Cryo-Milled ß-Glucan Nanoparticles for Oral Drug Delivery.

Gemcitabine is a nucleoside analog effective against a number of cancers. However, it has an oral bioavailability of less than 10%, due to its high hydrophilicity and low permeability through the intestinal epithelium. Therefore, the aim of this project was to develop a novel nanoparticulate drug delivery system for the oral delivery of gemcitabine to improve its oral bioavailability. In this study, gemcitabine-loaded ß-glucan NPs were fabricated using a film-casting method followed by a freezer-milling technique. As a result, the NPs showed a small particle size of 447.6 ± 14.2 nm, and a high drug entrapment efficiency of 64.3 ± 2.1%. By encapsulating gemcitabine into ß-glucan NPs, a sustained drug release profile was obtained, and the anomalous diffusion release mechanism was analyzed, indicating that the drug release was governed by diffusion through the NP matrix as well as matrix erosion. The drug-loaded NPs had a greater ex vivo drug permeation through the porcine intestinal epithelial membrane compared to the plain drug solution. Cytotoxicity studies showed a safety profile of the ß-glucan polymers, and the IC50s of drug solution and drug-loaded ß-glucan NPs were calculated as 228.8 ± 31.2 ng·mL-1 and 306.1 ± 46.3 ng·mL-1, respectively. Additionally, the LD50 of BALB/c nude mice was determined as 204.17 mg/kg in the acute toxicity studies. Notably, pharmacokinetic studies showed that drug-loaded ß-glucan NPs could achieve a 7.4-fold longer T1/2 and a 5.1-fold increase in oral bioavailability compared with plain drug solution. Finally, in vivo pharmacodynamic studies showed the promising capability of gemcitabine-loaded ß-glucan NPs to inhibit the 4T1 breast tumor growth, with a 3.04- and 1.74-fold reduction compared to the untreated control and drug solution groups, respectively. In conclusion, the presented freezer-milled ß-glucan NP system is a suitable drug delivery method for the oral delivery of gemcitabine and demonstrates a promising potential platform for oral chemotherapy.

Synthesis and characterization of antimicrobial colloidal polyanilines.

The potential application of colloidal polyaniline (PANI) as an antimicrobial is limited by challenges related to solubility in common organic solvents, scalability, and antimicrobial potency. To address these limitations, we introduced a functionalized PANI (fPANI) with carboxyl groups through the polymerisation of aniline and 3-aminobenzoic acid in a 1:1 molar ratio. fPANI is more soluble than PANI which was determined using a qualitative study. We further enhanced the solubility and antimicrobial activity of fPANI by incorporating Ag nanoparticles onto the synthesized fPANI colloid via direct addition of 10 mM AgNO3. The improved solubility can be attributed to an approximately 3-fold reduction in size of particles. Mean particle sizes are measured at 1322 nm for fPANI colloid and 473 nm for fPANI-Ag colloid, showing a high dispersion and deagglomeration effect from Ag nanoparticles. Antimicrobial tests demonstrated that fPANI-Ag colloids exhibited superior potency against Gram-positive Staphylococcus aureus, Gram-negative Escherichia coli, and Bacteriophage PhiX 174 when compared to fPANI alone. The minimum bactericidal concentration (MBC) and minimum virucidal concentration (MVC) values were halved for fPANI-Ag compared to fPANI colloid and attributed to the combination of Ag nanoparticles with the fPANI polymer. The antimicrobial fPANI-Ag colloid presented in this study shows promising results, and further exploration into scale-up can be pursued for potential biomedical applications.

Encapsulation of the growth factor neurotrophin-3 in heparinised poloxamer hydrogel stabilises bioactivity and provides sustained release.

Poloxamer-based hydrogels show promise to stabilise and sustain the delivery of growth factors in tissue engineering applications, such as following spinal cord injury. Typically, growth factors such as neurotrophin-3 (NT-3) degrade rapidly in solution. Similarly, poloxamer hydrogels also degrade readily and are, therefore, only capable of sustaining the release of a payload over a small number of days. In this study, we focused on optimising a hydrogel formulation, incorporating both poloxamer 188 and 407, for the sustained delivery of bioactive NT-3. Hyaluronic acid blended into the hydrogels significantly reduced the degradation of the gel. We identified an optimal hydrogel composition consisting of 20 % w/w poloxamer 407, 5 % w/w poloxamer 188, 0.6 % w/w NaCl, and 1.5 % w/w hyaluronic acid. Heparin was chemically bound to the poloxamer chains to enhance interactions between the hydrogel and the growth factor. The unmodified and heparin-modified hydrogels exhibited sustained release of NT-3 for 28 days while preserving the bioactivity of NT-3. Moreover, these hydrogels demonstrated excellent cytocompatibility and had properties suitable for injection into the intrathecal space, underscoring their suitability as a growth factor delivery system. The findings presented here contribute valuable insights to the development of effective delivery strategies for therapeutic growth factors for tissue engineering approaches, including the treatment of spinal cord injury.

Translating ultrasound-mediated drug delivery technologies for CNS applications.

Ultrasound enhances drug delivery into the central nervous system (CNS) by opening barriers between the blood and CNS and by triggering release of drugs from carriers. A key challenge in translating setups from in vitro to in vivo settings is achieving equivalent acoustic energy delivery. Multiple devices have now been demonstrated to focus ultrasound to the brain, with concepts emerging to also target the spinal cord. Clinical trials to date have used ultrasound to facilitate the opening of the blood-brain barrier. While most have focused on feasibility and safety considerations, therapeutic benefits are beginning to emerge. To advance translation of these technologies for CNS applications, researchers should standardise exposure protocol and fine-tune ultrasound parameters. Computational modelling should be increasingly used as a core component to develop both in vitro and in vivo setups for delivering accurate and reproducible ultrasound to the CNS. This field holds promise for transformative advancements in the management and pharmacological treatment of complex and challenging CNS disorders.

Cellular Uptake and Transport Mechanism Investigations of PEGylated Niosomes for Improving the Oral Delivery of Thymopentin.

BACKGROUND: Although its immunomodulatory properties make thymopentin (TP5) appealing, its rapid metabolism and inactivation in the digestive system pose significant challenges for global scientists. PEGylated niosomal nanocarriers are hypothesized to improve the physicochemical stability of TP5, and to enhance its intestinal permeability for oral administration. METHODS: TP5-loaded PEGylated niosomes were fabricated using the thin film hydration method. Co-cultured Caco-2 and HT29 cells with different ratios were screened as in vitro intestinal models. The cytotoxicity of TP5 and its formulations were evaluated using an MTT assay. The cellular uptake and transport studies were investigated in the absence or presence of variable inhibitors or enhancers, and their mechanisms were explored. RESULTS AND DISCUSSION: All TP5 solutions and their niosomal formulations were nontoxic to Caco-2 and HT-29 cells. The uptake of TP5-PEG-niosomes by cells relied on active endocytosis, exhibiting dependence on time, energy, and concentration, which has the potential to significantly enhance its cellular uptake compared to TP5 in solution. Nevertheless, cellular transport rates were similar between TP5 in solution and its niosomal groups. The cellular transport of TP5 in solution was carried out mainly through MRP5 endocytosis and a passive pathway and effluxed by MRP5 transporters, while that of TP5-niosomes and TP5-PEG-niosomes was carried out through adsorptive- and clathrin-mediated endocytosis requiring energy. The permeability and transport rate was further enhanced when EDTA and sodium taurocholate were used as the penetration enhancers. CONCLUSIONS: This research has illustrated that PEG-niosomes were able to enhance the cellular uptake and maintain the cellular transport of TP5. This study also shows this formulation's potential to serve as an effective carrier for improving the oral delivery of peptides.

Roadmap on multifunctional materials for drug delivery.

This Roadmap on drug delivery aims to cover some of the most recent advances in the field of materials for drug delivery systems (DDSs) and emphasizes the role that multifunctional materials play in advancing the performance of modern DDSs in the context of the most current challenges presented. The Roadmap is comprised of multiple sections, each of which introduces the status of the field, the current and future challenges faced, and a perspective of the required advances necessary for biomaterial science to tackle these challenges. It is our hope that this collective vision will contribute to the initiation of conversation and collaboration across all areas of multifunctional materials for DDSs. We stress that this article is not meant to be a fully comprehensive review but rather an up-to-date snapshot of different areas of research, with a minimal number of references that focus upon the very latest research developments.

An open-label pilot trial assessing tolerability and feasibility of LSD microdosing in patients with major depressive disorder (LSDDEP1).

BACKGROUND: Globally, an estimated 260 million people suffer from depression [1], and there is a clear need for the development of new, alternative antidepressant therapies. In light of problems with the tolerability and efficacy of available treatments [2], a global trend is emerging for patients to self-treat depression with microdoses of psychedelic drugs such as lysergic acid diethylamide (LSD) and psilocybin [3]. Beyond anecdotal reports from those who self-medicate in this way, few clinical trials have evaluated this practice. In our recently published phase 1 study in healthy volunteers [4], we determined that LSD microdosing was relatively safe and well tolerated in that cohort. Furthermore, the data demonstrated that conducting such microdosing trials is broadly feasible, with excellent adherence and compliance to the regimen observed. In this open-label pilot trial of patients with major depressive disorder (LSDDEP1), we will test the tolerability and feasibility of an 8-week regimen of LSD microdosing in this patient group prior to a larger subsequent randomised controlled trial (LSDDEP2). METHODS: Twenty patients meeting the DSM-5 criteria for major depressive disorder will receive an 8-week LSD microdosing treatment regimen. The treatment protocol will use a sublingual formulation of LSD (MB-22001) delivered twice per week under a titration schedule using a dose of 5-15 µg. Tolerability will be assessed by quantifying the percentage of participants who withdraw from the trial due to adverse events attributable to the treatment regimen, while feasibility will be assessed by quantifying the percentage of attended clinic visits once enrolled. To determine whether there is any antidepressant response to the LSD microdosing regimen, MADRS scores will be assessed at baseline and 2, 4, 6, and 8 weeks after the commencement of the regimen. DISCUSSION: The results of LSDDEP1 will provide valuable information regarding the tolerability and feasibility of a proposed LSD microdosing regimen in patients with MDD. Such information is critically important to optimise trial design prior to commencing a subsequent and more resource-intensive randomised controlled trial. TRIAL REGISTRATION: ANZCTR, ACTRN12623000486628. Registered on 12 May 2023.

Generation of direct current electrical fields as regenerative therapy for spinal cord injury: A review.

Electrical stimulation (ES) shows promise as a therapy to promote recovery and regeneration after spinal cord injury. ES therapy establishes beneficial electric fields (EFs) and has been investigated in numerous studies, which date back nearly a century. In this review, we discuss the various engineering approaches available to generate regenerative EFs through direct current electrical stimulation and very low frequency electrical stimulation. We highlight the electrode-tissue interface, which is important for the appropriate choice of electrode material and stimulator circuitry. We discuss how to best estimate and control the generated field, which is an important measure for comparability of studies. Finally, we assess the methods used in these studies to measure functional recovery after the injury and treatment. This work reviews studies in the field of ES therapy with the goal of supporting decisions regarding best stimulation strategy and recovery assessment for future work.

Hydroxypropyl Methylcellulose Bioadhesive Hydrogels for Topical Application and Sustained Drug Release: The Effect of Polyvinylpyrrolidone on the Physicomechanical Properties of Hydrogel.

Hydrogels are homogeneous three-dimensional polymeric networks capable of holding large amounts of water and are widely used in topical formulations. Herein, the physicomechanical, rheological, bioadhesive, and drug-release properties of hydrogels containing hydroxypropyl methylcellulose (HPMC) and polyvinylpyrrolidone (PVP) were examined, and the intermolecular interactions between the polymers were explored. A three-level factorial design was used to form HPMC-PVP binary hydrogels. The physicomechanical properties of the binary hydrogels alongside the homopolymeric HPMC hydrogels were characterized using a texture analyzer. Rheological properties of the gels were studied using a cone and plate rheometer. The bioadhesiveness of selected binary hydrogels was tested on porcine skin. Hydrophilic benzophenone-4 was loaded into both homopolymeric and binary gels, and drug-release profiles were investigated over 24 h at 33 °C. Fourier transform infrared spectroscopy (FTIR) was used to understand the inter-molecular drug-gel interactions. Factorial design analysis supported the dominant role of the HPMC in determining the gel properties, rather than the PVP, with the effect of both polymer concentrations being non-linear. The addition of PVP to the HPMC gels improved adhesiveness without significantly affecting other properties such as hardness, shear-thinning feature, and viscosity, thereby improving bioadhesiveness for sustained skin retention without negatively impacting cosmetic acceptability or ease of use. The release of benzophenone-4 in the HPMC hydrogels followed zero-order kinetics, with benzophenone-4 release being significantly retarded by the presence of PVP, likely due to intermolecular interactions between the drug and the PVP polymer, as confirmed by the FTIR. The HPMC-PVP binary hydrogels demonstrate strong bioadhesiveness resulting from the addition of PVP with desirable shear-thinning properties that allow the formulation to have extended skin-retention times. The developed HPMC-PVP binary hydrogel is a promising sustained-release platform for topical drug delivery.

A simple and reliable isocratic high-performance chromatographic assay for the simultaneous determination of hydrophilic benzophenone-4 and lipophilic octocrylene in sunscreens.

OBJECTIVE: This work aimed to develop a simple HPLC method for the simultaneous quantitative determination of the ultraviolet (UV) filters, hydrophilic benzophenone-4 and lipophilic octocrylene, in the presence of three other commonly used UV filters, avobenzone, octisalate and homosalate. METHODS: Reverse-phased HPLC was performed on a C18 column. A scouting gradient was initially used to determine the approximate mobile phase composition required for efficient analyte elution and separation before further optimization. The assay was validated with regard to specificity, linearity, intra- and inter-day accuracy and precision, limits of detection and limits of quantification. An ultrasound dispersion extraction method for the UV filters from a commercial sunscreen was developed, and the extraction efficiencies from spiked samples were calculated. RESULTS: An acetonitrile-methanol-water mixture (20:67:13, v/v/v), where the water component contained 0.2% trifluoroacetic acid (v/v), was found to be the optimal mobile phase at a flow rate of 1.0 mL/min. The assay was linear between 1.0-100 µg/mL for both benzophenone-4 and octocrylene (both correlation coefficients were above 0.999). There was no interference from the excipients of the sunscreen nor from the three other UV filters. The intra- and inter-day accuracy was between 90.0-104.6% for both analytes. Extraction recoveries from a spiked commercial sunscreen were between 95.4 ± 2.1% to 98.5 ± 2.1% for benzophenone-4, and between 87.3 ± 2.3% and 98.9 ± 3.1% for octocrylene. All validation parameters were within the acceptance criteria set out in the International Council for Harmonization (ICH) guidelines. The HPLC assay showed the extracted quantities of benzophenone-4 and octocrylene from the commercial sunscreen closely matched claimed quantities. CONCLUSION: The developed isocratic HPLC method was suitable for simultaneously determining the hydrophilic benzophenone-4 and lipophilic octocrylene in the presence of other commonly used UV filters. Additionally, the extraction method was simple and effective for accurately quantifying the UV filters in a commercial sunscreen.

OBJECTIF: Ces travaux visaient à développer une méthode de chromatographie en phase liquide à haute performance simple pour la détermination quantitative simultanée de la benzophénone-4 hydrophile et de l'octocrylène lipophile, des filtres ultraviolets (UV), en présence de trois autres filtres UV couramment utilisés, l'avobenzone, l'octisalate et l'homosalate. MÉTHODES: Une chromatographie en phase liquide à haute performance en phase inverse a été réalisée sur une colonne C18. Un gradient de référence a été initialement utilisé pour déterminer la composition approximative de la phase mobile requise pour une élution et une séparation efficace de l'analyte avant une optimisation plus poussée. Le dosage a été validé en termes de spécificité, de linéarité, d'exactitude et de précision intra- et inter-journalières, de limites de détection et de limites de quantification. Une méthode d'extraction par dispersion ultrasonique des filtres UV d'une crème solaire commerciale a été mise au point, et les efficacités d'extraction des échantillons artificiellement traités ont été calculées. RÉSULTATS: Un mélange acétonitrile-méthanol-eau (20:67:13, v/v/v), où la composante eau contenait 0,2 % d'acide trifluoroacétique (v/v), s'est avéré être la phase mobile optimale à un débit de 1,0 ml/min. Le dosage était linéaire entre 1,0 et 100 µg/ml pour la benzophénone-4 et l'octocrylène (les deux coefficients de corrélation étaient supérieurs à 0,999). Aucune interférence n'a été observée entre les excipients de l'écran solaire et les trois autres filtres UV. La précision intra et inter-journalière était comprise entre 90,0 et 104,6 % pour les deux analytes. Les récupérations par extraction à partir d'une crème solaire commerciale artificiellement traitée étaient comprises entre 95,4 % ± 2,1 % et 98,5 % ± 2,1 % pour la benzophénone-4, et entre 87,3 % ± 2,3 % et 98,9 % ± 3,1 % pour l'octocrylène. Tous les paramètres de validation étaient conformes aux critères d'acceptation définis dans les lignes directrices du Conseil international d'harmonisation (ICH). Le dosage par chromatographie en phase liquide à haute performance a montré que les quantités extraites de benzophénone-4 et d'octocrylène de la crème solaire commerciale correspondaient étroitement aux quantités revendiquées. CONCLUSION: La méthode de chromatographie en phase liquide à haute performance isocratique mise au point a permis de déterminer simultanément la benzophénone-4 hydrophile et l'octocrylène lipophile en présence d'autres filtres UV couramment utilisés. En outre, la méthode d'extraction était simple et efficace pour quantifier avec précision les filtres UV dans une crème solaire commerciale.

Safety and efficacy of intraosseous ropivacaine in lower extremity (SORE) study.

BACKGROUND: Day stay surgery for anterior cruciate ligament (ACL) reconstructions is an increasingly common practice and has driven clinicians to develop postoperative pain regimes that allow same day mobilization and a safe and timely discharge. There is a paucity of literature surrounding the use of intraosseous (IO) ropivacaine used as a Bier's block to provide both intraoperative and postoperative analgesia in lower limb surgery. METHODS: This patient blinded, pilot study randomized 15 patients undergoing ACL reconstruction to receive either IO ropivacaine 1.5 or 2.0 mg/kg; or 300 mg of ropivacaine as local infiltration. The primary outcome for this study was arterial plasma concentration of ropivacaine. Samples were taken via an arterial line at prespecified times after tourniquet deflation. Secondary outcomes included immediate postoperative pain scores using the visual analogue scale and perioperative opioid equivalent consumption. RESULTS: All patients in the intervention group receiving IO ropivacaine had plasma concentrations well below the threshold for central nervous system (CNS) toxicity (0.60 µg/mL). The highest plasma concentration was achieved in the intervention group receiving 1.5 mg/kg dose of ropivacaine reaching 2.93 mg/mL. This would equate to 0.18 µg/mL of free plasma ropivacaine. There were no differences across the three groups regarding pain scores or perioperative opioid consumption. CONCLUSIONS: This study demonstrates that IO ropivacaine is both safe and effective in reducing perioperative pain in patients undergoing ACL reconstruction. There may be scope to increase the IO dose further or utilize other analgesics via the IO regional route to improve perioperative pain relief.

Electrically responsive release of proteins from conducting polymer hydrogels.

Electrically modulated delivery of proteins provides an avenue to target local tissues specifically and tune the dose to the application. This approach prolongs and enhances activity at the target site whilst reducing off-target effects associated with systemic drug delivery. The work presented here explores an electrically active composite material comprising of a biocompatible hydrogel, gelatin methacryloyl (GelMA) and a conducting polymer, poly(3,4-ethylenedioxythiophene), generating a conducting polymer hydrogel. In this paper, the key characteristics of electroactivity, mechanical properties, and morphology are characterized using electrochemistry techniques, atomic force, and scanning electron microscopy. Cytocompatibility is established through exposure of human cells to the materials. By applying different electrical-stimuli, the short-term release profiles of a model protein can be controlled over 4 h, demonstrating tunable delivery patterns. This is followed by extended-release studies over 21 days which reveal a bimodal delivery mechanism influenced by both GelMA degradation and electrical stimulation events. This data demonstrates an electroactive and cytocompatible material suitable for the delivery of protein payloads over 3 weeks. This material is well suited for use as a treatment delivery platform in tissue engineering applications where targeted and spatio-temporal controlled delivery of therapeutic proteins is required. STATEMENT OF SIGNIFICANCE: Growth factor use in tissue engineering typically requires sustained and tunable delivery to generate optimal outcomes. While conducting polymer hydrogels (CPH) have been explored for the electrically responsive release of small bioactives, we report on a CPH capable of releasing a protein payload in response to electrical stimulus. The composite material combines the benefits of soft hydrogels acting as a drug reservoir and redox-active properties from the conducting polymer enabling electrical responsiveness. The CPH is able to sustain protein delivery over 3 weeks, with electrical stimulus used to modulate release. The described material is well suited as a treatment delivery platform to deliver large quantities of proteins in applications where spatio-temporal delivery patterns are paramount.

Investigating the influence of ultrasound parameters on ibuprofen drug release from hydrogels.

Hydrogels are promising ultrasound-responsive drug delivery systems. In this study, we investigated how different ultrasound parameters affected drug release and structural integrity of self-healing hydrogels composed of alginate or poloxamers. The effects of amplitude and duty cycle at low frequency (24 kHz) ultrasound stimulation were first investigated using alginate hydrogels at 2% w/v and 2.5% w/v. Increasing ultrasound amplitude increased drug release from these gels, although high amplitudes caused large variations in release and damaged the gel structure. Increasing duty cycle also increased drug release, although a threshold was observed with the lower pulsed 50% duty cycle achieving similar levels of drug release to a continuous 100% duty cycle. Poloxamer-based hydrogels were also responsive to the optimised parameters at low frequency (24 kHz, 20% amplitude, 50% duty cycle for 30 s) and showed similar drug release results to a 2.5% w/v alginate hydrogel. Weight loss studies demonstrated that the 2% w/v alginate hydrogel underwent significant erosion following ultrasound application, whereas the 2.5% w/v alginate and the poloxamer gels were unaffected by application of the same parameters (24 kHz, 20% amplitude, 50% duty cycle for 30 s). The rheological properties of the hydrogels were also unaffected and the FTIR spectra remained unchanged after low frequency ultrasound stimulation (24 kHz, 20% amplitude, 50% duty cycle for 30 s). Finally, high-frequency ultrasound stimulation (1 MHz, 3 W.cm-2, 50% duty cycle) was also trialled; the alginate gels were less responsive to this frequency, while no statistically significant impact on drug release was observed from the poloxamer gels. This study demonstrates the importance of ultrasound parameters and polymer selection in designing ultrasound-responsive hydrogels.

Can Targeting Sphincter Spasm Reduce Post-Haemorrhoidectomy Pain? A Systematic Review and Meta-Analysis.

BACKGROUND: Haemorrhoidectomy is often complicated by significant post-operative pain, to which spasm of the internal anal sphincter is thought to be a contributing factor. This study appraises the evidence behind interventions aimed at lowering sphincter spasm to relieve post-haemorrhoidectomy pain. METHODS: A Preferred Reporting Items for Systematic Reviews and Meta-analyses compliant systematic review was conducted. Medline, EMBASE, and CENTRAL databases were systematically searched. All RCTs which compared interventions targeting the internal anal sphincter to relieve pain post excisional haemorrhoidectomy were included. The primary outcome measure was pain on the visual analogue scale. RESULTS: Of the initial 10,221 search results, 39 articles were included in a qualitative synthesis, and 33 studies were included in a meta-analysis. Topical glyceryl trinitrate (GTN) reduced pain on day 7 (7 studies, 485 participants), with a mean difference and 95% confidence interval (MD, 95% CI) of -1.34 (-2.31; -0.37), I2 = 91%. Diltiazem reduced pain on day 3 on the VAS, and the MD was -2.75 (-398; -1.51) shown in five studies (n = 227). Botulinum toxin reduced pain on day 7, in four studies with 178 participants, MD -1.43 (-2.50; -0.35) I2 = 62%. The addition of Lateral Internal Sphincterotomy to haemorrhoidectomy reduced pain on day 2 in three studies with 275 participants, MD of -2.13 (-3.49; -0.77) I2 = 92%. The results were limited by high heterogeneity and risk of bias. CONCLUSION: Evidence suggests that lateral sphincterotomy, administration of botulinum toxin and the application of topical diltiazem or GTN can reduce post-operative pain after haemorrhoidectomy. Lateral sphincterotomy should not be routinely used due to the risk of incontinence.

Stability and compatibility of admixtures containing bupivacaine hydrochloride and ketorolac tromethamine for parenteral use.

OBJECTIVE: Bupivacaine hydrochloride (BH) and ketorolac tromethamine (KT) are commonly used in parenteral admixtures to manage postoperative pain. However, stability and compatibility data for these admixtures applicable to current practice are limited, posing the patient to potential risk. METHODS: The stability of BH/KT admixtures in commonly used parenteral fluids was studied in Eppendorf tubes and glass vials at ambient room temperature using a newly developed and validated stability-indicating high-performance liquid chromatography (HPLC) method capable of the simultaneous quantification of both drugs. The chemical compatibility of BH/KT was assessed using Fourier transform infrared spectroscopy (FTIR) and thermal analysis. Additionally, the validity of the developed HPLC method for the quantification of BH/KT in human plasma was evaluated. RESULTS: BH and KT demonstrated <10% loss of their initial concentrations when prepared in Ringer, normal saline or dextrose solution at ambient temperature for up to 4 weeks. FTIR and thermal analysis demonstrated mild intermolecular interactions between BH and KT in solution, with no evidence of incompatibility. The developed HPLC method demonstrated satisfactory accuracy and precision for the simultaneous quantification of BH and KT in human plasma over the range of 0.2-3.2 µg·mL-1. CONCLUSION: BH/KT parenteral admixtures are chemically stable for a period of 4 weeks when stored at room temperature. The stability-indicating HPLC method is valid for BH/KT simultaneous determination in human plasma, facilitating pharmacokinetics studies.

The role of glutathione conjugation on the transcellular transport process of PEGylated liposomes across the blood brain barrier.

Notwithstanding the growing evidence of improved drug delivery efficiency to the brain by ligand modification of PEGylated liposomes, the comprehensive knowledge of their transport processes and payload across the BBB is yet to be revealed. Herein, this study sought to understand the glutathione (GSH) ligand effect on transcellular transport mechanisms of liposomes through the blood-brain barrier (BBB) by comparing PEGylated liposomes (PEG-L) and GSH PEGylated liposomes (GSH-PEG-L). Endocytosis and exocytosis of liposomes including the role of secreted extracellular vesicles (EVs) of brain endothelial cells (BECs) were assessed. Furthermore, pharmacokinetics and brain distribution analysis of gemcitabine loaded liposomes were carried out in healthy rats to ascertain the in vivo applicability. Our findings suggested that the presence of GSH increased the cellular uptake of liposomes by up to 3-fold in human brain microvascular endothelial cells depending on the dose but not in astrocytes. The cell exposure to liposomes particularly GSH-PEG-L dramatically increased the cell secretion of small and microvesicles with liposomal components, though different liposomes preferred different vesicles for exocytosis. This correlated with GSH-PEG-L transport efficiency of 4 % across the in vitro BBB model in 24 h, 1.7-fold higher than that of PEG-L (p < 0.05). In rats, while PEG-L and GSH-PEG-L showed similar pharmacokinetic profiles and prolonged circulation properties, 3.8 % of the total injected dose (ID) of gemcitabine was found in the brain of the GSH-PEG-L group at 8 h post-injection, compared with 2.8 % ID in the PEG-L group. A brain: blood concentration ratio of 1.27 ± 0.12 indicated that an active transport mechanism to cross the BBB for GSH-PEG-L. Overall, this study revealed that GSH augmented the transcellular transport efficiency of liposomes through BBB to improve targeted brain delivery by enhancing cellular uptake and vesicular exocytosis route of BECs.

Increasing the Hydrophobic Component of Poloxamers and the Inclusion of Salt Extend the Release of Bupivacaine from Injectable In Situ Gels, While Common Polymer Additives Have Little Effect.

Various strategies have been applied to reduce the initial burst of drug release and sustain release from poloxamer-based thermoresponsive gels. This work focussed on investigating different formulation approaches to minimise the initial burst of release and sustain the release of the small hydrophilic drug bupivacaine hydrochloride from poloxamer-based thermoresponsive gels. Various in situ gel formulations were prepared by varying the polypropylene oxide (PPO)/polyethylene oxide (PEO) ratio and by adding additives previously described in the literature. It was observed that increasing the PPO/PEO ratio from 0.28 to 0.30 reduced the initial burst release from 17.3% ± 1.8 to 9.1% ± 1.2 during the first six hours and extended the release profile from 10 to 14 days. Notably, the inclusion of sodium chloride (NaCl 0.4% w/w) further reduced the initial burst release to 1.8% ± 1.1 over the first 6 h. Meanwhile, physical blending with additive polymers had a negligible effect on the burst release and overall release profile. The findings suggest that extended release of bupivacaine hydrochloride, with reduced initial burst release, can be achieved simply by increasing the PPO/PEO ratio and the inclusion of NaCl.

Patternable Gelatin Methacrylate/PEDOT/Polystyrene Sulfonate Microelectrode Coatings for Neuronal Recording.

This manuscript addresses the need for new soft biomaterials that can be fabricated on the surface of microelectrodes to reduce the mechanical mismatch between biological tissues and electrodes and improve the performance at the neural interface. By electrochemical polymerization of poly(3,4-dioxythiophene) (PEDOT)/polystyrene sulfonate (PSS) through a gelatin methacrylate (GelMA) hydrogel, we demonstrate the synthesis of a conducting polymer hydrogel (CPH) to meet the performance criteria of bioelectrodes. The hybrid material can be photolithographically patterned and covalently attached to gold microelectrodes, forming an interpenetrating network, as confirmed by infrared spectroscopy. The GelMA/PEDOT/PSS coatings were found to be reversibly electroactive by cyclic voltammetry and had low impedance compared to bare gold and GelMA-coated microelectrodes. The CPH coatings showed impedance at levels similar to conventional PEDOT/PSS coatings at a frequency of 1000 Hz. CPH exhibited electrochemical stability over 1000 CV cycles, and its performance was maintained over 14 days. Biocompatibility of the CPH coatings was confirmed by primary hippocampal neuronal cultures via a neuronal viability assay. The CPH-coated microelectrode arrays (MEAs) successfully recorded neuronal activity from primary hippocampal neuronal cells. The CPH GelMA/PEDOT/PSS is a highly promising coating material to enhance microelectrode performance at the neural interface.

Exploring ex vivo peptideolysis of thymopentin and lipid-based nanocarriers towards oral formulations.

The oral delivery of medicines is the most popular route of administration for patients. However, thymopentin (TP5) is only available in the market in forms for parenteral administration. In large part, this is because of extensive peptidolytic degradation in the gastrointestinal tract (GIT), which decreases the amount of TP5 available for absorption. This study aims to understand the extent of TP5 peptideolysis and determine effective inhibitors and suitable lipid-based nanocarriers to aid in the development of an effective oral delivery formulation. Enzymatic degradation kinetics of TP5 was investigated in the presence or absence of mucosal and luminal components extracted from various parts of the rat intestine, including the duodenum, jejunum, ileum, and colon. Inhibition of TP5 enzymatic peptidolysis was screened in the presence or absence of EDTA, trypsin and chymotrypsin inhibitors from soybean (SBTCI), and bestatin. TP5 with SBTCI was loaded into lipid-based nanocarriers, including microemulsions, niosomes and solid lipid nanoparticles. These TP5-loaded nanocarriers were investigated through characterization of morphology, particle size, zeta potential, entrapment efficacy (EE%), and ex vivo rat intestinal degradation studies to select a lead formulation for a future oral drug delivery study. The degradation kinetics of TP5 followed pseudo-first-order kinetics, and the biological metabolism of TP5 was displayed in the presence of luminal contents, indicating that TP5 is sensitive to luminal enzymes. Notably, a considerable decrease in TP5 peptidolysis was found in the presence of SBTCI, bestatin, and EDTA. TP5 and SBTCI were loaded into three lipid-based delivery systems, displaying superior protection under ex vivo intestinal luminal contents and mucosal homogenates for 6 h compared with the pure drug solution. These findings suggest that using select inhibitors and lipid-based nanocarriers can decrease peptide degradation and may improve oral bioavailability of TP5 following oral administration.

Development of agarose-gelatin bioinks for extrusion-based bioprinting and cell encapsulation.

Three-dimensional bioprinting continues to advance as an attractive biofabrication technique to employ cell-laden hydrogel scaffolds in the creation of precise, user-defined constructs that can recapitulate the native tissue environment. Development and characterisation of new bioinks to expand the existing library helps to open avenues that can support a diversity of tissue engineering purposes and fulfil requirements in terms of both printability and supporting cell attachment. In this paper, we report the development and characterisation of agarose-gelatin (AG-Gel) hydrogel blends as a bioink for extrusion-based bioprinting. Four different AG-Gel hydrogel blend formulations with varying gelatin concentration were systematically characterised to evaluate suitability as a potential bioink for extrusion-based bioprinting. Additionally, autoclave and filter sterilisation methods were compared to evaluate their effect on bioink properties. Finally, the ability of the AG-Gel bioink to support cell viability and culture after printing was evaluated using SH-SY5Y cells encapsulated in bioprinted droplets of the AG-Gel. All bioink formulations demonstrate rheological, mechanical and swelling properties suitable for bioprinting and cell encapsulation. Autoclave sterilisation significantly affected the rheological properties of the AG-Gel bioinks compared to filter sterilisation. SH-SY5Y cells printed and differentiated into neuronal-like cells using the developed AG-Gel bioinks demonstrated high viability (>90%) after 23 d in culture. This study demonstrates the properties of AG-Gel as a printable and biocompatible material applicable for use as a bioink.