Drug Concentrations In Tissues Research Articles

Comparative In Vitro Killing by Pradofloxacin in Comparison to Ceftiofur, Enrofloxacin, Florfenicol, Marbofloxacin, Tildipirosin, Tilmicosin and Tulathromycin against Bovine Respiratory Bacterial Pathogens

Pradofloxacin is the newest of the veterinary fluoroquinolones to be approved for use in animals—initially companion animals and most recently food animals. It has a broad spectrum of in vitro activity, working actively against Gram-positive/negative, atypical and some anaerobic microorganisms. It simultaneously targets DNA gyrase (topoisomerase type II) and topoisomerase type IV, suggesting a lower propensity to select for antimicrobial resistance. The purpose of this study was to determine the rate and extent of bacterial killing by pradofloxacin against bovine strains of Mannheimia haemolytica and Pasteurella multocida, in comparison with several other agents (ceftiofur, enrofloxacin, florfenicol, marbofloxacin, tildipirosin, tilmicosin and tulathromycin) using four clinically relevant drug concentrations: minimum inhibitory and mutant prevention drug concentration, maximum serum and maximum tissue drug concentrations. At the maximum serum and tissue drug concentrations, pradofloxacin killed 99.99% of M. haemolytica cells following 5 min of drug exposure (versus growth to 76% kill rate for the other agents) and 94.1–98.6% of P. multocida following 60–120 min of drug exposure (versus growth to 98.6% kill rate for the other agents). Statistically significant differences in kill rates were seen between the various drugs tested depending on drug concentration and time of sampling after drug exposure.

Nebulized inhalation of nintedanib-loaded biomimetic nano-liposomes attenuated bleomycin-induced interstitial lung fibrosis in mice

Idiopathic pulmonary fibrosis (IPF) is an irreversible interstitial lung disease with a poor prognosis. However, there are currently few drugs available for its treatment. Nintedanib is clinically effective but is associated with gastrointestinal adverse effects and weight loss. Due to drug intolerance, the overall outcomes of nintedanib therapy are substantially compromised in quite a few patients. In the present study, we synthesized nintedanib-loaded biomimetic liposomes (Nin-lipo) to improve the antifibrotic efficacy and drug tolerance of nintedanib. It was observed that nebulized inhalation of small doses of Nin-lipo (2 mg/kg) resulted in greater delivery efficiency and higher drug concentrations in lung tissue than conventional oral doses of nintedanib (60 mg/kg). Furthermore, Nin-lipo significantly inhibited bleomycin (BLM)-induced pulmonary fibrosis and improved lung function in mice. The possible molecular mechanism of anti-fibrosis by Nin-lipo was investigated. Nin-lipo was found to act mechanistically on alveolar macrophages via alveolar surfactant proteins A and D (SP-A/D) by simulating pulmonary surfactants and inhibiting the polarization of M2 macrophages. These effects thereby reduced the secretion of transforming growth factor 1 (TGF-β1) in macrophages. Moreover, Nin-lipo demonstrated significant efficacy against weight loss and liver function abnormalities in a mouse model caused by nintedanib. Therefore, nebulized Nin-lipo could greatly improve the antifibrotic efficacy of nintedanib while maintaining an excellent safety profile. Nin-lipo could potentially be developed as a new therapy for IPF.

Does PAD and microcirculation status impact the tissue availability of intravenously administered antibiotics in patients with infected diabetic foot? Results of the DFIATIM substudy.

The aim of this substudy (Eudra CT No:2019-001997-27)was to assess ATB availability in patients with infected diabetic foot ulcers(IDFUs)in the context of microcirculation and macrocirculation status. For this substudy, we enrolled 23 patients with IDFU. Patients were treated with boluses of amoxicillin/clavulanic acid(AMC)(12patients) or ceftazidime(CTZ)(11patients). After induction of a steady ATB state, microdialysis was performed near the IDFU. Tissue fluid samples from the foot and blood samples from peripheral blood were taken within 6 hours. ATB potential efficacy was assessed by evaluating the maximum serum and tissue ATB concentrations(Cmax and Cmax-tissue)and the percentage of time the unbound drug tissue concentration exceeds the minimum inhibitory concentration (MIC)(≥100% tissue and ≥50%/60% tissue fT>MIC). Vascular status was assessed by triplex ultrasound, ankle-brachial and toe-brachial index tests, occlusive plethysmography comprising two arterial flow phases, and transcutaneous oxygen pressure(TcPO2). Following bolus administration, the Cmax of AMC was 91.8 ± 52.5 μgmL-1 and the Cmax-tissue of AMC was 7.25 ± 4.5 μgmL-1(P<0.001). The Cmax for CTZ was 186.8 ± 44.1 μgmL-1 and the Cmax-tissue of CTZ was 18.6 ± 7.4 μgmL-1(P<0.0001). Additionally, 67% of patients treated with AMC and 55% of those treated with CTZ achieved tissue fT>MIC levels exceeding 50% and 60%, respectively. We observed positive correlations between both Cmax-tissue and AUCtissue and arterial flow. Specifically, the correlation coefficient for the first phase was r=0.42; (P=0.045), and for the second phase, it was r=0.55(P=0.01)and r=0.5(P=0.021). Bactericidal activity proved satisfactory in only half to two-thirds of patients with IDFUs, an outcome that appears to correlate primarily with arterial flow.

Abstract PS07-01: Exemestane and breast cancer prevention: how low can we go? Drug and biomarker tissue levels in a randomized presurgical trial on exemestane alternative dosing regimen

Abstract Exemestane is an effective drug to reduce breast cancer risk reaching an overall 65% reduction in breast cancer in the placebo–controlled phase III MAP.3 trial. To improve its acceptability in primary prevention programs, we are seeking the minimal effective dose. In a 3-arm presurgical trial of 4-6 weeks before breast surgery in 180 postmenopausal women with ER-positive breast cancer, we investigated the activity of alternative exemestane schedules: 25 mg per day (QD), 25 mg three times/week (TIW) or 25 mg per week (QW) and showed that in adherent participants TIW was not inferior to QD in reducing circulating estradiol (Serrano et al JAMA Oncol. doi:10.1001/jamaoncol.2023.0089). Moreover, Ki67 reduction was seen in all arms with no significant difference among arms. Here, we analyzed the concentration of sex steroids, exemestane, and its main metabolite in the cancer and adjacent non-cancerous breast tissue. Tissues samples were homogenized before liquid-liquid extraction. After reconstitution, samples were analyzed by coupling liquid chromatography with tandem mass spectrometry (Sciex QTRAP 6500, Nexera system, Shimadzu). We obtained breast cancer tissue from 93 and non-cancerous breast tissue from 117 participants to measure exemestane, 17-OH-exemestane, and sex steroids. Exemestane and 17-OH-exemestane concentrations were detectable only in the QD arm, while in TIW and QW arms levels were below the Lower Limit of Detection (&amp;lt; LLD). Median exemestane level was 3807 fmol/g and 17485 fmol/g and median 17-OH-exemestane level was 338 fmol/g and 1343 fmol/g in cancer and non-cancerous tissue, respectively. Interestingly, drug and its metabolite accumulated 4-5-fold in non-cancerous tissue compared to cancer tissue in the QD arm. Despite the between-arm drug concentration difference, estradiol was almost completely suppressed in all arms in the non-cancerous tissue, attaining level &amp;lt; LLD in QD and TIW arms, and barely detectable in QW arm. The median in the QW arm was &amp;lt; LLD (&amp;lt; LLD, interquartile range &amp;lt; LLD, 25.5 fmol/g) showing no differences in QD vs TIW and QD vs QW (p = 0.364 and p = 0.693 respectively). While a dose-response trend was observed in cancer tissue, estradiol level was &amp;lt; LLD (&amp;lt; LLD,52.2 fmol/g) on QD, 17.1 (&amp;lt; LLD, 125.3) on TIW, and 128 (&amp;lt; LLD, 224.8) on QW (p=0.046 QD vs TIW arms). Estrone showed a clear dose response trend among arms, whereas no differences were observed for testosterone and androstenedione for both cancer and non-cancerous tissue in all arms. The Ki-67 change was analyzed in the previous paper; here we report the data for those patients who had drug and hormones tissue concentration measured, where Ki-67 decreased in all arms: median Ki67 change from baseline was QD -8 (-10, -3), TIW -6 (-11, -2), QW -4 (-8, -1). Conclusions: Exemestane 25 mg three times a week maintains comparable activity to the standard dose on tissue estradiol suppression and Ki67 decrease. Considering the estradiol suppression in non-cancerous tissue of the lowest exemestane dose, QW might even be considered for breast cancer risk reduction in primary prevention. Further analyses are ongoing to investigate the correlation with other biomarkers including the role of polymorphic UGT2B17 genotype that could identify candidates to lower exemestane dosage. Citation Format: Davide Serrano, Harriet Johansson, Bjørn-Erik Bertelsen, Gunnar Mellgren, Parijatham Thomas, Katherine Crew, Nagi B Kumar, Debora Macis, Valentina Aristarco, Aliana Guerrieri Gonzaga, Sara Gandini, Mauro D’Amico, Tania Buttiron Webber, Irene Maria Briata, Stefano Spinaci, Viviana Galimberti, Giuseppe Viale, Lana A. Vornik, Eduardo Villar-Sanchez, Powel Brown, Brandy M Heckman-Stoddard, Eva Szabo, Bernardo Bonanni, Andrea De Censi. Exemestane and breast cancer prevention: how low can we go? Drug and biomarker tissue levels in a randomized presurgical trial on exemestane alternative dosing regimen [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PS07-01.

In-silico research on the effects of variable voltage pulse protocols on the cell survival and permeabilization fractions in electroporated cancerous tissues

Reversible electroporation is used to increase the cell membrane permeability by the application of short duration, high voltage electric pulses with electrodes strategically positioned to induce localized drug concentration in the tumor tissue. However, inadequate selection of pulses’ characteristics can lead to relevant loss of cell viability or lack of cell permeabilization, affecting aversively the results of the therapy. Accordingly, the balance between cell membrane electro-permeabilization and cell death is crucial, and the recursive modification of electroporation parameters can favor this balance to increase the drug uptake into viable cells. Particularly, the controlled diminution of the voltage level as the number of pulses increases can reduce the cell damage without compromising the membrane electro-permeabilization. In this work, a previously developed in-silico tool, based on the Global Method of Approximate Particular Solutions (GMAPS), is calibrated, validated, and used to study the differences between constant voltage and variable voltage pulse protocols (CVP and VVP) in terms of the magnitude and distribution of cell survival and permeabilization fractions along the tissue domain, and the internalization efficiency of the therapy. In VVP protocols, the reduction of the applied voltage with the number of pulses is numerically estimated to reach a target volume-averaged survival fraction in the most sensitive zone of the tissue. Numerical results indicate that differences between the pulse protocol types (CVP and VVP) depend on the initial voltage level ∅0 and number of pulses K, with the VVP protocol bringing about superior results for the larger values of ∅0 and K considered here.

Cefepime distribution by microdialysis in peritoneal fluid of rats with or without experimental peritonitis.

The aim of this study was to investigate the penetration of cefepime into rat peritoneal fluid by microdialysis and to determine the relationship between unbound drug plasma and tissue concentration in healthy animals and in a sepsis model established through cecal ligation and puncture-induced peritonitis. Probe recovery was performed by dialysis and retrodialysis. Cefepime was administered at a dose of 110 mg/kg intravenously. Samples were collected for about 4 h, and concentrations were determined by liquid chromatography-electrospray ionization-QTOF MS. Tissue penetration was also determined. Probe recovery in vivo was 38.78% ± 3.31% and 38.83% ± 2.74% in the control and peritonitis groups, respectively. Cefepime was rapidly distributed in the peritoneal fluid in both groups. The peritoneal fluid/plasma cefepime ratio was 0.38 and 0.32 for the control and peritonitis groups, respectively. Cefepime concentrations were above the MIC of 4 mg/L for the main enterobacteria. The infection model that was used had no apparent effect on the pharmacokinetics of cefepime in rats. This was the first study to determine free cefepime concentrations in the peritoneal fluid of healthy rats and rats with experimental peritonitis.

Quantification of Unencapsulated Drug in Target Tissues Demonstrates Pharmacological Properties and Therapeutic Effects of Liposomal Topotecan (FF-10850)

PurposeQuantifying unencapsulated drug concentrations in tissues is crucial for understanding the mechanisms underlying the efficacy and safety of liposomal drugs; however, the methodology for this has not been fully established. Herein, we aimed to investigate the enhanced therapeutic potential of a pegylated liposomal formulation of topotecan (FF-10850) by analyzing the concentrations of the unencapsulated drug in target tissues, to guide the improvement of its dosing regimen.MethodsWe developed a method for measuring unencapsulated topotecan concentrations in tumor and bone marrow interstitial fluid (BM-ISF) and applied this method to pharmacokinetic assessments. The ratios of the area under the concentration–time curves (AUCs) between tumor and BM-ISF were calculated for total and unencapsulated topotecan. DNA damage and antitumor effects of FF-10850 or non-liposomal topotecan (TPT) were evaluated in an ES-2 mice xenograft model.ResultsFF-10850 exhibited a much larger AUC ratio between tumor and BM-ISF for unencapsulated topotecan (2.96), but not for total topotecan (0.752), than TPT (0.833). FF-10850 promoted milder DNA damage in the bone marrow than TPT; however, FF-10850 and TPT elicited comparable DNA damage in the tumor. These findings highlight the greater tumor exposure to unencapsulated topotecan and lower bone marrow exposure to FF-10850 than TPT. The dosing regimen was successfully improved based on the kinetics of unencapsulated topotecan and DNA damage.ConclusionsTissue pharmacokinetics of unencapsulated topotecan elucidated the favorable pharmacological properties of FF-10850. Evaluation of tissue exposure to an unencapsulated drug with appropriate pharmacodynamic markers can be valuable in optimizing liposomal drugs and dosing regimens.

Thermosensitive In Situ Gelling Poloxamers/Hyaluronic Acid Gels for Hydrocortisone Ocular Delivery.

This study endeavored to overcome the physiological barriers hindering optimal bioavailability in ophthalmic therapeutics by devising drug delivery platforms that allow therapeutically effective drug concentrations in ocular tissues for prolonged times. Thermosensitive drug delivery platforms were formulated by blending poloxamers (F68 and F127) with low-molecular-weight hyaluronic acid (HA) in various concentrations and loaded with hydrocortisone (HC). Among the formulations examined, only three were deemed suitable based on their desirable gelling properties at a temperature close to the eye's surface conditions while also ensuring minimal gelation time for swift ocular application. Rheological analyses unveiled the ability of the formulations to develop gels at suitable temperatures, elucidating the gel-like characteristics around the physiological temperature essential for sustained drug release. The differential scanning calorimetry findings elucidated intricate hydrogel-water interactions, indicating that HA affects the water-polymer interactions within the gel by increasing the platform hydrophilicity. Also, in vitro drug release studies demonstrated significant hydrocortisone release within 8 h, governed by an anomalous transport mechanism, prompting further investigation for optimized release kinetics. The produced platforms offer promising prospects for efficacious ocular drug delivery, addressing pivotal challenges in ocular therapeutics and heralding future advancements in the domain.

Successful Prediction of Human Hepatic Concentrations of Transported Drugs Using the Proteomics-Informed Relative Expression Factor Approach.

Tissue drug concentrations determine the efficacy and toxicity of drugs. When a drug is the substrate of transporters that are present at the blood:tissue barrier, the steady-state unbound tissue drug concentrations cannot be predicted from their corresponding plasma concentrations. To accurately predict transporter-modulated tissue drug concentrations, all clearances (CLs) mediating the drug's entry and exit (including metabolism) from the tissue must be accurately predicted. Because primary cells of most tissues are not available, we have proposed an alternative approach to predict such CLs, that is the use of transporter-expressing cells/vesicles (TECs/TEVs) and relative expression factor (REF). The REF represents the abundance of the relevant transporters in the tissue vs. in the TECs/TEVs. Here, we determined the transporter-based intrinsic CL of glyburide (GLB) and pitavastatin (PTV) in OATP1B1, OATP1B3, OATP2B1, and NTCP-expressing cells and MRP3-, BCRP-, P-gp-, and MRP2-expressing vesicles and scaled these CLs to in vivo using REF. These predictions fell within a priori set twofold range of the hepatobiliary CLs of GLB and PTV, estimated from their hepatic positron emission tomography imaging data: 272.3 and 607.8 mL/min for in vivo hepatic sinusoidal uptake CL, 47.8 and 17.4 mL/min for sinusoidal efflux CL, and 0 and 4.20 mL/min for biliary efflux CL, respectively. Moreover, their predicted hepatic concentrations (area under the hepatic concentration-time curve (AUC) and maximum plasma concentration (Cmax )), fell within twofold of their mean observed data. These data, together with our previous findings, confirm that the REF approach can successfully predict transporter-based drug CLs and tissue concentrations to enhance success in drug development.

Ex-vivo rectal tissue infection with HIV-1 to assess time to protection following oral preexposure prophylaxis with tenofovir disoproxil/emtricitabine.

We wished to assess time to protection from HIV-1 infection following oral tenofovir disoproxil and emtricitabine (TDF/FTC) as preexposure prophylaxis (PrEP), using ex-vivo rectal tissue infections and drug concentration measures in blood and rectal tissue. Participants from the ANRS PREVENIR study (NCT03113123) were offered this sub-study after a 14-day wash-out. We used an ex-vivo model to evaluate rectal tissue HIV-1 susceptibility before and after PrEP, 2 h after two pills or 7 days of a daily pill of TDF/FTC. PrEP efficacy was expressed by the difference (after-before) of 14-day cumulative p24 antigen levels. TFV-DP and FTC-TP levels were measured in rectal tissue and PBMCs and correlated with HIV-1 infection. Twelve and 11 men were analyzed in the 2 h-double dose and 7 days-single dose groups, respectively. Cumulative p24 differences after-before PrEP were -144 pg/ml/mg (IQR[-259;-108]) for the 2 h-double dose group ( P = 0.0005) and -179 pg/ml/mg (IQR [-253;-86]) for the 7 days-single dose group ( P = 0.001), with no differences between groups ( P = 0.93). Rectal TFV-DP was below quantification after a double dose, but FTC-TP levels were similar to levels at 7 days. There was a significant correlation between rectal FTC-TP levels and p24 changes after a double dose ( R = -0.84; P = 0.0001). Oral TDF/FTC provided similar protection against HIV-1 infection of rectal tissue 2 h after a double dose or 7 days of a daily dose. At 2 h, this protection seems driven by high FTC-TP concentrations in rectal tissue. This confirms the importance of combining TDF and FTC to achieve early protection.

The Breakdown of Blood-Labyrinth Barrier Makes it Easier for Drugs to Enter the Inner Ear.

This study aimed to investigate dynamic change of permeability of blood-labyrinth barrier (BLB) after noise exposure and its effect on the drug delivery efficiency of systemic administration. Gadopentetate dimeglumine (Gd-DTPA) and dexamethasone (DEX) were used as tracers, and magnetic resonance imaging (MRI) and immunofluorescence were used to observe the change of the BLB after strong noise exposure in guinea pigs. High-performance liquid chromatography-mass spectrometry (LC-MS) was used to observe the effect of the breakdown of BLB after noise exposure on the drug delivery efficiency of intravenous DEX. The guinea pigs were divided into 6 groups: normal group (N), 1, 3, 5, 8, and 12 days after noise exposure groups (P1, P3, P5, P8, P12), with 5 animals in each group. The BLB changes dynamically after noise exposure. Increased permeability of the blood-endolymph barrier, the endolymph-perilymph barrier, and the blood-nerve barrier was observed at days 1-3, 1-5, and 1-8, respectively, after noise exposure in guinea pigs. Higher drug concentration in the cochlear tissue was obtained by intravenous administration of DEX in guinea pigs during the time window of increased permeability of the BLB. After noise exposure, the increased BLB permeability makes it easier for drugs to enter the inner ear from blood. In guinea pigs, 1-8 days after strong noise exposure, the drug delivery efficiency of systemic administration increased. After 8 days, the efficiency gradually returned to normal level. 1-8 days after noise exposure may be the best intervention time for systemic administration. NA Laryngoscope, 134:2377-2386, 2024.

Design and use of an ex vivo peripheral simulating bioreactor system for pharmacokinetic analysis of a drug coated stent.

Currently, there are no ex vivo systems that can model the motion of peripheral arteries and allow for the evaluation of pharmacokinetics (PK) of endovascular devices. The objective of this study was to develop a novel peripheral simulating bioreactor system to evaluate drug pharmacokinetics of stents. We utilized 3D-printed and off-the-shelf components to construct a peripheral-simulating bioreactor system capable of mimicking the motion of peripheral arteries. Servo motors were primarily used to shorten/elongate, twist, and bend explanted porcine carotid arteries. To evaluate the pharmacokinetics in the bioreactor, drug-eluting stents were deployed within explanted arteries and subjected to vascular motion along with pulsatile flow conditions. Following 30 min and 24 h, the arteries were removed, and paclitaxel levels were measured. Scanning electron microscopy was also performed to evaluate the stent surface. Arterial paclitaxel levels of the stent-treated arteries were found to be higher at 30 min than at 24 h following pulsatile and no vascular motion and even higher at 24 h following pulsatile flow and vascular motion. The residual drug on the stent significantly decreased from 30 min to 24 h. Scanning electron microscopy confirmed the loss of paclitaxel coating at 24 h and greater disturbance in stents under peripheral motion versus pulsatile only. This system represents the first ex vivo system to determine the PK of drug-eluting stents under physiological flow and vascular motion conditions. This work provides a novel system for a quick and inexpensive preclinical tool to study acute drug tissue concentration kinetics of drug-releasing interventional vascular devices designed for peripheral applications.

Influence of focused ultrasound on locoregional drug delivery to the brain: Potential implications for brain tumor therapy

IntroductionEfficient delivery of therapeutics across the blood-brain barrier (BBB) for the treatment of central nervous system (CNS) tumors is a major challenge to the development of safe and efficacious therapies. Locoregional drug delivery platforms offer an improved therapeutic index by achieving high drug concentrations in the target tissue with negligible systemic exposure. Intrathecal (intraventricular) [IT] and convection-enhanced delivery [CED] are two clinically relevant methods being employed for various CNS malignancies. Both of these standalone platforms suffer from passive post-administration distribution forces, sometimes limiting the desired distribution for tumor therapy. Focused ultrasound and microbubble-mediated blood-brain barrier opening (FUS-BBBO) is a recent modality used for enhanced drug delivery. It is postulated that coupling of FUS with these alternative delivery routes may provide benefits. Multimodality FUS may provide the desired ability to increase the depth of parenchymal delivery following IT administration and provide a means for contour directionality with CED. Further, the transient enhanced permeability achieved with FUS-BBBO is well established, but drug residence and transit times, important to clinical dose scheduling, have not yet been defined. The present investigation comprises two discrete studies: 1. Conduct a comprehensive quantitative evaluation to elucidate the effect of FUS-BBBO as it relates to varying routes of administration (IT and IV) in its capacity to facilitate drug penetration within the striatal-thalamic region. 2. Investigate the impact of combining FUS-BBBO with CED on drug distribution, with a specific focus on the temporal dynamics of drug retention within the target region. MethodsFirstly, we quantitatively assessed how FUS-BBBO coupled with IT and IV altered fluorescent dye (Dextran 2000 kDa and 70 kDa) distribution and concentration in a predetermined striatal-thalamic region in naïve mice. Secondly, we analyzed the pharmacokinetic effects of using FUS mediated BBB disruption coupled with CED by measuring the volume of distribution and time-dependent concentration of the dye. ResultsOur results indicate that IV administration coupled with FUS-BBBO successfully enhances delivery of dye into the pre-defined sonication targets. Conversely, measurable dye in the sonication target was consistently less after IT administration. FUS enhances the distribution volume of dye after CED. Furthermore, a shorter time of residence was observed when CED was coupled with FUS-BBBO application when compared to CED alone. Conclusion1. Based on our findings, IV delivery coupled with FUS-BBBO is a more efficient means for delivery to deep targets (i.e. striatal-thalamic region) within a predefined spatial conformation compared to IT administration. 2. FUS-BBBO increases the volume of distribution (Vd) of dye after CED administration, but results in a shorter time of residence. Whether this finding is reproducible with other classes of agents (e.g., cytotoxic agents, antibodies, viral particles, cellular therapies) needs to be studied.

Microdialysis as a safe and feasible method to study target-site piperacillin-tazobactam disposition in septic piglets and children

ObjectivesKnowledge on the tissue penetration of piperacillin-tazobactam in children with sepsis is lacking. In this study, the feasibility and performance of microdialysis experiments were explored in septic piglets and children as part of a translational research project. MethodsMultiple-day microdialysis investigations were performed in muscle tissue of 22 piglets (of which 11 were septic) and 6 children with sepsis. An in vitro experiment preceded the (pre)clinical trials to derive optimal experimental settings and calibration technique. Linear mixed-effects models quantified the impact of sepsis on relative recovery (RR) and intercatheter, interindividual, interoccasion, and residual variability. ResultsIn vivo microdialysis was well tolerated in piglets and children, with no significant adverse events reported. Using identical experimental settings, lower RR values were recorded in healthy and septic piglets (range: piperacillin, 17.2–29.1% and tazobactam, 23.5–29.1%) compared with the in vitro experiment (piperacillin, 43.3% and tazobactam, 55.3%), and there were unacceptably low values in children with sepsis (<10%). As a result, methodological changes were made in the pediatric trial. Realistic tissue concentration-time curves were derived in piglets and children. In piglets, sepsis reduced the RR. The greatest contributors to RR variability were residual (>40%) and interoccasion (>30%) variability. The internal standard method was the preferred calibration technique in both piglets and children. ConclusionsMicrodialysis is a safe and applicable method for the measurement of tissue drug concentrations in piglets and children. This study demonstrated the impact of experimental settings, sepsis, and target population on individual RR.

SubQ-Sim: A Subcutaneous Physiologically Based Biopharmaceutics Model. Part 1: The Injection and System Parameters.

To construct a detailed mechanistic and physiologically based biopharmaceutics model capable of predicting 1) device-formulation-tissue interaction during the injection process and 2) binding, degradation, local distribution, diffusion, and drug absorption, following subcutaneous injection. This paper is part of a series and focusses on the first aspect. A mathematical model, SubQ-Sim, was developed incorporating the details of the various substructures within the subcutaneous environment together with the calculation of dynamic drug disposition towards the lymph ducts and venous capillaries. Literature was searched to derive key model parameters in healthy and diseased subjects. External factors such as body temperature, exercise, body position, food or stress provide a means to calculate the impact of "life events" on the pharmacokinetics of subcutaneously administered drugs. The model predicts the tissue backpressure time profile during the injection as a function of injection rate, volume injected, solution viscosity, and interstitial fluid viscosity. The shape of the depot and the concentrations of the formulation and proteins in the depot are described. The model enables prediction of formulation backflow following premature needle removal and the resulting formulation losses. Finally, the effect of disease (type 2 diabetes) or the presence of recombinant human hyaluronidase in the formulation on the injection pressure, are explored. This novel model can successfully predict tissue back pressure, depot dimensions, drug and protein concentration and formulation losses due to incorrect injection, which are all important starting conditions for predicting drug absorption from a subcutaneous dose. The next article will describe the absorption model and validation against clinical data.

Development of tetracycline-modified nanoparticles for bone-targeted delivery of anti-tubercular drug.

Background: Since the poor response to existing anti-tuberculosis drugs and low drug concentration in local bone tissues, the traditional drug therapy does not result in satisfactory treatment of osteoarticular tuberculosis. Thus, we report a rifapentine release system with imparted bone targeting potential using tetracycline (TC) -modified nanoparticles (NPs). Methods: TC was conjugated to PLGA-PEG copolymer via a DCC/NHS technique. Rifapentine-loaded NPs were prepared by premix membrane emulsification technique. The resulting NPs were characterized in terms of physicochemical characterization, hemolytic study, cytotoxicity, bone mineral binding ability, in vitro drug release, stability test and antitubercular activity. The pharmacokinetic and biodistribution studies were also performed in mice. Results: Rifapentine loaded TC-PLGA-PEG NPs were proved to be 48.8nm in size with encapsulation efficiency and drug loading of 83.3% ± 5.5% and 8.1% ± 0.4%, respectively. The release of rifapentine from NPs could be maintained for more than 60h. Most (68.0%) TC-PLGA-PEG NPs could bind to HAp powder in vitro. The cellular studies revealed that NPs were safe for intravenous administration. In vivo evaluations also revealed that the drug concentration of bone tissue in TC-PLGA-PEG group was significantly higher than that in other groups at all time (p < 0.05). Both NPs could improve pharmacokinetic parameters without evident organ toxicity. The minimal inhibitory concentration of NPs was 0.094μg/mL, whereas this of free rifapentine was 0.25μg/mL. Conclusion: Rifapentine loaded TC-PLGA-PEG NPs could increase the amount of rifapentine in bone tissue, prolong drug release in systemic circulation, enhance anti-tuberculosis activity, and thereby reducing dose and frequency of drug therapy for osteoarticular tuberculosis.

BSLD-01 DYNAMIC CONTROL OF CSF FOR PERSONALIZED CNS DRUG DELIVERY FOR LEPTOMINGEAL DISEASE

Abstract BACKGROUND Appropriate drug distribution is needed for effective treatment of brain metastases and leptomeningeal disease. Lack of proper drug bioavailability in the CNS contributes to the poor outcome in these patients. EnClear Therapies has developed a device delivering intrathecal therapeutics utilizing the dynamic control of CSF flow through an external pump. Herein, we look at intrathecal drug delivery of methotrexate with EnClear’s system and its impact of drug concentration in CNS tissue in sheep and non-human primates. METHODS EnClear’s system utilizes two implantable catheters (lateral ventricle and lumbar thecal sac) and an extracorporeal pump that controls the speed and direction of CSF flow. Software continuously monitors and reports the output from sensor arrays for pressure, respiration, and heart rate. Imaging studies were used to track the CSF flow characteristics during the use of EnClear’s system. Data from administration of methotrexate followed by the use of EnClear’s system was compared to the current standard of delivery, intracerebroventricular or lumbar intrathecal administration. Methotrexate levels were measured with LC/MS in CSF, blood, and multiple CNS and peripheral tissues. RESULTS There was a two-fold increase in methotrexate levels in multiple regions of the brain including deeper brain structures including the striatum using EnClear's system, compared to traditional lumbar intrathecal and intracerebroventricular delivery. Higher peak levels of methotrexate were reached in the CSF with the use of EnClear’s system, with simultaneous reduction in the peripheral nerves and systemic tissues – a potential source of toxicity. CONCLUSIONS In large animal studies, EnClear’s system has for the first time, demonstrated increased brain parenchymal drug levels via intrathecal delivery. Drug delivery with this novel device has shown improved distribution throughout the CNS and leptomeninges as compared to traditional intrathecal drug delivery and decreased peripheral distribution.

Evaluation of bioadhesive gels for local action in the esophagus

Direct drug administration to the esophagus faces several obstacles, including continuous salivary dilution and removal of the dosage form from the tissue surface due to esophageal peristalsis. These actions often result in short exposure times and reduced concentrations of drug at the esophageal surface, providing limited opportunities for drug absorption into or across the esophageal mucosa. A variety of bioadhesive polymers were investigated for their ability to resist removal by salivary washings using an ex vivo porcine esophageal tissue model. Hydroxypropylmethylcellulose and carboxymethylcellulose both have reported bioadhesive properties, but neither was able to withstand repeated exposure to saliva, and the gels formulated with these polymers were quickly removed from the esophageal surface. Two polyacrylic polymers, carbomer and polycarbophil, also showed limited esophageal surface retention when exposed to salivary washing, likely due to the ionic composition of saliva affecting the inter-polymer interactions necessary for these polymers to maintain their increased viscosities. In situ gel forming polysaccharide gels (ion-triggered), including xanthan gum, gellan gum, and sodium alginate, showed superior tissue surface retention, and formulations containing these bioadhesive polymers along with ciclesonide, an anti-inflammatory soft prodrug, were investigated as potential, locally-acting esophageal delivery systems. Exposure of a segment of esophagus to the ciclesonide-containing gels resulted in therapeutic concentrations of des-ciclesonide, the active drug metabolite, in the tissues within 30 min. Increasing des-CIC concentrations were also observed over a 3-hour exposure interval suggesting continued release and absorption of ciclesonide into the esophageal tissues. These results demonstrate the ability to achieve therapeutic drug concentrations in the esophageal tissues using in situ gel-forming bioadhesive polymer delivery systems, and these systems provide promising opportunities for the local treatment of esophageal disease.

Anatomical Targeting of Anticancer Drugs to Solid Tumors Using Specific Administration Routes: Review.

Despite remarkable recent progress in developing anti-cancer agents, outcomes of patients with solid tumors remain unsatisfactory. In general, anti-cancer drugs are systemically administered through peripheral veins and delivered throughout the body. The major problem with systemic chemotherapy is insufficient uptake of intravenous (IV) drugs by targeted tumor tissue. Although dose escalation and treatment intensification have been attempted in order to increase regional concentrations of anti-tumor drugs, these approaches have produced only marginal benefits in terms of patient outcomes, while often damaging healthy organs. To overcome this problem, local administration of anti-cancer agents can yield markedly higher drug concentrations in tumor tissue with less systemic toxicity. This strategy is most commonly used for liver and brain tumors, as well as pleural or peritoneal malignancies. Although the concept is theoretically reasonable, survival benefits are still limited. This review summarizes clinical results and problems and discusses future directions of regional cancer therapy with local administration of chemotherapeutants.

Phase 1b/2a safety and tolerability study of bemcentinib (BEM) with pembrolizumab/carboplatin/pemetrexed in first line (1L) advanced or metastatic non-squamous non-small cell lung cancer (NSCLC) without/with a STK11 mutation.

TPS9154 Background: The combination of platinum, pemetrexed, and pembrolizumab (CIT) has become the standard of care in 1L non–oncogene addicted NSCLC. Despite an initial improvement in response rate and survival, the 5-year survival of NSCLC remains approximately 20-30%, due to the emergence of primary and acquired resistance. Additionally, the presence of brain metastases occurs in ˜30-50% of NSCLC patients and confers a poor prognosis. Among the currently non-actionable mutations, STK11/LKB1 mutations (STK11m) are common (˜20%) in NSCLC. Recent evidence suggests that STK11m NSCLC patients have a minimal response to checkpoint inhibitors and to chemo-immunotherapy in the first line setting. STK11m tumors are characterized by an immune-suppressed phenotype which is highly associated with AXL signalling. BEM, a first-in-class, oral, selective AXL inhibitor, has demonstrated the ability to prevent chemoresistance, re-sensitize STK11m NSCLC tumors to pembrolizumab, and enhance efficacy of CIT in preclinical lung models. Moreover, following oral administration, BEM readily distributes in brain tumour tissue in recurrent glioblastoma patients, with a 25.9 mean ratio of drug concentration in brain tissue to plasma. Therefore, the addition of BEM to CIT has the potential to improve 1L treatment outcomes in NSCLC overall and particularly in STK11m tumors. Methods: This is an open-label, multi-center, phase 1b/2a study to assess the safety, tolerability, and preliminary anti-tumor activity of BEM + CIT as 1L treatment in patients with advanced (Stage IIIb/IIIc) or metastatic (Stage IV) non-squamous NSCLC without actionable mutations. Patients with stable brain metastases are eligible to participate. Phase 1b follows a 3+3 design and will explore CIT in combination with one of 3 BEM dose levels: Cohort 1 = 75mg; Cohort 2 = 100 mg; or Cohort 3 = 150 mg. BEM is administered orally once/day on Day 1 of each 21-day treatment cycle. After 4 cycles of CIT + BEM, maintenance with BEM + pemetrexed + pembrolizumab is administered for up to 2 years. An independent data safety monitoring board will assess the safety data at the end of the dose-limiting toxicity period (the first 21 days of treatment for each patient, i.e. cycle 1) of each cohort and will recommend the BEM dose for the phase 2a expansion. In the phase 2a, up to 40 patients harboring a STK11m (regardless of their co-mutational status), in the absence of driver mutations will be enrolled. The study will include extensive co-mutational analyses via next-generation sequencing to identify potential sub-groups of patients deriving particular benefit. The trial is open to patient enrolment in phase1b in the US; recruitment for phase 2a is planned to open in Q2 2023 in Europe and US. EudraCT 2019‐003806‐28/NA/124645. Clinical trial information: NCT05469178 .