Pluronic F127-modified liposome-containing tacrolimus-cyclodextrin inclusion complexes:improved solubility, cellular uptake and intestinal penetration

Objective The aim of this study was to investigate Pluronic F127-modified liposome-containing cyclodextrin (CD) inclusion complex (FLIC) for improving the solubility, cellular uptake and intestinal penetration of tacrolimus (FK 506) in the gastrointestinal (GI) tract. Methods Molecular modelling was performed to screen the optimal CD for the solubilization of FK 506. FLIC was prepared by thin-lipid film hydration with the inclusion complex solutions followed by membrane extrusion. Dilution tests were conducted in simulated gastric fluids and phosphate-buffered solution of sodium taurocholate to investigate the solubility improvement of FK506. The cellular uptake of nanocarriers was studied in Caco-2 cells, and intestinal mucous membrane penetration in the GI tract was evaluated in Sprague-Dawley rats. Key findings The results showed that β-CD had the strongest binding energy with the guest molecule among the CDs. The prepared FLIC has an average diameter of 180.8 ± 8.1 nm with a spherical shape. The solubility and cellular uptake of FK 506 was greatly improved by the incorporation of CD complexes in the Pluronic F127-modified liposomes. Intestinal mucous membrane penetration was also significantly improved by the preparation of FLIC. Conclusion With improved drug solubility and intestinal mucous membrane penetration, FLIC shows a promising oral delivery system for FK 506. © 2013 Royal Pharmaceutical Society.

Excipients in medicines for children:scientific and regulatory paradigms

There is an ongoing debate over the use of pharmaceutical excipients in medicines for children, triggered by the increased number of formulations suitable for this target patient population. Pharmaceutical excipients can be regarded as essential / necessary enablers in formulation development. These are materials other than the 'active pharmaceutical ingredient' which are added to the formulation to achieve a specific function1. This may include aiding in the processing or manufacture of the drug delivery system such as lubricants or flow aids, controlling the release of the active ingredient to achieve modified release, enhance patient acceptability by improving taste of medicines or to develop easily swallowed dosage forms.

Dosage form preference consultation study in children and young adults:paving the way for patient-centred and patient-informed dosage form development

Objectives: The current study aims to evaluate dosage form preferences in children and young adults together with identifying the key pragmatic dosage form characteristics that would enable appropriate formulation of orally disintegrating tablets (ODTs). Methods: International, multisite, cross-sectional questionnaire of children and young adults aged from 6 to 18 years. Eligibility was based on age, ability to communicate and previous experience in taking medications. The study was carried out at three locations: the UK, Saudi Arabia and Jordan. The questionnaire instrument was designed for participant self-completion under supervision of the study team.Results 104 questionnaires were completed by the study cohort (n=120, response rate 87%). Results: showed that ODTs were the most preferred oral dosage forms (58%) followed by liquids (20%), tablets (12%) and capsules (11%). The preferred colours were pink or white while the preferred size was small (<8 mm) with a round shape. With regard to flavour, strawberry was the most preferred (30.8%), while orange was the least preferred (5.8%). The results also showed that the most important physical characteristics of ODTs were disintegration time followed by taste, size and flavour, respectively. Conclusions: The results of our study support the WHO's claim for a shift of paradigm from liquid towards ODTs dosage forms for drug administration to young children older than 6 years. Data from this study will also equip formulators to prioritise development of key physical/performance attributes within the delivery system.

Development of a novel in vitro system for nasal drug delivery development

There is currently, no ideal system for studying nasal drug delivery in vitro. The existing techniques such as the Ussing chamber and cell culture all have major disadvantages. Most importantly, none of the existing techniques accurately represent the interior of the nasal cavity, with its airflow and humidity; neither do they allow the investigation of solid dosage forms.The work in this thesis represents the development of an in vitro model system in which the interior characteristics of the nasal cavity are closely represented, and solid or minimal volume dosage forms can be investigated. The complete nasal chamber consists of two sections: a lower tissue, viability chamber and an upper nasal chamber. The lower tissue viability chamber has been shown, using existing tissue viability monitoring techniques, to maintain the viability of a number of epithelial tissues, including porcine and rabbit nasal tissue, and rat ileal and Payers' patch tissue. The complete chamber including the upper nasal chamber has been shown to provide tissue viability for porcine and rabbit nasal tissue above that available using the existing Ussing chamber techniques. Adaptation of the complete system, and the development of the necessary experimental protocols that allow aerosol particle-sizing, together with videography, has shown that the new factors investigated, humidity and airflow, have a measurable effect on the delivered dose from a typical nasal pump. Similarly, adaptation of the chamber to fit under a confocal microscope, and the development of the necessary protocols has shown the effect of surface and size on the penetration of microparticulate materials into nasal epithelial tissues. The system developed in this thesis has been shown to be flexible, in allowing the development of the confocal and particle-sizing systems. For future nasal drug delivery studies, the ability to measure such factors as the size of the delivered system in the nasal cavity, the depth of penetration of the formulation into the tissue are essential. Additionally, to have access to other data such as that obtained from drug transport in the same system, and to have the tissue available for histological examination represents a significant advance in the usefulness of such an in vitro technique for nasal delivery.

Liposomal vaccine delivery systems

INTRODUCTION: Liposomes remain at the forefront of drug and vaccine design owing to their well-documented abilities to act as delivery vehicles. Nevertheless, the concept of liposomes as delivery vehicles is not a new one, with most works focusing on their use for the delivery of genes and drugs. However, in the last 10 years a significant amount of research has focused on using liposomes as vaccine adjuvants, not only as an antigen delivery vehicle but also as a tool to increase the immunogenicity of peptide and protein antigens. AREAS COVERED: This paper reviews liposomal adjuvants now in vaccine development, with particular emphasis on their adjuvant mechanism and how specific physicochemical characteristics of liposomes affect the immune response. The inclusion of immunomodulators is also discussed, with prominence given to Toll-like receptor ligands. EXPERT OPINION: The use of liposomes as vaccine delivery systems is evolving rapidly owing to the combined increase in technological advances and understanding of the immune system. Liposomes that contain and deliver immunostimulators and antigens are now being developed to target diseases that require stimulation of both humoral and cell-mediated immune responses. The CAF liposomal system, described in detail in this review, is one liposomal model that shows such flexibility.

Strategies and therapeutic opportunities for the delivery of drugs to the esophagus

Targeting of drugs and therapies locally to the esophagus is an important objective in the development of new and more effective dosage forms. Therapies that are retained within the oral cavity for both local and systemic action have been utilized for many years, although delivery to the esophagus has been far less reported. Esophageal disease states, including infections, motility disorders, gastric reflux, and cancers, would all benefit from localized drug delivery. Therefore, research in this area provides significant opportunities. The key limitation to effective drug delivery within the esophagus is sufficient retention at this site coupled with activity profiles to correspond with these retention times; therefore, a suitable formulation needs to provide the drug in a ready-to-work form at the site of action during the rapid transit through this organ. A successfully designed esophageal-targeted system can overcome these obstacles. This review presents a range of dosage form approaches for targeting the esophagus, including bioadhesive liquids and orally retained lozenges, chewing gums, gels, and films, as well as endoscopically delivered therapeutics. The techniques used to measure efficacy both in vitro and in vivo are also discussed. Drug delivery is a growing driver within the pharmaceutical industry and offers benefits both in terms of clinical efficacy, as well as in market positioning, as a means of extending a drug's exclusivity and profitability. Emerging systems that can be used to target the esophagus are reported within this review, as well as the potential of alternative formulations that offer benefits in this exciting area.

Using system dynamics in a discrete-event simulation study of a manufacturing plant

Purpose - To provide an example of the use of system dynamics within the context of a discrete-event simulation study. Design/methodology/approach - A discrete-event simulation study of a production-planning facility in a gas cylinder-manufacturing plant is presented. The case study evidence incorporates questionnaire responses from sales managers involved in the order-scheduling process. Findings - As the project progressed it became clear that, although the discrete-event simulation would meet the objectives of the study in a technical sense, the organizational problem of "delivery performance" would not be solved by the discrete-event simulation study alone. The case shows how the qualitative outcomes of the discrete-event simulation study led to an analysis using the system dynamics technique. The system dynamics technique was able to model the decision-makers in the sales and production process and provide a deeper understanding of the performance of the system. Research limitations/implications - The case study describes a traditional discrete-event simulation study which incorporated an unplanned investigation using system dynamics. Further, case studies using a planned approach to showing consideration of organizational issues in discrete-event simulation studies are required. Then the role of both qualitative data in a discrete-event simulation study and the use of supplementary tools which incorporate organizational aspects may help generate a methodology for discrete-event simulation that incorporates human aspects and so improve its relevance for decision making. Practical implications - It is argued that system dynamics can provide a useful addition to the toolkit of the discrete-event simulation practitioner in helping them incorporate a human aspect in their analysis. Originality/value - Helps decision makers gain a broader perspective on the tools available to them by showing the use of system dynamics to supplement the use of discrete-event simulation. © Emerald Group Publishing Limited.

Development of a co-operative distributed process mining system for quality assurance

In this paper, a co-operative distributed process mining system (CDPMS) is developed to streamline the workflow along the supply chain in order to offer shorter delivery times, more flexibility and higher customer satisfaction with learning ability. The proposed system is equipped with the ‘distributed process mining’ feature which is used to discover the hidden relationships among each working decision in distributed manner. This method incorporates the concept of data mining and knowledge refinement into decision making process for ensuring ‘doing the right things’ within the workflow. An example of implementation is given, based on the case of slider manufacturer.

Addressing the project implementation challenges in the Saudi Arabian power supply industry: an investigative approach towards improving project delivery

For many decades, the Kingdom of Saudi Arabia has been widely known for being a reliable oil exporter. This fact, however, has not exempted it from facing significant domestic energy challenges. One of the most pressing of these challenges involves bridging the widening electricity supply-demand gap where, currently, the demand is growing at a very fast rate. One crucial means to address this challenge is through delivering power supply projects with maximum efficiency. Project delivery delay, however, is not uncommon in this highly capital-intensive industry, indicating electricity supplies are not coping with the demand increases. To provide a deeper insight into the challenges of project implementation and efficient practice, this research adopts a pragmatic approach by triangulating literature, questionnaires and semi-structured interviews. The research was conducted in the Saudi Arabian power supply industry – Western Operating Area. A total of 105 usable questionnaires were collected, and 28 recorded, semi-structured interviews were conducted, analysed and synthesised to produce a conceptual model of what constitutes the project implementation challenges in the investigated industry. This was achieved by conducting a comprehensive ranking analysis applied to all 58 identified and surveyed factors which, according to project practitioners in the investigated industry, contribute to project delay. 28 of these project delay factors were selected as the "most important" ones. Factor Analysis was employed to structure these 28 most important project delay factors into the following meaningful set of 7 project implementation challenges: Saudi Electricity Company's contractual commitments, Saudi Electricity Company's communication and coordination effectiveness, contractors' project planning and project control effectiveness, consultant-related aspects, manpower challenges and material uncertainties, Saudi Electricity Company's tendering system, and lack of project requirements clarity. The study has implications for industry policy in that it provides a coherent assessment of the key project stakeholders' central problems. From this analysis, pragmatic recommendations are proposed that, if enacted, will minimise the significance of the identified problems on future project outcomes, thus helping to ensure the electricity supply-demand gap is diminished.

Phonophoresis and topical drug delivery

In this study, investigations into phonophoresis were conducted by employing 3 distinct in vitro models. The aim of the first model was to evaluate the effect of ultrasound on the migration rate of different classes of molecules through agar gel. The derived data suggested that small, relatively hydrophobic molecules are more susceptible to ultrasound-enhanced diffusion through the water-filled channels of the agar gel. The application of heat alone increased drug migration by a similar magnitude as the ultrasound, indicating that ultrasonic heating directly increases the thermodynamic potential for diffusion. In the second experimental system, whole rat skin was pre-sonicated and then examined for changes in its barrier properties. At high intensities (1 to 2W cm-2), ultrasonic waves irreversibly compromised the barrier properties of the skin, following the general patterns described in the literature reports. At low intensities (< 1W cm-2), ultrasound discharged sebum from the sebaceous glands so as to fill much of the hair follicle shafts. This entirely novel phenomenon is probably produced by the mechanical effects of the beam. The deposition of sebaceous lipids within the hair follicle shafts can mean that this absorption pathway is blocked for hydrophilic molecules that penetrate via this route. Consequently, this phenomenon can be utilised as a probe to measure the relative follicular contribution to total penetration for these molecules. In the final phonophoresis model, modified Franz cells were employed in order to assess the ultrasound effect on the concurrent transdermal permeation of various molecules through whole rat skin. For the most lipophilic agent tested, the rate-limiting step of absorption was partitioning from the stratum corneum into the viable epidermis. Sonication did not accelerate this step.

Formulation and characterisation of an effective particulate delivery vehicle for the novel sub-unit vaccine antigen, Ag85B-ESAT-6

This research focused on the formation of particulate delivery systems for the sub-unit fusion protein, Ag85B-ESAT-6, a promising tuberculosis (TB) vaccine candidate. Initial work concentrated on formulating and characterising, both physico-chemically and immunologically, cationic liposomes based on the potent adjuvant dimethyl dioctadecyl ammonium (DDA). These studies demonstrated that addition of the immunomodulatory trehalose dibehenate (TDB) enhanced the physical stability of the system whilst also adding further adjuvanticity. Indeed, this formulation was effective in stimulating both a cell mediated and humoural immune response. In order to investigate an alternative to the DDA-TDB system, microspheres based on poly(DL-lactide-co-glycolide) (PLGA) incorporating the adjuvants DDA and TDB, either alone or in combination, were first optimised in terms of physico-chemical characteristics, followed by immunological analysis. The formulation incorporating PLGA and DDA emerged as the lead candidate, with promising protection data against TB. Subsequent optimisation of the lead microsphere formulation investigated the effect of several variables involved in the formulation process on physico-chemical and immunological characteristics of the particles produced. Further, freeze-drying studies were carried out with both sugar-based and amino acid-based cryoprotectants, in order to formulate a stable freexe-dried product. Finally, environmental scanning electron microscopy (ESEM) was investigated as a potential alternative to conventional SEM for the morphological investigation of microsphere formulations. Results revealed that the DDA-TDB liposome system proved to be the most immunologically efficient delivery vehicle studied, with high levels of antibody and cytokine production, particularly gamma-interferon (IFN-ϒ), considered the key cytokine marker for anti-mycobacterial immunity. Of the microsphere systems investigated, PLGA in combination with DDA showed the most promise, with an ability to initiate a broad spectrum of cytokine production, as well as antigen specific spleen cell proliferation comparable to that of the DDA-TDB formulation.

Novel bioadhesive formulations for mucosal and parenteral delivery of vaccines

In this work we have established the efficient mucosal delivery of vaccines using absorption enhancers and chitosan. In addition, the use of chitosan was shown to enhance the action of other known adjuvants, such as CTB or Quil-A. Collectively, the results presented herein indicate that chitosan has excellent potential as a mucosal adjuvant. We have evaluated a number of absorption enhancers for their adjuvant activity in vivo. Polyornithine was shown to engender high scrum immune reasons to nasally delivered antigens, with higher molecular weight polyornithine facilitating the best results. We have demonstrated for the first time that vitamin E TPGS can act as mucosal adjuvant. Deoxycholic acid, cyclodextrins and acylcarnitines were also identified as effective mucosal adjuvants and showed enhanced immune responses to nasally delivered TT, DT and Yersinia pestis V and F1 antigens. Previously, none of these agents, common in their action as absorption enhancing agents, have been shown to have immunopotentiating activity for mucosal immunisation. We have successfully developed novel surface modified microspheres using chitosan as an emulsion stabiliser during the preparation of PLA microspheres. It was found that immune responses could be substantially increased, effectively exploiting the immunopenetrating characteristics of both chitosan and PLA microspheres in the same delivery vehicle. In the same study, comparison of intranasal and intramuscular routes of administration showed that with these formulations, the nasal route could be as effective as intramuscular delivery, highlighting the potential of mucosal administration for these particulate delivery systems. Chitosan was co-administered with polymer microspheres. It was demonstrated that this strategy facilitates markedly enhanced immune responses in both magnitude and duration following intramuscular administration. We conclude that this combination shows potential for single dose administration of vaccines. In another study, we have shown that the addition of chitosan to alum adsorbed TT was able to enhance immune responses. PLA micro/nanospheres were prepared and characterised with discreet particle size ranges. A smaller particle size was shown to facilitate higher scrum IgG responses following nasal administration. A lower antigen loading was additionally identified as being preferential for the induction of immune responses in combination with the smaller particle size. This may be due to the fact that the number of particles will be increased when antigen loading is low, which may in turn facilitate a more widespread uptake of particles. PLA lamellar particles were prepared and characterised. Adsorbed TT was evaluated for the potential to engender immune responses in vivo. These formulations were shown to generate effective immune responses following intramuscular administration. Positively charged polyethylcyanoacrylate and PLA nanoparticies were designed and characterised and their potential as delivery vehicles for DNA vaccines was investigated. Successful preparation of particles with narrow size distribution and positive surface charge (imparted by the inclusion of chitosan) was achieved. In the evaluation of antibody responses to DNA encoded antigen in the presence of alum administered intranasally, discrimination between the groups was only seen following intramuscular boosting with the corresponding protein. Our study showed that DNA vaccines in the presence of either alum or Quil-A may advantageously influence priming of the immune system by a mucosal route. The potential for the combination of adjuvants, Quil-A and chitosan, to enhance antibody responses to plasmid encoded antigen co-administered with the corresponding protein antigen was shown and this is worthy of further investigation. The findings here have identified novel adjuvants and approaches to vaccine delivery. In particular, chitosan or vitamin E TPGS are shown here to have considerable promise as non-toxic, safe mucosal adjuvants. In addition, biodegradable mucoadhesive delivery systems, surface modified with chitosan in a single step process, may have application for other uses such as drug and gene delivery.

Comparison and characterisation of ribozyme delivery in cultured glial and neuronal cells in vivo and in vitro

Ribozymes are short strands of RNA that possess a huge potential as biological tools for studying gene expression and as therapeutic agents to down-regulate undesirable gene expression. Successful application of ribozymes requires delivery to the target site in sufficient amounts for an adequate duration. However, due to their large size and polyanionic character ribozymes are not amenable to transport across biological membranes. In this study a chemically modified ribozyme with enhanced biological stability, targeted against the EGFR mRNA has been evaluated for cellular delivery to cultured glial and neuronal cells with a view to developing treatments for brain tumours. Cellular delivery of free ribozyme was characterised in cultured glial and neuronal cells from the human and rat. Delivery was very limited and time dependent with no consistent difference observed between glial and neuronal cells in both species. Cellular association was largely temperature and energy-dependent with a small component of non-energy dependent association. Further studies showed that ribozyme cellular association was inhibited with self and cross competition with nucleic and non-nucleic acid polyanions indicating the presence of cell surface ribozyme-binding molecules. Trypsin washing experiments further implied that the ribozyme binding surface molecules were protein by nature. Dependence of cellular association on pH indicated that interaction of ribozyme with cell surface molecules was based on ionic interactions. Fluoresence studies indicated that, post cell association, ribozymes were sequestered in sub-cellular vesicles. South-Western blots identified several cell surface proteins which bind to ribozymes and could facilitate cellular association. The limited cellular association observed with free ribozyme required the development and evaluation of polylactide-co-glycolide microspheres incorporating ribozyme for enhanced cellular delivery. Characterisation of microsphere mediated delivery of ribozyme in cultured glial and neuronal cells showed that association increased by 18 to 27-fold in all cell types with no differences observed between cell lines and species. Microsphere mediated delivery was temperature and energy dependent and independent of pH. In order to assess the potential of PLGA micro spheres for the CNS delivery of ribozyme the distribution of ribozyme entrapping microspheres was investigated in rat CNS after intracerebroventricular injection. Distribution studies demonstrated that after 24 hours there was no free ribozyme present in the brain parenchyma, however microsphere entrapped ribozyme was found in the CNS. Microspheres remained in the ventricular system after deposition and passed from the lateral ventricles to the third and fourth ventricle and in the subarachnoid space. Investigation of the influence of microsphere size on the distribution in CNS demonstrated that particles up to 2.5 and O.5f.lm remained in the ventricles around the choroid plexus and ependymal lining.

Influence of microbial antigen formulation and delivery route on the immune response

Recent technological advances have resulted in the production of safe subunit and synthetic small peptide vaccines. Unfortunately, these vaccines are weakly or non-immunogenic in the absence of an immunological adjuvant (agents that can induce strong immunity to antigens). In addition, in order to prevent and/or control infection at the mucosal surface, stimulation of the mucosal immune system is essential. This may be achieved via the common mucosal immune system by exposure to antigen at a mucosal surface remote from the area of infection. Initial studies investigated the potential of multiple emulsions in effecting oral absorption and the subsequent immune responses to a lipopolysaccharide vaccine (LPS) after immunisation. Nasal delivery of LPS was carried out in parallel work using either aqueous solution or gel formulations. Tetanus toxoid vaccine in simple solution was delivered to guinea pigs as free antigen or entrapped in DSPC liposomes. In addition, adsorbed tetanus toxoid vaccine was delivered nasally free or in an aerosil gel formulation. This work was extended to investigate guinea pigs immunised by various mucosal routes with a herpes simplex virus subunit vaccine prepared from virus infected cells and delivered in gels, multiple emulsions and liposomes. Comparable serum antibody responses resulted but failed to produce enhanced protection against vaginal challenge when compared to subcutaneous immunisation with alhydrogel adjuvanted vaccine. Thus, immunisation of the mucosal surface by these methods may have been inadequate. These studies were extended in an attempt to protect against HSV genital challenge by construction of an attenuated Salmonella typhimurium HWSH aroA mutant expressing a cloned glycoprotein D-l gene fused to the Es-cherichia coli lac z promoter. Preliminary work on the colonisation of guinea pigs with S. typhimurium HWSH aroA mutants were carried out, with the aim of using the guinea pig HSV vaginal model to investigate protection.

Poly (D,L-Lactide) based microspheres for pulmonary delivery of proteins

Initial work focused on the preparation, optimisation and characterisation of poly (D,L-lactide) (PLA) microspheres with the aim of optimising their formulation based on minimizing the particle size into the range suitable for pulmonary delivery to alveoli. In order to produce dry powders and to enhance their long-term physico-chemical stability, microspheres were prepared as a dry powder via freeze-drying. Optimisation studies showed that using appropriate concentrations of polymer 3% (w/v) in organic phase and emulsifier 10% (w/v) in external aqueous phase, the double solvent evaporation method produced high protein loading microspheres (72 ± 0.5%) with an appropriate particle size for pulmonary drug delivery. Combined use of trehalose and leucine as cyroprotectants (6% and 1% respectively, w/v) produced freeze-dried powders with the best aerosolisation profile among those tested. Although the freeze-dried PLA microsphere powders were not particularly respirable in dry powder inhalation, nebulisation of the rehydrated powders using an ultrasonic nebuliser resulted in improved aerosilisation performance compared to the air-jet nebuliser. When tested in vitro using a macrophage cell line, the PLA microspheres system exhibited a low cytotoxicity and the microspheres induced phagocytic activity in macrophages. However, interestingly, the addition of an immunomodulator to the microsphere formulations (4%, w/w of polymer) reduced this phagocytic activity and macrophage activation compared to microspheres formulated using PLA alone. This suggested that the addition of trehalose dibehenate may not enhance the ability of these microspheres to be used as vaccine delivery systems.