Sarah Gordon

In vitro and in vivo investigation of thermosensitive chitosan hydrogels containing silica nanoparticles for vaccine delivery.

In this work silica nanoparticles (SNP) containing the model antigen ovalbumin (OVA) were incorporated into a thermosensitive chitosan hydrogel, and the resulting formulation investigated for its potential to act as a particulate sustained release vaccine delivery system. OVA-loaded SNP and chitosan hydrogels containing OVA-loaded SNP were prepared and characterised in vitro, and examined for their ability to elicit OVA-specific immune responses in vivo. Optimised SNP were found to be approximately 300nm in size with a moderate level of heterogeneity, a highly negative zeta potential, and an entrapment efficiency of approximately 7%. A porous particulate structure was indicated both by electron microscopy and a rapid release of fluorescently-labelled OVA (FITC-OVA) from SNP. Following successful incorporation of SNP into chitosan hydrogels, the release of both soluble and SNP-associated antigen from gel systems was quantified. Approximately 16% of total protein was released in a particulate form over a 14-day period, while approximately 35% was released as soluble antigen. Gel-based systems containing SNP-associated or soluble antigen in the presence or absence of the adjuvant Quil A (QA) demonstrated an ability to stimulate both cell mediated and humoral immunity in vivo. Chitosan gels containing OVA-loaded SNP and the adjuvant QA showed a significantly greater ability to induce CD4(+) T cell proliferation than chitosan gel containing soluble OVA and QA, indicating the future promise for such a system.

Comparison of chitosan nanoparticles and chitosan hydrogels for vaccine delivery.

In this work the potential of chitosan nanoparticles (CNP) and thermosensitive chitosan hydrogels as particulate and sustained release vaccine delivery systems was investigated. CNP and chitosan hydrogels were prepared, loaded with the model protein antigen ovalbumin (OVA) and characterised. The immunostimulatory capacity of these vaccine delivery systems was assessed in‐vitro and in‐vivo. Particle sizing measurements and SEM images showed that optimised OVA‐loaded CNP had a size of approximately 200 nm, a polydispersity index < 0.2, and a positive zeta‐potential of approximately 18 mV. The amount of OVA adsorbed onto CNP was high with an adsorption efficacy of greater than 96%. Raman spectroscopy indicated conformational changes of OVA when adsorbed onto the surface of CNP. Uptake of the dispersions and immunological activation of murine dendritic cells in‐vitro could be demonstrated. Investigation of the release of fluorescently‐labelled OVA (FITC‐OVA) from CNP and chitosan hydrogels in‐vitro showed that approximately 50% of the total protein was released from CNP within a period of ten days; release of antigen from chitosan gel occurred in a more sustained manner, with < 10% of total protein being released after 10 days. The slow release from gel formulations may be explained by the strong interactions of the protein with chitosan. While OVA‐loaded CNP showed no significant immunogenicity, formulations of OVA in chitosan gel were able to stimulate both cell‐mediated and humoral immunity in‐vivo.

Preparation of an amorphous sodium furosemide salt improves solubility and dissolution rate and leads to a faster Tmax after oral dosing to rats.

Amorphous forms of furosemide sodium salt and furosemide free acid were prepared by spray drying. For the preparation of the amorphous free acid, methanol was utilised as the solvent, whereas the amorphous sodium salt was formed from a sodium hydroxide-containing aqueous solvent in equimolar amounts of NaOH and furosemide. Information about the structural differences between the two amorphous forms was obtained by Fourier Transform Infrared Spectroscopy (FTIR), and glass transition temperature (Tg) was determined using Differential Scanning Calorimetry (DSC). The stability and devitrification tendency of the two amorphous forms were investigated by X-ray Powder Diffraction (XRPD). The apparent solubility of the two amorphous forms and the crystalline free acid form of furosemide in various gastric and intestinal stimulated media was determined. Moreover, the dissolution characteristics of the two amorphous forms and of crystalline free acid were investigated. FTIR confirmed molecular differences between the amorphous free acid and salt. The amorphous salt showed a Tg of 101.2 °C, whereas the Tg for the amorphous free acid was found to be 61.8 °C. The amorphous free acid was physically stable for 4 days at 22 °C and 33% relative humidity (RH), while the amorphous salt exhibited physical stability for 291 days at the same storage conditions. When storing the amorphous forms at 40 °C and 75% RH both forms converted to crystalline forms after 2 days. The apparent solubility of the amorphous salt form was higher than that of both amorphous and crystalline free acid in all media studied. All three forms of furosemide exhibited a greater solubility in the presence of biorelevant media as compared to buffer, however, an overall trend for a further increase in solubility in relation to an increase in media surfactant concentration was not seen. The amorphous salt demonstrated an 8- and 20-fold higher intrinsic dissolution rate (IDR) when compared to amorphous and crystalline free acid, respectively. The promising properties of the amorphous salt in vitro were further evaluated in an in vivo study, where solid dosage forms of the amorphous salt, amorphous and crystalline free acid and a solution of furosemide were administered orally to rats. The amorphous salt exhibited a significantly faster Tmax compared to the solution and amorphous and crystalline free acid. Cmax for the solution was significantly higher compared to the three furosemide forms. No significant difference was found in AUC and absolute bioavailability for the solution, crystalline free acid and the two amorphous forms of furosemide. It can be concluded that the higher IDR and higher apparent solubility of the amorphous salt resulted in a faster Tmax compared to the amorphous and crystalline free acid.

Chitosan hydrogels containing liposomes and cubosomes as particulate sustained release vaccine delivery systems

Sustained release depot systems have been widely investigated for their potential to improve the efficacy of subunit vaccines and reduce the requirement for boosting. The present study aimed to further enhance the immunogenicity of a sustained release vaccine by combining a depot formulation with a particulate antigen delivery system. Sustained release of the model subunit antigen, ovalbumin (OVA), was observed in vivo from chitosan thermogel-based formulations containing cationic, nanosized liposomes loaded with OVA and the immunopotentiator, Quil A (QA). Such formulations demonstrated the ability to induce cluster of differentiation (CD)8+ and CD4+ T-cell proliferation and interferon (IFN)-γ production, as well as the production of OVA-specific antibody. However, gel-incorporated liposomes showed evidence of instability and similar in vivo immune responses to liposomes in gel formulations were induced by gel-based systems loaded with soluble OVA and QA. The immunogenicity of chitosan thermogels containing cubosomes, a more stable lipidic particulate system, was therefore examined. Similarly, all gel-based formulations produced comparable effector immune responses in experimental mice, irrespective of whether the antigen and immunopotentiator were present in gels within cubosomes or in a soluble form. This work demonstrates the potential for sustained release thermogelling systems and highlights the importance of matching the physicochemical and immunological properties of the particulate system to that of the depot.

Non-animal models of epithelial barriers (skin, intestine and lung) in research, industrial applications and regulatory toxicology

Models of the outer epithelia of the human body - namely the skin, the intestine and the lung - have found valid applications in both research and industrial settings as attractive alternatives to animal testing. A variety of approaches to model these barriers are currently employed in such fields, ranging from the utilization of ex vivo tissue to reconstructed in vitro models, and further to chip-based technologies, synthetic membrane systems and, of increasing current interest, in silico modeling approaches. An international group of experts in the field of epithelial barriers was convened from academia, industry and regulatory bodies to present both the current state of the art of non-animal models of the skin, intestinal and pulmonary barriers in their various fields of application, and to discuss research-based, industry-driven and regulatory-relevant future directions for both the development of new models and the refinement of existing test methods. Issues of model relevance and preference, validation and standardization, acceptance, and the need for simplicity versus complexity were focal themes of the discussions. The outcomes of workshop presentations and discussions, in relation to both current status and future directions in the utilization and development of epithelial barrier models, are presented by the attending experts in the current report.

Real-time dissolution behavior of furosemide in biorelevant media as determined by UV imaging

The potential of UV imaging as a new small scale flow-through dissolution testing platform and its ability to incorporate biorelevant media was tested. Furosemide was utilized as a model poorly soluble drug, and dissolution media simulating conditions in the small intestine (5/1.25 mM and 40/10 mM bile salt/phospholipid, pH 6.5) together with corresponding blank buffer were employed. Dissolution rates as a function of flow rate (0.2–1.0 mL/min) were determined directly from UV images, and by analysis of collected effluent using UV spectrophotometry. A good agreement in dissolution rates was observed, however repeatability of data based on measurement of collected effluent was superior to that obtained by UV imaging in the utilized prototypic flow cell. Both methods indicated that biorelevant media did not markedly increase the dissolution rate of furosemide as compared to buffer. Qualitatively, UV images indicated that uncontrolled swelling/precipitation of furosemide on the compact surface was occurring in some samples. In situ Raman spectroscopy together with X-ray diffraction analysis confirmed that the observations were not due to a solid form transformation of furosemide. The presented results highlight the complementary features of the utilized techniques and, in particular, the detailed information related to dissolution behavior which can be achieved by UV imaging.

Biorelevant characterisation of amorphous furosemide salt exhibits conversion to a furosemide hydrate during dissolution.

Biorelevant dissolution behaviour of the amorphous sodium salt and amorphous acid forms of furosemide was evaluated, together with investigations of the solid state changes during in vitro dissolution in medium simulating the conditions in the small intestine. UV imaging of the two amorphous forms, as well as of crystalline furosemide salt and acid showed a higher rate of dissolution of the salt forms in comparison with the two acid forms. The measured dissolution rates of the four furosemide forms from the UV imaging system and from eluted effluent samples were consistent with dissolution rates obtained from micro dissolution experiments. Partial least squares-discriminant analysis of Raman spectra of the amorphous acid form during flow through dissolution showed that the amorphous acid exhibited a fast conversion to the crystalline acid. Flow through dissolution coupled with Raman spectroscopy showed a conversion of the amorphous furosemide salt to a more stable polymorph. It was found by thermogravimetric analysis and hot stage microscopy that the salt forms of furosemide converted to a trihydrate during dissolution. It can be concluded that during biorelevant dissolution, the amorphous and crystalline furosemide salt converted to a trihydrate, whereas the amorphous acid exhibited fast conversion to the crystalline acid.

Recovery of evidence‐based practice

Consumer recovery is now enshrined in the national mental health policy of many countries. If this construct, which stems from the consumer/user/survivor movement, is truly to be the official and formal goal of mental health services, then it must be the yardstick against which evidence-based practice (EBP) is judged. From a consumer-recovery perspective, this paper re-examines aspects of services chosen for study, methodologies, outcomes measures, and standards of evidence associated with EBP, those previously having been identified as deficient and in need of expansion. One of the significant differences between previous investigations and the present study is that the work, writing, perspectives, and advocacy of the consumer movement has developed to such a degree that we now have a much more extensive body of material upon which to critique EBP and inform and support the expansion of EBP. Our examination reinforces previous findings and the ongoing need for expansion. The consumer recovery-focused direction, resources, frameworks, and approaches identified through the present paper should be used to expand the aspects of services chosen for study, methodologies, outcomes measures, and standards of evidence. This expansion will ultimately enable services to practice in a manner consistent with the key characteristics of supporting personal recovery.

Development of a Self-Assessed Consumer Recovery Outcome Measure: My Voice, My Life

We report the development of a self-assessed consumer recovery outcome measure by way of a consumer led and focused iterative process, informed by exploratory and confirmatory factor analysis. The process began with a deliberately over-inclusive preliminary measure of 127 items, based on 12 presumptive domains derived from the recovery literature and consumer consultation, being piloted with over 500 mental health consumers. The full 504 participant data set was randomly split into two discrete sets of 300 and 204 to provide one for the initial exploratory factor analysis and another (of independence) for the subsequent confirmatory factor analysis and reliability estimation. Analyses identified and confirmed (using the separate data sets) a robust factor structure, with 11 distinct and relatively independent factors (relationships; day-to-day life; culture; physical health; quality of life; mental health; recovery; hope and empowerment; spirituality; resources; and satisfaction with services) underlying one substantial principal construct (that we refer to as consumer recovery). The measure was refined to 65 items, between three and ten items for each of the 11 domains, the reliabilities for which are uniformly high.

Core dimensions of recovery: a psychometric analysis.

Core recovery dimensions lie between the large general factor of recovery and its underlying components. Identifying these could enhance recovery frameworks, practice and research. In contrast to existing conceptually based taxonomies, we sought to empirically identify the core dimensions of recovery through further psychometric analysis of a robust eleven factor (sub-scale) consumer recovery outcome measure, My Voice, My Life. We subjected the sub-scale scores of 504 consumers to further principal components analyses, beginning with a single unrotated factor and progressing through two to nine factors with varimax rotation. We found the five-factor solution to provide an orderly intermediate configuration with the eleven recovery factors having either aligned and/or disengaged through the process to result in the following core dimensions: (1) Belonging and relating (encompassing the individual factors of spirituality, culture, and relationships); (2) Being and doing (encompassing the individual factors of physical health, day-to-day life, and quality of life); (3) Thinking and feeling (encompassing the individual factors of recovery, mental health, and hope and empowerment); (4) Resources (which maintained its independence); and (5) Satisfaction with Services (which also maintained its independence). We compare this empirical configuration with conceptually based taxonomies.