High Drug Concentrations Research Articles

Stochastic demethylation and redundant epigenetic suppressive mechanisms generate highly heterogeneous responses to pharmacological DNA methyltransferase inhibition

BackgroundDespite promising preclinical studies, the application of DNA methyltransferase inhibitors in treating patients with solid cancers has thus far produced only modest outcomes. The presence of intratumoral heterogeneity in response to DNA methyltransferase inhibitors could significantly influence clinical efficacy, yet our understanding of the single-cell response to these drugs in solid tumors remains very limited.MethodsIn this study, we used cancer/testis antigen genes as a model for methylation-dependent gene expression to examine the activity of DNA methyltransferase inhibitors and their potential synergistic effect with histone deacetylase inhibitors at the single-cancer cell level. The analysis was performed on breast cancer patient-derived xenograft tumors and cell lines, employing a comprehensive set of techniques, including targeted single-cell mRNA sequencing. Mechanistic insights were further gained through DNA methylation profiling and chromatin structure analysis.ResultsWe show that breast cancer tumors and cell cultures exhibit a highly heterogenous response to DNA methyltransferase inhibitors, persisting even under high drug concentrations and efficient DNA methyltransferase depletion. The observed variability in response to DNA methyltransferase inhibitors was independent of cancer-associated aberrations and clonal genetic diversity. Instead, these variations were attributed to stochastic demethylation of regulatory CpG sites and the DNA methylation-independent suppressive function of histone deacetylases.ConclusionsOur findings point to intratumoral heterogeneity as a limiting factor in the use of DNA methyltransferase inhibitors as single agents in treatment of solid cancers and highlight histone deacetylase inhibitors as essential partners to DNA methyltransferase inhibitors in the clinic.

Hot-melt extruded-FDM 3D-printed polyethylene oxide tablets: Dissolution imaging analysis of swelling and drug release.

Recent developments in pharmacogenetics have emphasised the importance of customised medication, driving interest in technologies like FDM 3D-printing for tailored drug delivery. FDM 3D-printing is a promising technique for the on-demand manufacturing of customised oral dosage forms, providing flexibility in terms of shape and size, dose and drug release profiles. This study investigates the fabrication and characterisation of 3D-printed oral dosage forms using PEO as the primary polymer and PEG 6 K as a plasticiser. Firstly, the printability of the PEO filaments with different propranolol hydrochloride concentrations was explored using the hot-melt extrusion technology. The influence of the propranolol hydrochloride concentrations on the mechanical properties of the filaments was examined was then examined after which surface characteristics, including roughness and wettability, were evaluated. Dissolution imaging was used to visualise the effects of drug content on the swelling and dissolution characteristics of the PEO-based 3D-printed tablets. Results showed a reduction in the flexural stress of the filaments with increasing drug load. It was also observed that increasing the drug load led to higher surface roughness and lower contact angles of the 3D-printed PEO tablets, implying increased surface hydrophilicity. The swelling behaviour of the tablets increased with higher drug concentrations, resulting in a larger gel layer formation. When comparing the drug release percentages, the release rate was higher in the 10 mg propranolol tablets, suggesting that a lower drug content led to a faster release. The greater gel layer of the 40 mg PPN tablets hindered the drug release by acting as a diffusion barrier, while the 10 mg PPN tablets, with less swelling and gel formation, experienced a faster drug release. These findings show the importance of drug content in modifying the surface properties, swelling behaviour, and drug release profiles of 3D-printed PEO tablets. The study also demonstrates the novel use of dissolution imaging for 3D-printed dosage forms, providing valuable quantitative and qualitative insights into swelling dynamics and channel formation to optimise 3D-printed tablets for drug delivery systems.

The fluoroquinolone compounds potentiate the antifungal activity of the echinocandins against Aspergillus fumigatus.

The antifungal drugs of the echinocandin family show high efficacy against Aspergillus fumigatus. However, their paradoxical effect, which restores fungal growth at high drug concentrations, and the emergence of resistant strains necessitate improvements. We identified 13 fluoroquinolone compounds from a chemical library containing 10,000 compounds that potentiate the antifungal activity of caspofungin. Among them, NE-E07 significantly enhanced the efficacy of echinocandins against A. fumigatus, including resistant strains, without potentiating other antifungal families like voriconazole or amphotericin B. Specifically, NE-E07 demonstrated a unique ability to potentiate caspofungin's activity against the echinocandin-resistant strain USHM-M0051 isolated from patients. Our experiments revealed that NE-E07, in combination with caspofungin, affected ergosterol biosynthesis in a manner consistent with azole drugs. Docking tests suggest NE-E07 has a high binding affinity with CYP51, which affects ergosterol biosynthesis similarly to azole drugs. Interestingly, known fluoroquinolones like ciprofloxacin, nalidixic acid, and norfloxacin did not show this potentiating effect, suggesting that NE-E07's unique structure is critical for its activity. Moreover, NE-E07 did not enhance echinocandin activity against Candida albicans or Cryptococcus neoformans, highlighting its specific action against A. fumigatus. In vivo studies demonstrated that co-treatment with NE-E07 and caspofungin increased the survival rate of mice infected with A. fumigatus. This significant improvement in survival underscores the potential clinical relevance of NE-E07 as a co-administered drug with echinocandins for treating fungal infections, particularly those resistant to echinocandins.

Protein abundance of drug transporters and drug-metabolizing enzymes in paired healthy and tumor tissue from colorectal cancer patients.

The widespread prevalence of colorectal cancer and its high mortality rate emphasize the urgent need for more effective therapies. When developing new drug products, a key aspect is ensuring that sufficiently high concentrations of the active drug are reached at the site of action. Drug transporters and drug-metabolizing enzymes can significantly influence the absorption and local accumulation of drugs in intestinal tissue. To understand how their presence may affect local drug disposition, the protein abundance of multiple drug transporters and drug-metabolizing enzymes was quantified in paired healthy colonic mucosa and colorectal adenocarcinoma tissue from colorectal cancer patients, utilizing mass spectrometry-based targeted proteomics. Statistically significant changes in protein expression were observed for two transporters (MRP1 and BCRP) and three of the studied enzymes (CES1, CES2 and UGT2B17). MRP1 displayed higher levels in cancerous tissue compared to healthy mucosa samples, while BCRP, CES1, CES2 and UGT2B17 showed the opposite. Other proteins of interest which could be quantified in colonic samples were the drug transporters P-gp, MRP3, MRP4, OATP2B1, MCT1 and enzymes CYP4F2, CYP2J2 and UGT1A1. The insights from this study enhance our understanding of the extent to which drug disposition in tumor tissue of colorectal cancer patients could be impacted by drug transporters and drug-metabolizing enzymes and may facilitate a more accurate prediction of local drug concentrations.

Nebulized inhalation drug delivery: clinical applications and advancements in research.

Nebulized inhalation administration refers to the dispersion of drugs into small droplets suspended in the gas through a nebulized device, which are deposited in the respiratory tract by inhalation, to achieve the local therapeutic effect of the respiratory tract. Compared with other drug delivery methods, nebulized inhalation has the advantages of fast effect, high local drug concentration, less dosage, convenient application and less systemic adverse reactions, and has become one of the main drug delivery methods for the treatment of respiratory diseases. In this review, we first discuss the characteristics of nebulized inhalation, including its principles and influencing factors. Next, we compare the advantages and disadvantages of different types of nebulizers. Finally, we explore the clinical applications and recent research developments of nebulized inhalation therapy. By delving into these aspects, we aim to gain a deeper understanding of its pivotal role in contemporary medical treatment.

Protective Action of Cannabidiol on Tiamulin Toxicity in Humans-In Vitro Study.

The growing awareness and need to protect public health, including food safety, require a thorough study of the mechanism of action of veterinary drugs in consumers to reduce their negative impact on humans. Inappropriate use of veterinary drugs in animal husbandry, such as tiamulin, leads to the appearance of residues in edible animal tissues. The use of natural substances of plant origin, extracted from hemp (Cannabis sativa L.), such as cannabidiol (CBD), is one of the solutions to minimize the negative effects of tiamulin. This study aimed to determine the effect of CBD on the cytotoxicity of tiamulin in humans. The cytotoxic activity of tiamulin and the effect of its mixtures with CBD were tested after 72 h exposure to three human cell lines: SH-SY5Y, HepG2 and HEK-293. Cytotoxic concentrations (IC50) of the tested drug and in combination with CBD were assessed using five biochemical endpoints: mitochondrial and lysosomal activity, proliferation, cell membrane integrity and effects on DNA synthesis. Oxidative stress, cell death and cellular morphology were also assessed. The nature of the interaction between the veterinary drug and CBD was assessed using the combination index. The long-term effect of tiamulin inhibited lysosomal (SH-SY5SY) and mitochondrial (HepG2) activity and DNA synthesis (HEK-293). IC50 values for tiamulin ranged from 2.1 to >200 µg/mL (SH-SY5SY), 13.9 to 39.5 µg/mL (HepG2) and 8.5 to 76.9 µg/mL (HEK-293). IC50 values for the drug/CBD mixtures were higher. Reduced levels of oxidative stress, apoptosis and changes in cell morphology were demonstrated after exposure to the mixtures. Interactions between the veterinary drug and CBD showed a concentration-dependent nature of tiamulin in cell culture, ranging from antagonistic (low concentrations) to synergistic effects at high drug concentrations. The increased risk to human health associated with the presence of the veterinary drug in food products and the protective nature of CBD use underline the importance of these studies in food toxicology and require further investigation.

5-Fluorouracil Loaded Prebiotic-Probiotic Liposomes Modulating Gut Microbiota for Improving Colorectal Cancer Chemotherapy.

The gut microbiota exerts inhibitory effects on the occurrence and progression of colorectal cancer (CRC) through various mechanisms. Compared to traditional microbiota regulation methods, prebiotics and probiotics demonstrate significant advantages in terms of safety and patient adaptability. Their synergy not only improves the intestinal environment but also enhances the host's anti-tumor immune response. 5-Fluorouracil (5-FU) is a first-line chemotherapy drug that has a short half-life and low bioavailability. However, if administered in an untargeted manner, 5-FU also causes adverse reactions. Liposomes can improve the pharmacokinetic profile of drugs and provide targeted delivery to the tumor site, thereby reducing side effects. In this work, a 5-FU-loaded liposome is modified with the prebiotic xylan derivative Sxy and the probiotic Akkermansia muciniphila active phospholipid homolog 1,2-dipalmitoylphosphatidy-lethanolamine (DPPE) to construct FLSK. The latter effectively prolongs the intestinal transport and release of 5-FU, maintaining high drug concentrations at the tumor site. FLSK is found to inhibit tumor growth and significantly extends the survival period of mice. In addition, FLSK promotes anti-tumor immunity and regulation of the gut microbiota. Combining the merits of prebiotics and probiotics, FLSK provides a potential strategy for integrating chemotherapy with gut microbiota regulation therapy for the treatment of CRC.

Quantifying interstitial fluid by direct osmotic pressure measurements in vivo via telemetry-enabled Nanofluidic implants

Interstitial fluid (IF) is pivotal in maintaining balance within tissues and organs, facilitating molecular transport and supporting homeostasis. Various drug delivery systems, such as long-acting depots or implants, rely on IF to distribute drugs locally before they enter the bloodstream. The volume and accessibility of this fluid directly influence how drugs diffuse and the build-up of the osmotic pressure in areas with high drug concentration, ultimately impacting the performance of the delivery systems. Consequently, differences in free fluid availability contribute to discrepancies in drug delivery in vitro versus in vivo. Accurately estimating the volume of IF in vivo would significantly improve the design of in vitro drug release experiments and enhance the outcomes of animal studies. However, accurately measuring free IF and its effect on drug delivery systems in living organisms poses challenges. In response, we developed a reservoir-membrane subcutaneous (SQ) implant similar to a long-acting drug delivery system. The implant measures fluid availability in surrounding tissues by measuring real-time osmotic pressure changes resulting from fluid permeating through a nanoporous membrane, using an integrated pressure transducer and Bluetooth connectivity. By correlating in vitro and in vivo data using a computational model of molecular transport across the membrane, we estimated a 93 % reduction in free fluid availability in the subcutaneous tissue surrounding the implant as compared to our ideal in vitro setting with implant immersed within sink fluids. Applicable to various implantation sites, our study highlights a practical approach to directly assessing free fluid availability in different tissues, enhancing in vitro drug delivery experimental design and evaluating the performance of drug delivery systems in physiological contexts.

Release Rates of Prednisolone-21-Hydrogen- Succinate from 3D-Printed Silicone as Material for Patient-Individualized Drug Releasing Implants

Abstract For treating idiopathic sudden sensorineural hearing loss, prednisolone is commonly used. However, systemic or middle ear injections often lead to insufficient drug delivery to the inner ear, causing ineffective treatment and systemic side effects. An implant inserted into the middle ear and delivering the drug directly to the inner ear offers a promising solution, providing controlled, long-term drug release with potentially better efficacy and fewer side effects. Individualized implants made of prednisolone-containing silicone can optimize inner ear treatment by fitting the patient's middle ear anatomy. To gauge the properties of prednisolone-21- hydrogen succinate containing silicone, samples with different geometries and drug concentrations have been 3D-printed. The shore hardness of samples with three different drug concentrations was assessed. Three different shapes with four different drug concentrations were incubated in artificial perilymph for up to 56 days to evaluate the release rates. The resulting eluates were analyzed via Ultra high precision liquid chromatography coupled with a time-of-flight micro-mass spectrometer. Samples were softer when a higher drug concentration was used. A high burst release of prednisolone after one hour was measured. Afterward, the release rates decreased and reached a relatively constant rate after ten days and stayed there for at least another 46 days. The release rates were multiple times higher when the samples had a higher surface-to-volume ratio. The softer the sample, the higher the release rate, unproportional to the concentration increase.

Rationale for the Use of Topical Calcineurin Inhibitors in the Management of Oral Lichen Planus and Mucosal Inflammatory Diseases.

Oral lichen planus (OLP) is a chronic inflammatory condition that affects the mucous membranes of the oral cavity and is characterized by a T-cell-mediated autoimmune response. It presents a therapeutic challenge due to its relapsing nature, causing significantly decreased quality of life and, in some cases, increasing the risk of malignant transformation. While topical corticosteroids have long been the first-line therapy for OLP, their long-term use is associated with adverse effects, such as mucosal atrophy and candidiasis. This has driven interest in alternative therapies, particularly topical calcineurin inhibitors (TCIs), such as tacrolimus, which offer a steroid-sparing approach. This review explores the pathophysiological basis of OLP, examines the role of TCIs in its treatment, and evaluates emerging therapies, with a specific focus on the use of a topical liposomal formulation of tacrolimus. These formulations aim to achieve high local drug concentrations while minimizing systemic absorption.OLP is a complex and multifactorial disease that requires a multifaceted approach to management. While current therapies provide symptomatic relief, there is a need for more effective and safer treatment options. Emerging therapies, including advanced drug delivery systems, biologics, and alternative therapies, hold promise for improving the management of OLP. Future research should focus on identifying novel therapeutic targets and developing strategies that can achieve sustained remission with minimal side effects.

Identification of TAK-756, A Potent TAK1 Inhibitor for the Treatment of Osteoarthritis through Intra-Articular Administration.

Osteoarthritis (OA) is a chronic and degenerative joint disease affecting more than 500 million patients worldwide with no disease-modifying treatment approved to date. Several publications report on the transforming growth factor β-activated kinase 1 (TAK1) as a potential molecular target for OA, with complementary anti-catabolic and anti-inflammatory effects. We report herein on the development of TAK1 inhibitors with physicochemical properties suitable for intra-articular injection, with the aim to achieve high drug concentration at the affected joint, while avoiding severe toxicity associated with systemic inhibition. More specifically, reducing solubility by increasing crystallinity, while maintaining moderate lipophilicity proved to be a good compromise to ensure high and sustained free drug exposures in the joint. Furthermore, structure-based design allowed for an improvement of selectivity versus interleukin-1 receptor-associated kinases 1 and 4 (IRAK1/4). Finally, TAK-756 was discovered as a potent TAK1 inhibitor with good selectivity versus IRAK1/4 as well as excellent intra-articular pharmacokinetic properties.

Dissolution Enhancement of Ketoconazole by Melt Granulation Co-Processing

Background: Melt granulation (MG) is a simple operation involving a uniform mixture of active ingredients with a melted polymeric carrier. However, this process can also enhance a drug’s biopharmaceutical properties by augmenting its dissolution rate and, thus, its absorption. Purpose: By applying MG technology, current research focuses on developing co-processed ketoconazole with a higher aqueous dissolution rate than its pure form. Methods: A measure of how the type and proportion of polymeric carriers affect the crystallinity and dissolution rate of co-processed ketoconazole materials was performed. MG prepared materials in a high-shear mixer using co-povidone (Kollidon®) VA 64, HPMCAS HF as polymeric carriers, PEG 1450 (Kollisolv®) and triethyl citrate as plasticizers. Results: The co-processed ketoconazole materials exhibited miscibility in the polymeric systems, as indicated by the reduction in the enthalpy of fusion. Drug crystallinity was significantly reduced in the HPMCAS HF polymeric system, confirmed by XRPD and ATR-FTIR studies. The dissolution rate was enhanced by using a higher drug concentration in a co-povidone VA 64 environment; contrarily, for HPMCAS HF, a higher drug dilution was observed to favor the dissolution rate. Conclusions: MG is a handy, low-cost technology that develops dissolution-enhanced co-processed active pharmaceutical ingredients, spotting specific carrier-drug interactions. MG yields scalable, proven processes, raising interest in its applications in optimizing drug therapeutic efficacy. Ultimately, this technology for dissolution enhancement could bring lower-cost, high-efficiency drugs to improve patients’ quality of life.

Hyaluronic acid-based hydrogels as codelivery systems: The effect of intermolecular interactions investigated by HR-MAS and solid-state NMR Spectroscopy

Hydrogels based on hyaluronic acid and agarose-carbomer, due to their peculiar 3D architecture and biocompatibility, are promising candidates for pharmaceutical strategies based on the codelivery of drugs targeting different diseases. The successful development of these applications requires a precise understanding of drug-drug interactions and their effects on transport and release mechanisms. In this study, such an investigation is carried out on hydrogels loaded with ethosuximide and sodium salicylate at different concentrations. Intermolecular interactions and transport properties are characterized by means of High Resolution Magic Angle Spinning and solid-state Magic Angle Spinning NMR Spectroscopy.At variance with our previous findings on single-drug formulations, the two drugs exhibit closely similar diffusion patterns when co-loaded in the HA-based hydrogels, plausibly due to drug-drug intermolecular interactions. At the highest drug concentrations, where superdiffusion comes into play, we find a fraction of molecules with time-varying diffusion coefficients. A trapping-release mechanism is proposed to explain this observation, which also accounts for the role of drug-hydrogel interactions in drug diffusion motion. The effects of drug-drug interactions on release profiles are finally assessed by means of in vitro release experiments.

Abstract 4121530: Comparison of Drug-Coated Balloon Versus Drug-Eluting Stents in Acute Myocardial Infarction Patients Undergoing Percutaneous Coronary Intervention: A Systematic Review and Meta-Analysis

Background: Percutaneous coronary intervention (PCI) is the preferred revascularization strategy for acute myocardial infarction (AMI). Drug-eluting stents (DES) are linked to higher risks of stent restenosis and stent thrombosis when implanted for AMI. Drug-coated balloons (DCB) provide a high concentration of anti-proliferative drugs over the target lesion without using the polymeric stent structures. The current literature comparing DCB to DES for AMI PCI is limited. Methods: A systematic literature search was performed on the major electronic databases for studies comparing DCB to DES for AMI PCI. Mean difference (MD) and odds ratio (OR) with their corresponding 95% confidence intervals were pooled using a random-effects model, and a p-value of <0.05 was considered statistically significant. Results: A total of 8 studies with 1401 AMI patients were included (545: DCB and 856: DES). The pooled analysis demonstrated that DCB was associated with significantly lower mean lumen diameter on follow-up [MD: -0.26; 95% CI: -0.47, -0.05; p=0.02] compared to DES. However, there was no statistically significant difference in mean in-stent late lumen loss [MD: 0.07; 95% CI: -0.03, 0.18], cardiovascular mortality [OR: 0.90; 95% CI: 0.35, 2.34], all-cause mortality [OR: 0.80; 95% CI: 0.25, 2.63], myocardial infarction [OR: 0.94; 95% CI: 0.36, 2.45], major adverse cardiovascular events [OR: 0.97; 95% CI: 0.47, 2.00], target lesion revascularization [OR: 1.59; 95% CI: 0.52, 4.87], and stent thrombosis [OR: 0.48; 95% CI: 0.05, 4.94]. Conclusion: In patients with AMI, PCI using DCB leads to a significant reduction in the minimum lumen diameter on follow-up compared to DES. No statistically significant difference was noted in mean in-stent late lumen loss, cardiovascular mortality, all-cause mortality, myocardial infarction, major adverse cardiovascular events, target vessel revascularization, and stent thrombosis. Further trials are warranted to confirm these findings.

AGOMELATINE ETHOSOMES FOR ENHANCED TRANSDERMAL DRUG DELIVERY

Objective: The current study aimed to prepare and optimize Agomelatine (AMN) ethosomes for enhanced transdermal drug delivery. Methods: In this study cold method was employed to manufacture the AMN-loaded ethosomes with dissimilar quantities of Phosphatidyl Choline (PC): Cholesterol: Ethanol. Transmission Electron Microscopy (TEM) was employed to evaluate the appearance of the formed ethosomes. Other formulation parameters like vesicle size and zeta potential, polydispersity index, transition temperature, and entrapment efficiency were also investigated. Results: The microscopy results showed that AMN ethosomes have a smooth surface. It was discovered that the AMN-3 formulation of transdermal ethosomes had 92.15±1.3 entrapment efficiency with good vesicle diameter. The release of agomelatine adhered to the zero-order release model. The polydispersity Index (PI) and zeta potential of the optimized formulation were found to be 0.209 and-14.09±1.95 mV, respectively. The maximum flux for the ethosome formulation (AMN-3) was 34.29 µg. h/cm2. A 10.71 fold increment was observed in the bioavailability of optimized formulation than control (oral suspension). A higher drug concentration in the blood suggested better systemic absorption of ethosomes. The optimized formula has a Tmax of 4.0±0.08h and 73.38±1.37 of Cmax. The AMN ethosomes were found to be more stable when stored at 4 °C. Conclusion: The current study suggests that ethosomal vesicles may improve transdermal dispersion without causing skin irritation. Agomelatine-loaded ethosome has the potential to be one of the most important transdermal application techniques for the treatment of depression.

Ultrasound Irradiation as a Candidate Procedure to Improve the Transdermal Drug Delivery to the Tail Edema of a Mouse Model.

Drug therapy for secondary lymphedema has not yet been established. Conventional oral and intravenous administration is difficult to administer in sufficient doses due to adverse events. Therefore, it is necessary to develop a transdermal delivery system that can deliver high concentrations of drugs to the edema area. In this study, we examined the efficacy of transdermal drug delivery in a mouse model of tail edema using ultrasound irradiation (sonication method). Ultrasound irradiation can deliver high-molecular-weight substances subcutaneously, and the percutaneous administration of clobetasol propionate to the mouse tail edema model prevented the enlargement of lymphatic vessels with reduced tail volume. Therefore, steroid administration utilizing ultrasound irradiation is effective in decreasing tail swelling in a mouse tail edema model. Thus, ultrasound irradiation could have the potential to innovate the treatment of secondary lymphedema by directly administering the drug to the edema.

Comparing the Effects of Propofol and Thiopental on Human Renal HEK-293 Cells With a Focus on Reactive Oxygen Species (ROS) Production, Cytotoxicity, and Apoptosis: Insights Into Dose-Dependent Toxicity.

Propofol and thiopental are widely used as hypnotic, sedative, antiepileptic, and analgesic agents in general anesthesia and intensive care; however, their side effects remain unknown. They are used for long periods and at high doses for sedation in total intravenous anesthesia (TIVA) and intensive care units. Long-term and high-dose use of these drugs can lead to accumulation in plasma and tissues, resulting in high drug concentrations and increasing the risk of potential toxicity (e.g., nephrotoxicity). In our study, the cytotoxic and apoptotic effects of propofol and thiopental on kidney cells (HEK-293) and their effects on the formation of reactive oxygen species (ROS) when used in high doses were investigated and compared in vitro. The half-maximal inhibitory concentration (IC50) of each drug in HEK-293 cells was determined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide method. The apoptotic effects were assessed at two different doses of each drug using the annexin V method. Morphological examinations were conducted using the acridine orange/ethidium bromide method, and intracellular ROS levels were determined by flow cytometry. The IC50 values of propofol and thiopental for HEK-293 cells were 206.59 μg/ml and 109.68 μg/ml, respectively. Compared to the control group, thiopental at ≥25 μg/ml and propofol at ≥50 μg/ml exhibited cytotoxicity. Additionally, propofol exhibited significantly lower cytotoxic effects than thiopental did. Our study showed that both propofol and thiopental exerted significant cytotoxic effects on HEK-293 cells at concentrations exceeding clinical levels, primarily by increasing intracellular ROS levels and inducing apoptosis. Future research in this area will deepen our understanding of these mechanisms and improve patient safety in clinical anesthesia practice.

Subcutaneous versus intravenous infliximab therapy - a real-world study: toward higher drug concentrations.

Recently, a formula of subcutaneous infliximab (SC-IFX) has been approved for inflammatory bowel disease (IBD), demonstrating a better pharmacokinetic and immunogenic profiles, compared to intravenous infliximab (IV-IFX), with similar efficacy and safety. The aim of this study is to evaluate the clinical, biochemical, and pharmacological outcomes of IBD patients in clinical remission, who switched from IV-IFX to SC-IFX, with a follow-up period of 6 months. Retrospective cohort study, including IBD patients in clinical remission, previously medicated with IV-IFX, who switched to SC-IFX 120 mg every other week. Biochemical parameters were evaluated before the switch and 6 months after, namely infliximab serum concentrations, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and fecal calprotectin. Included 41 patients in clinical remission, 32 with Crohn's disease (78.0%) and 9 with ulcerative colitis (22.0%). All patients maintained clinical remission during the 6 months after the switch, with a treatment persistence rate of 100%, and no patients requiring corticosteroid therapy, switching back to IV-IFX, or IBD-related hospitalization. The mean infliximab serum concentrations were significantly higher after 6 months of SC-IFX (17.3 ± 6.6 vs. 9.1 ± 5.5 µg/ml, P < 0.001). However, there were no differences between values of ESR, CRP, and fecal calprotectin, before and after the switch ( P = 0.791, P = 0.246, and P = 0.639). Additionally, none of the patients developed antibodies to infliximab. Switching from IV-IFX to SC-IFX in IBD patients in clinical remission is effective and leads to higher infliximab serum concentrations, regardless of the combination with immunomodulatory therapy.

Region-independent active CNS net uptake of marketed H+/OC antiporter system substrates.

The pyrilamine-sensitive proton-coupled organic cation (H+/OC) antiporter system facilitates the active net uptake of several marketed organic cationic drugs across the blood-brain barrier (BBB). This rare phenomenon has garnered interest in the H+/OC antiporter system as a potential target for CNS drug delivery. However, analysis of pharmacovigilance data has uncovered a significant association between substrates of the H+/OC antiporter and neurotoxicity, particularly drug-induced seizures (DIS) and mood- and cognitive-related adverse events (MCAEs). This preclinical study aimed to elucidate the CNS regional disposition of H+/OC antiporter substrates at therapeutically relevant plasma concentrations to uncover potential pharmacokinetic mechanisms underlying DIS and MCAEs. Here, we investigated the neuropharmacokinetics of pyrilamine, diphenhydramine, bupropion, tramadol, oxycodone, and memantine. Using the Combinatory Mapping Approach for Regions of Interest (CMA-ROI), we characterized the transport of unbound drugs across the BBB in specific CNS regions, as well as the blood-spinal cord barrier (BSCB) and the blood-cerebrospinal fluid barrier (BCSFB). Our findings demonstrated active net uptake across the BBB and BSCB, with unbound ROI-to-plasma concentration ratio, Kp,uu,ROI, values consistently exceeding unity in all assessed regions. Despite minor regional differences, no significant distinctions were found when comparing the whole brain to investigated regions of interest, indicating region-independent active transport. Furthermore, we observed intracellular accumulation via lysosomal trapping for all studied drugs. These results provide new insights into the CNS regional neuropharmacokinetics of these drugs, suggesting that while the brain uptake is region-independent, the active transport mechanism enables high extracellular and intracellular drug concentrations, potentially contributing to neurotoxicity. This finding emphasizes the necessity of thorough neuropharmacokinetic evaluation and neurotoxicity profiling in the development of drugs that utilize this transport pathway.

Effects of Inosine-5′-monophosphate Dehydrogenase (IMPDH/GuaB) Inhibitors on Borrelia burgdorferi Growth in Standard and Modified Culture Conditions

Borrelia burgdorferi’s inosine-5′-monophosphate dehydrogenase (IMPDH, GuaB encoded by the guaB gene) is a potential therapeutic target. GuaB is necessary for B. burgdorferi replication in mammalian hosts but not in standard laboratory culture conditions. Therefore, we cannot test novel GuaB inhibitors against B. burgdorferi without utilizing mammalian infection models. This study aimed to evaluate modifications to a standard growth medium that may mimic mammalian conditions and induce the requirement of GuaB usage for replication. The effects of two GuaB inhibitors (mycophenolic acid, 6-chloropurine riboside at 125 μM and 250 μM) were assessed against B. burgdorferi (guaB+) grown in standard Barbour–Stoenner–Kelly-II (BSK-II) medium (6% rabbit serum) and BSK-II modified to 60% concentration rabbit serum (BSK-II/60% serum). BSK-II directly supplemented with adenine, hypoxanthine, and nicotinamide (75 μM each, BSK-II/AHN) was also considered as a comparison group. In standard BSK-II, neither mycophenolic acid nor 6-chloropurine riboside affected B. burgdorferi growth. Based on an ANOVA, a dose-dependent increase in drug effects was observed in the modified growth conditions (F = 4.471, p = 0.001). Considering higher drug concentrations at exponential growth, mycophenolic acid at 250 μM reduced spirochete replication by 48% in BSK-II/60% serum and by 50% in BSK-II/AHN (p &lt; 0.001 each). 6-chloropurine riboside was more effective in both mediums than mycophenolic acid, reducing replication by 64% in BSK-II/60% serum and 65% in BSK-II/AHN (p &lt; 0.001 each). These results demonstrate that modifying BSK-II medium with physiologically relevant levels of mammalian serum supports replication and induces the effects of GuaB inhibitors. This represents the first use of GuaB inhibitors against Borrelia burgdorferi, building on tests against purified B. burgdorferi GuaB. The strong effects of 6-chloropurine riboside indicate that B. burgdorferi can salvage and phosphorylate these purine derivative analogs. Therefore, this type of molecule may be considered for future drug development. Optimization of this culture system will allow for better assessment of novel Borrelia-specific GuaB inhibitor molecules for Lyme disease interventions. The use of GuaB inhibitors as broadcast sprays or feed baits should also be evaluated to reduce spirochete load in competent reservoir hosts.