatory bowel disease (IBD). We have validated the homogenous mobility shift assay (HMSA) for IFX biosimilars and describe exposure from a large population of patients with IBD treated with IFX and biosimilars. Methods Validation of the biosimilars, infliximab-dyyb (Inflectra®) and infliximab-abda (Renflexis®), was conducted in a reference clinical laboratory (Prometheus Laboratories, Inc.) for performance equivalence to the 1st international World Health Organization (WHO) IFX standard (16/170) by HMSA. The evaluated performance characteristics consisted of accuracy, precision, sensitivity, specificity, range, and linearity using spiked human serum. Following validation and implementation in the clinical laboratory, the drug median with interquartile range (IQR) and antibody to drug (ATI) prevalence and percentage relative to low-titer antibody cut-point of 10 U/mL (Am J Gastroenterol 2021;00:1-12), using de-identified patients, was evaluated by comparing treatment with IFX or the two validated biosimilars. Results The reportable range for the biosimilars was 0.98 μg/mL (precision: 5.5% CV; accuracy: 110.7% recovery) to 34 µg/mL (precision: 6.3% CV; accuracy: 105.4% recovery). Biosimilar intra-day, inter-day precision (CV) and accuracy (% recovery) across the reportable range were 3.8%, 3.6% and 105.1%, respectively. Furthermore, HMSA calibrated with IFX originator or biosimilar showed congruent results when compared to calibration with the WHO standard for the determination of drug concentrations using 20 clinical samples spanning the reportable range (Fig. 1). Median drug concentrations with IQR were 10.9 µg/mL (4.8–19.7 µg/mL) for infliximab originator, 9.8 µg/mL (3.9–18.1) for infliximab-dyyb, and 9.5 µg/mL (3.6–18.3) for infliximab-abda over a three-year period of testing, which also demonstrated similar ATI positivity rates. Conclusion HMSA is validated to be used as a tool for therapeutic drug monitoring (TDM) of patients treated with IFX originator and biosimilars.

The Use of a Closed Feed Frame for the Development of Near-Infrared Spectroscopic Calibration Model to Determine Drug Concentration.

This study evaluates the use of the closed feed frame as a material sparing approach to develop near-infrared (NIR) spectroscopic calibration models for monitoring blend uniformity. The effect of shear induced by recirculation on NIR spectra was also studied. Calibration models were developed using NIR spectra obtained in the closed feed frame for two cases. For case 2, blends that flowed through the open feed frame were predicted with the model. The shear effect of the feed frame on the blends was assessed through the characterization of powder properties before and after recirculation. The physical characterization of the blends confirmed that the powder properties were not altered after recirculation within the closed feed frame. Both calibration models provided highly accurate predictions of the test sets with low bias (0.03% w/w and -0.06% w/w) and relative standard error of prediction (1.9% and 3.7%), respectively. The predictive performance of the calibration models was not affected by the shear effect. Recirculation within the closed feed frame did not change the physical properties of the blends studied. The prediction of blends flowing through the open feed frame was possible with a calibration model developed in the closed feed frame. The closed feed frame could reduce the materials needed to develop calibration models by more than 90%.

Multiclass determination of drug residues in water and fish for bioaccumulation potential assessment

In this work, a wide-scope liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the quantitative determination of environmental levels of multiclass drugs and their metabolites in water and fish samples was developed. The method allowed the reliable determination of 44 drugs, covering a rather wide range of chemistries and physicochemical characteristics. In order to obtain a reliable and robust analytical protocol, different combinations of extraction and cleanup techniques were systematically examined. Aqueous samples were extracted using a simple Oasis HLB SPE enrichment protocol with pH-optimized sample percolation (pH 3). The extraction of cryo-homogenized biota samples was performed using double extraction with MeOH basified with 0.5% NH3, which allowed high extraction recoveries for all target analytes. The problem of the coextracted lipid matrix, which is known to be the key obstacle for reliable biota analysis, was systematically examined in a series of model cleanup experiments. A combination of cryo-precipitation, filtration, and HLB SPE cleanup was proposed as a protocol, which allowed reliable and robust analysis of all target compounds at low ng/g levels. At the final conditions, the method which was validated at three concentration levels showed high extraction recoveries (68–97%), acceptable matrix effects (12 to −32%), accuracies (81–129%), and reproducibilities (3–32%) for all analytes. The developed method was used to determine drug concentrations in river water and in feral freshwater fish, including whole fish and muscle tissue, from the Sava River (Croatia), in order to estimate their corresponding bioaccumulation potential. With respect to bioaccumulation potential in whole fish and fish muscle, the most relevant drugs were lisinopril, sertraline, terbinafine, torsemide, diazepam, desloratadine, and loratadine with estimated bioaccumulation factors ranging from 20 to 838 and from 1 to 431, respectively.

Self-Nanoemulsifying Drug Delivery System-Containing the Poorly Absorbed Drug - Valsartan in Post-Bariatric Surgery.

Morbid obesity and its related metabolic syndrome are an important health issue. Recently, sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB) have accounted for the most popular bariatric surgeries. Valsartan (VST) is a common hypertension drug, and nano-carriers can increase its solubility and bioavailability. This study aims to explore the nano-VST formula in bariatric surgery subjects. High-fat fed animals were used as obese models. Operations were performed according to a standardized protocol. The drug was administrated by gavage, and blood samples were taken by serial tail vein sampling. Caco-2 cells were used for examining cell viability and drug uptake. A self-nano-emusifying drug delivery system (SNEDDS) formula was composed of sefsol-218, RH-40 and propylene glycol by a specified ratio, while high-performance liquid chromatography (HPLC) was used for determining drug concentrations. Post-operatively, subjects that underwent RYGB lost more body weight compared to the SG group. The SNEDDS did not exhibit cytotoxicity after adequate dilution, and the cytotoxicity was not related to VST dose. A better cellular uptake of SNEDDS was observed in vitro. The SNEDDS formula achieved a diameter of 84 nm in distilled water and 140 nm in simulated gastric fluid. In obese animals, the maximum serum concentration (Cmax) of VST was increased 1.68-folds by SNEDDS. In RYGB with SUS, the Cmax was reduced to less than 50% of the obese group. SNEDDS increased the Cmax to 3.5 folds higher than SUS and resulted in 3.28-folds higher AUC0-24 in the RYGB group. Fluorescence imaging also confirmed a stronger signal of SNEDDS in the gastrointestinal mucosa. SNEDDS accumulated a higher drug concentration than suspension alone in the liver of the obese group. SNEDDS could reverse the VST malabsorption in RYGB. Further studies are mandatory to clarify post-SG change of drug absorption.

Abstract 1093: Measuring and inhibiting purine metabolism in patients with glioblastoma

Abstract Introduction: We have previously found that purine metabolism is an important metabolic mediator of treatment resistance in glioblastoma (GBM). Mycophenolate mofetil (MMF), an inhibitor of purine synthesis, synergizes with radiation and temozolomide in mouse models of GBM. No measurements of purine synthesis have been performed in human cancer patients, nor has the purine inhibitor MMF been used clinically for patients with GBM. Methods: We infused clinical-grade 13C6 glucose into patients undergoing craniotomy for presumed GBM and used mass spectrometry to measure carbon incorporation into purines in cortex and disparate tumor regions. We are conducting a phase 0/1 trial (NCT04477200) to determine the safety and potential efficacy of the purine inhibitor MMF in patients with GBM. In the phase 0 arm, patients with recurrent GBM needing tumor re-resection receive MMF for one week prior to surgery and tumor and brain tissue is analyzed by mass spectrometry to determine drug concentrations and target engagement. In the phase 1 portions, patients (age &amp;gt;18, KPS ≥ 60) with recurrent GBM are treated with MMF and a second course of radiation while patients with newly diagnosed GBM are treated with radiation (RT), temozolomide (TMZ) and MMF followed by cyclic MMF and TMZ. A TITE-CRM algorithm is employed to dose-escalate MMF (range 500-2000 mg BID) and determine its maximum tolerated dose in combination with RT and/or TMZ. Results: Stable isotope tracing has been performed on 8 patients with suspected GBM. Purine synthesis was increased in tumor tissue compared to normal cortex in all patients, with most patients having 10-30-fold increased purine labeling in tumor. We have enrolled 8 patients on our phase 0 peri-surgical study and all had active concentrations of mycophenolic acid (the active metabolite of MMF) in enhancing and non-enhancing GBM tissue. We have enrolled 28 evaluable phase 1 patients (13 recurrent, 15 new). No dose-limiting toxicities have been observed with MMF (1000-2000 mg BID) in combination with re-irradiation or cyclic TMZ. In concurrent chemoradiation with MMF, we have observed two dose limiting grade 3 toxicities at 2000 mg, both improved with treatment break. Other main toxicities are mild nausea and fatigue. Interim median overall survival in recurrent phase 1 patients is 15.6 months, which compares favorably with typical survival time of 8-10 months in this population. In the newly diagnosed cohort, median survival is not yet reached, but 14 of 15 patients are alive and without progressive tumor. Conclusions: Glucose-derived purine synthesis is elevated in human GBM compared to cortex, which could provide a favorable therapeutic index for purine synthesis inhibition. The purine synthesis inhibitor MMF achieves active concentrations in human GBM, is reasonably well tolerated in combination with standard GBM treatments, and is associated with promising preliminary clinical outcomes. Citation Format: Yoshie Umemura, Andrew J. Scott, Wajd Al-Holou, Anjali Mittal, Weihua Zhou, Kari Wilder-Romans, Jie Xu, Nathan Qi, Maureen Kachman, Michelle Kim, Larry Junck, Denise Leung, Nathan Clarke, Jason Heth, Bo Wen, Amit Pai, Vijay Tarnal, Deepak Nagrath, Theodore Lawrence, Costas A. Lyssiotis, Daniel R. Wahl. Measuring and inhibiting purine metabolism in patients with glioblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1093.