Measurement Of Drug Concentrations Research Articles

Assessment of Analytical Techniques for Precise Quantification of Four Antiviral Drugs in Pharmaceutical Research and Development: A Comprehensive Review

Abstract: Precise measurement of drug concentration in pharmaceutical research is critical, especially for anti-viral drugs like boceprevir, elvitegravir, indinavir, and saquinavir that combat viral infections. It is well-known that analytical techniques play an imperative role in identifying and characterizing active pharmaceutical ingredients in biological samples and drug formulations. Moreover, precise drug assessment directly influences safety, stability, and efficacy while providing in-depth insight into drug pharmacokinetics. Other than this, analytical techniques also aid in identifying impurities, deteriorated products, and potential pollutants. Thus, reliable analytical methods have become crucial for addressing challenges imposed by complex drug formulations. The most commonly used analytical technique is UV spectrophotometry, which does not have the high sensitivity to detect complex drug formulations. In contrast, Liquid Chromatography-Mass Spectrometry/Mass Spectrometry (LC-MS/MS) merges two analytical techniques, chromatography and mass spectrometry, to accurately quantify biological samples. Furthermore, Ultra-Performance Liquid Chromatography (UPLC) provides enhanced resolution, faster analysis in short duration, and low solvent consumption in contrast to HPLC. This comprehensive review aims to critically assess each analytical approach's accuracy, applicability, selectivity, and limitation to provide valuable insights for researchers and analysts. Understanding the weaknesses and strengths of these analytical techniques will enable the researchers to select the suitable analytical method based on their needs and requirements for quality assessment, precise drug quantification, and optimal therapeutic efficiency. Eventually, this review intends to advance pharmaceutical research and development, specifically for anti-viral drugs, by ensuring the effective and secure administration of therapies.

A validated UPLC-MS/MS method for the quantification of immunosuppressive drugs in peripheral blood mononuclear cells using liquid-liquid extraction with low temperature purification without complex pretreatment steps

Immunosuppressive drugs (ISDs) are given to avoid the allograft rejection after transplantation. The concentrations of ISDs should be closely monitored owing to their wide inter-individual variability in its pharmacokinetics and narrow therapeutic window. Currently, the whole blood concentration measurement is the major approach of therapeutic drug monitoring of clinical ISDs in organ transplantation. Its correlation with the efficacy of ISDs remains elusive. While the acute rejection after transplantation may occur even when whole-blood ISDs concentrations are within the target range. Since the site of action of ISDs are within the lymphocyte, direct measurement of drug exposure in target cells may more accurately reflect the clinical efficacy of ISDs. Although several methods have been developed for the peripheral blood mononuclear cells (PBMCs) extraction and drug concentration measurement, the complex pre-processing has limited the study of the relationship between intracellular ISDs concentrations and the occurrence of rejection. In this study, the extraction of ISDs in PBMCs was carried out by the liquid-liquid extraction with low temperature purification, without centrifugation. The lower limit of quantitation were 0.2ng/mL for cyclosporine A, tacrolimus and sirolimus, 1.0ng/mL for mycophenolic acid, and the within-run and between-run coefficient of variations were both less than 12.4%. The calibration curves of mycophenolic acid had a linear range (ng/mL): 1.0-128.0 (r2 = 0.9992). The calibration curves of other three ISDs had a linear range (ng/mL): 0.2-20.48 (r2 > 0.9956). A total of 157 clinical samples were analyzed by the UPLC-MS/MS for ISDs concentration in blood or plasma ([ISD]blood or plasma) and the concentration within PBMCs ([ISD]PBMC). Although there was strong association between [ISD]PBMC and [ISD]blood or plasma, the large discrepancies between concentration within [ISD]blood or plasma and [ISD]PBMC were observed in a small proportion of clinical samples. The developed method with short analysis time and little amounts of blood sample can be successfully applied to therapeutic drug monitoring of ISDs in PBMCs for analysis of large numbers of clinical samples and is helpful to explore the clinical value of ISDs concentration in PBMCs.

Astragalus Polysaccharide Enhances Voriconazole Metabolism under Inflammatory Conditions through the Gut Microbiota.

Voriconazole (VRC), a widely used antifungal drug, often causes hepatotoxicity, which presents a significant clinical challenge. Previous studies demonstrated that Astragalus polysaccharide (APS) can regulate VRC metabolism, thereby potentially mitigating its hepatotoxic effects. In this study, we aimed to explore the mechanism by which APS regulates VRC metabolism. First, we assessed the association of abnormal VRC metabolism with hepatotoxicity using the Roussel Uclaf Causality Assessment Method scale. Second, we conducted a series of basic experiments to verify the promotive effect of APS on VRC metabolism. Various in vitro and in vivo assays, including cytokine profiling, immunohistochemistry, quantitative polymerase chain reaction, metabolite analysis, and drug concentration measurements, were performed using a lipopolysaccharide-induced rat inflammation model. Finally, experiments such as intestinal biodiversity analysis, intestinal clearance assessments, and Bifidobacterium bifidum replenishment were performed to examine the ability of B. bifidum to regulate the expression of the VRC-metabolizing enzyme CYP2C19 through the gut-liver axis. The results indicated that APS does not have a direct effect on hepatocytes. However, the assessment of gut microbiota function revealed that APS significantly increases the abundance of B. bifidum, which could lead to an anti-inflammatory response in the liver and indirectly enhance VRC metabolism. The dual-luciferase reporter gene assay revealed that APS can hinder the secretion of pro-inflammatory mediators and reduce the inhibitory effect on CYP2C19 transcription through the nuclear factor-κB signaling pathway. The study offers valuable insights into the mechanism by which APS alleviates VRC-induced liver damage, highlighting its immunomodulatory influence on hepatic tissues and its indirect regulatory control of VRC-metabolizing enzymes within hepatocytes.

Intraperitoneal pharmacokinetics of systemic oxaliplatin, 5-fluorouracil and bevacizumab in patients with colorectal peritoneal metastases

BackgroundPeritoneal metastases (PM) commonly occur in colorectal cancer patients. Systemic chemotherapy yields poor outcomes for these patients. It is hypothesised that traditional systemic chemotherapy is not very effective for this patient population. This study investigates to what extent systemic anti-cancer therapy crosses the peritoneal barrier. MethodsIn a Phase I study, eighteen patients received systemic oxaliplatin, 5-FU, and bevacizumab. Plasma and peritoneal fluid samples were collected to measure drug concentrations. A non-compartmental analysis determined the Area Under the Curve (AUC) for oxaliplatin and 5-FU in both matrices. Intraperitoneal (IP) and intravenous (IV) exposure ratios were calculated, along with the bevacizumab concentration IP/IV ratio. The relationship between tumour load and IP/IV ratios and the correlation between the IP/IV ratios of different treatments were assessed statistically. ResultsA total of 438 5-FU samples and 578 oxaliplatin samples were analysed in plasma and peritoneal fluid. Bevacizumab was quantified with 17 measurements in plasma and 15 measurements IP. Median IP/IV ratios were 0.143, 0.352 and 0.085 for 5-FU, oxaliplatin and bevacizumab, respectively. Oxaliplatin exhibited a longer IP half-life than 5-FU. A correlation was found between oxaliplatin and bevacizumab IP/IV ratios (R=0.69, p=0.01). No statistical correlations were found between the other investigated drugs. ConclusionsOur findings indicate that only a small percentage of systemically administered anti-cancer treatment reaches the IP cavity, questioning their efficacy against PM. This strengthens the hypothesis for repeated intraperitoneal chemotherapy to reach adequate anti-cancer drug levels.

Therapeutic Drug Monitoring in Psychiatry: Enhancing Treatment Precision and Patient Outcomes.

Psychiatric disorders often require pharmacological interventions to alleviate symptoms and improve quality of life. However, achieving an optimal therapeutic outcome is challenging due to several factors, including variability in the individual response, inter-individual differences in drug metabolism, and drug interactions in polytherapy. Therapeutic drug monitoring (TDM), by measuring drug concentrations in biological samples, represents a valuable tool to address these challenges, by tailoring medication regimens to each individual. This review analyzes the current landscape of TDM in psychiatric practice, highlighting its significance in optimizing drug dosages, minimizing adverse effects, and improving therapeutic efficacy. The metabolism of psychiatric medications (i.e., mood stabilizers, antipsychotics, antidepressants) often exhibits significant inter-patient variability. TDM can help address this variability by enhancing treatment personalization, facilitating early suboptimal- or toxic-level detection, and allowing for timely interventions to prevent treatment failure or adverse effects. Furthermore, this review briefly discusses technological advancements and analytical methods supporting the implementation of TDM in psychiatric settings. These innovations enable quick and cost-effective drug concentration measurements, fostering the widespread adoption of TDM as a routine practice in psychiatric care. In conclusion, the integration of TDM in psychiatry can improve treatment outcomes by individualizing medication regimens within the so-called precision medicine.

Note on importance of correct stoichiometric assumptions for modeling of monoclonal antibodies.

Pharmacokinetic modeling of monoclonal antibodies (mAbs) with non-linear binding is based on equations of the target-mediated drug disposition (Mager and Jusko, J Pharmacokinet Pharmacodyn 28:507-532, 2001). These equations demonstrated their utility in countless examples and drug development programs. The model assumes that the mAb drug and the target have only one binding site each while, in reality, most antibodies have two binding sites. Thus, the currently used model does not correspond to the biological process that it aims to describe. The correct mechanistic model should take into account both binding sites. We investigated, using simulations, whether this discrepancy is important and when it is advisable to use a model with correct stoichiometric 2-to-1 ratio. We show that for soluble targets when elimination rate of the drug-target complex is comparable with the elimination rate of the drug or lower, and when measurements of both total drug and total target concentrations are available, the model with 1-to-1 (monovalent) binding cannot describe data simulated from the model with 2-to-1 (bivalent) binding. In these cases, models with correct stoichiometric assumptions may be necessary for an adequate description of the observed data. Also, a model with allosteric binding that encompasses both 2-to-1 and 1-to-1 binding models as particular cases was proposed and applied. It was shown to be identifiable given the detailed concentration data of total drug and total target.

Role of therapeutic drug monitoring in the treatment of multi-drug resistant tuberculosis

Tuberculosis (TB) is a leading cause of mortality worldwide, and resistance to anti-tuberculosis drugs is a challenge to effective treatment. Multi-drug resistant TB (MDR-TB) can be difficult to treat, requiring long durations of therapy and the use of second line drugs, increasing a patient’s risk for toxicities and treatment failure. Given the challenges treating MDR-TB, clinicians can improve the likelihood of successful outcomes by utilizing therapeutic drug monitoring (TDM). TDM is a clinical technique that utilizes measured drug concentrations from the patient to adjust therapy, increasing likelihood of therapeutic drug concentrations while minimizing the risk of toxic drug concentrations. This review paper provides an overview of the TDM process, pharmacokinetic parameters for MDR-TB drugs, and recommendations for dose adjustments following TDM.

Ten-year results of an international external quality control programme for measurement of anti-tuberculosis drug concentrations.

Participation in an external (interlaboratory) quality control (QC) programme is an essential part of quality assurance as it provides laboratories with valuable insights into their analytical performance. We describe the 10 year results of an international QC programme for the measurement of anti-tuberculosis (TB) drugs. Each year, two rounds were organized in which serum (or plasma) samples, spiked with known concentrations of anti-TB drugs, were provided to participating laboratories for analysis. Reported measurements within 80%-120% of weighed-in concentrations were considered accurate. Mixed model linear regression was performed to assess the effect of the measured drug, concentration level, analytical technique and performing laboratory on the absolute inaccuracy. By 2022, 31 laboratories had participated in the QC programme and 13 anti-TB drugs and metabolites were included. In total 1407 measurements were reported. First-line TB drugs (isoniazid, rifampicin, pyrazinamide and ethambutol) represented 58% of all measurements. Overall, 83.2% of 1407 measurements were accurate, and the median absolute inaccuracy was 7.3% (IQR, 3.3%-15.1%). The absolute inaccuracy was related to the measured anti-TB drug and to the performing laboratory, but not to the concentration level or to the analytical technique used. The median absolute inaccuracies of rifampicin and isoniazid were relatively high (10.2% and 10.9%, respectively). The 10 year results of this external QC programme illustrate the need for continuous external QC for the measurement of anti-TB drugs for research and patient care purposes, because one in six measurements was inaccurate. Participation in the programme alerts laboratories to previously undetected analytical problems.

Influence of ultrafiltration conditions on the measurement of unbound drug concentrations: flucloxacillin as an example.

When performing therapeutic drug monitoring (TDM) for flucloxacillin, it is advised to measure the unbound, not the total, flucloxacillin concentration. To be able to accurately quantify unbound flucloxacillin concentrations, a reliable analytical method is indispensable. To determine the influence of temperature and pH of the sample during ultrafiltration on the measured unbound fraction of flucloxacillin. We performed three different experiments. In a single laboratory experiment, we investigated the influence of ultrafiltration temperature (10°C, room temperature and 37°C) on the measured unbound fraction of flucloxacillin for three concentration levels. In a multiple laboratory experiment, the results of eight laboratories participating in an international quality control programme measuring unbound flucloxacillin concentrations were analysed. In the third experiment, patient samples were ultrafiltrated using four different conditions: (i) physiological pH and room temperature; (ii) unadjusted pH (pH 9 after freezing) and room temperature; (iii) physiological pH and 37°C and (iv) unadjusted pH and 37°C. For all experiments, measurement of samples that were ultrafiltrated at room temperature resulted in a substantially lower unbound fraction compared to samples that were ultrafiltrated at 37°C. Adjusting the pH to physiological pH only had a minimal impact on the measured unbound fraction. On the basis of these findings and considering the need for fast, simple and reproducible sample pretreatment for TDM purposes, we conclude that ultrafiltration of flucloxacillin should be performed at physiological temperature (37°C), but adjustment of pH does not seem to be necessary.

Abstract 6447: Development of a fully automated immunoassay system of serum pembrolizumab to forecast therapeutic effectiveness

Abstract Recently, immuno-oncology treatments utilizing immune checkpoint inhibitors including pembrolizumab have attracted attention. Such treatments demonstrate potential effectiveness against cancers resistant to existing drugs, while offering the benefit of reduced side effects. Nonetheless, there is a specific group of patients who do not experience adequate therapeutic benefits from pembrolizumab. Despite the issue, the development of a comprehensive evaluation system to forecast therapeutic effectiveness is still in development. A strategy to predict therapeutic effectiveness involves evaluating the trough level or the steady state plasma-concentration of a drug in the blood. Ohuchi, M. et al. (Lung Cancer, 2022) demonstrated that patients with lower trough levels have shorter overall survival and progression-free survival durations, according to LC-MS/MS measurement of pembrolizumab. Furthermore, Wang, N. et al (Lung Cancer, 2023) demonstrated that the optimization of the dosage interval, grounded on the steady state plasma-concentration (target concentration, 15 µg/mL) of pembrolizumab, extended the duration of progression-free survival. Despite the potential of LC-MS/MS measurements in predicting patient prognosis and the benefits of PK-guided therapy, their implementation in clinical settings is hindered by the complex and time-consuming pre-treatment process for samples. Consequently, there is a growing need for a practical and clinically feasible drug concentration measurement system. Aiming to construct a clinically applicable pembrolizumab measurement system, we have been dedicated to developing a fully automated immunoassay system using anti-pembrolizumab antibodies. We developed two measurement systems of pembrolizumab in serum using two different antibodies targeting pembrolizumab. Using less than 10 µl serum, these systems can quantify the concentration of pembrolizumab ranging from 0.125 to 500 µg/mL within an hour, thereby enabling PK-guided therapy in clinical settings. After developing the measurement systems, we performed a correlation analysis with the LC-MS/MS system, using 70 samples with varying pembrolizumab concentrations ranging from 1.80 to 85.0 µg/mL. The results demonstrated that our measurement systems have a good correlation with LC-MS/MS measurement. Furthermore, the two immunometric measurement systems demonstrated a significant correlation with each other, substantiating the accuracy of the newly developed measurement system in determining the levels of pembrolizumab in the serum. The fully automated immunoassay systems we developed can measure pembrolizumab in serum within an hour, potentially paving the way for personalized treatment based on the serum concentration of pembrolizumab in clinical practice. Citation Format: Naotaka Noda, Takuya Takahashi, Shigehiro Yagishita, Masahiro Miura, Yusuke Takahashi, Yasuhiro Irino, Masatoshi Yanagida, Akinobu Hamada. Development of a fully automated immunoassay system of serum pembrolizumab to forecast therapeutic effectiveness [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6447.

How the Hemostasis Laboratory Can Help Clinicians to Manage Patients on Oral Anticoagulants.

Oral anticoagulants are widely used to treat or prevent cardiovascular diseases in millions of patients worldwide. They are the drugs of choice for stroke prevention and systemic embolism in patients with non-valvular atrial fibrillation and prosthetic heart valves, as well as for treatment/prevention of venous thromboembolism. Oral anticoagulants include vitamin K antagonists (VKAs) and direct oral anticoagulants (DOACs). The hemostasis laboratory plays a crucial role in the management of treated patients, spanning from dose adjustment based on laboratory testing that applies to VKAs to the measurement of drug concentrations in special situations that apply to DOACs. This article aims to overview how the hemostasis laboratory can help clinicians manage patients on oral anticoagulants. Special interest is devoted to the international normalized ratio, used to manage patients on VKAs and to the measurement of DOAC concentrations, for which the role of the laboratory is still not very well defined, and most interferences of DOACs with some of the most common hemostatic parameters are not widely appreciated.

Effect of Extraction Procedure Substitution on Automated Tacrolimus, Sirolimus, and Cyclosporine Assays.

An erroneously high tacrolimus level was reported to a clinician. A root cause analysis investigation failed to determine the cause of the error. It was suspected that the incorrect preanalytical extraction reagent and procedure was used during testing; however, how this would affect the assayed drug concentration was unclear. Here we investigated the effect of the substitution of sirolimus, tacrolimus, and cyclosporine extraction reagents on assayed drug concentration. Tacrolimus, sirolimus, and cyclosporine concentration were measured on the Abbott Architect i2000 analyzer. Each assay requires a preanalytical extraction step, with a distinct reagent. We investigated the effect of the substitution of the extraction reagents and procedure between the 3 assays on the measured drug concentration. Two experiments were performed, one on samples of known drug concentration and one on samples with no drug present. Substituting cyclosporine and sirolimus extraction procedures increased assayed tacrolimus concentrations from 5.6 to 8.47 (+51.25%) and 8.13 (+45.18%) ng/mL, respectively. Extraction procedure substitutions decreased assayed sirolimus from 13.63 to 4.60 (-66.25%) and 8.07 (-40.79%) ng/mL for cyclosporine and tacrolimus. Cyclosporine concentration increased from 274.60 to 391.30 (+42.50%) ng/mL using sirolimus extraction reagents and to 757.30 (+175.78%) ng/mL using tacrolimus extraction reagents. Cross-reactivity was observed between the tacrolimus assay and sirolimus and cyclosporine extraction reagents. Significant changes, both positive and negative, are observed in assayed drug concentration when incorrect extraction procedures are used in the Abbott i2000 tacrolimus, sirolimus, and cyclosporine assays. Preanalytic extraction procedures should be investigated when performing root cause analysis for erroneous therapeutic drug values.

Acute ischemic stroke and measurement of apixaban and rivaroxaban: an observational cohort implementation study

BackgroundTreatment with intravenous thrombolysis for acute ischemic stroke is contraindicated with intake of apixaban/rivaroxaban in the last 48 hours. Recent European Stroke Organization guidelines suggest that thrombolysis can be considered if anti-factor Xa activity (AFXa) is <0.5 × 103 IU/L with low-molecular-weight (LMWH) or unfractionated heparin (UFH) calibrated assays. Some centers also use apixaban/rivaroxaban-calibrated AFXa assays to identify patients with low drug concentrations. ObjectivesTo prospectively evaluate the first year of implementation of drug-calibrated AFXa assays at our center with 2500 yearly admittances with suspected stroke. MethodsSamples were analyzed on Sysmex CS-5100 instruments with Innovance anti-Xa reagents. Thrombolysis could be considered with drug concentrations <25 μg/L. Patients were registered in an institutionally approved quality register. Outcomes included (1) the number of patients receiving thrombolysis after drug measurement, (2) turn-around time for drug concentration measurements, and (3) sensitivity of LMWH/UFH AFXa to apixaban and rivaroxaban. ResultsApixaban or rivaroxaban was measured in 148 samples, and 4 patients who previously would have been ineligible for thrombolysis were treated with thrombolysis. In total, thrombolysis was administered in 123 patient episodes in the study period. The median turn-around time for the drug measurements was 38 minutes. Apixaban concentrations of 25 μg/L and 50 μg/L corresponded to LMWH/UFH AFXa of 0.13 and 0.27 × 103 IU/L, respectively. There were too few rivaroxaban results for regression analysis. ConclusionImplementation of apixaban and rivaroxaban measurements led to a small increase in the number of patients receiving thrombolysis. Excluding significant concentrations of apixaban or rivaroxaban using LMWH/UFH AFXa may be feasible.

A high-throughput LC-MS/MS assay for piperaquine from dried blood spots: Improving malaria treatment in resource-limited settings

BackgroundMalaria is a parasitic disease that affects many of the poorest economies, resulting in approximately 241 million clinical episodes and 627,000 deaths annually. Piperaquine, when administered with dihydroartemisinin, is an effective drug against the disease. Drug concentration measurements taken on day 7 after treatment initiation have been shown to be a good predictor of therapeutic success with piperaquine. A simple capillary blood collection technique, where blood is dried onto filter paper, is especially suitable for drug studies in remote areas or resource-limited settings or when taking samples from children, toddlers, and infants. MethodsThree 3.2 mm discs were punched out from a dried blood spot (DBS) and then extracted in a 96-well plate using solid phase extraction on a fully automated liquid handling system. The analysis was performed using LC-MS/MS with a calibration range of 3 – 1000 ng/mL. ResultsThe recovery rate was approximately 54–72 %, and the relative standard deviation was below 9 % for low, middle and high quality control levels. The LC-MS/MS quantification limit of 3 ng/mL is sensitive enough to detect piperaquine for up to 4–8 weeks after drug administration, which is crucial when evaluating recrudescence and drug resistance development. While different hematocrit levels can affect DBS drug measurements, the effect was minimal for piperaquine. ConclusionA sensitive LC-MS/MS method, in combination with fully automated extraction in a 96-well plate format, was developed and validated for the quantification of piperaquine in DBS. The assay was implemented in a bioanalytical laboratory for processing large-scale clinical trial samples.

Translational PK-PD/TD modeling of antitumor effects and peripheral neuropathy in gemcitabine and nab-paclitaxel chemotherapy from xenograft mice to patients for optimal dose and schedule.

Gemcitabine and nab-paclitaxel (GnP) treatment, the standard first-line chemotherapy for unresectable pancreatic cancer, often causes peripheral neuropathy (PN). To develop alternative dosing strategies to avoid severe PN, understanding the relationship between pharmacokinetics (PK) and pharmacodynamics/toxicodynamics (PD/TD) is necessary. We established a PK-PD/TD model of GnP treatment to develop an optimal dose schedule. A mouse xenograft model of human pancreatic cancer was generated to measure drug concentrations in the plasma and tumor, antitumor effects, and PN after GnP treatment. The Simeoni tumor growth inhibition model with tumor concentrations and empirical indirect response models were used for the PD and TD models, respectively. Clinical outcomes were predicted with reported population estimates of PK parameters in cancer patients. The PK-PD/TD model simultaneously described the observed tumor volume and paw withdrawal frequency in the von Frey test. For the standard GnP regimen, the model predicted clinical overall response (75.1%), which was overestimated compared to that in a recent phase II study (42.1%) but lower than the observed disease control rate (96.5%). Model simulation showed that dose reduction to less than 40% GnP dose was not effective; a change of dose schedule from every week for 3weeks to every 2weeks was a more favorable approach than dose reduction to 60% every week. The PK-PD/TD model-based translational approach provides a guide for optimal dose determination to avoid severe PN while maintaining antitumor effects during GnP chemotherapy. Further research is needed to enhance its applicability and potential for combination chemotherapy regimens.

Design and Development of a Lipid-Based Self-Nano Emulsifying Drug Delivery System of Rosuvastatin Calcium

The work aimed at design and development of a self-nanoemulsifying drug delivery system to increase the solubility and further to evaluate pharmacokinetic parameters of Rosuvastatin calcium (SNEDDS).A unique High Performance Liquid Chromatography technique was used to measure drug concentration in albino rat blood plasma, optimized Self-Nano emulsified formulation had greater absorption than the drug suspension. Lab solutions software were used to analyse the plasma drug concentration data.

A first-in-human study of Brozopentyl Sodium, following single and multiple ascending intravenous infusion in Chinese healthy volunteers

BackgroundBrozopentyl Sodium (BZP), a novel agent for ischemic stroke, has shown promising results in preclinical pharmacological studies, prompting the initiation of the first-in-human investigation. PurposeThis study aimed to assess the safety, tolerability, and pharmacokinetic (PK) characteristics of BZP in Chinese healthy volunteers. MethodsThe study consisted of two parts. Part I was a single-center, randomized, single-blinded, placebo-controlled, single-ascending study with six BZP dose cohorts (SAD: 25, 50, 100, 200, 300, and 400 mg). Part II was a single-center, randomized, single-blinded, placebo-controlled, multi-dose- and dose-elevated study with three BZP dose cohorts (MAD: 50, 100, and 200 mg). Doses were administered once daily on days 1 and 7 and twice daily on days 2–6. The PK properties of BZP and its bioactive metabolites, BNBP, were assessed. Safety and tolerability evaluations were also conducted. ResultsIn the SAD study, BZP reached peak plasma concentrations (Tmax) at the end of administration, with median Tmax values ranging from 1 to 1.03 h, while BNBP reached Tmax between 1.25 to 1.38 h. The terminal half-lives (T1/2) were approximately 8 h for BZP and 15 h for BNBP. In the MAD study, steady-state plasma concentrations of BZP were reached by day 5. There was minimal accumulation of both BZP and BNBP after 7 days of administration. The area under the plasma concentration-time curve from 0 to time of the last measurable concentration (AUC0-t) and maximum plasma drug concentration (Cmax) showed dose-proportional increases for BZP but not for BNBP in both study parts. Single and multiple doses of BZP demonstrated a good safety profile and were well-tolerated. ConclusionBZP displayed safety, good tolerability and predictable PK characteristics following both single and multiple ascending intravenous administrations. These findings provide a basis for further clinical development of BZP for ischemic stroke patients.

Higher Serum Infliximab Concentrations Following Subcutaneous Dosing are Associated with Deep Remission in Patients with Inflammatory Bowel Disease

Abstract Background The relationship between subcutaneous infliximab [SC-IFX] concentrations and favourable therapeutic outcomes in patients with Crohn’s disease [CD] and ulcerative colitis [UC] remains elusive. Patients and Methods This cross-sectional study included consecutive adult patients with inflammatory bowel disease [IBD] treated with SC-IFX at a maintenance dose of 120 mg/2 weeks. Investigated therapeutic outcomes included sustained clinical remission; composite clinical and biomarker remission [clinical remission and C-reactive protein &amp;lt;5 mg/L]; biochemical remission [faecal calprotectin &amp;lt;250 µg/g]; and deep remission [clinical, biological, and biochemical remission]. Results Of 91 patients identified, 71 qualified for inclusion in the study [70% with CD; 27% with concomitant immunomodulators]. At the time of drug concentration measurement [median 13.5 months after switch], 55 [77%] patients had sustained clinical remission; n = 44 [62%] composite clinical and biomarker remission; n = 40 [56%] biochemical remission; and n = 31 [43%] deep remission. The mean SC-IFX concentrations were significantly higher in patients with sustained clinical remission [p = 0.014]; composite clinical and biomarker remission [p = 0.003]; biochemical remission [p &amp;lt; 0.001]; and deep remission [p &amp;lt; 0.001] compared to patients without having these outcomes. In multivariate analysis, SC-IFX concentration was the only factor independently associated with sustained clinical remission (odds ratio [OR]: 4.7, 95% confidence interval [CI]: 3.1–12.2, p = 0.005); clinical and biomarker remission [OR: 9.21, 95% CI: 6.09–18.7, p = 0.006]; biochemical remission [OR: 37, 95% CI: 14–39.3, p &amp;lt; 0.001]; and deep remission [OR: 29, 95% CI: 15.7–37.4, p &amp;lt; 0.001]. The optimal SC-IFX concentration cut-off associated with deep remission based on ROC analysis was 20 µg/mL [sensitivity: 0.91, specificity: 0.80, accuracy: 0.85]. Combination with an immunomodulator failed to improve SC-IFX pharmacokinetics. Conclusion Higher SC-IFX concentrations are associated with higher rates of favourable therapeutic outcomes in IBD patients. Serum SC-IFX concentrations &amp;gt;20 µg/mL were significantly associated with deep remission.

Validation of a quantitative liquid chromatography tandem mass spectrometry assay for linezolid in cerebrospinal fluid and its application to patients with HIV-associated TB-meningitis

Tuberculous meningitis treatment outcomes are poor and alternative regimens are under investigation. Reliable methods to measure drug concentrations in cerebrospinal fluid are required to evaluate distribution into the cerebrospinal fluid. A simple and quick method was developed and validated to analyse linezolid in human cerebrospinal fluid. Samples were prepared by protein precipitation followed by isocratic liquid chromatography and tandem mass spectrometry. The run time was 3.5 min. Accuracy and precision were assessed in three independent validation batches with a calibration range of 0.100–20.0 μg/mL. The method was used to analyse cerebrospinal fluid samples from patients with tuberculous meningitis enrolled in a clinical trial. Potentially infective patient samples could be decontaminated using Nanosep® nylon and Costar® nylon filter tubes under biosafety level 3 conditions before analysis. The filtration process did not significantly affect the quantification of linezolid. Linezolid concentration in cerebrospinal fluid obtained from tuberculous meningitis patients ranged from 0.197 μg/mL to 15.0 μg/mL. The ratio between average CSF and plasma linezolid concentrations varied with time, reaching a maximum of 0.9 at 6 h after dosing.

Characterization of the US Food and Drug Administration Post-Marketing Commitments and Requirements for Pregnancy and Lactation.

Enactment of the US Food and Drug Administration Amendments Act (FDAAA) in 2007 and the Pregnancy and Lactation Labeling Rule (PLLR) in 2015 are important milestones giving the FDA the authority to request studies in pregnant and lactating women. Our objective was to characterize trends of pregnancy and lactation-related postmarketing commitments (PMCs) and postmarketing requirements (PMRs) for new molecular entities approved by the FDA between 2000 and 2022. Approval letters of original New Drug Applications (NDAs, N = 488) for new molecular entities were obtained from the FDA website. NDAs with pregnancy and lactation-based PMCs/PMRs were identified, and data extracted. Data included: PMC/PMR timelines and attributes of requested study(ies) (type, design elements, and outcomes) when available. Fifty-nine NDAs included 92 PMCs/PMRs related to pregnancy and lactation. Forty-one NDAs had pregnancy-related PMRs/PMCs, 4 had lactation-related PMRs, and 14 had both. Most PMRs/PMCs were for nervous system medications (N = 33). Forty-seven NDAs specified safety data collection in infants in at least the first year of life. All pregnancy-related PMRs were issued after 2008, most PMCs (N = 8) were issued before 2008. Only one PMC requested a pharmacokinetic study in pregnant women. All lactation-related PMRs (N = 18) requested measurement of drug concentrations in breast milk with one also requiring measurement of maternal blood concentrations. Eighty-nine percent of lactation-related PMRs were requested after 2015. There was a steady increase in pregnancy and lactation-related PMRs following enactment of FDAAA and PLLR. Additions involved information collection pertaining to safety of the medication in pregnant and lactating women and children exposed to medications during pregnancy and breastfeeding.