Showing papers in "Drug Delivery and Translational Research in 2015"
TL;DR: Using 70:30 % ratio (known in literature as 2:1), it is possible to reach the most stable formulation to guarantee a controlled and reproducible release for drugs with different physicochemical characteristics and pharmaceutical applications.
Abstract: Cholesterol plays a strategic role in liposome composition; however, the quantity used to achieve an appropriate formulation has not been yet clarified. Therefore, by screening arrangement of lipids and cholesterol ratio, the main aim of this study is to investigate the most suitable amount of cholesterol in lipids in order to prepare stable and controlled drug release vehicles. For the preparation of liposomes, DMPC, DPPC and DSPC phospholipids were used and combined with different molar ratios of cholesterol (e.g. 100, 80–20, 70–30, 60–40 and 50–50 %). Stability studies were conducted by storing the formulations at 37 and 50 °C for 30 days and by analysing them by AFM, DLS and FT-IR. By detecting the two most stable formulations from the stability results, drug encapsulation and in vitro release studies in PBS were performed by encapsulating atenolol and quinine. The release results were validated using a simulation model to ensure the reliability and suitable interpretation of the data. The generated model showed a good correlation between the prediction and the in vitro obtained results. By using 70:30 % ratio (known in literature as 2:1), it is possible to reach the most stable formulation to guarantee a controlled and reproducible release for drugs with different physicochemical characteristics and pharmaceutical applications.
421 citations
TL;DR: This review gives a brief overview of the components of a theranostic system and the challenges that designing truly multifunctional nanoparticles present.
Abstract: Theranostics is a promising field that combines therapeutics and diagnostics into single multifunctional formulations. This field is driven by advancements in nanoparticle systems capable of providing the necessary functionalities. By utilizing these powerful nanomedicines, the concept of personalized medicine can be realized by tailoring treatment strategies to the individual. This review gives a brief overview of the components of a theranostic system and the challenges that designing truly multifunctional nanoparticles present. Considerations when choosing a class of nanoparticle include the size, shape, charge, and surface chemistry, while classes of nanoparticles discussed are polymers, liposomes, dendrimers, and polymeric micelles. Targeting to disease states can be achieved either through passive or active targeting which uses specific ligands to target receptors that are overexpressed in tumors and common targeting elements are presented. To image the interactions with disease states, contrast agents are included in the nanoparticle formulation. Imaging options include optical imaging techniques, computed tomography, nuclear based, and magnetic resonance imaging. The interplay between all of these components needs to be carefully considered when designing a theranostic system.
88 citations
TL;DR: It is clear that MN poses a very low risk to human health when used appropriately, as evidenced here by low endotoxin levels and absence of microbial contamination, but if guarantees of absolute sterility of MN products are ultimately required by regulatory authorities, it will be necessary to investigate the effect of lower gamma doses on dissolving MN loaded with active pharmaceutical ingredients and lyophilised wafers loaded with biomolecules.
Abstract: We describe, for the first time, considerations in the sterile manufacture of polymeric microneedle arrays. Microneedles (MN) made from dissolving polymeric matrices and loaded with the model drugs ovalbumin (OVA) and ibuprofen sodium and hydrogel-forming MN composed of “super-swelling” polymers and their corresponding lyophilised wafer drug reservoirs loaded with OVA and ibuprofen sodium were prepared aseptically or sterilised using commonly employed sterilisation techniques. Moist and dry heat sterilisation, understandably, damaged all devices, leaving aseptic production and gamma sterilisation as the only viable options. No measureable bioburden was detected in any of the prepared devices, and endotoxin levels were always below the US Food & Drug Administration limits (20 endotoxin units/device). Hydrogel-forming MN were unaffected by gamma irradiation (25 kGy) in terms of their physical properties or capabilities in delivering OVA and ibuprofen sodium across excised neonatal porcine skin in vitro. However, OVA content in dissolving MN (down from approximately 101.1 % recovery to approximately 58.3 % recovery) and lyophilised wafer-type drug reservoirs (down from approximately 99.7 % recovery to approximately 60.1 % recovery) was significantly reduced by gamma irradiation, while the skin permeation profile of ibuprofen sodium from gamma-irradiated dissolving MN was markedly different from their non-irradiated counterparts. It is clear that MN poses a very low risk to human health when used appropriately, as evidenced here by low endotoxin levels and absence of microbial contamination. However, if guarantees of absolute sterility of MN products are ultimately required by regulatory authorities, it will be necessary to investigate the effect of lower gamma doses on dissolving MN loaded with active pharmaceutical ingredients and lyophilised wafers loaded with biomolecules in order to avoid the expense and inconvenience of aseptic processing.
87 citations
TL;DR: Results establish PEG–MAL engineered matrices as a vascular-inductive cell delivery vehicle and warrant their further investigation as islet transplantation vehicles in diabetic animal models.
Abstract: Biofunctionalized polyethylene glycol maleimide (PEG-MAL) hydrogels were engineered as a platform to deliver pancreatic islets to the small bowel mesentery and promote graft vascularization. VEGF, a potent stimulator of angiogenesis, was incorporated into the hydrogel to be released in an on-demand manner through enzymatic degradation. PEG-MAL hydrogel enabled extended in vivo release of VEGF. Isolated rat islets encapsulated in PEG-MAL hydrogels remained viable in culture and secreted insulin. Islets encapsulated in PEG-MAL matrix and transplanted to the small bowel mesentery of healthy rats grafted to the host tissue and revascularized by 4 weeks. Addition of VEGF release to the PEG-MAL matrix greatly augmented the vascularization response. These results establish PEG-MAL engineered matrices as a vascular-inductive cell delivery vehicle and warrant their further investigation as islet transplantation vehicles in diabetic animal models.
87 citations
TL;DR: This review highlights the mechanical tests and insertion analytical techniques used by various groups to characterise microneedles and exposes the urgent need for consistency across the range ofmicroneedle systems in order to promote innovation and the successful commercialisation of micronedle products.
Abstract: With interest in microneedles as a novel drug transdermal delivery system increasing rapidly since the late 1990s (Margetts and Sawyer Contin Educ Anaesthesia Crit Care Pain. 7(5):171-76, 2007), a diverse range of microneedle systems have been fabricated with varying designs and dimensions. However, there are still very few commercially available microneedle products. One major issue regarding microneedle manufacture on an industrial scale is the lack of specific quality standards for this novel dosage form in the context of Good Manufacturing Practice (GMP). A range of mechanical characterisation tests and microneedle insertion analysis techniques are used by researchers working on microneedle systems to assess the safety and performance profiles of their various designs. The lack of standardised tests and equipment used to demonstrate microneedle mechanical properties and insertion capability makes it difficult to directly compare the in use performance of candidate systems. This review highlights the mechanical tests and insertion analytical techniques used by various groups to characterise microneedles. This in turn exposes the urgent need for consistency across the range of microneedle systems in order to promote innovation and the successful commercialisation of microneedle products.
84 citations
TL;DR: Preliminary data with commercially available porous microneedles is shown and future directions in this field of research are described, which could be a valuable addition to the othermicroneedle-based drug delivery approaches.
Abstract: In the literature, several types of microneedles have been extensively described. However, porous microneedle arrays only received minimal attention. Hence, only little is known about drug delivery via these microneedles. However, porous microneedle arrays may have potential for future microneedle-based drug and vaccine delivery and could be a valuable addition to the other microneedle-based drug delivery approaches. To gain more insight into porous microneedle technologies, the scientific and patent literature is reviewed, and we focus on the possibilities and constraints of porous microneedle technologies for dermal drug delivery. Furthermore, we show preliminary data with commercially available porous microneedles and describe future directions in this field of research.
79 citations
TL;DR: Dissolving microneedle patches are a promising advance for influenza cutaneous vaccination due to improved immune responses using less immunogenic influenza antigens and enhanced stability.
Abstract: Prevention of seasonal influenza epidemics and pandemics relies on widespread vaccination coverage to induce protective immunity. In addition to a good antigenic match with the circulating viruses, the effectiveness of individual strains represented in the trivalent vaccines depends on their immunogenicity. In this study, we evaluated the immunogenicity of H1N1, H3N2, and B seasonal influenza virus vaccine strains delivered individually with a novel dissolving microneedle patch and the stability of this formulation during storage at 25 °C. Our data demonstrate that all strains retained their antigenic activity after incorporation in the dissolving patches as measured by single radial diffusion (SRID) assay and immune responses to vaccination in BALB/c mice. After a single immunization, all three antigens delivered with microneedle patches induced superior neutralizing antibody titers compared to intramuscular immunization. Cutaneous antigen delivery was especially beneficial for the less immunogenic B strain. Mice immunized with dissolving microneedle patches encapsulating influenza A/Brisbane/59/07 (H1N1) vaccine were fully protected against lethal challenge by homologous mouse-adapted influenza virus. All vaccine components retained activity during storage at room temperature for at least 3 months as measured in vitro by SRID assay and in vivo by mouse immunization studies. Our data demonstrate that dissolving microneedle patches are a promising advance for influenza cutaneous vaccination due to improved immune responses using less immunogenic influenza antigens and enhanced stability.
74 citations
TL;DR: Inkjet printing was proved an effective approach for transdermal delivery of insulin in solid state and showed homogeneous insulin–polymer layers without any phase separation while SOL demonstrated the best performance.
Abstract: Inkjet printing technology was used to apply insulin polymeric layers on metal microneedles for transdermal delivery. A range of various polymers such as gelatin (GLN), polyvinyl caprolactame-polyvinyl acetate-polyethylene glycol (SOL), poly(2-ethyl-2-oxazoline) (POX) and trehalose (THL) were assessed for their capacity to form thin uniform and homogeneous layers that preserve insulin intact. Atomic force microscopy (AFM) showed homogeneous insulin–polymer layers without any phase separation while SOL demonstrated the best performance. Circular discroism (CD) analysis of rehydrated films showed that insulin’s alpha helices and β–sheet were well preserved for THL and SOL. In contrast, GLN and POX insulin layers revealed small band shifts indicating possible conformational changes. Insulin release in Franz diffusion cells from MNs inserted into porcine skin showed rapid release rates for POX and GLN within the first 20 min. Inkjet printing was proved an effective approach for transdermal delivery of insulin in solid state.
66 citations
TL;DR: Various methods of fabricating drug- and gene-encapsulated nanofibrous meshes, which can be prepared by electrospinning, are described to increase tissue regeneration rates and reduce scar formation in normal and diabetic wounds.
Abstract: Electrospun nanofibrous mats have recently been employed as drug reservoirs for their unique features, such as high surface-to-volume ratios and easy fabrication process. We describe herein various methods of fabricating drug- and gene-encapsulated nanofibrous meshes, which can be prepared by electrospinning. The electrospinning process of nanofibrous mats is affected by many parameters, including viscosity and ejection speeds of the polymeric solutions and the electrical potential applied to the system. Both single- and dual-nozzle systems are widely employed in the preparation of electrospun nanofibers encapsulating drugs and genes, which are usually incorporated into the electrospun mats either by physical mixing with polymeric solutions before electrospinning or by physical incorporation after electrospinning. Various strategies have been tailored to maintain the bioactivity of proteins for tissue regeneration before and after electrospinning. Nucleic acids, such as DNA and siRNA, are also incorporated into nanofibrous meshes to enhance tissue regeneration by expressing transgenes or silencing domestic genes in specific tissues. Drug- or gene-incorporated nanofibrous meshes can greatly increase tissue regeneration rates and reduce scar formation in normal and diabetic wounds. Hybrid nanofibers, with multiple cell layers or hydrogels, have also been used to improve wound healing efficiency by increasing cell infiltration.
66 citations
TL;DR: This work aimed to optimize the RGD-decorated nanoparticle systems for inhibiting αvβ3 integrin receptor overexpressing tumor cell metastasis and increasing nanoparticle accumulation to tumor site.
Abstract: αvβ3 integrin receptors expressed on cancer cell surfaces play a crucial role in promoting tumor angiogenesis and cancer cell metastasis. Thus, cyclic arginyl-glycyl-aspartic acid (cRGD) peptides have been explored as a αvβ3 integrin receptor-specific targeting moiety for the targeted delivery of nanoparticle-loaded therapeutics. However, our previous study showed that cyclic RGD could act as a double-edged sword that, on one hand, extended the retention of cRGD-modified solid lipid nanoparticles (RGD-SLNs) at αvβ3 integrin receptor overexpressing breast carcinoma, and yet on the other hand, decreased the amount of tumor accumulation of RGD-SLNs attributable to the greater uptake by the mononuclear phagocyte system (MPS). Therefore, we aimed to optimize the RGD-decorated nanoparticle systems for (1) inhibiting αvβ3 integrin receptor overexpressing tumor cell metastasis and (2) increasing nanoparticle accumulation to tumor site. SLNs with cRGD content ranging from 0 to 10 % mol of total polyethyleneglycol (PEG) chains were synthesized. The binding of RGD-SLNs with αvβ3 integrin receptors increased with increasing cRGD concentration on the nanoparticles. RGD-SLNs were demonstrated to inhibit MDA-MB-231 cell adhesion to fibronectin and invasion through Matrigel. In vivo whole-body fluorescence imaging revealed that 1 % cRGD on the SLNs’ surface had maximum tumor accumulation with extended tumor retention among all formulations tested in an orthotopic MDA-MB-231/EGFP breast tumor model. This work has laid a foundation for further development of anticancer drug-loaded optimized cRGD nanoparticle formulations for the treatment of breast cancer metastasis.
64 citations
TL;DR: It is shown that hydrogels functionalized with fucoidan can direct the formation of mature vasculature through a local release of VEGF165 and can be a useful tool in ischemic tissues to guide therapeutic angiogenesis.
Abstract: The aim of this study was to functionalize 3D porous cross-linked scaffolds with natural non-animal sulfated polysaccharide fucoidans in order to allow a delivery of vascular endothelial growth factor (VEGF) and potentiate its angiogenic activity Microporous (20 μm) and macroporous (200 μm) scaffolds were functionalized with low, medium, or high molecular weight fucoidans (named LMWF, MMWF, and HMWF, respectively) In vitro, addition of fucoidans promoted endothelial progenitor cells proliferation in both micro- and macroporous scaffolds While control scaffolds without fucoidans loaded with VEGF165 (100 ng) showed a fast burst release in PBS during the first 24 h, MMWF significantly reduced the VEGF165 release (p < 0001) Surface plasmon resonance experiments confirmed a direct interaction between MMWF and VEGF165, characterized by an affinity K
D (K
d/K
a) of 1 × 10−9 M In a subcutaneous angiogenesis model in mice, fucoidan functionalized scaffolds showed a more intense vascularization response than control groups Expression of isolectin-B4 and α-smooth muscle actin, as well as confinement of erythrocytes, demonstrated the neoformed blood vessels functionality There was a significant difference in neovessel area and neovessel density between MMWF scaffolds or VEGF165 scaffolds and MMWF+VEGF165 scaffolds (p < 0001 for all cases) Here, we demonstrate that fucoidan sequesters VEGF165 and delivers biological cues promoting angiogenesis In conclusion, this study shows that hydrogels functionalized with fucoidan can direct the formation of mature vasculature through a local release of VEGF165 and can be a useful tool in ischemic tissues to guide therapeutic angiogenesis
TL;DR: In vivo biodistribution studies indicated very low levels of Amphotericin B in kidneys when given as AmbiOnp as compared to that of marketed formulation proving its safety and was further corroborated by renal toxicity studies.
Abstract: Amphotericin B, a gold standard broad spectrum antibiotic used in treatment of systemic fungal infections and visceral leishmaniasis, though is effective parenterally offers severe nephrotoxicity whereas the oral delivery is reported to give very meager oral bioavailability. Thus, to alleviate the toxicity and to improve oral bioavailability, an effective oral delivery approach in the form of solid lipid nanoparticles of amphotericin B (AmbiOnp) was reported earlier by our group. In this investigation, we report the predominant formation of nontoxic superaggregated form of amphotericin B, resulting from the probe sonication-assisted nanoprecipitation technique. The developed formulation was further confirmed to retain this nontoxic form and was found to be stable over the varied gastrointestinal conditions. Further, in vitro antifungal activity of AmbiOnp against Candida albicans showed minimum inhibitory concentration value of 7.812 μg/mL attributed to controlled release of drug from nanoparticulate matrix. In vivo pharmacokinetic studies revealed a relative bioavailability of AmbiOnp to be 1.05-fold with a Cmax of 1109.31 ± 104.79 ng/mL at the end of 24 h which was comparable to Cmax of 1417.49 ± 85.52 ng/mL achieved with that of marketed formulation (Fungizone®) given intravenously establishing efficacy of AmbiOnp. In vivo biodistribution studies indicated very low levels of Amphotericin B in kidneys when given as AmbiOnp as compared to that of marketed formulation proving its safety and was further corroborated by renal toxicity studies. Further, the formulations were found to be stable under refrigeration condition over a period of 3 months.
TL;DR: The advancement of microneedle-mediated DNA delivery is detailed from proof-of-concept to the delivery of DNA encoding clinically relevant proteins and antigens and the key considerations for the improvement of the technology and progress into a clinically applicable delivery system are examined.
Abstract: The advent of microneedle (MN) technology has provided a revolutionary platform for the delivery of therapeutic agents, particularly in the field of gene therapy. For over 20 years, the area of gene therapy has undergone intense innovation and progression which has seen advancement of the technology from an experimental concept to a widely acknowledged strategy for the treatment and prevention of numerous disease states. However, the true potential of gene therapy has yet to be achieved due to limitations in formulation and delivery technologies beyond parenteral injection of the DNA. Microneedle-mediated delivery provides a unique platform for the delivery of DNA therapeutics clinically. It provides a means to overcome the skin barriers to gene delivery and deposit the DNA directly into the dermal layers, a key site for delivery of therapeutics to treat a wide range of skin and cutaneous diseases. Additionally, the skin is a tissue rich in immune sentinels, an ideal target for the delivery of a DNA vaccine directly to the desired target cell populations. This review details the advancement of MN-mediated DNA delivery from proof-of-concept to the delivery of DNA encoding clinically relevant proteins and antigens and examines the key considerations for the improvement of the technology and progress into a clinically applicable delivery system.
TL;DR: Microneedles have many advantages over conventional needle-and-syringe-based delivery systems for biological agents, in particular, in terms of reduced pain, infection risk and the ability to control administration, and significant further growth is anticipated.
Abstract: Despite the limited number of drugs amenable to administration across the skin, due to the excellent barrier properties of the stratum corneum, the worldwide transdermal product market is worth approximately $32 billion per year. The major growth drivers are greater patient acceptance leading to wider market penetration, lowered development costs and introduction of novel technologies instigating market growth. The cost of new drug discovery has spiralled to around $800 million and time to market can be 13 to 15 years. However, transdermal delivery development of existing drugs costs less (approx $10 to $15 million) and involves a shorter timeline (4 to 8 years), enabling improved product lifecycle management by extending IP protection. As industry increasingly recognises the market potential for transdermal delivery, R&D efforts have increased, leading to an influx of new technologies aimed at increasing the range of drug types deliverable transdermally. A key market area for development is transdermal delivery of therapeutic peptides and proteins. There are over 100 biotechnology-derived medicines marketed, covering nine major therapeutic areas, now representing approximately 15 % of all prescriptions. Today, more than 4000 companies worldwide are involved in biotechnology research, with total revenue increasing from $7.7 billion in 1993 to around $103 billion in 2013. A major challenge to successful clinical use of these hydrophilic, highmolecular weight Bbiotech^molecules is drug delivery. Due to enzymatic breakdown and poor GI absorption, the parenteral route is presently the only option. Microneedles, minimally invasive devices that painlessly, and without drawing blood penetrate the skin’s stratum corneum barrier, have the potential to effectively overcome this problem. Thus, such systems could greatly enhance market size by removing dependence of efficient transdermal transport on drug physicochemical properties, allowing a much greater range of drugs to be delivered transdermally. In fact, microneedle arrays have already successfully delivered oligonucleotides, desmopressin, DNA, vaccines, insulin and human growth hormone in vivo. Indeed, a report fromGreystone Associates, Microneedles in Medicine: Technology, Devices, Markets and Prospects, put the potential market for microneedle drug delivery systems at just under $400 million globally in 2012. Since microneedles are frequently targeted not only to the $32 billion transdermal drug delivery and $25 billion global vaccine markets but also to the $120 billion global biologics market, significant further growth is anticipated. The future appears to be very bright for new delivery and, potentially, monitoring/diagnostic systems based upon microneedle technologies. The ever-increasing amount of fundamental knowledge appears to be feeding industrial development. Microneedles have many advantages over conventional needle-and-syringe-based delivery systems for biological agents, in particular, in terms of reduced pain, infection risk and the ability to control administration. Skin barrier function disturbance is minimal and recovery rapid. Once regulatory hurdles are overcome and manufacturing processes developed, optimised and validated to current good manufacturing practice standards, the benefits for patients, and ultimately for the industry, will be considerable. Given the inherent safety features of microneedle systems, it is easy to foresee a time within the next 10 years when vaccination programmes in the developing world are based around microneedles. The fact that most microneedle * Ryan Donnelly R.Donnelly@qub.ac.uk
TL;DR: Investigation of the effects of microneedle treatment on in vitro transdermal delivery of vismodegib with different needle lengths, skin equilibration times, and micronedle insertion durations found positive correlation between drug permeability and micronesian treatment duration was observed.
Abstract: The present study investigated the effects of microneedle treatment (maltose microneedles, Admin Pen™ 1200, and Admin Pen™ 1500) on in vitro transdermal delivery of vismodegib with different needle lengths, skin equilibration times, and microneedle insertion durations. The influence of microneedle treatment on the dimensions of microchannels (dye binding, calcein imaging, histology, and confocal microscopy studies), transepidermal water loss, and skin permeability of vismodegib was also evaluated. Skin viscoelasticity was assessed using a rheometer, and microneedle geometry was characterized by scanning electron microscopy. Permeation studies of vismodegib through dermatomed porcine ear skin were conducted using vertical Franz diffusion cells. Skin irritation potential of vismodegib formulation was assessed using an in vitro reconstructed human epidermis model. Results of the in vitro permeation studies revealed significant enhancement in permeation of vismodegib through microneedle-treated skin. As the needle length increased from 500 to 1100 and 1400 μm, drug delivery increased from 14.50 ± 2.35 to 32.38 ± 3.33 and 74.40 ± 15.86 μg/cm2, respectively. Positive correlation between drug permeability and microneedle treatment duration was observed. The equilibration time was also found to affect the delivery of vismodegib. Thus, changes in microneedle length, equilibration time, and duration of treatment altered transdermal delivery of vismodegib.
TL;DR: In vitro testing showed PB-TCA-SA microcapsules improved β-cell survival under hyperglycemic states and reduced the pro-inflammatory cytokine TNF-α while increasing insulin secretions compared with PB-SAmicrocapsules, suggesting desirable targeted release properties and potential applications in the oral delivery of PB in T2D.
Abstract: In recent studies, we designed multi-compartmental microcapsules as a platform for the targeted oral delivery of lipophilic drugs in an animal model of type 2 diabetes (T2D). Probucol (PB) is a highly lipophilic, antihyperlipidemic drug with potential antidiabetic effects. PB has low bioavailability and high inter-individual variations in absorption, which limits its clinical applications. In a new study, the bile acid, taurocholic acid (TCA), exerted permeation enhancing effects in vivo. Accordingly, this study aimed to design and characterize TCA-based PB microcapsules and examine the effects of TCA on the microcapsules' morphology, stability, and release profiles. Microcapsules were prepared using the polymer sodium alginate (SA). Two types of microcapsules were produced, one without TCA (PB-SA, control) and one with TCA (PB-TCA-SA, test). Microcapsules were studied in terms of morphology, surface structure and composition, size, drug contents, cross-sectional imaging (using microtomography (Micro-CT) analysis), Zeta potential, thermal and chemical profiles, rheological parameters, swelling, mechanical strength, and release studies at various temperature and pH values. The production yield and the encapsulation efficiency were also studied together with in vitro efficacy testing of cell viability at various glucose concentrations and insulin and TNF-α production using clonal-mouse pancreatic β-cells. PB-TCA-SA microcapsules showed uniform structure and even distribution of TCA within the microcapsules. Drug contents, Zeta potential, size, rheological parameters, production yield, and the microencapsulation efficiency remained similar after TCA addition. In vitro testing showed PB-TCA-SA microcapsules improved β-cell survival under hyperglycemic states and reduced the pro-inflammatory cytokine TNF-α while increasing insulin secretions compared with PB-SA microcapsules. PB-TCA-SA microcapsules also showed good stability, better mechanical (p < 0.01) and swelling (p < 0.01) characteristics, and optimized controlled release at pH 7.8 (p < 0.01) compared with control, suggesting desirable targeted release properties and potential applications in the oral delivery of PB in T2D.
TL;DR: The present review showcases the efficacy of amorphous solid dispersion technique in the research and evolution of different drug formulations particularly for those with poor water soluble properties.
Abstract: Solid dispersion has emerged as a method of choice and has been extensively investigated to ascertain the in vivo improved performance of many drug formulations. It generally involves dispersion of drug in amorphous particles (clusters) or in crystalline particles. Comparatively, in the last decade, amorphous drug-polymer solid dispersion has evolved into a platform technology for delivering poorly water-soluble small molecules. However, the success of this technique in the pharmaceutical industry mainly relies on different drug-polymer attributes like physico-chemical stability, bioavailability and manufacturability. The present review showcases the efficacy of amorphous solid dispersion technique in the research and evolution of different drug formulations particularly for those with poor water soluble properties. Apart from the numerous mechanisms of action involved, a comprehensive summary of different key parameters required for the solubility enhancement and their translational efficacy to clinics is also emphasized.
TL;DR: The history and current technologies of drug, protein, and gene delivery in the context of regenerative medicine are discussed and case examples of how delivery technologies are being applied to promote angiogenesis in nonhealing wounds or prevent angiogenic in age related macular degeneration are presented.
Abstract: Regenerative medicine has the potential to drastically change the field of health care from reactive to preventative and restorative Exciting advances in stem cell biology and cellular reprogramming have fueled the progress of this field Biochemical cues in the form of small molecule drugs, growth factors, zinc finger protein transcription factors and nucleases, transcription activator-like effector nucleases, monoclonal antibodies, plasmid DNA, aptamers, or RNA interference agents can play an important role to influence stem cell differentiation and the outcome of tissue regeneration Many of these biochemical factors are fragile and must act intracellularly at the molecular level They require an effective delivery system, which can take the form of a scaffold (eg, hydrogels and electrospun fibers), carrier (viral and nonviral), nano- and microparticle, or genetically modified cell In this review, we will discuss the history and current technologies of drug, protein, and gene delivery in the context of regenerative medicine Next, we will present case examples of how delivery technologies are being applied to promote angiogenesis in nonhealing wounds or prevent angiogenesis in age related macular degeneration Finally, we will conclude with a brief discussion of the regulatory pathway from bench to bedside for the clinical translation of these novel therapeutics
TL;DR: Treatment modalities that have reached preclinical and clinical trials are discussed, with emphasis on controlled release systems for bone tissue engineering, the most advanced application with several products already in clinic.
Abstract: Strategies that utilize controlled release of drugs and proteins for tissue engineering have enormous potential to regenerate damaged organs and tissues. The multiple advantages of controlled release strategies merit overcoming the significant challenges to translation, including high costs and long, difficult regulatory pathways. This review highlights the potential of controlled release of proteins for tissue engineering and regenerative medicine. We specifically discuss treatment modalities that have reached preclinical and clinical trials, with emphasis on controlled release systems for bone tissue engineering, the most advanced application with several products already in clinic. Possible strategies to address translational and regulatory concerns are also discussed.
TL;DR: The present work builds upon prior models of gel coating flows and drug diffusion (without convection) in the vaginal environment and extends these initial approaches in several key ways, including linking convective drug transport due to gel spreading with drug diffusion and accounting for natural variations in dimensions of the canal and the site of gel placement therein.
Abstract: Gels are one of the soft material platforms being evaluated to deliver topically acting anti-HIV drugs (microbicides) to the vaginal environment. For each drug, its loaded concentration, gel properties and applied volume, and frequency of dosing can be designed to optimize PK and, thence, PD. These factors also impact user sensory perceptions and acceptability. Deterministic compartmental modeling of vaginal deployment and drug delivery achieved by test gels can help delineate how multiple parameters characterizing drug, vehicle, vaginal environment, and dosing govern details of PK and PD and also gel leakage from the canal. Such microbicide delivery is a transport process combining convection, e.g., from gel spreading along the vaginal canal, with drug diffusion in multiple compartments, including gel, mucosal epithelium, and stroma. The present work builds upon prior models of gel coating flows and drug diffusion (without convection) in the vaginal environment. It combines and extends these initial approaches in several key ways, including: (1) linking convective drug transport due to gel spreading with drug diffusion and (2) accounting for natural variations in dimensions of the canal and the site of gel placement therein. Results are obtained for a leading microbicide drug, tenofovir, delivered by three prototype microbicide gels, with a range of rheological properties. The model includes phosphorylation of tenofovir to tenofovir diphosphate (which manifests reverse transcriptase activity in host cells), the stromal concentration distributions of which are related to reference prophylactic values against HIV. This yields a computed summary measure related to gel protection (“percent protected”). Analyses illustrate tradeoffs amongst gel properties, drug loading, volume and site of placement, and vaginal dimensions, in the time and space history of gel distribution and tenofovir transport to sites of its anti-HIV action and concentrations and potential prophylactic actions of tenofovir diphosphate therein.
TL;DR: A multiplex immunodiagnostic device incorporating mechanisms to detect multiple antigens simultaneously, as well as internal assay controls for result validation, is described and a novel detection method is also proposed that enables signal detection specifically at microneedle tips and therefore may aid the construction of depth profiles of skin biomarkers.
Abstract: Immunodiagnostic microneedles provide a novel way to extract protein biomarkers from the skin in a minimally invasive manner for analysis in vitro. The technology could overcome challenges in biomarker analysis specifically in solid tissue, which currently often involves invasive biopsies. This study describes the development of a multiplex immunodiagnostic device incorporating mechanisms to detect multiple antigens simultaneously, as well as internal assay controls for result validation. A novel detection method is also proposed. It enables signal detection specifically at microneedle tips and therefore may aid the construction of depth profiles of skin biomarkers. The detection method can be coupled with computerised densitometry for signal quantitation. The antigen specificity, sensitivity and functional stability of the device were assessed against a number of model biomarkers. Detection and analysis of endogenous antigens (interleukins 1α and 6) from the skin using the device was demonstrated. The results were verified using conventional enzyme-linked immunosorbent assays. The detection limit of the microneedle device, at ≤10 pg/mL, was at least comparable to conventional plate-based solid-phase enzyme immunoassays.
TL;DR: Control release of DOX from CG hydrogels cross-linked with TG shows a significant potential as a carrier for cell delivery and addition of TG enhanced theCG hydrogel stability significantly.
Abstract: Although local cell delivery is an option to repair tissues, particularly using chitosan-based hydrogels, significant attrition of injected cells prior to engraftment has been a problem. To address this problem, we explored the possibility of stabilizing the chitosan-gelatin (CG) injectable hydrogels using (1) controlled release of doxycycline (DOX) to prevent premature degradation due to increased gelatinase activity (MMP-2 and MMP-9), and (2) transglutaminase (TG) to in situ cross-link gelatin to improve the mechanical stability. We prepared DOX-loaded PLGA nanoparticles, loaded into the CG hydrogels, measured DOX release for 5 days, and modeled using a single-compartmental assumption. Next, we assessed the influence of TG and DOX on hydrogel compression properties by incubating hydrogels for 7 days in PBS. We evaluated the effect of these changes on retention of fibroblasts and alterations in MMP-2/MMP-9 activity by seeding 500,000 fibroblasts for 5 days. These results showed that 90 % of DOX released from cross-linked CG hydrogels after 4 days, unlike CG hydrogels where 90 % of DOX was released within the first day. Addition of TG enhanced the CG hydrogel stability significantly. More than 60 % of seeded fibroblasts were recovered from the CG-TG hydrogels at day 5, unlike 40 % recovered from CG-hydrogels. Inhibition of MMP-2/MMP-9 were observed. In summary, controlled release of DOX from CG hydrogels cross-linked with TG shows a significant potential as a carrier for cell delivery.
TL;DR: The modified C12-C 12-Cx43 MP, with its prolonged vitreous stability, showed significantly lower levels of Cx43 expression post-injury, with a trend towards a greater reduction in vessel leak and further RGC protection, suggesting that these molecules may be a clinically relevant neuroprotective tool in the treatment of optic neuropathy.
Abstract: Optic neuropathy is associated with retinal ganglion cell (RGC) loss leading to optic nerve damage and visual impairment. Recent research has shown that transient block of connexin43 (Cx43) hemichannels by a Cx43 mimetic peptide (MP), Peptide5, delivered systemically or by intravitreal injection after retinal ischemia inhibits uncontrolled hemichannel opening to provide significantly reduced vessel leak and inflammation as well as significantly enhanced RGC survival. We have previously shown, in vitro, that a chemically modified C12-C12-Cx43 MP has a twofold greater half-life in bovine vitreous (ex vivo) than the native peptide. The present study investigated the ability of intravitreally injected, chemically modified C12-C12-Cx43 MP to further enhance RGC survival in a rat retinal ischemia-reperfusion model. Intravitreally injected native Cx43 MP or C12-C12-Cx43 MP both minimized vessel leak, reduced inflammation, and protected RGC after ischemic injury. However, the modified C12-C12-Cx43 MP, with its prolonged vitreous stability, showed significantly lower levels of Cx43 expression post-injury, with a trend towards a greater reduction in vessel leak and further RGC protection, suggesting that these molecules may be a clinically relevant neuroprotective tool in the treatment of optic neuropathy.
TL;DR: Intradermal delivery of insulin is a viable delivery route alternative providing reduced time for insulin absorption with less intra-subject variability and lower glycemic response, in T1DM patients on continuous subcutaneous insulin infusion.
Abstract: Rapid uptake previously demonstrated by intradermal (ID) drug administration indicates compound delivery within the dermis may have clinical and pharmacological advantages for certain drug therapies. This study is the first clinical trial to evaluate continuous microneedle-based drug infusion, device wearability, and intradermal microneedle insulin kinetics over a multi-day (72 h) wear period. This was a single center, open-label, two-period crossover study in T1DM patients on continuous subcutaneous insulin infusion (CSII). Patients received treatment during interventional visits: one SC and one ID basal/bolus infusion of insulin aspart (NovoRapid® U-100) administered over 3 days in a randomized order. Twenty-eight patients were randomized and exposed to trial product, and 23 completed the study. Bolus insulin infusions were given prior to standardized breakfast and lunch test meals on each of the three treatment days. Blood samples were drawn at predefined time points for measurements of insulin aspart and blood glucose in serum. The primary endpoint insulin Tmax demonstrated that ID bolus infusion was associated with a significantly shorter Tmax with statistically significantly smaller intra-subject variability, compared to SC infusion, and this difference was maintained over three treatment days. Analyses of secondary PK endpoints corresponded with the primary endpoint findings. Postprandial glycemic response was significantly less pronounced after ID bolus: For most endpoints ID vs. SC, differences were statistically significant within the 0–1.5 or 0–2 h time period. Intradermal delivery of insulin is a viable delivery route alternative providing reduced time for insulin absorption with less intra-subject variability and lower glycemic response.
TL;DR: A subconjunctival TM microfilm is developed for sustained, long-term delivery of TM to the eyes, using the biodegradable elastomer poly(lactide-co-caprolactone) (PLC), which is biocompatible and has flexibility and mechanical characteristics suitable for a patient-acceptable implant.
Abstract: Timolol maleate (TM) has been used for many years for the reduction of intraocular pressure (IOP) in glaucoma patients. However, the topical mode of administration (eyedrops) is far from optimal because of the issues of low bioavailability, high drug wastage, and lack of patient compliance. Suboptimal control of the IOP leads to disease progression and eventually to blindness. Ideally, TM is delivered to the patient so that its action is both localized and sustained for 3 months or more. In this work, we developed a subconjunctival TM microfilm for sustained, long-term delivery of TM to the eyes, using the biodegradable elastomer poly(lactide-co-caprolactone) (PLC). The copolymer is biocompatible and has flexibility and mechanical characteristics suitable for a patient-acceptable implant. Controlling the release of TM for 3 months is challenging, and this work describes how, by using a combination of multilayering and blending with poly(ethylene glycol) (PEG) copolymers, we were able to develop a TM-incorporated biodegradable film that can deliver TM at a therapeutic dose for 90 days in vitro. The data was further confirmed in a diseased primate model, with sustained IOP-lowering effects for 5 months with a single implant, with acceptable biocompatibility and partial degradation.
TL;DR: The results suggest that synergistic effects of nanofiber topography and sustained delivery of RA and/or BDNF may contribute towards the design of a multifunctional artificial stem cell niche for NPC neuronal differentiation.
Abstract: The treatment of an injured central nervous system using stem-cell-based regenerative medicine still faces considerable hurdles that need to be overcome. Chief among which is the lack of efficient strategies to generate functional neurons from stem cells. The sustained delivery of biochemical cues and synergistic topographical signaling from electrospun nanofibrous scaffolds may be a potential strategy to enhance neuronal differentiation of stem cells for therapeutic purposes. In this study, retinoic acid (RA) and brain-derived neurotrophic factor (BDNF) were encapsulated into a copolymer of e-caprolactone and ethyl ethylene phosphate to form a multifunctional, electrospun nanofibrous scaffold. Sustained release of RA and BDNF was achieved for at least 7 and 14 days, respectively. Despite lower cumulative release of drugs as compared to bolus delivery to plain nanofibers (at least 2× and 50× lower for RA and BDNF, respectively), nanofiber-mediated delivery of RA and/or BDNF resulted in similar capacity for neuronal differentiation of mouse neural progenitor cells (NPCs). In addition, nanofiber topography significantly increased neuronal differentiation (with BDNF, 47.4 % Map2+ cells on 2D vs. 53.4 to 56.5 % on nanofibers, p < 0.05) and reduced glial cell differentiation. BDNF was a more potent inducer of neuronal differentiation than RA. RA supplementation alone resulted in minimal effect on NPC differentiation, and dual supplementation of RA and BDNF did not further enhance the neuronal differentiation of NPCs. Collectively, the results suggest that synergistic effects of nanofiber topography and sustained delivery of RA and/or BDNF may contribute towards the design of a multifunctional artificial stem cell niche for NPC neuronal differentiation.
TL;DR: The results suggest that the electrospun nanofibers incorporated with basic fibroblast growth factor have the potential to be used as an advanced membrane that actively enhances bone regeneration.
Abstract: The concept of guided bone regeneration facilitated by barrier membranes has been widely considered to achieve enhanced bone healing in maxillofacial surgery. However, the currently available membranes are limited in their active regulation of cellular activities. In this study, we fabricated polycaprolactone/gelatin composite electrospun nanofibers incorporated with basic fibroblast growth factor (bFGF) to direct bone regeneration. The fibrous morphology was maintained after the crosslinking and subsequent conjugation of heparin. Release of bFGF from electrospun nanofibers without heparin resulted in a spontaneous burst, while the heparin-mediated release of bFGF decreased the burst release in 24 h. The bFGF released from the nanofibers enhanced the proliferation and migration of human mesenchymal stem cells as well as the tubule formation of human umbilical cord blood cells. The subcutaneous implantation of fibers incorporated with bFGF mobilized a large number of cells positive for CD31 and smooth muscle alpha actin within 2 weeks. The effect of the nanofibers incorporated with bFGF on bone regeneration was evaluated on a calvarial critical size defect model. As compared to the mice that received fibers without bFGF, which presented minimal new bone formation (5.36 ± 3.4 % of the defect), those that received implants of heparinized nanofibers incorporated with 50 or 100 ng/mL bFGF significantly enhanced new bone formation (10.82 ± 2.2 and 17.55 ± 6.08 %). Taken together, our results suggest that the electrospun nanofibers incorporating bFGF have the potential to be used as an advanced membrane that actively enhances bone regeneration.
TL;DR: Novel carrier VBP-1 (organosulphur compound) was successfully employed to enhance the dissolution of AC using co-grinding technique and an oral formulation of the same was developed.
Abstract: Atorvastatin calcium (AC) is a BCS class II drug which shows poor bioavailability due to inadequate dissolution. Solid dispersions present a promising option to enhance the solubility of poorly soluble drugs. Co-grinding with hydrophilic excipients is an easy and economical technique to improve the solubility of poorly soluble drugs and is free from usage of organic solvents. The aim of the present study was to explore novel carrier VBP-1 (organosulphur compound) for formulating a solid dispersion by using a simple, commercially viable co-grinding technique to enhance the dissolution of AC and to develop an oral formulation of the same. Composition of the solid dispersion was optimized based on the release profile in pH 1.2 buffer. The optimized solid dispersion was further characterized for flow properties, DSC, FTIR spectroscopy, XRD, contact angle, SEM studies and release profile in phosphate buffer pH 6.8. The developed solid dispersion gave similar release profile as the innovator formulation (Lipitor® tablets) in both pH 1.2 buffer and phosphate buffer pH 6.8. The developed solid dispersion was formulated into hard gelatin capsules (size 3). The developed capsules were found to give similar release as the innovator formulation in both pH 1.2 buffer and phosphate buffer pH 6.8. The developed capsules were found to be stable for a period of 6 months. Anti-hyperlipidemic efficacy studies in rats showed higher reduction in cholesterol and triglyceride levels by the developed capsules in comparison to pure AC. In conclusion, novel carrier VBP-1 was successfully employed to enhance the dissolution of AC using co-grinding technique.
TL;DR: The incorporation of gelatin-collagen microparticles increased the resistance of the scaffolds to in vitro enzymatic degradation, as well as their association with the C. officinalis flower extract, and a sharp decrease in cytotoxicity was attained.
Abstract: Aiming to develop biological skin dresses with improved performance in the treatment of skin wounds, acellular collagen I scaffolds were modified with polymeric microparticles and the subsequent loading of a hydroglycolic extract of Calendula officinalis flowers. Microparticles made of gelatin-collagen were produced by a water-in-oil emulsion/cross-linking method. Thereafter, these microparticles were mixed with collagen suspensions at three increasing concentrations and the resulting mixtures lyophilized to make microparticle-loaded porous collagen scaffolds. Resistance to enzymatic degradation, ability to associate with the C. officinalis extract, and the extract release profile of the three gelatin-collagen microparticle-scaffold prototypes were assessed in vitro and compared to collagen scaffolds without microparticles used as control. Data indicated that the incorporation of gelatin-collagen microparticles increased the resistance of the scaffolds to in vitro enzymatic degradation, as well as their association with the C. officinalis flower extract. In addition, a sharp decrease in cytotoxicity, as well as more prolonged release of the extract, was attained. Overall results support the potential of these systems to develop innovative dermal substitutes with improved features. Furthermore, the gelatin-collagen mixture represents a low-cost and scalable alternative with high clinical transferability, especially appealing in developing countries.
TL;DR: A light actuated drug delivery-on-demand strategy that uses visible and near-infrared (NIR) light and biocompatible chromophores: cardiogreen, methylene blue, and riboflavin has been described and pulsatile release of bovine serum albumin from thermally responsive hydrogels was achieved over 4 days.
Abstract: The need for temporal-spatial control over the release of biologically active molecules has motivated efforts to engineer novel drug delivery-on-demand strategies actuated via light irradiation. Many systems, however, have been limited to in vitro proof-of-concept due to biocompatibility issues with the photo-responsive moieties or the light wavelength, intensity, and duration. To overcome these limitations, this paper describes a light actuated drug delivery-on-demand strategy that uses visible and near-infrared (NIR) light and biocompatible chromophores: cardiogreen, methylene blue, and riboflavin. All three chromophores are capable of significant photothermal reaction upon exposure to NIR and visible light, and the amount of temperature change is dependent upon light intensity, wavelength as well as chromophore concentration. Pulsatile release of bovine serum albumin (BSA) from thermally responsive hydrogels was achieved over 4 days. These findings have the potential to translate light-actuated drug delivery-on-demand systems from the bench to clinical applications that require explicit control over the presentation of biologically active molecules.