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Curcumin is widely used as a nutraceutical ingredient in food and beverage products. It has been reported that curcumin has a broad spectrum of biological activities such as anticancer, anti-inflammatory, antioxidant, and antibacterial effects. Despite the potent therapeutic effect of curcumin, its low aqueous solubility, stability, and oral bioavailability limits its effectiveness. In order to improve the physical and chemical properties of curcumin, we have formulated curcumin as a nanosuspension by using the emulsion templated freeze-drying technique. This approach produces a solid that can be dispersed as required to form a nanosuspension. The formulations were investigated in a screening process using various excipients, resulting in the identification of one curcumin nanosuspension sample which contained only polyethylene glycol (PEG) as the excipient. This formulation exhibited a small diameter (211 nm), low polydispersity (0.06) and zeta potential of −25 mV and was therefore chosen for further in vitro investigations. Various experimental parameters such as active agent and excipient concentrations, and sonication time were varied to tune the size and polydispersity of the chosen formulation. The resulting nanosuspension showed an improved chemical stability at pH values that mimic the gastrointestinal tract. An in vitro bioaccessibility experiment showed that the nanosuspension formulation resulted in more dissolution of the curcumin but this was also coupled with reduced stability. Cytotoxicity studies showed that the nanosuspension offered a reduced cytotoxicity profile compared to the solubilised curcumin on both cell lines investigated. This redispersible curcumin nanosuspension formulation may provide new opportunities for the oral dosing of curcumin.

Successful development of a chemoprophylaxis against SARS-CoV-2 could provide a tool for infection prevention implementable alongside vaccination programmes. Camostat and nafamostat are serine protease inhibitors that inhibit SARS-CoV-2 viral entry in vitro but have not been characterised for chemoprophylaxis in animal models. Clinically, nafamostat is limited to intravenous delivery and while camostat is orally available, both drugs have extremely short plasma half-lives. This study sought to determine whether intranasal dosing at 5 mg/kg twice daily was able to prevent airborne transmission of SARS-CoV-2 from infected to uninfected Syrian golden hamsters. SARS-CoV-2 viral RNA was above the limits of quantification in both saline- and camostat-treated hamsters 5 days after cohabitation with a SARS-CoV-2 inoculated hamster. However, intranasal nafamostat-treated hamsters remained RNA negative for the full 7 days of cohabitation. Changes in body weight over the course of the experiment were supportive of a lack of clinical symptomology in nafamostat-treated but not saline- or camostat-treated animals. These data are strongly supportive of the utility of intranasally delivered nafamostat for prevention of SARS-CoV-2 infection and further studies are underway to confirm absence of pulmonary infection and pathological changes.

Currently nitazoxanide is being assessed as a candidate therapeutic for SARS-CoV-2. Unlike many other candidates being investigated, tizoxanide (the active metabolite of nitazoxanide) plasma concentrations achieve antiviral levels after administration of the approved dose, although higher doses are expected to be needed to maintain these concentrations across the dosing interval in the majority of patients. Here an LC-MS/MS assay is described that has been validated in accordance with Food and Drug Administration (FDA) guidelines. Fundamental parameters have been evaluated, and these included accuracy, precision and sensitivity. The assay was validated for human plasma, mouse plasma and Dulbeccos Modified Eagles Medium (DMEM) containing varying concentrations of Foetal Bovine Serum (FBS). Matrix effects are a well-documented source of concern for chromatographic analysis, with the potential to impact various stages of the analytical process, including suppression or enhancement of ionisation. Therefore, a robustly validated LC-MS/MS analytical method is presented capable of quantifying tizoxanide in multiple matrices with minimal impact of matrix effects. The validated assay presented here was linear from 15.6ng/mL to 1000ng/mL. Accuracy and precision ranged between 102.2% and 113.5%, 100.1% and 105.4%, respectively. The presented assay here has applications in both pre-clinical and clinical research and may be used to facilitate further investigations into the application of nitazoxanide against SARS-CoV-2.

BackgroundSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been declared a global pandemic by the World Health Organisation and urgent treatment and prevention strategies are needed. Many clinical trials have been initiated with existing medications, but assessments of the expected plasma and lung exposures at the selected doses have not featured in the prioritisation process. Although no antiviral data is currently available for the major phenolic circulating metabolite of nitazoxanide (known as tizoxanide), the parent ester drug has been shown to exhibitin vitroactivity against SARS-CoV-2. Nitazoxanide is an anthelmintic drug and its metabolite tizoxanide has been described to have broad antiviral activity against influenza and other coronaviruses. The present study used physiologically-based pharmacokinetic (PBPK) modelling to inform optimal doses of nitazoxanide capable of maintaining plasma and lung tizoxanide exposures above the reported nitazoxanide 90% effective concentration (EC90) against SARS-CoV-2.MethodsA whole-body PBPK model was constructed for oral administration of nitazoxanide and validated against available tizoxanide pharmacokinetic data for healthy individuals receiving single doses between 500 mg – 4000 mg with and without food. Additional validation against multiple-dose pharmacokinetic data when given with food was conducted. The validated model was then used to predict alternative doses expected to maintain tizoxanide plasma and lung concentrations over the reported nitazoxanide EC90in >90% of the simulated population. Optimal design software PopDes was used to estimate an optimal sparse sampling strategy for future clinical trials.ResultsThe PBPK model was validated with AAFE values between 1.01 – 1.58 and a difference less than 2-fold between observed and simulated values for all the reported clinical doses. The model predicted optimal doses of 1200 mg QID, 1600 mg TID, 2900 mg BID in the fasted state and 700 mg QID, 900 mg TID and 1400 mg BID when given with food, to provide tizoxanide plasma and lung concentrations over the reportedin vitroEC90of nitazoxanide against SARS-CoV-2. For BID regimens an optimal sparse sampling strategy of 0.25, 1, 3 and 12h post dose was estimated.ConclusionThe PBPK model predicted that it was possible to achieve plasma and lung tizoxanide concentrations, using proven safe doses of nitazoxanide, that exceed the EC90for SARS-CoV-2. The PBPK model describing tizoxanide plasma pharmacokinetics after oral administration of nitazoxanide was successfully validated against clinical data. This dose prediction assumes that the tizoxanide metabolite has activity against SARS-CoV-2 similar to that reported for nitazoxanide, as has been reported for other viruses. The model and the reported dosing strategies provide a rational basis for the design (optimising plasma and lung exposures) of future clinical trials of nitazoxanide in the treatment or prevention of SARS-CoV-2 infection.

Enhancing the activity of existing antimicrobial agents may help to address the emergence of resistant bacteria. Nanoparticles of antimicrobial agents have previously been shown to provide potential activity enhancements and here we report a high-throughput nanoprecipitation approach to identify viable nanosuspensions of the antimicrobial compound triclosan. Through careful choice of the components of the nanoprecipitation, amorphous nanosuspensions were created, freeze-dried and redispersed in water with z-average diameters varying from 170–290 nm. Particle size was shown to be controlled by a series of factors including polymer/surfactant concentration and concentration of triclosan solution prior to nanoprecipitation. A ten-fold decrease (i.e. higher activity) in the Escherichia coli (E. coli) inhibitory concentration (IC50) of triclosan, compared to an aqueous control, was observed for nanoparticles prepared using Pluronic® F68 and the cationic surfactant Hyamine. This overall approach offers a rapid route for identifying viable nanosuspensions and enhancing the properties of commercially available biologically active compounds with poor water-solubility.

Suboptimal adherence to antiretroviral (ARV) therapy can lead to insufficient drug exposure leading to viral rebound and increased likelihood of resistance. This has driven the development of long-acting injectable (LAI) formulations which may mitigate some of these problems. Maraviroc (MVC) is an orally dosed CCR5 antagonist approved for use in patients infected with CCR5-trophic HIV-1. MVC prevents viral entry into host cells, is readily distributed to biologically relevant tissues and has an alternative resistance profile compared to more commonly used therapies. This makes a MVC LAI formulation particularly appealing for implementation in Pre-Exposure Prophylaxis (PrEP). A 70 wt% MVC-loaded nanodispersion stabilised with polyvinyl alcohol (PVA) and sodium 1,4-bis(2-ethylhexoxy)-1,4-dioxobutane-2-sulfonate (AOT) was prepared using emulsion-templated freeze-drying. In vitro release rate studies revealed over a 22% decrease in MVC release rate constant across a size selective membrane compared with an aqueous solution of MVC (

Human Immunodeficiency Virus (HIV) is a global health concern to which nanomedicine approaches provide opportunities to improve the bioavailability of existing drugs used to treat HIV. In this article, lipid polymer hybrid nanoparticles (LPHNs) were developed as a system to provide a combination drug delivery of two leading antiretroviral drugs; darunavir (DRV) and its pharmacokinetic enhancer ritonavir (RTV). The LPHNs were designed with a poly(D, l -lactide-co-glycolide) (PLGA) core, and soybean lecithin (SBL) and Brij 78 as the stabilizers. The LPHNs were prepared by modified nanoprecipitation and the effect of synthetic conditions on the particle properties was studied, which included the Z-average diameter and polydispersity index of LPHNs in water and phosphate buffered saline, and the morphology of the particles. This investigation aimed to prepare a formulation that could be stored in its dry and redispersible form, therefore avoiding the challenges associated with storage of dispersions. The optimum ratio of stabilizer to polymer core was established at 20% w/w, and Brij 78 was found to be crucial in providing colloidal stability in physiological solutions; the minimum amount of Brij 78 required to provide stability in phosphate buffered saline was 70% w/w of the total stabilizer mass. Viable formulations of LPHNs containing DRV and RTV in the clinically used 8:1 ratio were prepared containing 20% w/w DRV with respect to the PLGA mass. The use of cryoprotectant, polyethylene glycol, combined with freeze-drying yielded LPHNs with a Z-average diameter of 150 nm when the particles were re-dispersed in water. The oral absorption behavior was assessed using an in vitro triple culture model. Whilst the use of cryoprotectant and freeze-drying led to no improvement of the transcellular permeability compared to the unformulated drugs, the non-freeze-dried samples with the highest soybean lecithin led to increased transcellular permeability, revealing the potential of LPHNs for enhancing HIV treatment.

Oral drug administration remains the preferred approach for treatment of HIV in most patients. Maraviroc (MVC) is the first in class co-receptor antagonist, which blocks HIV entry into host cells. MVC has an oral bioavailability of approximately 33%, which is limited by poor permeability as well as affinity for CYP3A and several drug transporters. While once-daily doses are now the favoured option for HIV therapy, dose-limiting postural hypotension has been of theoretical concern when administering doses high enough to achieve this for MVC (particularly during coadministration of enzyme inhibitors). To overcome low bioavailability and modify the pharmacokinetic profile, a series of 70 wt% MVC solid drug nanoparticle (SDN) formulations (containing 30 wt% of various polymer/surfactant excipients) were generated using emulsion templated freeze-drying. The lead formulation contained PVA and AOT excipients (MVCSDNPVA/AOT), and was demonstrated to be fully water-dispersible to release drug nanoparticles with z-average diameter of 728 nm and polydispersity index of 0.3. In vitro and in vivo studies of MVCSDNPVA/AOT showed increased apparent permeability of MVC, compared to a conventional MVC preparation, with in vivo studies in rats showing a 2.5-fold increase in AUC (145.33 vs. 58.71 ng h ml−1). MVC tissue distribution was similar or slightly increased in tissues examined compared to the conventional MVC preparation, with the exception of the liver, spleen and kidneys, which showed statistically significant increases in MVC for MVCSDNPVA/AOT. These data support a novel oral format with the potential for dose reduction while maintaining therapeutic MVC exposure and potentially enabling a once-daily fixed dose combination product.