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.

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.

Cryo-Milled β-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 β-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 β-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 β-glucan polymers, and the IC50s of drug solution and drug-loaded β-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 β-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 β-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 β-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.

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.

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.

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.

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 regards 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 was 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.

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.

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.

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.

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.

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.

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.

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.

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.

A Subdural Bioelectronic Implant to Record Electrical Activity from the Spinal Cord in Freely Moving Rats

Bioelectronic devices have found use at the interface with neural tissue to investigate and treat nervous system disorders. Here, the development and characterization of a very thin flexible bioelectronic implant inserted along the thoracic spinal cord in rats directly in contact with and conformable to the dorsal surface of the spinal cord are presented. There is no negative impact on hind-limb functionality nor any change in the volume or shape of the spinal cord. The bioelectronic implant is maintained in rats for a period of 12 weeks. The first subdural recordings of spinal cord activity in freely moving animals are presented; rats are plugged in via a recording cable and allowed to freely behave and move around on a raised platform. Recordings contained multiple distinct voltage waveforms spatially localize to individual electrodes. This device has great potential to monitor electrical signaling in the spinal cord after an injury and in the future, this implant will facilitate the identification of biomarkers in spinal cord injury and recovery, while enabling the delivery of localized electroceutical and chemical treatments.

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 hydrogel blends as a bioink for extrusion-based bioprinting. Four different agarose-gelatin 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 agarose-gelatin bioink to support cell viability and culture after printing was evaluated using SH-SY5Y cells encapsulated in bioprinted droplets of the agarose-gelatin. All bioink formulations demonstrate rheological, mechanical and swelling properties suitable for bioprinting and cell encapsulation. Autoclave sterilisation significantly affected the rheological properties of the agarose-gelatin bioinks compared to filter sterilisation. SH-SY5Y cells printed and differentiated into neuronal-like cells using the developed agarose-gelatin bioinks demonstrated high viability (>90%) after 23 days in culture. This study demonstrates the properties of agarose-gelatin as a printable and biocompatible material applicable for use as a bioink.

Quantification and composition of pharmaceutical waste in New Zealand

This study aimed to quantify the amount of pharmaceutical waste produced in New Zealand, and determine the composition of pharmaceutical waste from community pharmacies in Auckland, New Zealand. Pharmaceutical waste collected in New Zealand is increasing, peaking at 542 tonne in 2019. Pharmaceutical waste collected from hospitals and pharmacies in Auckland increased by more than fourfold from 2016 to 2020. An audit of the types of pharmaceutical waste collected from community pharmacies revealed that the most common classes of drugs identified in this waste stream belonged to the nervous system, cardiovascular system and alimentary tract, and metabolism. Following examination of the contents of 12 pharmaceutical waste bins, 475 different pharmaceutical products were identified, highlighting the breadth of drugs in this waste stream. A range of dosage forms and hence materials were identified, which could present challenges for future waste treatment approaches. Hazardous drugs were identified including cytotoxic compounds, which should go into a separate waste stream for incineration. There is a need for similar data to be collected from multiple sites to fully appreciate the magnitude and composition of pharmaceutical waste. This will allow for the suitability of current practices for managing this hazardous waste stream to be evaluated.

Evaluation of the inflammatory profile following uncomplicated elective colectomy

Background

Attenuation of the inflammatory response in patients undergoing colectomy with modern perioperative care and laparoscopic surgery has been a focus of research in recent years. Despite reported benefits, significant heterogeneity remains with studies including patients undergoing both rectal and colon surgery and including surgery with postoperative complications. Therefore, the aim of the study was to evaluate the inflammatory response in patients undergoing elective colectomy without complications, specifically comparing open and laparoscopic approaches.

Methods

A multicenter prospective study was conducted across four public hospitals in Auckland and Christchurch, New Zealand. Consecutive adults undergoing elective colectomy were included over a 3‐year period. Perioperative blood samples were collected and analysed for the following inflammatory markers: IL‐6, IL‐1β, TNFα, IL‐10, CRP, leucocyte and neutrophil count. Statistical analysis was performed using SPSS statistical software.

Results

A total of 168 colectomy patients without complications were included in the analysis. Patients that underwent laparoscopy had significantly reduced IL‐6, neutrophils and CRP on postoperative day (POD) 1 (p < 0.05) compared to an open approach. IL‐10 and TNFα were significantly reduced on POD 2 (p < 0.05) in laparoscopic patients. Patients with a Body Mass Index (BMI) greater than 30 kg/m² had significantly higher levels of CRP regardless of operative approach. Statins altered both preoperative and postoperative inflammatory markers.

Conclusion

The postoperative inflammatory response is influenced by surgical approach, perioperative medications, and patient factors. These findings have important implications in the utility of biomarkers in the diagnosis of postoperative surgical complications, in particular in the early diagnosis of anastomotic leak.

Conducting polymer hydrogels with electrically-tuneable mechanical properties as dynamic cell culture substrates

Hydrogels are a popular substrate for cell culture due to their mechanical properties closely resembling natural tissue. Stimuli-responsive hydrogels are a good platform for studying cell response to dynamic stimuli. Poly(N-isopropylacrylamide) (pNIPAM) is a thermo-responsive polymer that undergoes a volume-phase transition when heated to 32 °C. Conducting polymers can be incorporated into hydrogels to introduce electrically responsive properties. The conducting polymer, polypyrrole (PPy), has been widely studied as electrochemical actuators due to its electrochemical stability, fast actuation and high strains. We determine the volume-phase transition temperature of pNIPAM hydrogels with PPy electropolymerised with different salts as a film within the hydrogel network. We also investigate the electro-mechanical properties at the transition temperature (32 °C) and physiological temperature (37 °C). We show statistically significant differences in the Young's modulus of the hybrid hydrogel at elevated temperatures upon electrochemical stimulation, with a 5 kPa difference at the transition temperature. Furthermore, we show a three-fold increase in actuation at transition temperature compared to room temperature and physiological temperature, attributed to the movement of ions in/out of the PPy film that induce the volume-phase transition of the pNIPAM hydrogel. Furthermore, cell adhesion to the hybrid hydrogel was demonstrated with mouse articular chondrocytes.

An interpenetrating and patternable conducting polymer hydrogel for electrically stimulated release of glutamate

Recent advances in drug delivery have made it possible to release bioactive agents from neural implants specifically to local tissues. Conducting polymer coatings have been explored as a delivery platform in bioelectronics, however, their utility is restricted by their limited loading capacity and stability. This study presents the fabrication of a stable conducting polymer hydrogel (CPH), comprising the hydrogel gelatin methacrylate (GelMA), and conducting polymer polypyrrole (PPy) for the electrically controlled delivery of glutamate (Glu). The hybrid GelMA/PPy/Glu can be photolithographically patterned and covalently bonded to an electrode. Fourier-transform infrared (FTIR) analysis confirmed the interpenetrating nature of PPy through the GelMA hydrogels. Electrochemical polymerisation of PPy/Glu through the GelMA hydrogels resulted in a significant increase in the charge storage capacity as determined by cyclic voltammetry (CV). Long-term electrochemical and mechanical stability was demonstrated over 1000 CV cycles and extracts of the materials were cytocompatible with SH-SY5Y neuroblastoma cell lines. Release of Glu from the CPH was responsive to electrical stimulation with almost five times the amount of Glu released upon constant reduction (-0.6 V) compared to when no stimulus was applied. Notably, GelMA/PPy/Glu was able to deliver almost 14 times higher amounts of Glu compared to conventional PPy/Glu films. The described CPH coatings are well suited in implantable drug delivery applications and compared to conducting polymer films can deliver higher quantities of drug in response to mild electrical stimulus. STATEMENT OF SIGNIFICANCE: Conducting polymer hydrogels (CPH) have been explored for the electrically controlled release of bioactives from implantable devices. Typically, the conducting polymer component does not fully penetrate the hydrogel. We report, for the first time, a completely interpenetrating CPH allowing for the full benefits of the composite material to be realised, the hydrogels provide a reservoir for drug delivery, and conducting polymer renders the material responsive to electrical stimulation for drug release. We report a CPH for the electrically controlled delivery of glutamate (excitatory neurotransmitter) where several-fold more glutamate can be delivered compared to conducting polymer films. The described CPH coatings are well suited for use in bioelectronic devices to deliver large quantities of drug in response to mild electrical stimulus.

N-trimethyl chitosan coated nano-complexes enhance the oral bioavailability and chemotherapeutic effects of gemcitabine

N-trimethyl chitosan (TMC) is a multifunctional polymer that can be used in various nanoparticle forms in the pharmaceutical, nutraceutical and biomedical fields. In this study, TMC was used as a mucoadhesive adjuvant to enhance the oral bioavailability and hence antitumour effects of gemcitabine formulated into nanocomplexes composed of poly(lactic-co-glycolic acid) nanoparticles (PLGA NPs) conjugated with d-α-tocopheryl polyethylene glycol 1000 succinate (TPGS). A central composite design was applied to achieve the optimal formulation. Cellular uptake and drug transportation studies revealed the nanocomplexes permeate over the intestinal cells via adsorptive-mediated and caveolae-mediated endocytosis. Pharmacokinetic studies demonstrated the oral drug bioavailability of the nanocomplexes was increased 5.1-fold compared with drug solution. In pharmacodynamic studies, the formulation reduced tumour size 3.1-fold compared with the drug solution. The data demonstrates that TMC modified nanocomplexes can enhance gemcitabine oral bioavailability and promote the anticancer efficacy.

Photosensitive drug delivery systems for cancer therapy: Mechanisms and applications

Over the past three decades, various photosensitive nanoparticles have been developed as potential therapies in human health, ranging from photodynamic therapy technologies that have already reached clinical use, to drug delivery systems that are still in the preclinical stages. Many of these systems are designed to achieve a high spatial and temporal on-demand drug release via phototriggerable mechanisms. This review examines the current clinical and experimental applications in cancer treatment of photosensitive drug release systems, including nanocarriers such as liposomes, micelles, polymeric nanoparticles, and hydrogels. We will focus on the three main physicochemical mechanisms of imparting photosensitivity to a delivery system: i) photochemical reactions (oxidation, cleavage, and polymerization), ii) photoisomerization, iii) and photothermal reactions. Photosensitive nanoparticles have a multitude of different applications including controlled drug release, resulting from physical/conformational changes in the delivery systems in response to light of specific wavelengths. Most of the recent research in these delivery systems has primarily focused on improving the efficacy and safety of cancer treatments such as photodynamic and photothermal therapy. Combinations of multiple treatment modalities using photosensitive nanoparticulate delivery systems have also garnered great interest in combating multi-drug resistant cancers due to their synergistic effects. Finally, the challenges and future potential of photosensitive drug delivery systems in biomedical applications is outlined.

Stretchable microchannel-on-a-chip: A simple model for evaluating the effects of uniaxial strain on neuronal injury

BACKGROUND

Axonal injury is a major component of traumatic spinal cord injury (SCI), associated with rapid deformation of spinal tissue and axonal projections. In vitro models enable us to examine these effects and screen potential therapies in a controlled, reproducible manner.

NEW METHOD

A customized, stretchable microchannel system was developed using polydimethylsiloxane microchannels. Cortical and spinal embryonic rat neurons were cultured within the microchannel structures, allowing a uniaxial strain to be applied to isolated axonal processes. Global strains of up to 52% were applied to the stretchable microchannel-on-a-chip platform leading to local strains of up to 12% being experienced by axons isolated in the microchannels.

RESULTS

Individual axons exposed to local strains between 3.2% and 8.7% developed beading within 30-minutes of injury. At higher local strains of 9.8% and 12% individual axons ruptured within 30-minutes of injury. Axon bundles, or fascicles, were more resistant to rupture at each strain level, compared to individual axons. At lower local strain of 3.2%, axon bundles inside microchannels and neuronal cells near entrances of them progressively swelled and degenerated over a period of 7 days after injury.

COMPARISON WITH EXISTING METHOD(S)

This method is simple, reliable and reproducible with good control and measurement of injury tolerance and morphological deformations using standard laboratory equipment. By measuring local strains, we observed that axonal injuries occur at a lower strain magnitude and a lower strain rate than previous methods reporting global strains, which may not accurately reflect the true axonal strain.

CONCLUSIONS

We describe a novel stretchable microchannel-on-a-chip platform to study the effect of varying local strain on morphological characteristics of neuronal injury.

Injectable thermoresponsive gels offer sustained dual release of bupivacaine hydrochloride and ketorolac tromethamine for up to two weeks

Bupivacaine and ketorolac are commonly used in combination to reduce perioperative pain. This study aimed to develop and characterize an injectable system that offers simultaneous and prolonged release of bupivacaine and ketorolac. Formulations were prepared using poloxamer 407 with increasing concentrations of poloxamer 188 and sodium chloride. Small Angle X-ray Scattering (SAXS) experiments demonstrated that the poloxamers form gels with a cubic lattice arrangement regardless of the matrix composition, whereas the system porosity is driven by poloxamers concentration. Drug loading slightly reduced the intermicellar spacing. Fourier transform infrared spectroscopy and thermal analysis suggested electrostatic interactions between the loaded drugs and poloxamers. Mechanical and rheological studies confirmed the formulations exhibit Newtonian-like flow at room temperature followed by a transition to a viscous gel at body temperature. Importantly, the developed formulations demonstrated steady and sustained release of both bupivacaine and ketorolac over two weeks. Sodium chloride reduced the initial burst release over the first six hours for BH, from 8.6 ± 0.18% to 1.6 ± 0.11%, and KT, from 7.7 ± 0.27% to 1.5 ± 0.10%. Hence, poloxamer-based thermoresponsive gelling systems are promising delivery platforms for the sustained delivery of bupivacaine and ketorolac, with potential clinical benefits for managing perioperative pain.

Transcutaneous Electrical Stimulation for Neurogenic Bladder Dysfunction Following Spinal Cord Injury: Meta-Analysis of Randomized Controlled Trials

OBJECTIVES

To assess the efficacy of transcutaneous electrical nerve stimulation (TENS) for neurogenic bladder dysfunction secondary to spinal cord injury (SCI).

MATERIALS AND METHODS

A systematic search of MEDLINE, EMBASE, Web of Science, Scopus, and Cochrane libraries up to February 2021 was performed using PRISMA methodology. All randomized controlled trials (RCTs) that studied TENS for neurogenic bladder in a SCI population were included. The primary outcomes of interest were maximum cystometric capacity (MCC) and maximum detrusor pressure (Pdet). Meta-analysis was conducted with RevMan v5.3.

RESULTS

Six RCTs involving 353 participants were included. Meta-analysis showed that TENS significantly increased MCC (standardized mean difference 1.11, 95% confidence interval [CI] 0.08-2.14, p = 0.03, I²  = 54%) in acute SCI. No benefits were seen for maximum Pdet. TENS was associated with no major adverse events.

CONCLUSIONS

TENS may be an effective, safe intervention for neurogenic bladder dysfunction following SCI. Further studies are essential to confirm these results and more work is required to determine optimal stimulation parameters and duration of the treatment.

Zebularine suppressed gemcitabine-induced senescence and improved the cellular and plasma pharmacokinetics of gemcitabine, augmented by liposomal co-delivery

Chemoresistance is a major factor driving cancer recurrence. This study investigated the potential of zebularine, a dual cytidine deaminase (CDA)/epigenetic inhibitor, to circumvent gemcitabine-resistance in pancreatic cancer using a nanomedicine co-delivery approach. The mRNA expression of key metabolic enzymes, including CDA for gemcitabine deactivation in a gemcitabine-resistant cell line Gr2000 and its parental MIA PaCa-2 was compared using quantitative reverse transcription polymerase chain reaction. A highly gemcitabine-resistant population (HRP) in Gr2000 were characterised for their growth pattern, β-galactosidase activity (a hallmark of senescence) and chemosensitivity to zebularine after isolation. The CDA inhibition effects of zebularine on the intracellular gemcitabine accumulation and pharmacokinetics in rats when co-delivered with pH-sensitive liposomes (pSL) were investigated. Gr2000 had a 3-time upregulated mRNA expression and enzyme activity for CDA. The HRP (28% of bulk Gr2000) were predominately senescent cells which re-proliferated following a growth arrest for a week. Zebularine suppressed the regrowth of senescent cells, meanwhile enhanced cellular gemcitabine concentration by 2-fold. When co-delivered with pSL, zebularine increased cellular gemcitabine concentration by 4-fold, and extended the half-life of gemcitabine in plasma by 22-fold in rats. In conclusion, multiple mechanisms including therapy-induced senescence were identified with gemcitabine-resistance. Co-delivery of zebularine using liposomes could provide multifaceted benefits in gemcitabine therapy for pancreatic cancer treatment.

Ex vivo evaluation of the influence of pH on the ophthalmic safety, antibacterial efficacy and storage stability of povidone-iodine

CLINICAL RELEVANCE

The monitoring and controlling of pH is important when preparing solutions for ophthalmic administration. In the case of povidone-iodine, dilution in an appropriate buffer is needed to improve its ophthalmic safety.

BACKGROUND

Povidone-iodine is a broad-spectrum antiseptic agent that is commonly used in ophthalmic applications due to its cost-effectiveness and accessibility. However, native povidone-iodine has a pH of about 4.0 and is known to irritate the ocular surface. This study assessed whether adjusting povidone-iodine formulation pH would influence its ex vivo ophthalmic safety, alongside its impact on antibacterial efficacy and storage stability.

METHODS

One per cent w/v povidone-iodine was diluted in normal saline, or 0.1-mol/l citrate or phosphate buffers to yield solutions with a pH ranging from 4.0 to 7.0. Ocular irritancy was evaluated using the bovine cornea opacity and permeability assay. Antibacterial efficacy was assessed by evaluating povidone-iodine minimum inhibitory concentration and minimum bactericidal concentration at varied pH. Storage stability of the preparations was determined over 30-days at room temperature (20-25°C).

RESULTS

Combining povidone-iodine with phosphate buffer notably decreased ocular irritancy of the antiseptic. Surprisingly, combining povidone-iodine with citrate buffer potentiated irritant effects of the preparation. Antibacterial efficacy of povidone-iodine was reduced when formulation pH was increased from 4.0 to 7.0, although its general activity was retained. Finally, povidone-iodine remained stable in both normal saline and phosphate buffer over 30-days.

CONCLUSION

Ophthalmic application of povidone-iodine can be optimised by adjusting the pH of the formulation to 7.0 using phosphate buffer, reducing irritancy while maintaining adequate antibacterial efficacy and storage stability.

Externally triggered release of growth factors - A tissue regeneration approach

Tissue regeneration aims to achieve functional restoration following injury by creating an environment to enable the body to self-repair. Strategies for regeneration rely on the introduction of biomaterial scaffolding, cells and bioactive molecules into the body, at or near the injury site. Of these bioactive molecules, growth factors (GFs) play a pivotal role in directing regenerative pathways for many cell populations. However, the therapeutic use of GFs has been limited by the complexity of biological injury and repair, and the properties of the GFs themselves, including their short half-life, poor tissue penetration, and off-target side effects. Externally triggered delivery systems have the potential to facilitate the delivery of GFs into the target tissues with considerations of the timing, sequence, amount, and location of GF presentation. This review briefly discusses the challenges facing the therapeutic use of GFs, then, we discuss approaches to externally trigger GF release from delivery systems categorised by stimulation type; ultrasound, temperature, light, magnetic fields and electric fields. Overall, while the use of GFs for tissue regeneration is still in its infancy, externally controlled GF delivery technologies have the potential to achieve robust and effective solutions to present GFs to injured tissues. Future technological developments must occur in conjunction with a comprehensive understanding of the biology at the injury site to ensure translation of promising technologies into real world benefit.

Development of a Low Cost & Low Noise Amplification System For In Vitro Neuronal Recording through Microelectrode Arrays

In order to effectively record from electrically active cells through microelectrode arrays a low-noise amplification and data acquisition system is required. Although commercially available, these systems can be expensive and lack the freedom to customise hardware and software. In this work we present a low-cost (US$21 for the first channel + US$11 for each additional channel), low-noise amplifier coupled with an analog to digital converter from National Instruments. The amplifier was designed to (i) operate between 0 and 5 V utilising a DC battery power supply, (ii) operate within a bandwidth of 10 kHz, (iii) remove DC voltage created at the electrode/electrolyte interface with a high-pass cut-off frequency of 0.7 Hz and (iv) have a gain of 2000. Strategies to reduce environment electromagnetic interference at the amplifier front end were employed and involved a customised neural interface board connected between the microelectrode array and amplifier. The constructed amplifier achieved an intrinsic noise amplitude of 0.8 μV_rms, which facilitated high quality recordings as exemplified by in vitro recordings from primary hippocampal neurons.

Dual or multiple drug loaded nanoparticles to target breast cancer stem cells

Breast cancer stem(-like) cells (BCSCs) have been found to be responsible for therapeutic resistance and disease relapse. BCSCs are difficult to eradicate due to their high resistance to conventional treatments and high plasticity. Functionalised nanoparticles have been investigated as smart vehicles to transport across various barriers and increase the interaction of therapeutic agents with cancer cells, as well as BCSCs. In this review, we discuss the different characteristics of BCSCs, and challenges to tackle BCSCs at cellular and molecular levels. The mechanisms of action and physicochemical properties of the current BCSC targeting agents are also covered. We will focus on the rational design and recent advances of "Nano + Nano" or single tumour targeting nanoparticle systems loaded with dual or multiple agents to kill all cancer cells including BCSCs. These cocktail therapies include the combination of a chemotherapy agent with a BCSC-specific inhibitor, a phytochemical agent or RNA based therapy. Given the heterogeneity of breast tumour tissue, targeting both BCSCs and bulk breast cancer cells simultaneously with multiple agents holds great promise in eliminating breast cancer. The future research needs to focus on overcoming various barriers in the 'clinical translation' of BCSC-targeting nanomedicines to cure breast cancer, which requires a significant multidisciplinary effort.

Alcohol-free Extemporaneous Formulations of Furosemide Are Chemically and Physically Stable in Ora-Blend Products for 30 Days

Commercially available oral liquid formulations of furosemide contain ethanol. However, ethanol can lead to toxicity, particularly in neonates and young children. This study's objective was the development of ethanol-free furosemide suspensions and to determine whether suspending vehicles, temperature, and pH have an impact on the physical and chemical stability over a 30-day period. Formulations containing 2 mg/mL furosemide were prepared by crushing furosemide tablets and mixing with commercial vehicles Ora-Blend, Ora-Blend SF, or SyrSpend-SF Alka. As the stability of furosemide is reported to be pH-dependent, Ora-Blend and Ora-Blend SF were used both with and without pH adjustment. The resulting suspensions were stored at either 4oC or 25oC over 30 days with physical and chemical stability monitored. Negligible changes were noted in appearance over 30 days. The pH of all formulations remained relatively consistent throughout the study period. All formulations were chemically stable, as determined by high-performance liquid chromatography, retaining >90% of initial concentration over 30 days at 4oC and 25oC. Interestingly, suspensions remained chemically stable regardless of the pH of the vehicle, with the pH of the formulations ranging from 4.2 to 7.7. A simple extemporaneous compounding method was used to prepare alcohol-free furosemide suspensions that were stable for 30 days at 4oC and 25oC. These findings are important for patients who cannot tolerate, or wish to avoid, alcohol, including the pediatric population.

The Effect of Manufacturer on the Compounding of Omeprazole Suspensions and Their Stability Assessment

In New Zealand, there are no liquid formulations of omeprazole commercially available, therefore suspensions must be extemporaneously compounded from solid dosage forms for patients with swallowing difficulties. The funding for solid dosage forms of omeprazole changes frequently, often every one to two years, without consideration of the impact this may have when extemporaneously compounded liquid dosage forms are required. This study examined suspensions compounded from various solid dosage forms of omeprazole with the purpose of identifying suitable quality formulations and evaluating their chemical and physical stability. Six different solid dosage forms of omeprazole that are available in New Zealand, including capsules, tablets, and powder, were used to prepare 2-mg/mL suspensions in 8.4% w/v sodium bicarbonate solution. The suspensions were then assessed visually for quality and by quantifying sedimentation rate over 120 minutes. Two products, stored in amber bottles at either 4°C or 25°C, demonstrated acceptable quality over a 30-day period whilst monitoring physical and chemical stability on day 0, 7, 14, 20, and 30. Four of the formulated suspensions were deemed to be of poor quality due to either a lack of uniformity or rapid sedimentation, attributes that could lead to inaccurate dosing. Acceptable quality suspensions were prepared from Losec and Dr. Reddy's brands of omeprazole 20-mg capsules. For both brands, a change in color was observed after 20 days and 7 days when stored at 4°C and 25°C, respectively. Chemical stability was determined using a stability-indicating high-performance liquid chromatographic method, with >90% of the active remaining for 30 days when kept at 4°C, and 20 days when stored at 25°C. Not all brands are suitable for extemporaneously compounding omeprazole suspensions. Losec and Dr. Reddy's brands of capsules were suitable to prepare quality omeprazole suspensions. Omeprazole suspensions compounded from these products are stable for 20 days if stored at 4°C and protected from light.

Association between perioperative intraperitoneal local anaesthetic infusion and long-term survival and cancer recurrence after colectomy: follow-up analysis of a previous randomized controlled trial

BACKGROUND

High concentrations of local anaesthetic have an anti-proliferative effect on colonic cancer in vitro. Intraperitoneal local anaesthetic (IPLA) has shown analgesic benefit and improved recovery in the perioperative setting. The long-term effects of IPLA in colon cancer resection have not been examined. This study aims to review the survival and oncological outcomes of a previously conducted trial that compared perioperative IPLA with placebo.

METHODS

Sixty patients underwent colonic resection for benign and malignant disease as part of a double-blinded, randomized, placebo-controlled study between September 2008 and November 2009. The IPLA group received instillation of intraperitoneal ropivacaine before dissection followed by a 3-day infusion. The placebo group was treated identically but with 0.9% saline solution. A follow-up analysis was conducted to evaluate overall survival, disease-free survival and recurrence specifically for patients undergoing resection for stages I-III colon cancer. Kaplan-Meier analysis was performed, and the log-rank test was used to evaluate difference in survival between groups.

RESULTS

Thirty-seven of the 60 patients had stages I-III colon cancer and were included in this analysis. Nineteen patients were in the placebo group. There was no significant difference in overall survival or all-cause mortality. There was a higher incidence of cancer-specific mortality in the local anaesthetic group (P < 0.046).

CONCLUSION

It does not appear that IPLA is associated with a significant survival benefit in patients with colonic malignancy undergoing colectomy. Other studies are needed to analyse the long-term outcomes.

Formulation strategies to modulate drug release from poloxamer based in situ gelling systems

Introduction: Poloxamer based in situ gelling systems offer numerous advantages in drug delivery; however, their application as prolonged-release delivery platforms is limited mainly due to their weak mechanical properties and the interconnected aqueous network causing fast gel erosion and drug diffusion.Area covered: The focus of this review is to provide an insightful discussion on the formulation strategies that can be employed to sustain/prolong the drug release from poloxamer based in situ gelling systems. The review also outlines the formulation factors, influencing drug release from these systems.Expert opinion: The nature, composition, and concentration of poloxamers are the most critical factors in defining the rate of drug release from an in situ gelling matrix. Hydrophobic gel matrices have compact micellar arrangements resulting in slow diffusion and erosion. Depending on the intended clinical application, gel characteristics can be modulated, either by physical blending or by chemical crosslinking with additive materials, to slow release and improve residence time at the administration site. Incorporating drug-loaded particles into poloxamer gels sustains drug release by creating multiple rate-limiting release barriers. Chemical modification of poloxamers appears to be a promising strategy to obtain prolonged sustained release for parenteral application without compromising the rheological properties of the formulation.

A NAG-Guided Nano-Delivery System for Redox- and pH-Triggered Intracellularly Sequential Drug Release in Cancer Cells

Aim

Sequential treatment with paclitaxel (PTXL) and gemcitabine (GEM) is considered clinically beneficial for non-small-cell lung cancer. This study aimed to investigate the effectiveness of a nano-system capable of sequential release of PTXL and GEM within cancer cells.

Methods

PTXL-ss-poly(6-O-methacryloyl-d-galactopyranose)-GEM (PTXL-ss-PMAGP-GEM) was designed by conjugating PMAGP with PTXL via disulfide bonds (-ss-), while GEM via succinic anhydride (PTXL:GEM=1:3). An amphiphilic block copolymer N-acetyl-d-glucosamine(NAG)-poly(styrene-alt-maleic anhydride)₅₈-b-polystyrene₁₃₀ acted as a targeting moiety and emulsifier in formation of nanostructures (NLCs).

Results

The PTXL-ss-PMAGP-GEM/NAG NLCs (119.6 nm) provided a sequential in vitro release of, first PTXL (redox-triggered), then GEM (pH-triggered). The redox- and pH-sensitive NLCs readily distributed homogenously in the cytoplasm. NAG augmented the uptake of NLCs by the cancer cells and tumor accumulation. PTXL-ss-PMAGP-GEM/NAG NLCs exhibited synergistic cytotoxicity in vitro and strongest antitumor effects in tumor-bearing mice compared to NLCs lacking pH/redox sensitivities or free drug combination.

Conclusion

This study demonstrated the abilities of PTXL-ss-PMAGP-GEM/NAG NLCs to achieve synergistic antitumor effect by targeted intracellularly sequential drug release.