Rheological properties of cellulosic thickeners in hydro-alcoholic media: The science behind the formulation of hand sanitizer gels.

Cellulosic-based thickeners are commonly used in the preparation of hydro-alcoholic hand sanitisers. Yet, little is known about the behaviour of these polymeric dispersions in hydro-alcoholic mixtures. Here, we studied the dispersion ability and rheology of hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methylcellulose and sodium carboxymethyl cellulose in water-ethanol mixtures. Hydroxypropyl cellulose formed transparent dispersions across the entire range of ethanol concentrations, while a critical ethanol concentration (CEC), above which dispersions became turbid, was found for all the other polymers. At and below the CEC, all the rheological parameters followed a bell-like shape profile as a function of ethanol concentration. Moreover, the molecular weight and degree of substitution of the polymers influenced the rheological properties. The CEC and rheological behaviour of the dispersions were both dependent on the ethanol/polymer and water/polymer interactions. As hand disinfectants should contain 60-95% ethanol, polymers of higher CEC, such as hydroxypropyl cellulose and hydroxypropyl methylcellulose, are recommended.

Permeability-enhancing effects of three laurate-disaccharide monoesters across isolated rat intestinal mucosae.

Laurate (C12)-sucrose esters are established intestinal epithelial permeation enhancers (PEs) with potential for use in oral delivery. Most studies have examined blends of ester rather than specific monoesters, with little variation on the sugar moiety. To investigate the influence of varying the sugar moiety on monoester performance, we compared three monoesters: C12-sucrose, C12-lactose, and C12-trehalose. The assays were: critical micellar concentration (CMC) in Krebs-Henseleit buffer, MTS and lactate dehydrogenase assays in Caco-2 cells, transepithelial electrical resistance (TEER) and apparent permeability coefficient (Papp) of [14C] mannitol across isolated rat intestinal mucosae, and tissue histology. For CMC, the rank order was C12-trehalose (0.21 mM) < C12-sucrose (0.34 mM) < C12-lactose (0.43 mM). Exposure to Caco-2 cells for 120 min produced TC50 values in the MTS assay from 0.1 to 0.4 mM. Each ester produced a concentration-dependent decrease in TEER across rat mucosae with 80% reduction seen with 8 mM in 5 min, but C12-trehalose was less potent. C12-sucrose and C12-lactose increased the Papp of [14C] mannitol across mucosae with similar potency and efficacy, whereas C12-trehalose was not as potent or efficacious, even though it still increased flux. In the presence of the three esters, gross intestinal histology was unaffected except at 8 mM for C12-sucrose and C12-lactose. In conclusion, the three esters enhanced permeability likely via tight junction modulation in rat intestinal tissue. C12-trehalose was not quite as efficacious, but neither did it damage tissue to the same extent. All three can be considered as potential PEs to be included in oral formulations.

Amyloid Self-Assembly of Lysozyme in Self-Crowded Conditions: The Formation of a Protein Oligomer Hydrogel.

A method is designed to quickly form protein hydrogels, based on the self-assembly of highly concentrated lysozyme solutions in acidic conditions. Their properties can be easily modulated by selecting the curing temperature. Molecular insights on the gelation pathway, derived by in situ FTIR spectroscopy, are related to calorimetric and rheological results, providing a consistent picture on structure-property correlations. In these self-crowded samples, the thermal unfolding induces the rapid formation of amyloid aggregates, leading to temperature-dependent quasi-stationary levels of antiparallel cross ß-sheet links, attributed to kinetically trapped oligomers. Upon subsequent cooling, thermoreversible hydrogels develop by the formation of interoligomer contacts. Through heating/cooling cycles, the starting solutions can be largely recovered back, due to oligomer-to-monomer dissociation and refolding. Overall, transparent protein hydrogels can be easily formed in self-crowding conditions and their properties explained, considering the formation of interconnected amyloid oligomers. This type of biomaterial might be relevant in different fields, along with analogous systems of a fibrillar nature more commonly considered.

Advancing the understanding of the tablet disintegration phenomenon - An update on recent studies.

Disintegration is the de-aggregation of particles within tablets upon exposure to aqueous fluids. Being an essential step in the bioavailability cascade, disintegration is a fundamental quality attribute of immediate release tablets. Although the disintegration phenomenon has been studied for over six decades, some gaps of knowledge and research questions still exist. Three reviews, published in 2015, 2016 and 2017, have discussed the literature relative to tablet disintegration and summarised the understanding of this topic. Yet, since then more studies have been published, adding to the established body of knowledge. This article guides a step forward towards the comprehension of disintegration by reviewing, concisely, the most recent scientific updates on this topic. Initially, we revisit the mechanisms of disintegration with relation to the three most used superdisintegrants, namely sodium starch glycolate, croscarmellose sodium and crospovidone. Then, the influence of formulation, storage, manufacturing and media conditions on disintegration is analysed. This is followed by an excursus on novel disintegrants. Finally, we highlight unanswered research questions and envision future research venues in the field.

Hand sanitisers amid CoViD-19: A critical review of alcohol-based products on the market and formulation approaches to respond to increasing demand.

The world is facing a medical crisis amid the CoViD-19 pandemic and the role of adequate hygiene and hand sanitisers is inevitable in controlling the spread of infection in public places and healthcare institutions. There has been a great surge in demand for hand sanitisation products leading to shortages in their supply. A consequent increase of substandard products in the market has raised safety concerns. This article, therefore, presents a critical review of hand sanitation approaches and products available on the market in light of the scientific evidence available to date. This review also provides a range of hand sanitisation product formulations, and manufacturing instructions to allow for extemporaneous preparations at the community and hospital pharmacies during this urgent crisis. In addition, this emergent situation is expected to continue, hence hand sanitisers will be in demand for an extended time, and the availability and purchase of substandard products on the market create an ongoing safety concern. Therefore, this article shall also provide various commercial organisations, interested in stepping forward the production and marketing of hand sanitisers, with a guide on the development of products of standardised ingredients and formulations.

Recent Progress in Histone Deacetylase Inhibitors as Anticancer Agents.

Histone Deacetylase (HDAC) inhibitors are a relatively new class of anti-cancer agents that play important roles in epigenetic or non-epigenetic regulation, inducing death, apoptosis, and cell cycle arrest in cancer cells. Recently, their use has been clinically validated in cancer patients resulting in the approval by the FDA of four HDAC inhibitors, vorinostat, romidepsin, belinostat and panobinostat, used for the treatment of cutaneous/peripheral T-cell lymphoma and multiple myeloma. Many more HDAC inhibitors are at different stages of clinical development for the treatment of hematological malignancies as well as solid tumors. Also, clinical trials of several HDAC inhibitors for use as anti-cancer drugs (alone or in combination with other anti-cancer therapeutics) are ongoing. In the intensifying efforts to discover new, hopefully, more therapeutically efficacious HDAC inhibitors, molecular modelingbased rational drug design has played an important role. In this review, we summarize four major structural classes of HDAC inhibitors (hydroxamic acid derivatives, aminobenzamide, cyclic peptide and short-chain fatty acids) that are in clinical trials and different computer modeling tools available for their structural modifications as a guide to discover additional HDAC inhibitors with greater therapeutic utility.

Chitosan Loaded into a Hydrogel Delivery System as a Strategy to Treat Vaginal Co-Infection.

Polymeric hydrogels are common dosage forms designed for the topical administration of antimicrobial drugs to treat vaginal infections. One of the major advantages of using chitosan in these formulations is related to the intrinsic and broad antimicrobial activity exerted on bacteria and fungi by this natural polymer. Most vaginal yeast infections are caused by the pathogenic fungus Candida albicans. However, despite the anti-Candida activity towards and strains susceptibility to low molecular weight chitosan being documented, no information is available regarding the antimicrobial efficacy of mixed hydrogels in which chitosan is dispersed in a polymeric matrix. Therefore, the aim of the study is to evaluate the anti-Candida activity against eight different albicans and non-albicans strains of a mixed hydroxypropyl methylcellulose (HPMC)/chitosan hydrogel. Importantly, chitosan was dispersed in HPMC matrix either assembled in nanoparticles or in a monomolecular state to eventually correlate any variation in terms of rheological and mucoadhesive properties, as well as anti-Candida activity, with the chitosan form. Hydrogels containing 1% w/w chitosan, either as free polymer chain or assembled in nanoparticles, showed an improved mucoadhesiveness and an anti-Candida effect against all tested albicans and non-albicans strains. Overall, the results demonstrate the feasibility of preparing HPMC/CS mixed hydrogels intended for the prevention and treatment of Candida infections after vaginal administration.

Aggregation of zein in aqueous ethanol dispersions: Effect on cast film properties.

In this study, we evaluate the influence of zein aggregation in aqueous ethanol dispersions on the properties of zein films. The effects of zein concentration, ethanol content and temperature on transmittance of zein dispersions were investigated. Dynamic light scattering was used to measure the degree of zein aggregation in the dispersions. The results indicate that particle size of zein increased with higher zein concentration, lower ethanol level and at lower temperatures. Zein films were prepared by casting from 70% and 90% aqueous ethanol dispersions at different drying temperatures and were evaluated for appearance, thermomechanical and mechanical properties. Higher ethanol levels and higher drying temperatures promoted the formation of more homogenous films. Films made from higher ethanol dispersions had lower glass transition temperatures than those made from lower ethanol dispersions. Moreover, the fragility factor classified the films as strong systems. Mechanical properties of films were measured at different drying temperatures. Stiffer and more resistant films were developed as the drying temperature increased. In conclusion, film properties can be tailored by controlling the composition of the film casting solvent and the drying temperature. Differences in film properties were found to relate to differences in initial degree of aggregation of zein dispersions.

Heating treatments affect the thermal behaviour of doxorubicin loaded in PEGylated liposomes.

Doxil® is a stealth marketed PEGylated liposomal formulation, containing the anticancer drug doxorubicin. After loading via a pH gradient, fibrillar supramolecular structures of doxorubicin sulfate originates inside the core of the liposomes. Recently, the crystallinity of doxorubicin sulfate has been confirmed by high-resolution calorimetry. However, no detailed information are available on the nature of doxorubicin sulfate nanocrystals and on the effect of different thermal treatments. Thus, the aim of this work was to characterize the thermal behaviour of Doxil® in comparison to the unloaded liposomes using microcalorimetry, dynamic light scattering and high-resolution ultrasound spectroscopy (HR-US). Different thermal programmes were applied with the aim to highlight the effect of the treatments on the formulation. The used techniques confirmed the ordered state of doxorubicin nanocrystals inside PEGylated liposomes. Particularly, microcalorimetry and HR-US highlighted the changes in the thermal behaviour of the drug under different heating programmes. Doxorubicin nanocrystals were found to be stable after heating up to 80°C, but an irreversible thermal behaviour was observed after a prolonged heating at elevated temperature (2h at 80°C). The non-reversibility could be related to the formation of a different ordered structure and enhanced by the slight leakage of the drug occurring after a prolonged heating.

Water-in-Oil Microemulsions for Protein Delivery: Loading Optimization and Stability.

BACKGROUND: Microemulsions are attractive delivery systems for therapeutic proteins and peptides due to their ability to enhance bioavailability. Although different proteins and peptides have been successfully delivered through such ternary systems, no information can be found about protein loading and the formulation stability when such microemulsions are prepared with pharmaceuticallyapproved oils and surfactants. The aim of this work was to optimise a ternary system consisting of water/ ethyl oleate/Span® 80-Tween® 80 and to determine its protein loading capacity and stability, using bovine serum albumin (BSA) as a model of biomolecule. METHODS: The optimization was carried out using a Central Composite Design and all the prepared formulations were characterised through dynamic light scattering, rheology, optical and polarized microscopy. Subsequently, the maximum loading capacity was determined and the stability of the final microemulsion with the highest content of protein was followed over six months. To investigate the structural features of the protein, BSA was recovered from the microemulsion and analysed through fluorescence spectroscopy. RESULTS: After incorporation of the protein in the microemulsion, a decrease of its aqueous solubility was observed. However, the formulation remained stable over six months and the native-like state of the recovered protein was demonstrated by fluorescence spectroscopy Conclusion: This study demonstrated the feasibility of preparing microemulsions with the highest content of protein and their long-term stability.

Influence of Testing Parameters on In Vitro Tramadol Release from Poloxamer Thermogels using the Immersion Cell Method.

The immersion cell is an in vitro performance test of drug release from semisolids. Several studies made use of immersion cells to investigate drug release from thermosensitive Poloxamer-based gels; however, specifications on the parameter setting are not yet available. Therefore, the aim of this study was to evaluate the influence of testing parameters on tramadol (a model drug) release, release rate, and dissolution efficiency (DE) from Poloxamer gels, using immersion cells. The thermosensitive gelling formulation showed batch-to-batch uniformity of gelling behavior, drug content, and drug release. The use of a membrane in the immersion cell resulted in slower drug release as compared to the absence of a membrane. Moreover, the faster the paddle rotation, the faster the drug release was. Membrane thickness showed a strong and significant linear relationship with corresponding DE values (Pearson's correlation coefficient, r = -0.9470; p = 0.004). Factors that did not influence drug release include paddle position, i.e., distance between paddle and membrane, as well as membrane mean pore size. This study sets forth the importance of carefully controlling the following parameters including presence/absence of membrane, paddle rotation speed, and membrane thickness during the setup of release experiments from gels using immersion cells.

Characterization of biosurfactants produced by Lactobacillus spp. and their activity against oral streptococci biofilm.

Lactic acid bacteria (LAB) can interfere with pathogens through different mechanisms; one is the production of biosurfactants, a group of surface-active molecules, which inhibit the growth of potential pathogens. In the present study, biosurfactants produced by Lactobacillus reuteri DSM 17938, Lactobacillus acidophilus DDS-1, Lactobacillus rhamnosus ATCC 53103, and Lactobacillus paracasei B21060 were dialyzed (1 and 6 kDa) and characterized in term of reduction of surface tension and emulsifying activity. Then, aliquots of the different dialyzed biosurfactants were added to Streptococcus mutans ATCC 25175 and Streptococcus oralis ATCC 9811 in the culture medium during the formation of biofilm on titanium surface and the efficacy was determined by agar plate count, biomass analyses, and flow cytometry. Dialyzed biosurfactants showed abilities to reduce surface tension and to emulsifying paraffin oil. Moreover, they significantly inhibited the adhesion and biofilm formation on titanium surface of S. mutans and S. oralis in a dose-dependent way, as demonstrated by the remarkable decrease of cfu/ml values and biomass production. The antimicrobial properties observed for dialyzed biosurfactants produced by the tested lactobacilli opens future prospects for their use against microorganisms responsible of oral diseases.

Acoustic spectroscopy: A powerful analytical method for the pharmaceutical field?

Acoustics is one of the emerging technologies developed to minimize processing, maximize quality and ensure the safety of pharmaceutical, food and chemical products. The operating principle of acoustic spectroscopy is the measurement of the ultrasound pulse intensity and phase after its propagation through a sample. The main goal of this technique is to characterise concentrated colloidal dispersions without dilution, in such a way as to be able to analyse non-transparent and even highly structured systems. This review presents the state of the art of ultrasound-based techniques in pharmaceutical pre-formulation and formulation steps, showing their potential, applicability and limits. It reports in a simplified version the theory behind acoustic spectroscopy, describes the most common equipment on the market, and finally overviews different studies performed on systems and materials used in the pharmaceutical or related fields.

Could albumin affect the self-assembling properties of a block co-polymer system and drug release? An in-vitro study.

PURPOSE: This work investigated the influence of a model protein, bovine serum albumin (BSA), on the properties of a thermogelling formulation intended for administration inside body compartments where there is high albumin content, as in the case of inflamed joints; it also explored the relation between the variation of these properties and release performance of methotrexate (MTX), a drug used to treat forms of arthritis and rheumatic conditions. METHODS: The influence of BSA on the micellisation and gelation behaviour of Poloxamer 407, chosen as a model copolymer, was studied by differential scanning calorimetry (microDSC), dynamic light scattering (DLS), fluorescence spectroscopy and rheology studies. A release study of MTX loaded inside the hydrogel in presence and in absence of BSA was performed. RESULTS: DLS and microDSC data revealed that the micellisation process was not affected by the protein, as demonstrated by unaltered micellar size and thermodynamic parameters. While the presence of BSA in the copolymer system reduced gel consistency, the hydrogel release performance was only slightly affected. CONCLUSION: Our results suggested that the kinetics of MTX release mainly depended on the presence of the thermogelling copolymer, although other mechanisms related to BSA could be involved. Finally, the study assessed the feasibility of using a thermogelling hydrogel for in situ drug administration in areas with the presence of high protein concentrations.

Use of in-die powder densification parameters in the implementation of process analytical technologies for tablet production on industrial scale.

The use of process analytical technologies (PAT) to ensure final product quality is by now a well established practice in pharmaceutical industry. To date, most of the efforts in this field have focused on development of analytical methods using spectroscopic techniques (i.e., NIR, Raman, etc.). This work evaluated the possibility of using the parameters derived from the processing of in-line raw compaction data (the forces and displacement of the punches) as a PAT tool for controlling the tableting process. To reach this goal, two commercially available formulations were used, changing the quantitative composition and compressing them on a fully instrumented rotary pressing machine. The Heckel yield pressure and the compaction energies, together with the tablets hardness and compaction pressure, were selected and evaluated as discriminating parameters in all the prepared formulations. The apparent yield pressure, as shown in the obtained results, has the necessary sensitivity to be effectively included in a PAT strategy to monitor the tableting process. Additional investigations were performed to understand the criticalities and the mechanisms beyond this performing parameter and the associated implications. Specifically, it was discovered that the efficiency of the apparent yield pressure depends on the nominal drug title, the drug densification mechanism and the error in pycnometric density. In this study, the potential of using some parameters derived from the compaction raw data has been demonstrated to be an attractive alternative and complementary method to the well established spectroscopic techniques to monitor and control the tableting process. The compaction data monitoring method is also easy to set up and very cost effective.

Quantification, microbial contamination, physico-chemical stability of repackaged bevacizumab stored under different conditions.

In this work, the stability of Bevacizumab (Avastin(®)) repackaged in individual 1 mL single-use syringes and stored at different conditions was assessed. Bevacizumab repackaged in single-use syringes results from the off-label use of the drug as an intravitreal agent in the treatment of retinal diseases. Bevacizumab stability was assessed by assaying the anti-VEGF activity using an indirect ELISA method and a Dynamic Light Scattering study. The thermal stability of the drug was also studied by calorimetric analysis, aimed to evaluate thermodynamic parameters associated to the thermal unfolding process. Furthermore, microbiological and fungal tests on the Bevacizumab syringes were performed. As a result, a significant decrease of the anti-VEGF activity was detected when syringes were exposed to UV light at a temperature of 37°C. Under these conditions, the Dynamic Light Scattering study showed an increase of the average size of Bevacizumab; probably due to aggregation. In conclusion, Bevacizumab stability, when stored under different conditions, was assessed considering three different aspects: anti-VEGF activity, microbial contamination and physico-chemical properties. Bevacizumab was found to be stable, under sterile conditions, for 3 months at 4°C and for 7 days at room temperature, exposed to indirect light sources, while a brief exposure of the drug to direct UV radiation proved detrimental to drug stability.