Controlled release of dexamethasone from fibrin sealant for intratympanic administration in inner ear therapy

The aim of the present work was to show the sustainability of fibrin sealant in releasing dexamethasone and adjust the protocol for clinical application of the novel method in the treatment of Meniere’s disease (MD) and sudden sensorineural hearing loss (SSHL).Gelation occurred shortly after mixing dexamethasone-containing fibrinogen with thrombin.Dexamethasone was constantly released for at least 16 d at a stable level after 7d in protocol 1 (low-dose),while it was robustly released within 4 d and slowed afterward until 10 d in protocol 2(high-dose).There were significant differences among the time points in Protocol 2 (p<0.01,ANOVA),and the exponential model with the formula y=15.299*e~(-0.483*t) fits the association.The estimated concentration of dexamethasone released on 7 d in protocol 2 was slightly lower than that observed in protocol 1.The fibrin sealant is capable of constantly releasing dexamethasone with adjustable dynamics.Targeted and minimally invasive administration of the material can be achieved in the clinic by sequential injections of the fluids using a soft-tipped catheter.

A matrix metalloproteinase-responsive hydrogel system controls angiogenic peptide release for repair of cerebral ischemia/reperfusion injury

Vascular endothelial growth factor and its mimic peptide KLTWQELYQLKYKGI(QK)are widely used as the most potent angiogenic factors for the treatment of multiple ischemic diseases.However,conventional topical drug delivery often results in a burst release of the drug,leading to transient retention(inefficacy)and undesirable diffusion(toxicity)in vivo.Therefore,a drug delivery system that responds to changes in the microenvironment of tissue regeneration and controls vascular endothelial growth factor release is crucial to improve the treatment of ischemic stroke.Matrix metalloproteinase-2(MMP-2)is gradually upregulated after cerebral ischemia.Herein,vascular endothelial growth factor mimic peptide QK was self-assembled with MMP-2-cleaved peptide PLGLAG(TIMP)and customizable peptide amphiphilic(PA)molecules to construct nanofiber hydrogel PA-TIMP-QK.PA-TIMP-QK was found to control the delivery of QK by MMP-2 upregulation after cerebral ischemia/reperfusion and had a similar biological activity with vascular endothelial growth factor in vitro.The results indicated that PA-TIMP-QK promoted neuronal survival,restored local blood circulation,reduced blood-brain barrier permeability,and restored motor function.These findings suggest that the self-assembling nanofiber hydrogel PA-TIMP-QK may provide an intelligent drug delivery system that responds to the microenvironment and promotes regeneration and repair after cerebral ischemia/reperfusion injury.

Preparation and Drug-Release Property of Polycaprolactone (PCL)/Polyglycolic Acid (PGA) Composite Masterbatch with Drug of Tea Polyphenols (TPs)

In order to effectively control the drug-release rate of medical textiles,biodegradable polycaprolactone(PCL) and polyglycolic acid(PGA) were blended at various mass ratios to prepare composite masterbatches for medical textiles.The surface morphology and the chemical structure of the masterbatches were analyzed.The crystallization,mass losses,strengths and drug-release rates of the composite masterbatches at different PCL/PGA mass ratios were explored.The results show that the degradation rate of the PGA carrier is obvious higher than that of the PCL carrier,and PCL,PGA and the tea polyphenol(TP) drug just physically mix without chemical reaction.During the degradation,the strength of the composite masterbatches gradually decreases.In addition,the drug-release rates of composite masterbatches at different mass ratios are different,and the more the PGA in the composite masterbatches,the faster the drug release of the composite masterbatches.The drug-release rate of the composite masterbatches can be controlled by adjusting the contents of PCL and PGA.

Anorectal Pharmacodynamics and In Vitro Drug Release of Clerodendrum bungei Steud.Extract Gel

[Objectives]To determine the optimal preparation technology of Clerodendrum bungei Steud.extract gel by orthogonal test and gel quality test method in General Rule 0114 of Chinese Pharmacopoeia(Volume IV,2020 Edition),and to study its anorectal pharmacodynamics and drug release in vitro.[Methods]Carbomer 940,propylene glycol and absolute ethyl alcohol were selected as the main factors,and the preparation technology of C.bungei Steud.extract gel was optimized by orthogonal test.The mouse model of ulcerative hemorrhoids was established with glacial acetic acid(HAC)and compared with Ma Yinglong musk hemorrhoids ointment.The recovery of trauma was compared between the two groups.At the same time,porcine small intestine was used as semi-permeable membrane to make diffusion cell to simulate anal environment,and the drug release in vitro was studied.[Results]The C.bungei Steud.extract gel was smooth in appearance and good in stability.It could effectively treat anal ulcer in mice and release quickly in vitro.[Conclusions]The formula is reasonable,and the effect of animal experiment is remarkable,which can provide a new treatment plan for ulcerative hemorrhoids.

A Simplified Expression for a Diffusion-Dissolution Con-trolled Release of Drug from Matrix in TDDS

Chandrasekran-paul (1982) made an equation of drug release from matrix system as follows:In this paper a simplified expression has been deduced from it within ordinary range of experimental time and with appropriate values of K. The cumulative amount of drug release may vary in directproportion to the square root of time with an intercept,that is,The release behaviour of both nifedipine patch and propranolol patch has fit the expression with good correlation coefficient.The re0lease data of hydrocortisone creams (Shah,1989)also can be described by the same expression.Compared with Higuchi’s equation,the presence of the intercept,A〃,may be relative to drug dissolution characteristics

Development of composite PLGA microspheres containing exenatide-encapsulated lecithin nanoparticles for sustained drug release

This study aimed to prepare poly(D, L-lactic-co-glycolic acid) microspheres(PLGA-Ms)by a modified solid-in-oil-in-water(S/O/W) multi-emulsion technique in order to achieve sustained release with reduced initial burst and maintain efficient drug concentration for a prolonged period of time. Composite PLGA microspheres containing exenatideencapsulated lecithin nanoparticles(Ex-NPs-PLGA-Ms) were obtained by initial fabrication of exenatide-loaded lecithin nanoparticles(Ex-NPs) via the alcohol injection method,followed by encapsulation of Ex-NPs into PLGA microspheres. Compared to Ms prepared by the conventional water-in-oil-in-water(W/O/W) technique(Ex-PLGA-Ms), Ex-NPs-PLGAMs showed a more uniform particle size distribution, reduced initial burst release, and sustained release for over 60 d in vitro. Cytotoxicity studies showed that Ms prepared by both techniques had superior biocompatibility without causing any detectable cytotoxicity.In pharmacokinetic studies, the effective drug concentration was maintained for over 30 d following a single subcutaneous injection of two types of Ms formulation in rats, potentially prolonging the therapeutic action of Ex. In addition, administration of Ex-NPs-PLGA-Ms resulted in a more smooth plasma concentration-time profile with a higher area under the curve(AUC) compared to that of Ex-PLGA-Ms. Overall, Ex-NPs-PLGA-Ms prepared by the novel S/O/W method could be a promising sustained drug release system with reduced initial burst release and prolonged therapeutic efficacy.

Construction of hollow polydopamine nanoparticle based drug sustainable release system and its application in bone regeneration

Nanomaterial-based drug sustainable release systems have been tentatively applied to bone regeneration.They,however,still face disadvantages of high toxicity,low biocompatibility,and low drug-load capacity.In view of the low toxicity and high biocompatibility of polymer nanomaterials and the excellent load capacity of hollow nanomaterials with high specific surface area,we evaluated the hollow polydopamine nanoparticles(HPDA NPs),in order to find an optimal system to effectively deliver the osteogenic drugs to improve treatment of bone defect.Data demonstrated that the HPDA NPs synthesized herein could efficiently load four types of osteogenic drugs and the drugs can effectively release from the HPDA NPs for a relatively longer time in vitro and in vivo with low toxicity and high biocompatibility.Results of qRT-PCR,ALP,and alizarin red S staining showed that drugs released from the HPDA NPs could promote osteogenic differentiation and proliferation of rat bone marrow mesenchymal stem cells(rBMSCs)in vitro.Image data from micro-CT and H&E staining showed that all four osteogenic drugs released from the HPDA NPs effectively promoted bone regeneration in the defect of tooth extraction fossa in vivo,especially tacrolimus.These results suggest that the HPDA NPs,the biodegradable hollow polymer nanoparticles with high drug load rate and sustainable release ability,have good prospect to treat the bone defect in future clinical practice.

Influence of Sorbitan Monooleate on Morphology and Drug Release Behavior of Emulsion Electrospinning Polycaprolactone Nanofibers

Ultrafine polycaprolactone(PCL)fibers containing watersoluble drug tetracycline hydrochloride(Tet)were prepared by emulsion electrospinning.Sorbitan monooleate(Span80)was added as an essential additive to form stable water/oil emulsions and fabricate fibers with core-sheath structure.Different concentrations of Span80(0-40 g/L)were used to investigate the stability of emulsion and size of dispersed droplets.The scanning electron microscope(SEM)images indicated that the morphology of the fibers with Span80 were beaded-free with diameters of 200-400 nm,and Span80 enhanced the spinnability of electrospinning solution.The laser scanning confocal microscope(LSCM)images indicated that Tet was well encapsulated into the core region of the PCL fibers.The transmission electron microscope(TEM)image showed the formation of core-sheath structure.The loading efficiency(LE)and entrapment efficiency(EE)of Tet were calculated and release profiles in artificial saliva buffer solution(pH=6.8)were also analyzed.The results revealed that LE and EE of fibers with Span80decreased with the increase of its concentration.Fibers with coresheath structure had a longer effective release lifetime than without Span80.The increase of Span80 resulted in higher hydrophilicity of fibers and faster release rate of Tet.

Polymeric microneedle-mediated sustained release systems: Design strategies and promising applications for drug delivery

Parenteral sustained release drug formulations, acting as preferable platforms for longterm exposure therapy, have been wildly used in clinical practice. However, most of these delivery systems must be given by hypodermic injection. Therefore, issues including needle-phobic, needle-stick injuries and inappropriate reuse of needles would hamper the further applications of these delivery platforms. Microneedles (MNs) as a potential alternative system for hypodermic needles can benefit from minimally invasive and self-administration. Recently, polymeric microneedle-mediated sustained release systems (MN@SRS) have opened up a new way for treatment of many diseases. Here, we reviewed the recent researches in MN@SRS for transdermal delivery, and summed up its typical design strategies and applications in various diseases therapy, particularly focusing on the applications in contraception, infection, cancer, diabetes, and subcutaneous disease. An overview of the present clinical translation difficulties and future outlook of MN@SRS was also provided.

4D printing of core-shell hydrogel capsules for smart controlled drug release

Personalized drugs,as well as disease-specific and condition-dependent drug release,have been highly desired in drug delivery systems for effective and safe therapies.Four-dimensional(4 D)printing,as a newly emerging technique to develop drug capsules,displays unique advantages that can autonomously control drug release according to the actual physiological circumstances.Herein,core-shell structured hydrogel capsules were developed using a multimaterial extrusion-based 4 D printing method,which consists of a model drug as the core and UV cross-linked poly(N-isopropylacrylamide)(PNIPAM)hydrogel as the shell.Owing to the lower critical solution temperature(LCST)-induced shrinking/swelling properties,the prepared PNIPAM hydrogel capsules showed temperature-responsive drug release along with the topography changes in the cross-linked PNIPAM network.The in vitro drug release test confirmed that the PNIPAM hydrogel capsules can autonomously control their drug release behaviors according to changes in ambient temperature.Moreover,the increased shell thickness of these capsules causes an obvious reduction in drug release rate,distinctly indicating that the drug release behavior can be well adjusted by setting the shell thickness of the capsules.The proposed 4 D printing strategy pioneers the paradigm of smart drug release by showing great potential in the smart controlled release of drugs and macromolecular active agents.

Amino functionalized chiral mesoporous silica nanoparticles for improved loading and release of poorly water-soluble drug

In the present paper, chiral mesoporous silica nano-cocoon(A-CMSN) functionalized with amino group was synthesized, and its loading and release of indomethacin(IMC), a poorly soluble drug, was studied. Due to the use of chiral anionic surfactants as a template, ACMSN possessed 2D hexagonal nano-cocoon morphology with curled channels on its surface, which was quite different from another 2D hexagonal mesoporous silica nanoparticles(MCM-41) with straightway channels. After being loaded into the two silica carriers by hydrogen bond, crystalline IMC converted to amorphous form, leading to the improved drug dissolution. And IMC loading capacity of A-CMSN was higher than MCM-41 because curled loading process originating from curvature chiral channels can hold more drug molecules. Compared with IMC, IMC loaded A-CMSN presented obviously fast release throughout the in vitro release experiment, while IMC loaded MCM-41 released faster than IMC at the initial 5 h then showed controlled slow release afterwards, which was closely related to the mesoporous silica nanoparticles and different channel mesostructures of these two carriers. A-CMSN possessed nano-cocoon morphology with curled 2D hexagonal channel and its channel length was shorter than MCM-41, therefore IMC molecules can easily get rid of the constraint of A-CMSN then to be surrounded by dissolution medium.

Fabrication, characterization, in vitro drug release and glucose uptake activity of 14-deoxy,11, 12-didehydroandrographolide loaded polycaprolactone nanoparticles

Biodegradable polymer based novel drug delivery systems brought a considerable attention in enhancing the therapeutic efficacy and bioavailability of various drugs. 14-deoxy 11, 12-didehydro andrographolide(poorly water soluble compound) loaded polycaprolactone(nanoDDA) was synthesized using the solvent evaporation technique. Nano-DDA was characterized by scanning electron microscopy(SEM) and dynamic light scattering(DLS) studies. Fourier Transform InfraRed Spectroscopy(FTIR) was used to investigate the structural interaction between the drug and the polymer. Functional characterization of the formulation was determined using drug content, cellular uptake and in vitro drug release. 2-deoxy-D-[1-~3H] glucose uptake assay was carried out to assess the antidiabetic potential of nano-DDA in L6 myotubes.The nano-DDA displayed spherical shape with a smooth surface(252.898 nm diameter), zeta potential, encapsulation and loading efficiencies of -38.9 mV, 91.98 ± 0.13% and 15.09 ± 0.18% respectively. No structural alteration between the drug and the polymer was evidenced(FTIR analysis). Confocal microscopy studies with rhodamine 123 loaded polycaprolactone nanoparticles(Rh123-PCL NPs) revealed the internalization of Rh123-PCL NPs in a time dependent manner in L6 myoblasts. A dose dependent increase in glucose uptake was observed for nano-DDA with a maximal uptake of 108.54 ± 1.42% at 100 nM on L6 myotubes, thereby proving its anti-diabetic efficacy. A biphasic pattern of in vitro drug release demonstrated an initial burst release at 24 h followed by a sustained release for up to 11 days. To conclude,our results revealed that nano-DDA formulation can be a potent candidate for antidiabetic drug delivery.

5-Fluorouracil Loaded Chitosan–PVA/Na^+MMT Nanocomposite Films for Drug Release and Antimicrobial Activity

In the present study, chitosan and polyvinyl alcohol(PVA) were blended with different concentrations of sodium montmorillonite(Na^+MMT) clay solution by a solvent casting method. X-ray diffraction and transition electron microscope results show that the film properties are related to the co-existence of Na^+MMT intercalation/exfoliation in the blend and the interaction between chitosan–PVA and Na^+MMT. 5-Fluorouracil(5-FU) was loaded with chitosan–PVA/Na^+MMT nanocomposite films for in vitro drug delivery study. The antimicrobial activity of the chitosan–PVA/Na^+MMT films showed significant effect against Salmonella(Gram-negative) and Staphylococcus aureus(Gram-positive), whereas5-FU encapsulated chitosan–PVA/Na^+MMT bio-nanocomposite films did not show any inhibition against bacteria. Our results indicate that combination of a flexible and soft polymeric material with high drug loading ability of a hard inorganic porous material can produce improved control over degradation and drug release. It will be an economically viable method for preparation of advanced drug delivery vehicles and biodegradable implants or scaffolds.

Synthesis and Drug Release Properties of Thermosensitive Poly(N-vinylacetamide-co-vinylacetate) Hydrogels

Thermosensitive poly[N-vinylacetamide-co-vinylacetate][P（NVA-co-VAc）] hydrogels were prepared via free radical copolymerization from hydrophilic NVA and hydrophobic VAc in the presence of butylenes-bis （N-vinylacetamide）（Bis-NVA） as crosslinker. Scanning electron microscopy（SEM） images reveal that the as-prepared hydrogels were of three-dimensional network with irregular cave structure. The prepared hydrogels with more NVA in the feed swelled faster and the swelling ratio of the hydrogels gradually decreased with temperature increasing from 10 °C to 60 °C. The dynamic swelling studies indicate that the swelling process of the hydrogels was controlled by diffusion of water molecules considered as Fickian-controlled case. The adsorption amount of model drug, sodium salicylate（SS） was higher in the hydrogels containing more NVA units, whose corresponding release could reach equilibrium in about 6 h.

Optimizing pH-sensitive and time-dependent polymer formula of colonic pH-responsive pellets to achieve precise drug release

Time-sensitive and pH-dependent polymers are generally employed to prepare colon-site delivery system, and their coating thickness and order are very important in controlling the drug release. The traditional colon-site delivery systems consist of time-dependent polymers as inner layer and pH-sensitive polymers as outer layer. However, they suffer from low drug-loading rate and immature drug release. In this study, total alkaloids of sophora alopecuroides(TASA)-loaded pellets were prepared by extrusion-spheronization method and coated with Eudragit RS30D and Eudragit S100. Pellets using Eudragit RS30D as inner layer and Eudragit S100 as outer layer were named as ERS-ES100 TCO, while pellets with Eudragit S100 as inner layer and Eudragit RS30D as outer layer were ES100-ERS NCO. Both types of formulations with varying coating ratios and orders of Eudragit S100 and Eudragit RS30D were designed and prepared. The following in vitro drug release and SEM studies indicated that ERS-ES100 TCO(F2) with 12.8% Eudragit RS30D as inner layer and 21% Eudragit S100 as outer layer released up to 42% drug in 5 h. Interestingly, ES100-ERS NCO(F4) coated with 12.8% Eudragit S100 and 14.8% Eudragit RS30D showed optimal drug release in colon. In conclusion, ES100-ERS NCO colonic delivery system achieved reduced coating thickness and improved colonic targeting compared with traditional delivery system(ERS-ES100 TCO). In addition, the similarity factors( f 2) value of sophoridine and matrine for investigated formulation were within 50–100 and > 80, demonstrating that sophoridine and matrine in all formulations achieved a synchronous release.

Gallic Acid-loaded Cellulose Acetate Electrospun Nanofibers: Thermal Properties, Mechanical Properties, and Drug Release Behavior

The gallic acid-loaded electrospun cellulose acetate fibers were successfully prepared. The fiber containing 2.5% gallic acid was smooth surface but observed drug flake on the surface of the fiber when increasing drug content. The thermal properties, mechanical properties and drug release behavior of the fibers were investigated comparing to the corres-ponding films.

Fabrication and Drug Release Property of Silk Fibroin-Based Weft-Knitted Stents

This paper was to develop a weft-knitted stent coated by a drng-loaded electro-spun fibrous membrane and then investigate its morphology, mechan/cal properties and in vitro drug release property. This work was started by weft-knitting of an inner layer of such stent using polydioxanone （PDO） and silkf＇dment. Subsequently, 5-fluorouracil （5-FU） and curcnmin（CUR） loaded silk fibroin （SF） membranes were coated on the surface of the weft- knitted stent using electro-spinning technique to endow the drug delivery funct/on of the stent. The results show that the radial compression strength and c/renmferentlal expanding strength can reach above （9.1±0.4） cN/cm2 and （205.0± 0.2） cN/mm, respectively. The drug releasing behaviors can be sustained for 400 h. It is concluded that the stents have potential application as anintestinal stent in the future.

Hybrid lipopolymer vesicle drug delivery and release systems

Hybrid lipopolymer vesicles are membrane vesicles that can be self-assembled on both the micro-and nano-scale.On the nanoscale,they are potential novel smart materials for drug delivery systems that could combine the relative strengths of liposome and polymersome drug delivery systems without their respective weaknesses.However,little is known about their properties and how they could be tailored.Currently,most methods of investigation are limited to the microscale.Here we provide a brief review on hybrid vesicle systems with a specific focus on recent developments demonstrating that nanoscale hybrid vesicles have different properties from their macroscale counterparts.

A New Nano-Platform for Drug Release via Nanotubular Aluminum Oxide

Nanotubular materials have many favorable properties for drug delivery. We present here a pioneering study of controlled release of a model drug, amoxicillin, from the internal nanopore structure of self-ordered, periodically spaced-apart aluminum oxide with an innovative, nanotubular geometry. This aluminum oxide nanotube geometry has not yet been revealed for biological applications, thus we have selected this oxide nanotube structure and demonstrated its ability as a drug carrier. Controlled, sustained release was achieved for over 5 weeks. The release kinetics from the nanotube layer was thoroughly characterized and it was determined that the amount of drug released was proportional to the square root of time. This type of controlled release and longevity from the nanotube layer has potential for therapeutic surface coatings on medical implants. Furthermore, this type of geometry has many features that are advantageous and biologically relevant for enhancing tissue biointegration.

An Investigation of the Dimensional Changes of Polymer Mixture Tablets Containing a Soluble Drug, Using an Image Analysis Method. Influence of These Characteristics on Drug Release and Its Mechanism

The properties and characteristics of the polymer used for the preparation of matrix drug delivery systems considerably influence their performance and the extent of drug release and its mechanism. The objective of this research was to examine the dimensional changes, and gel evolution of polymer matrices consisting of three different polymers Polyox, sodium alginate (hydrophilic) and Ethocel (hydrophobic), using an image analysis method. Furthermore to explore how these changes influence the release rate of a soluble drug namely, venlafaxine. All tablets displayed marked dimensional expansion and gel growth particularly those consisting of two hydrophilic polymers Polyox/sodium alginate (POL/SA/V) compared to those consisting of the hydrophilic/hydrophobic Polyox/Ethocel (POL/ET/V). Similarly the thickness of the gel layer in POL/SA/V matrices increased considerably with time up to 8 hours. In general our findings show that the POL/SA/V matrices, due to their thicker gel layer produced a more effective barrier which results in a more pronounced sustained release delivery. This accounts for the slower and smaller overall drug release observed with the POL/SA/V matrices compared to those containing POL/ET/V and indicates that the formation of a thick and durable gel barrier is a characteristic necessary for the preparation of sustained drug release systems. Moreover the solubility of venlafaxine in combination with the polymer’s properties appears to play an important role on the extent of drug release and the release mechanism. Overall the polymer mixtures examined comprise a useful and promising combination of materials for the development and manufacture of sustained release preparations based on these polymers.