Polymer Matrix Systems Research Articles

Recent Advancements in Gallic Acid-Based Drug Delivery: Applications, Clinical Trials, and Future Directions.

Gallic acid (GA) is a well-known herbal bioactive compound found in many herbs and foods like tea, wine, cashew nuts, hazelnuts, walnuts, plums, grapes, mangoes, blackberries, blueberries, and strawberries. GA has been reported for several pharmacological activities, such as antioxidant, inflammatory, antineoplastic, antimicrobial, etc. Apart from its incredible therapeutic benefits, it has been associated with low permeability and bioavailability issues, limiting their efficacy. GA belongs to BCS (Biopharmaceutics classification system) class III (high solubility and low probability). In this context, novel drug delivery approaches played a vital role in resolving these GA issues. Nanocarrier systems help improve drug moiety's physical and chemical stability by encapsulating them into a lipidic or polymeric matrix or core system. In this regard, researchers have developed a wide range of nanocarrier systems for GA, including liposomes, transfersomes, niosomes, dendrimers, phytosomes, micelles, nanoemulsions, metallic nanoparticles, solid lipid nanoparticles (SLNs), nanoparticles, nanostructured lipid carriers, polymer conjugates, etc. In the present review, different search engines like Scopus, PubMed, ScienceDirect, and Google Scholar have been referred to for acquiring recent information on the theme of the work. Therefore, this review paper aims to emphasize several novel drug delivery systems, patents, and clinical updates of GA.

Glass fibre hybridization to improve the durability of circular flax fibre reinforced composites with off-the-shelf recyclable polymer matrix systems for large scale structural applications

Natural fibre composites (NFCs) are not durable in the long run because of the susceptibility of natural fibres to environmental conditions and specifically moisture. Hybridizing NFC laminates externally, with synthetic fibre reinforcements, may improve durability, due to their inherent environmental resistance. This work aims to investigate the effects of glass hybridization, on flax fibre composites, studied via accelerated ageing. In specific, the durability of hybrid flax/glass fibre reinforced polymer composites, with two recyclable polymer matrices was investigated. Unidirectional (UD) flax and UD glass fibre reinforcements were employed to fabricate laminates, with two fully-recyclable off-the-shelf resin systems, as matrix: (i) a bio-based epoxy resin and (ii) an acrylic liquid thermoplastic (Elium®). In addition, a standard petroleum-based epoxy polymer matrix was for reference purposes. Weathering and hygrothermal ageing were used to test the durability of coupons, exposed to UV radiation/condensation/water spray environment (weathering ageing), and full-immersion in distilled water at 23, 40, and 60°C (hygrothermal ageing). In all cases, ageing was performed for a total duration of 56 days. The performance of the unaged and aged composite coupons was assessed and compared in terms of flexural and viscoelastic performance as well as SEM (Scanning Electron Microscopy) analysis. It was revealed that the addition of glass fibres with flax fibres in the hybrid composites improves the performance and better resistance against ageing environments than their neat flax fibre composites.

Optimised herbal transdermal patch of ethnobotanical plant Costus igneus N. E. br. Developed through response surface methodology

Costus igneus (Family: Costaceae) has been used by the aboriginal humans since long through oral route. In our laboratory, we used biodegradable polymer for release control of this transdermal patch. This transdermal patch could be affixed in the lower abdominal region which releases intraperitoneally after principal meals, twice a day; which could be terminated instantly by removing the patch externally. Our objective is Formulation, evaluation and statistical designing of a Transdermal patch containing ethnobotanical plant Costus igneus. As Transdermal Patch reduces can be removed when termination of treatment is necessary and it also has the capability to bypass the different chemical changes that a oral pill has to go through. The Macro-physico evaluation parameters were calculated. The folding endurance was in between of 7 to 16, the maximum value was of the FOPT, the Tensile strength was relatively similar in all the formulations. FOPT showed the highest of all. In percentage elongation test the FOPT showed good resilience, thickness was relatively acceptable for all the formulations. % moisture content and %moisture uptake was acceptable in all of the formulations showed a good and satisfiable range. The drug content was calculated according the total quercetin content taking pure quercetin API as the reference FOPT had the highest drug content of 82.5%. The Response Surface Curve predicted the optimised formulation and the desirability score also gives us our optimised patch. The Kinetics for the optimum by the optimization of transdermal patch was observed in all the different type of plots. The FOPT had a good linearity of 0.938 in regression co-efficient with Korsmeyer-Peppas Plot . It explains the release of drug’s material through a polymeric matrix system while also considering Non-Fickian drug release mechanism. The different Response Surface Curve allows us to predict from the software that the FOPT Formulation is the Gem of Ten. This would produce beneficial blood-sugar content reduction. If we can commercialise this Herbal Transdermal Patch then, it can be an innovation remedy for this chronic disease.

Characterising flame-retardant mechanism of phosphorous-containing intumescent coating on polyethylene via ReaxFF MD simulations

Localised flame-retardant (FR) chemistry of polymer composites is complex, versatile and microscopic depending on the combination of polymer matrix and various FR systems. Particularly, the pyrolysis behaviour of the polymers can be varied and reinforced by effective microscopic synergistic effects between coating compositions. However, these atomistic reactions can be difficult to be characterised via experimental approaches. In this study, experimental studies and reactive molecular dynamic (ReaxFF-MD) simulation techniques were utilised to identify the thermal degradation behaviour of flame retarded high-density polyethylene (HDPE), coated with phosphoric acid (PA) and pentaerythritol (PER). The simulations tracked the pyrolysis product distribution under different heating temperatures and elucidated the pyrolysis hindrance offered by the FR system. The atomistic reaction pathways of phosphorus-based FR mechanism were also characterised, including secondary reactions and intermediate species, such as P-O-C and P-O-P cross-linking between FRs and radical capturing effects. These reactions were found to be increasing the C/H ratios of pyrolysed hydrocarbons and the aromaticity of residues. After applying the periodic removal techniques, the simulations can even predict the residue weight percentage of the polymer and exhibit similar degradation behaviour to the experimental results.

Encapsulation of Methanotrophs within a Polymeric Matrix Containing Copper- and Iron-Based Nanoparticles to Enhance Methanol Production from a Simulated Biogas.

The production of renewable energy or biochemicals is gaining more attention to minimize the emissions of greenhouse gases such as methane (CH4) and carbon dioxide for sustainable development. In the present study, the influence of copper (Cu)- and iron (Fe)-based nanoparticles (NPs), such as Cu, Fe3O4, and CuFe2O4, was evaluated during the growth of methanotrophs for inoculum preparation and on the development of a polymeric-matrix-based encapsulation system to enhance methanol production from simulated biogas (CH4 and CO2). The use of simulated biogas feed and the presence of NP-derived inoculums produce a remarkable enhancement in methanol production up to 149% and 167% for Methyloferula stellata and Methylocystis bryophila free-cells-based bioconversion, respectively, compared with the use of pure CH4 as a control feed during the growth stage. Furthermore, these methanotrophs encapsulated within a polymeric matrix and NPs-based systems exhibited high methanol production of up to 156%, with a maximum methanol accumulation of 12.8 mmol/L over free cells. Furthermore, after encapsulation, the methanotrophs improved the stability of residual methanol production and retained up to 62.5-fold higher production potential than free cells under repeated batch reusability of 10 cycles. In the presence of CH4 vectors, methanol production by M. bryophila improved up to 16.4 mmol/L and retained 20% higher recycling stability for methanol production in paraffin oil. These findings suggest that Cu and Fe NPs can be beneficially employed with a polymeric matrix to encapsulate methanotrophs and improve methanol production.

Selected technical ceramics as nanoreinforcement for polyvinyl butyral/epoxy polymer composites

In this study, various technical ceramics in the form of nanostructures, known for their exceptional mechanical properties and thermal resistance, were analysed as potential reinforcement of a polymer matrix system. A combined, hybrid composite matrix was considered, consisting of epoxy resin and polyvinyl butyral. The following nanostructures were incorporated into the polymer matrix by ultrasonication and solvent-casting technique: B4C, TiB2, CNT and INT-WS2. Polymer composites were prepared by solvent-casting of neat hybrid polymer matrix and polymer matrix reinforcing with each chosen individual nanostructure from a temporary solvent – ethanol. The characterisation of the obtained polymer composite samples encompassed Fourier transform infrared spectroscopy analysis, differential scanning calorimetry, tensile test, hardness measurement and examination of resistance to cavitation wear.

Recent Approaches of Matrix Release Tablet in NDDS System

The purpose of this analysis is to categorize matrix tablets according to the kind of polymer they are made of as well as the rate at which they release their contents. When it came to medicinal applications, the matrix system was the very first oral extended release platform ever developed. The utilization of matrix tablets enables the modification of drug release characteristics. They are highly favored for this kind of treatment because of the benefits they give for the patient in terms of better adherence to the treatment, more stable medication levels, decreased dose and bad effects, and a bigger safety margin for highly potent medications. Because of their versatility in delivering a desired drug release profile, cheap cost, and general regulatory acceptability, hydrophilic polymer matrix systems are frequently used in oral controlled drug delivery dosage forms. Because of the rapid diffusion of the dissolved medication via the hydrophilic gel network, the use of hydrophilic matrix alone for delayed drug release is not possible for medicines that are very water soluble. It is now generally accepted that the formulation of such drugs requires the use of matrix systems that incorporate hydrophobic polymers. It would appear that the most successful strategy would be to create a formulation for oral controlled release by employing matrix tablets.

Effect of graphene oxide fibre surface modification on low-velocity impact and fatigue performance of flax fibre reinforced composites

Fatigue and impact resistance are essential performance indicators in structural biocomposites. Integrating multilayer and oxygen-rich graphene oxide (GO) crystals as a fibre surface modification or reinforcing agent in polymer matrix systems have been shown to enhance the interfacial strength and toughness of natural fibre composites. However, the state-of-the-art literature on the GO-modification of composites has focused mainly on their microscale and quasi-static mechanical performance. Here, the fatigue testing results showed that surface modification of flax fibres with GO reduces the slope of the S-N curve by 17% and promotes fibre pull-outs upon failure. Based on the in-situ impact damage analysis, the GO-modification delayed the impact damage initiation and prolonged the stable damage progression phase. The impact perforation energy was similar for modified and unmodified specimens. At kinetic energies below the perforation limit, the GO-modification suppressed the extent of fibre failure and endowed flax-epoxy specimens with better damping performance.

The role of matrix tablet in controlled release drug delivery system

The purpose of this review article is to characterize all of the parameters regarding the types, polymers used, and release kinetics of matrix tablets. Matrix system was the earliest oral extended-release platform for medicinal use. Matrix tablets are most commonly used methods to modulate the release profile of drugs. They are much desirable and preferred for such therapy because they offer better patient compliance, maintain uniform drug levels, reduce dose and side effects, and increase safety margin for high potency drugs. Hydrophilic polymer matrix systems are widely used for designing oral controlled drug delivery dosage forms because of their flexibility to provide a desirable drug release profile, cost effectiveness, and broad regulatory acceptance. However, the use of hydrophilic matrix alone for extending drug release for highly water-soluble drugs is restricted due to rapid diffusion of the dissolved drug through the hydrophilic gel network. For such drugs it becomes essential to include hydrophobic polymers in the matrix system. This leads to the conclusion that matrix tablets seem to be most promising when developing an oral controlled release formulation.

Development of Doxazosin mesylate liquisolid system for improved manufacturing processability and bioavailability: in vitro and in vivo evaluation for tailored hypertension treatment approach with modified dissolution rates

In the present research, an attempt was made to optimize the blends of different carriers Neusiln US2, Avicel PH101, and Fujicalin SG by individually blending with each of coating materials Aerosil 200 and Syloid 244 FP that were proposed to contribute to a modified drug dissolution rates of Doxazosin mesylate (DX) through a liquisolid polymer matrix system. The liquisolid formulations were prepared using selected solvent, carriers, and coats by varying drug to polymer ratios. Further formulations were investigated for pre-compression processability by Heckel plot analysis, elastic recovery studies, and post-compression characteristics. In case of carriers, compared to Avicel PH101 highest flowable values (ф) were observed for Neusilin US2 and Fujicalin SG whereas, for coat these values were highest for Aerosil 200 than Sylloid 244 FP. Liquisolid compact with Fujicalin SG and Aerosil 200 exhibited fast release (FR) of 78% in 20 minutes. The liquisolid compact with Neusilin US2 and Syloid 244 FP exhibited prolonged release (PR) of 60% in 240 minutes. DSC and XRD analysis showed loss of DX crystallinity which was confirmed by SEM analysis indicating DX detention within the liquisolid system, in a molecularly dispersed solubilized form. The in vivo studies of DX liquisolid FR formulation exhibited 1.89 fold increase in the oral bioavailability which was 1.69 fold for DX PR formulation compared to pure DX which demonstrated a promising tailored hypertension treatment approach.

Effect of Nanoparticles and Their Anisometry on Adhesion and Strength in Hybrid Carbon-Fiber-Reinforced Epoxy Nanocomposites

Carbon-fiber-reinforced plastics are composite materials with record-high specific strength, which depends on the efficiency of stress redistribution between the reinforcing fibers by the polymer matrix. The problem is the accurate assessment of adhesion in the carbon fiber–polymer matrix system since it affects the overall strength of the composite. This paper provides a novel electrochemical method for determining adhesion by estimating the critical length of carbon fibers that protrude above the fracture surface of the fiber-reinforced composite using their electrical conductivity and insulating properties of the polymer matrix. The method has been successfully applied to evaluate adhesion in carbon plastics having an epoxy matrix filled with nanoparticles of different anisometry: carbon nanotubes, organomodified montmorillonite, or detonation nanodiamonds. In addition to adhesion measurements, the effect of nanoparticles on the viscosity of epoxy binder, its impregnation efficiency of carbon fibers, curing, glass transition, and tensile strength of fiber-reinforced composites was estimated. Nanodiamonds at a mass fraction of 0.1% proved to be the most effective for improving the quality of epoxy carbon plastics, increasing fiber–matrix adhesion by 2.5 times, tensile strength by 17%, and not decreasing the glass transition temperature.

Fiber-reinforced composites in dentistry - An insight into adhesion aspects of the material and the restored tooth construct.

This review aimed to highlight the insight into adhesion aspects within the components of the glass FRC (i.e., fiber and matrix) and between resin luting material and the glass FRC construction. The fundamentals of semi-interpenetrating polymer network (semi-IPN) based FRCs and their advantages in forming a solid adhesive interface with indirect FRC restoration, dental adhesive, and luting cement are elaborated. The important resin matrix systems and glass fibers used in FRCs are discussed. This is principally based on a survey of the literature over Medline/PubMed, Web of Science, and Scopus databases and a review of the relevant studies and publications in scientific papers in international peer-reviewed journals for the specific topic of biomaterials science. The keywords used for the search approach were: adhesion, fiber-reinforced composite, glass fiber, and semi-interpenetrating polymer network. The polymer matrix systems of semi-IPN-based FRCs and formation of secondary-IPN layer are pivotal for bonding of multiphasic indirect dental constructs and repair. Additionally, describing areas of indication for FRCs in dentistry, explaining the adhesion aspects of FRC for the cohesion of the material itself, and for obtaining durable adhesion when the FRC construct is luted to tooth and remaining dentition. Current progress in the field of FRC research and future directions are summarized and presented. By understanding the isotropic-anisotropic nature of fibers and the interfacial adhesion within the components of the FRC; between resin cement and the FRC construction, the clinically successful FRC-based multiphasic indirect tooth construct can be achieved. The interfacial adhesion within the components of the FRC and between resin luting material and the FRC construction play a key role in adhesion-based unibody dental restorations.

Irvingia gabonensis (O'Rorke) Bail polymer matrix system for controlled drug delivery.

Irvingia gabonensis kernel polymer has gained attention in drug delivery systems because of its compatibility and degradation under natural and physiological conditions. This study aimed to evaluate Irvingia gabonensis polymer as a matrix system for the controlled delivery of ibuprofen in comparison to xanthan gum and hydroxypropylmethylcellulose (HPMC). Irvingia gabonensis polymer was extracted using established methods and dried using the ovenand freeze-drying methods. Ibuprofen tablets were prepared by direct compression and the effects of polymer concentration (10-50%), excipients (lactose, microcrystalline cellulose and dicalcium phosphate dihydrate) and polymers (xanthan gum and HPMC) on the mechanical and drug release properties of the tablets were evaluated. Density measurements and the Heckel and Kawakita equations were used to determine the compression properties of the tablets. Friability, crushing strength and the crushing strength-friability ratio (CSFR) were used to evaluate the mechanical properties of the tablets, while dissolution times were used to evaluate drug release from the matrices. The drug release mechanisms were determined by fitting the dissolution data into classic kinetic equations. Irvingia gabonensis polymer deformed plastically with a fast onset and a high amount of plastic deformation compared with xanthan gum and HPMC. This polymer was directly compressible and formed intact non-disintegrating tablets; the mechanical and dissolution properties of Irvingia gabonensis polymer tablets generally decreased with increasing concentration of ibuprofen. The ranking of dissolution times was xanthan gum > freeze-dried Irvingia gabonensis > HPMC > oven-dried Irvingia gabonensis. The addition of the excipients improved the mechanical properties of the tablets, aided ibuprofen release, and altered the release kinetics, which was largely defined by the Korsmeyer-Peppas model. Increasing the proportion of xanthan gum and HPMC in the matrices resulted in a decreased amount of ibuprofen released after 9 h, with xanthan gum having a greater effect. Irvingia gabonensis polymer matrices may be effective in the preparation of controlled release tablets, and their right combination with xanthan gum or HPMC could provide a time-independent release for longer durations.

Comparison of internal friction measurements on Ni-Ti reinforced smart composites prepared by additive manufacturing

Polymer 3D printing has been utilised in aerospace to produce complex lightweight structures, in medical fields to print tissues and organs, and in a number of other industries to combat the rising demand for weight-saving engineering solutions. Pure polymer goods created through 3D printing, on the other hand, lack strength and functionality. Therefore, by combining matrix and reinforcing materials, 3D printing of polymer composites can overcome these problems. Also various researchers have used matrix system either epoxy resin or vinyl ester resin. Despite its wide usage, resins have few drawbacks like microleakage and high curing time which could be eliminated by 3D printing. In this work, we have focused on using 3D printed polymer matrix system. To enhance the property, shape memory alloys (SMAs) are introduced in the structure as a reinforcement. Shape memory alloys are a class of smart material that, when heated over a certain temperature, can recover deformation. SMAs exhibit two main characteristics i.e., shape memory effect (SME) and superelasticity (SE). SMAs are available in a variety of shapes, including wires, springs, sheets, and tubes. The SMA wires can be embedded in the composites for a variety of reasons, such as enhancing mechanical properties, shape morphing of structures and for use as actuators. Damping is one such mechanical property which can enhanced by reinforcing SMA wires. In this research work, the samples were fabricated using 3D printing of PLA and PETG with SMA wires embedded in two different forms i.e., continuous and discontinuous. The samples were then examined under a dynamic mechanical analyzer to study the damping (internal friction) behaviour of the smart composites. It has been found that the incorporation of SMA wires into the matrix had a significant influence on the dynamic mechanical properties. Also, the samples with SMA reinforced in continuous manner had the higher value of tan δ i.e., it had good damping properties in comparison to short fibre reinforced composites.

Design, Development, and Evaluation of Transdermal Patches Containing Donepezil Hydrochloride

This study aimed to develop a donepezil hydrochloride (DH) transdermal drug delivery system to address non-compliance due to dementia in Alzheimer’s patients. DH has a low dose, balanced hydrophilicity/lipophilicity, and low toxicity making it suitable for transdermal. DH transdermal patches were prepared using a polymer and plasticizer matrix system via box-Behnken design and evaluated for properties. Formulation B2 containing hydroxy propyl methyl cellulose (HPMC), ethyl cellulose (EC), and xanthan gum was optimal, exhibiting a maximum of ~99.17% in-vitro drug release for 48 hours. In-vivo pharmacokinetic parameters studied in rabbits were superior to commercial DH tablets. The study demonstrates the potential for DH transdermal patches as an alternative to oral medication for Alzheimer’s patients. The patches can provide sustained release for prolonged periods without requiring multiple doses. However, further confirmation is needed via in-vivo pharmacodynamic and human pharmacokinetic studies.

Abstract 304: Effect of paclitaxel stereochemistry on x-ray-triggered release of paclitaxel from CaWO4/paclitaxel-coloaded PEG-PLA nanoparticles

Abstract Head and neck squamous cell carcinoma (HNSCC) is the 8th most common cancer in the United States predominantly affecting people over 65 years of age with an increasing rate of incidence across the world. Current therapies for HNSCC include surgical resection, chemotherapy (CT), and radiotherapy (RT). For locally advanced/unresectable HNSCC, the CT-RT combination (“chemoradiation”) has been shown to be more effective than CT or RT alone, and is currently the standard of care. Intratumoral (IT) chemotherapy-based chemoradiation has the potential to overcome the limitations of conventional systemic CT-RT that severely affects a patient’s quality of life. For realization of maximum benefits from IT CT-RT, our team has developed a radiation-controlled drug release nanoparticle formulation (paclitaxel (PTX) and CaWO4 nanoparticles (CWO NPs) co-encapsulated within a capsule formed by poly(ethylene glycol)-poly (lactic acid) (PEG-PLA), named “PEG-PLA/CWO/PTX NPs”). This unique formulation releases PTX only when it is exposed to X-ray irradiation. We have previously reported that IT-administered PEG-PLA/CWO/PTX NPs stay within the tumor for at least a month, producing significant therapeutic effects in terms of tumor suppression and survival in mouse models of HNSCC. This work demonstrates the effect of PTX stereochemistry on radiation-controlled release of the drug from a nano polymer matrix system (PEG-PLA/CWO/PTX NPs). The stereoisomertic characteristics of PTX products from two different manufacturers (“PTX-S”, and “PTX-B”) were analyzed by Raman spectroscopy, circular dichroism and 2D HMQC/NOESY NMR measurements. In their unencapsulated (free) state, PTX-S and PTX-B were comparable in their ability to kill cancer cells in vitro. However, they were found to be significantly different in water solubility; PTX-S (water solubility ≈ 4.69 μg/mL) is about 19 times more water soluble than PTX-B (water solubility ≈ 0.25 μg/mL). This difference in water solubility was found to cause a large difference in X-ray-triggered release kinetics of the PTX loaded within the PEG-PLA/CWO/PTX NPs in both in vitro and in vivo environments; PTX-S is released from PEG-PLA/CWO NPs significantly faster upon X-ray irradiation than PTX-B. This difference in release kinetics produced an interesting difference in their time-dependent therapeutic effects; at short times (< 1 month), concurrent PEG-PLA/CWO/PTX-S NPs produced a greater tumor suppression effect; on the other hand, PEG-PLA/CWO/PTX-B NPs had a longer lasting radio-sensitizing effect. In summary, the stereoisomers of PTX exhibit significantly different PK characteristics when used with controlled release carriers, even though they are pharmacologically indistinguishable in their unformulated form. Citation Format: Kaustabh Sarkar, Sandra Torresgrossa-Allen, Mark P. Langer, Gregory Durm, Sanjeev Narayanan, Bennett D. Elzey, You-Yeon Won. Effect of paclitaxel stereochemistry on x-ray-triggered release of paclitaxel from CaWO4/paclitaxel-coloaded PEG-PLA nanoparticles [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 304.

Modeling of polyvinylidene fluoride nanocomposite utilizing BaTiO3@SiO2 for energy storage

Polymer-based nano dielectrics are attracting great attention in the research world. Such materials, primarily for embedded capacitors, offer greater feasible energy storage alternatives. This research aims to analyze the distribution of electric field in binary and core–shell BaTiO3@SiO2 structures of polyvinylidene fluoride (PVDF) nanocomposites with various filler concentrations of nanofibers using COMSOL Multiphysics® software-based finite element method. The core–shell structures enhanced the electric field strength and polarization as compared to binary nanocomposites. The novelty of the work is the design of the interface layer on the surface of nanoparticles was beneficial in reducing the local electric field in the filler/ polymer matrix system. According to a finite element simulation, the SiO2 shell may effectively reduce the electric field contrast between the polymer matrix and the BaTiO3 filler. The PVDF/BaTiO3@SiO2 nanocomposites show a maximum electric field strength of 380 MV/m, which is about 2.5 times larger than PVDF/BT nanocomposites under both the same filler content of 2.5 wt% and applied voltage. This work provides a prosperous path to achieving large-performance capacitors.

In Vitro and In Vivo Evaluation of Oral Controlled Release Formulation of BCS Class I Drug Using Polymer Matrix System.

Diltiazem hydrochloride is a calcium channel blocker, which belongs to the family of benzothiazepines. It is commonly used to treat hypertension and atrial fibrillation. Even though the drug has high solubility, its high permeability and rapid metabolism in the liver can limit the bioavailability and increase the dose frequencies for up to four times per day. This study focused on a polymer matrix system not only to control the drug release but also to prolong the duration of bioavailability. The polymer matrices were prepared using different ratios of poloxamer-188, hydroxypropyl methylcellulose, and stearyl alcohol. In vitro and in vivo assessments took place using 24 rabbits and the results were compared to commercially available product Tildiem® (60 mg tablet) as reference. Overall, the rate of drug release was sustained with the gradual increase of poloxamer-188 incorporated with hydroxypropyl methylcellulose and stearyl alcohol in the matrix system, achieving a maximum release period of 10 h. The oral bioavailability and pharmacokinetic parameters of diltiazem hydrochloride incorporated in polymer matrix system were similar to commercial reference Tildiem®. In conclusion, the combination of polymers can have a substantial effect on controlling and prolonging the drug release pattern. The outcomes showed that poloxamer-188 combined with hydroxypropyl methylcellulose and stearyl alcohol is a powerful matrix system for controlling release of diltiazem hydrochloride.

Characteristic Comparison of an Intraoral Thin Film Containing Astaxanthin Nanoemulsion Using Sodium Alginate and Gelatin Polymers

The present study was conducted to compare the characteristics of a thin film containing an astaxanthin-loaded nanoemulsion (TFANE) using two kinds of natural polymers, namely sodium alginate and gelatin. An astaxanthin nanoemulsion was prepared by using the self-nanoemulsifying method, followed by incorporation into a polymer matrix system by the solvent casting method to form TFANE. A characteristic comparison between the sodium alginate and gelatin matrix systems was carried out by comparing the physical and mechanical film properties. At the end of the study, in vitro dissolution tests were also assessed. An intraoral film with good physical and mechanical properties containing an astaxanthin-loaded nanoemulsion was developed successfully using a natural polymer matrix system. The film, made from a gelatin matrix system containing an astaxanthin nanoemulsion, was more flexible and harder than films made from a sodium alginate matrix system, where all of the films have ideal characteristics for intraoral delivery. The dissolution test results showed that, with both sodium alginate and gelatin, more than 90% of the drug was released at 15 minutes. Gelatin as a natural polymer appears to be promising for the preparation of an intraoral thin film delivery system.

Assessing the impact of counterion types on the sustained release characteristics of high-payload drug-ion complex: A case study on tetracycline hydrochloride

Complexation of ionized hydrophilic drugs with counterions (e.g. polyelectrolytes, ionic amphiphiles, multivalent salt ions) represents a well-established formulation approach to produce sustained release of highly soluble drugs while maintaining a high drug payload. This renders the drug-ion complex an attractive alternative to the conventional polymer matrix systems. The effects of the counterion's type on the sustained release characteristics of drug-ion complexes, however, have not been investigated before under the same dissolution environment. Using antibiotic tetracycline hydrochloride (TC•HCl) as the model hydrophilic drug, we investigated the effects of three types of counterions, sodium dextran sulfate (DXT), sodium dodecyl sulfate (SDS), and K2HPO4, on (1) the sustained release characteristics, (2) long-term storage stability, (3) preparation efficiency (i.e. yield, payload), and (4) antibiotic activity of the resultant (TC•HCl)-ion complexes. The results showed that the three complexes exhibited comparable TC•HCl payloads at approximately 80% (w/w) and yield between 40 and 60% (w/w). They also exhibited good storage stability after 18 months and uncompromised antibiotic activity compared to the native drug. In the intestinal fluid, all three complexes could produce sustained drug release profiles, albeit at different rates ((TC•HCl)-DXT > (TC•HCl)-SDS > (TC•HCl)-HPO4), whereas in the gastric fluid, only the (TC•HCl)-DXT complex could produce a sustained release profile suitable for oral delivery. The different sustained release profiles among the complexes were attributed to their different solid forms (amorphous versus crystalline), hydrophobicity, solubility, and drug release mechanisms. The present work highlighted the importance of selecting the most suitable counterion to achieve the desired sustained drug release profile.