Polymer blends for controlled release coatings

Formulation Study of a Poly(amino methacrylate) Film-Forming Solution for Transdermal Administration

BACKGROUND/OBJECTIVES

The objective of this paper is to design a novel film-forming system (FFS) based on Eudragit® E PO (EuE) polymeric solutions, differing in volatile solvents (i.e., isopropanol and ethanol) and plasticizers (i.e., tributylcitrate, glycerine, triacetin and PEG 400).

METHODS

The physicochemical and mechanical properties of the FFS and dried films were evaluated in terms of formation time, stickiness, Tg, tensile strength, break elongation and Young's modulus. The in vitro skin permeation studies were conducted on formulations containing caffeine and testosterone.

RESULTS

The FFS, consisting of EuE and PEG400 in isopropyl alcohol and ethanol (80:20, v/v), exhibited rapid film formation within about 5 min and the dried film allowed a high skin permeability compared to other formulations due to the ability to increase the thermodynamic activity of both drugs. When triiodothyronine (T3) was loaded as a model of a very low soluble drug, tocopherol polyethylene glycol succinate (TPGS) was added as a co-solvent and it allowed for the improvement of T3 retention in the skin.

CONCLUSIONS

Among the formulative variables, the nature and the amount of plasticizer represent the most critical variables to obtain an EuE-based film with satisfying physical and biopharmaceutical properties.

A Miscibility Study of p(MMA-co-HEMA)-Based Polymer Blends by Thermal Analysis and Solid-State NMR Relaxometry

Ternary amorphous solid dispersions (ASDs) consist of a multicomponent carrier with the aim of improving physical stability or dissolution performance. A polymer blend as a carrier that combines a water-insoluble and a water-soluble polymer may delay the drug release rate, minimizing the risk of precipitation from the supersaturated state. Different microstructures of the ternary ASD may result in different drug release performances; hence, understanding the phase morphology of the polymer blend is crucial prior to drug incorporation. The objective of this study is to investigate the miscibility of the water-insoluble p(MMA-co-HEMA) and water-soluble polymers such as HPC, HPMC, HPMC-AS, and Soluplus. To prepare the polymer blends, p(MMA-co-HEMA) was spray dried in 80/20 and 90/10 (w/w) ratios with one of the water-soluble polymers. Thermal analysis (mDSC and DMA) and solid-state (ss)NMR relaxometry were applied to study the miscibility of these blends. No conclusions regarding miscibility could be drawn from the Tg measurements by thermal analysis. However, phase-separation could be demonstrated in all blends by ssNMR relaxometry. Moreover, by measuring both the T1ρH and T1H relaxation times, domain sizes between 5 and 50 nm could be estimated. This work shows the importance of using complementary analytical techniques to investigate polymer miscibility.

Technological Strategies Applied to Pharmaceutical Systems for Intranasal Administration of Drugs Intended for Neurological Treatments: A Review

The complexity of treating neurological diseases has meant that new strategies have had to be developed to deliver drugs to the brain more efficiently and safely. Intranasal drug delivery is characterized by its ease of administration, safety, and rapid delivery directly from the nose to the brain. Several strategies have been developed to improve the delivery of drugs to the brain via nasal administration. These include the use of mucoadhesive and thermoresponsive polymers and their combination into polymer blends, as well as the use of liposomes, niosomes, and nano- and microemulsions. Therefore, this review focuses on technologies for developing pharmaceutical systems aimed at delivery via the nose to the brain, contributing to new treatments for difficult neurological disorders. Some of the most common and difficult-to-treat neurological conditions, the intranasal route of administration, and the anatomy of the nasal cavity have been discussed, as well as factors that may influence the absorption of drugs administered into the nose. The types of intranasal formulations and the devices that can be used to administer these products are also discussed in this review. Strategies for improving the transport of bioactive agents and increasing bioavailability are highlighted. The technologies discussed in this review can facilitate the development of formulations with improved properties, such as drug release and mucoadhesiveness, which have several advantages for patients requiring complex neurological treatments.

Exploring Immersion Coating as a Cost-Effective Method for Small-Scale Production of Enteric-Coated Gelatin Capsules

The coating process for solid dosage forms is widely used in the pharmaceutical industry but presents challenges for small-scale production, needed in personalized medicine and clinical or galenic settings. This study aimed to evaluate immersion coating, a cost-effective small-scale method, for enteric-coated gelatin capsules using standard equipment. Two enteric coating polymers and different polymer concentrations were tested, along with API solubility. Results were compared with commercially available enteric capsule shells. Successful preparation of enteric coating capsules via immersion necessitates a comprehensive grasp of API and enteric polymer behavior. However, utilizing commercially available enteric capsule shells does not guarantee ease or robustness, as their efficacy hinges on the attributes of the active ingredient and excipients. Notably, coating with Eudragit S100 stands out for its superior process robustness, requiring minimal or no development time, thus representing the best option for small-scale enteric capsule production.

Fabrication and Synthesis of Thiococlchicoside Loaded Matrix Type Transdermal Patch

BACKGROUND

The goal of this work was to synthesize and fabricate matrix type transdermal patches based on a combination of polymers (Eudragit L100, HPMC and PVP K30), plasticizer and crosslinking agents (propylene glycol and triethyl citrate) and adhesives (Dura Tak 87-6908) to increase Thiocolchicoside (THC) absorption via topical route. This method allows avoidance of first-pass metabolism along with a consistent and extended duration of therapeutic activity.

METHODS

Fabrication and casting of polymeric solutions containing THC was done either in petri plates or through lab coater to get transdermal patches. Finally, the formulated patches were studied for their physicochemical and biological evaluation using scanning electron microscopy, FTIR, DSC, XRD and ex-vivo permeation studies using pig ear skin.

RESULTS

FTIR studies confirm that the THC characteristics peaks (carbonyl (Amide I) at 1525.5 cm-1, C=O stretching (tropane ring) at 1664.4 cm-1, Amide II band (N-H stretching) at 3325.9 cm-1, thioether band at 2360.7 cm-1, and OH group stretching band at 3400.2 cm-1) are still present in the polymer mixture even after formulation as a transdermal patch, indicating compatibility among all excipients. While on the other hand, DSC studies confirm endothermic peaks for all the polymers along with THC with the highest enthalpy of 65.979 J/g, which is an indicator of sharp endothermic peak at 198°C, leading to the melting of THC. The percentage drug content and percentage moisture uptake of all the formulation was found in the range of 96 ± 2.04 to 98.56 ± 1.34% and 4.13 ± 1.16 to 8.23 ± 0.90%, respectively. Drug release and release kinetics studies confirm that it is dependent on the composition of individual formulation.

CONCLUSION

All these findings support the possibility of using suitable polymeric composition, as well as proper formulation and manufacturing circumstances, to create a one-of-a-kind technology platform for transdermal drug administration.

Recent Advances in Personal Glucose Meter-Based Biosensors for Food Safety Hazard Detection

Food safety has emerged as a significant concern for global public health and sustainable development. The development of analytical tools capable of rapidly, conveniently, and sensitively detecting food safety hazards is imperative. Over the past few decades, personal glucose meters (PGMs), characterized by their rapid response, low cost, and high degree of commercialization, have served as portable signal output devices extensively utilized in the construction of biosensors. This paper provides a comprehensive overview of the mechanism underlying the construction of PGM-based biosensors, which consists of three fundamental components: recognition, signal transduction, and signal output. It also detailedly enumerates available recognition and signal transduction elements, and their modes of integration. Then, a multitude of instances is examined to present the latest advancements in the application of PGMs in food safety detection, including targets such as pathogenic bacteria, mycotoxins, agricultural and veterinary drug residues, heavy metal ions, and illegal additives. Finally, the challenges and prospects of PGM-based biosensors are highlighted, aiming to offer valuable references for the iterative refinement of detection techniques and provide a comprehensive framework and inspiration for further investigations.

Ultra-high-resolution optical coherence tomography for the investigation of thin multilayered pharmaceutical coatings

Optical Coherence Tomography (OCT) has recently gained attention as a promising technology for in-line monitoring of pharmaceutical film-coating processes for (single-layered) tablet coatings and end-point detection with commercial systems. An increasing interest in the investigation of multiparticulate dosage forms with mostly multi-layered coatings below 20 µm final film thickness demands advancement in OCT technology for pharmaceutical imaging. We present an ultra-high-resolution (UHR-) OCT and investigate its performance based on three different multiparticulate dosage forms with different layer structures (one single-layered, two multi-layered) with layer thicknesses in a range from 5 to 50 µm. The achieved system resolution of 2.4 µm (axial) and 3.4 µm (lateral, both in air) enables the assessment of defects, film thickness variability and morphological features within the coating, previously unattainable using OCT. Despite the high transverse resolution, the provided depth of field was found sufficient to reach the core region of all dosage forms under test. We further demonstrate an automated segmentation and evaluation of UHR-OCT images for coating thicknesses, where human experts struggle using today's standard OCT systems.

New Straw Coating Material for Improving the Slow-Release Performance of Fertilizers

In this work, we extracted cellulose from agricultural waste and produced a new straw coating material (ethyl cellulose, EC) through a series of modification operations. The slow-release properties of ethyl cellulose-coated urea (EU) and its absorption and utilization by plants were evaluated. The surface of EU can form a smooth and fine film, and the initial nutrient release rate is only 37.91% that of the uncoated fertilizer. Compared with common urea, the nitrogen of plants cultivated with EU increased by 17.69%, and the leached nitrogen decreased by 61.29%, indicating that EU can reduce nitrogen waste to the greatest extent and continuously supply nutrients to crops. Therefore, the application of EU could be a more practical, environmentally friendly, and sustainable alternative to nitrogen fertilizers.

Chitosan-Based Polymer Blends for Drug Delivery Systems

Polymers have been widely used for the development of drug delivery systems accommodating the regulated release of therapeutic agents in consistent doses over a long period, cyclic dosing, and the adjustable release of both hydrophobic and hydrophilic drugs. Nowadays, polymer blends are increasingly employed in drug development as they generate more promising results when compared to those of homopolymers. This review article describes the recent research efforts focusing on the utilization of chitosan blends with other polymers in an attempt to enhance the properties of chitosan. Furthermore, the various applications of chitosan blends in drug delivery are thoroughly discussed herein. The literature from the past ten years was collected using various search engines such as ScienceDirect, J-Gate, Google Scholar, PubMed, and research data were compiled according to the various novel carrier systems. Nanocarriers made from chitosan and chitosan derivatives have a positive surface charge, which allows for control of the rate, duration, and location of drug release in the body, and can increase the safety and efficacy of the delivery system. Recently developed nanocarriers using chitosan blends have been shown to be cost-effective, more efficacious, and prolonged release carriers that can be incorporated into suitable dosage forms.

Evaluation of coating uniformity for the digestion-aid tablets by portable near-infrared spectroscopy

Process analysis can effectively stabilize pharmaceutical quality and optimize the control of production process. For the sustained-release digestion-aid tablets, the coating film thickness is an important indicator to measure the quality of products. Traditional method mainly spot-checks tablets and measures with visual microscopy, which is time-consuming and laborious. This study attempted to use a portable near-infrared spectroscopy for rapid detection of a Chinese medicine tablets from production line. First, PLS regression models were established for coating film at twelve different locations of the tablet section, and the results showed that the correlation coefficients of training and validation sets were all over 0.80. Subsequently, the twelve locations were divided into six groups to further establish regressions. After chemometrics optimization, the optimal of six group models were generally better than single location models, with R_c² and R_v² all above 0.85, and RMSEV values all below 2.0. The mean relative error of prediction of the optimal model was 9.49%. The pharmaceutical process detection based on the portable NIR spectroscopy met the demand of managing digestion-aid tablet coating data conveniently. The proposed approach can successfully realize on-site and online pharmaceutical monitoring and has a promising practical value.

Ascertain a minimum coating thickness for acid protection of enteric coatings by means of optical coherence tomography

Enteric coatings are designed to protect active pharmaceutical ingredients (APIs) against untimely release in the stomach. Acid protection of such coatings depends on the coating layer thickness and integrity, which must be determined in an accurate and reliable way to ensure the final product's desired performance. Our work addresses the use of optical coherence tomography (OCT) for characterizing the coating thickness and variability of an enteric-coated drug product and linking them to resistance against gastric fluid. In this study, three batches of enteric-coated tablets drawn during the manufacturing process were investigated. An industrial OCT system was used to establish the coating thickness variability of single tablets (intra-tablet), all tablets in a batch (inter-tablet) and between the batches (inter-batch). Based on the large amount of OCT data, we calculated a critical coating thickness for the investigated film coating, which was found to be 27.4 µm. The corresponding distribution has a mean coating thickness of 44.3 µm ± 7.8 µm. The final coated product has a final mean coating thickness of 63.4 µm ± 8.7 µm, guaranteeing that all tablets meet the quality criterion (i.e., acid protection). Based on the measured thickness distributions, already known distribution functions were considered and an additional, new function was proposed for characterizing the coating thickness distributions in the early stages of industrial coating processes. The proposed approach can be transferred to in-line monitoring of the tablet coating processes, which could drastically improve the production efficiency by ultimately allowing real-time release testing (RTRT).

Fabrication of delayed release hard capsule shells from zein/methacrylic acid copolymer blends

Hard capsule shells with an inherent delayed release action are useful for oral administration of active ingredients, which are acid-labile and/or enzymatically degradable in the gastric environment, without the need of film coating. The objective of this study was to fabricate delayed release hard capsule shells by the dip coating method. The film coating formulations comprised blends of zein and methacrylic acid copolymer (Eudragit® L100-55), with and without the addition of the plasticizer, polyethylene glycol 1000. The rheology parameters (loss modulus (G'), storage modulus (G") and loss tangent (tan δ, G"/G')) of the film coating solution were measured to investigate the processability. Central composite design was used to investigate the main, interaction and quadratic effects of the proportion of methacrylic acid copolymer, solid content of the film formers and level of polyethylene glycol 1000 on the capsule wall thickness and mechanical strength. Multiple response optimization was further conducted, and the design space was established. The in vitro drug release in simulated gastric and intestinal fluids of three different formulations in the design space was compared. The results showed that the tan δ value after the gelation point should be < 0.9 in order to form a thin and sturdy capsule shell. The gelation time and viscosity of the coating solution were related to the thickness of the capsule shell. The study showed that drug release from the capsule with a specified thickness and mechanical strength can be modulated by varying the ratio of zein to methacrylic acid copolymer. The delayed drug release profile was achieved through the capsule shell fabricated from zein to methacrylic acid copolymer at the ratios of 75:25 and 83.2:16.8, with 10% polyethylene glycol 1000.

Deltamethrin Microencapsulation in Emulsion Paint Binder and Its Long-Term Efficacy Against Dengue Vector Aedes aegypti

Various control interventions have been effective in the control of arthropod vectors to a certain extent; still, sustained vector control is an existing problem globally. Insecticide-based formulations have been found to be useful, however the proper delivery of active molecules to target vectors is important. Currently, synthetic pyrethroid deltamethrin (DM) has been microencapsulated in the emulsion paint binder and evaluated for long-term effectiveness against dengue vector Aedes aegypti. Different compositions of emulsion binder were prepared by varying the content of monomer and DM. A selection was made for the composition yielding the best combination of properties like solid content, intrinsic viscosity, and DM content. Developed formulation was tested against laboratory-reared and pathogen-free Ae. aegypti mosquitoes. Encapsulation of DM in emulsion binder during polymerization showed a uniform distribution. The optimized formulation was stable and did not have a considerable plasticizing effect. Scanning electron microscopy revealed that grain-like micro crystals of DM and surfactant sodium lauryl sulfate (SDS) were uniformly distributed on the formulation surface. The best optimized formulation was highly effective against dengue vector Ae. aegypti and found to provide efficacy for up to 18 months of application. The knockdown time (KDT) values KDT₁₀ and KDT₅₀ were 7.4 min (95% CI: 5.6–9.1) and 22.1 min (95% CI: 19.7–24.3) respectively, whereas 24 h corrected mortality was 90% (95% CI: 82.5–97.5) after 18 months of application (T18). The probit model used to determine knockdown values did not deviate from the linearity and displayed normal distribution of knockdown % with time for different formulations (p ≥ 0.1). Presently developed DM microencapsulated emulsion binder was stable, smooth, and uniform. The binder displayed excellent anti-insect property and was capable of providing long-term effectiveness against dengue vectors Ae. aegypti. Such a formulation after field-scale evaluation could be very useful in attaining long-term protection from arthropod vectors.

Towards a Better Understanding of Verapamil Release from Kollicoat SR:IR Coated Pellets Using Non-Invasive Analytical Tools

The aim of this study was to gain deeper insight into the mass transport mechanisms controlling drug release from polymer-coated pellets using non-invasive analytical tools. Pellet starter cores loaded with verapamil HCl (10% loading, 45% lactose, 45% microcrystalline cellulose) were prepared by extrusion/spheronization and coated with 5% Kollicoat SR:IR 95:5 or 10% Kollicoat SR:IR 90:10. Drug release was measured from ensembles of pellets as well as from single pellets upon exposure to acetate buffer pH = 3.5 and phosphate buffer pH = 7.4. The swelling of single pellets was observed by optical microscopy, while dynamic changes in the pH in the pellet cores were monitored by fluorescence spectroscopy. Also, mathematical modeling using a mechanistically realistic theory as well as SEM and Raman imaging were applied to elucidate whether drug release mainly occurs by diffusion through the intact film coatings or whether crack formation in the film coatings plays a role. Interestingly, fluorescence spectroscopy revealed that the pH within the pellet cores substantially differed upon exposure to acetate buffer pH = 3.5 and phosphate buffer pH = 7.4, resulting in significant differences in drug solubility (verapamil being a weak base) and faster drug release at lower pH: from ensembles of pellets and single pellets. The monitoring of drug release from and the swelling of single pellets indicated that crack formation in the film coatings likely plays a major role, irrespective of the Kollicoat SR:IR ratio/coating level. This was confirmed by mathematical modeling, SEM and Raman imaging. Importantly, the latter technique allowed also for non-invasive measurements, reducing the risk of artifact creation associated with sample cutting with a scalpel.

Injection-molded capsule bodies and caps based on polymer blends for controlled drug delivery

A variety of polymer:polymer blends was used to prepare hot melt extrudates and empty capsules (bodies and caps) by injection-molding using a benchtop extruder (Babyplast). KollidonSR:inulin and Carbothane:inulin blends were investigated. The impact of the blend ratio on the water uptake and dry mass loss kinetics upon exposure to 0.1 MHCl, phosphate buffer pH6.8 and culture medium optionally inoculated with fecal samples from Inflammatory Bowel Disease (IBD) patients were studied. Hot melt extrudates were loaded with up to 60% theophylline, capsules were filled with drug powder. Increasing the inulin content led to increased water uptake and dry mass loss rates, resulting in accelerated drug release from the dosage forms, irrespective of the type of polymer blend. This can be attributed to the higher hydrophilicity/water-solubility of this polymer compared to KollidonSR and Carbothane. Interestingly, the presence of fecal samples in culture medium increased the water uptake and dry mass loss of hot melt extrudates to a certain extent, suggesting partial system degradation by bacterial enzymes. However, these phenomena did not translate into any noteworthy impact of the presence of colonic bacteria on theophylline release from the investigated extrudates or capsules. Hence, drug release can be expected to be independent of the location "small intestine vs. colon" from these dosage forms, which can be advantageous for long term release throughout the entire gastro intestinal tract.

Secreted Enzyme-Responsive System for Controlled Antifungal Agent Release

Essential oil components (EOCs) such as eugenol play a significant role in plant antimicrobial defense. Due to the volatility and general reactivity of these molecules, plants have evolved smart systems for their storage and release, which are key prerequisites for their efficient use. In this study, biomimetic systems for the controlled release of eugenol, inspired by natural plant defense mechanisms, were prepared and their antifungal activity is described. Delivery and antifungal studies of mesoporous silica nanoparticles (MSN) loaded with eugenol and capped with different saccharide gates—starch, maltodextrin, maltose and glucose—against fungus Aspergillus niger—were performed. The maltodextrin- and maltose-capped systems show very low eugenol release in the absence of the fungus Aspergillus niger but high cargo delivery in its presence. The anchored saccharides are degraded by exogenous enzymes, resulting in eugenol release and efficient inhibition of fungal growth.

PLGA based film forming systems for superficial fungal infections treatment

As proven in clinical trials, superficial fungal infections can be effectively treated by single topical application of terbinafine hydrochloride (Ter-HCl) in a film forming system (FFS). Poly(lactic-co-glycolic acid) (PLGA) derivatives, originally synthesized with intention to get carriers with optimized properties for drug delivery, and multifunctional plasticizers - ethyl pyruvate, methyl salicylate, or triacetin - were used for formulation of Ter-HCl loaded FFSs. After spraying, a biodegradable, transparent, adhesive, and occlusive thin layer is formed on the skin, representing drug depot. In situ formed films were characterized by thermal, structural, viscoelastic, and antifungal properties as well as drug release and skin penetration. DSC and SEM showed fully amorphous films with Ter-HCl dissolved in PLGA in high concentration (up to 15%). FFSs are viscoelastic fluids with viscosity which can be easily adjusted by the type of plasticizer used and its concentration. The formulations showed excellent bioadhesion properties, thus ensuring persistence on the skin. In situ film based on branched PLGA/A plasticized with 10% of ethyl pyruvate allowed prolonged release of Ter-HCl by linear kinetics for the first 6 days with a total time of almost 14 days. During ex vivo human skin penetration experiment, Ter-HCl was found to be located only in its target layer, the epidermis. According to our results, plasticized branched PLGA derivatives loaded by Ter-HCl are suitable for the development of FFSs for superficial fungal infections treatment.

Covalent immobilization of the phytic acid-magnesium layer on titanium improves the osteogenic and antibacterial properties

In order to improve early osseointegration and long-term survival rate of implants, a multifunctional titanium surface that promotes osteogenesis and antibacterial properties is expected. Incorporation of bioactive trace elements such as magnesium ions was proved a promising method to improve osseointegration of titanium. Phytic acid has strong chelating ability with multivalent cations, which has been used in surface modification. Moreover, phytic acid was proved antibacterial potential. Herein, to improve the osteogenic and antibacterial properties, a phytic acid-magnesium (PA-Mg) layer was introduced on titanium using phytic acid as a cross-linker molecule. No obvious changes of the surface characterization were observed by scanning electron microscopy and atomic force microscopy. X-ray photoelectron spectroscopy confirmed that the PA-Mg layer covalently bond to the Ti surface, and the thickness of the PA-Mg layer was about 150 nm. Besides, improved hydrophilic and more protein adsorption were observed on Ti-PA-Mg. Notably, a relatively controlled magnesium release was also observed on Ti-PA-Mg. Human bone mesenchymal stem cells showed better adhesion, proliferation, and osteogenic differentiation on Ti-PA-Mg samples, indicating improved biocompatibility and osteoinductivity. Moreover, Ti-PA-Mg had better antibacterial properties against porphyromonas gingivalis than Ti. Overall, the PA-Mg layer on Ti surface improved the osteogenic and antibacterial properties, which may have promise for use in dental implantation.

Solvent-free temperature-facilitated direct extrusion 3D printing for pharmaceuticals

In an era moving towards digital health, 3D printing has successfully proven its applicability in providing personalised medicine through a technology-based approach. Among the different 3D printing techniques, direct extrusion 3D printing has been demonstrated as a promising approach for on demand manufacturing of solid dosage forms. However, it usually requires the use of elevated temperatures and/or the incorporation of an evaporable solvent (usually water). This can implicate the addition of a drying step, which may compromise the integrity of moisture- or temperature-sensitive drugs, and open the door for additional quality control challenges. Here, we demonstrate a new approach that simplifies direct extrusion 3D printing process with the elimination of the post-printing drying step, by merely adding a fatty glyceride, glyceryl monostearate (GMS), to a model drug (theophylline) and permeable water insoluble methacrylate polymers (Eudragit RL and RS). Indeed, rheological studies indicated that the addition of a combination of a plasticiser, (triethyl citrate), and GMS to theophylline: methacrylate polymer blends significantly reduced the extensional viscosity (to <2.5 kPa·Sec) at 90 °C. Interestingly, GMS demonstrated a dual temperature-dependant behaviour by acting both as a plasticiser and a lubricant at printing temperature (90-110 °C), while aiding solidification at room temperature. X-ray powder diffraction indicated incomplete miscibility of GMS within the polymeric matrix at room temperature with the presence of a subtle diffraction peak, at 2(Θ) = 20°. The 3D printed tablets showed acceptable compendial weight and content uniformity as well as sufficient mechanical resistance. In vitro theophylline release from 3D printed tablets was dependant on Eudragit RL:RS ratio. All in all, this work contributes to the efforts of developing a simplified, facile and low-cost 3D printing for small batch manufacturing of bespoke tablets that circumvents the use of high temperature and post-manufacturing drying step.

A new polymer-excipient for ethanol-resistant, sustained-release oral dosage forms

The use of alcoholic beverages can cause uncontrolled release of drugs from sustained-release solid oral dosage forms and pose severe risks to patient health. The aim of this work was to design a new polymeric excipient with ethanol resistance inherent to the polymer. Polymers were systematically designed, manufactured via emulsion polymerization, and fully characterized. Glass transition temperatures between 10 and 18 °C and minimum film forming temperatures between 10 and 25 °C were chosen because these parameters are ideal for aqueous film-coating processing. Three model drug formulations were made with the new polymer excipients and tested in the presence and absence of ethanol. The concept of an alcohol resistance factor based on Weibull regression analysis was introduced. In vitro results confirmed the hypothesized structure-function relationship between comonomer composition and ethanol resistance. That is, nonionic hydrophilic functional groups interacted more strongly with the ethanolic solvent, as compared with cationic hydrophilic comonomer that interacted more strongly with the surrounding water molecules. The alcohol resistance factor varied between - 44 ± 2% (slower drug release in presence of ethanol) and + 34 ± 0% (faster drug release in presence of ethanol) depending on the comonomer ratio. The main advantages of these new excipients compared with ethanol-resistant excipient blends include ease of use, plasticizers are not necessary, and shorter coating times.

Applications of polymer blends in drug delivery

Background

Polymers are essential components of many drug delivery systems and biomedical products. Despite the utility of many currently available polymers, there exists a demand for materials with improved characteristics and functionality. Due to the extensive safety testing required for new excipient approval, the introduction and use of new polymers is considerably limited. The blending of currently approved polymers provides a valuable solution by which the limitations of individual polymers can be addressed.

Main body

Polymer blends combine two or more polymers resulting in improved, augmented, or customized properties and functionality which can result in significant advantages in drug delivery applications. This review discusses the rationale for the use of polymer blends and blend polymer-polymer interactions. It provides examples of their use in commercially marketed products and drug delivery systems. Examples of polymer blends in amorphous solid dispersions and biodegradable systems are also discussed. A classification scheme for polymer blends based on the level of material processing and interaction is presented.

Conclusion

The use of polymer blends represents a valuable and under-utilized resource in addressing a diverse range of drug delivery challenges. It is anticipated that new drug molecule development challenges such as bioavailability enhancement and the demand for enabling excipients will lead to increased applications of polymer blends in pharmaceutical products.

Graphical abstract

Defects and defect engineering in Soft Matter

Soft matter covers a wide range of materials based on linear or branched polymers, gels and rubbers, amphiphilic (macro)molecules, colloids, and self-assembled structures. These materials have applications in various industries, all highly important for our daily life, and they control all biological functions; therefore, controlling and tailoring their properties is crucial. One way to approach this target is defect engineering, which aims to control defects in the material's structure, and/or to purposely add defects into it to trigger specific functions. While this approach has been a striking success story in crystalline inorganic hard matter, both for mechanical and electronic properties, and has also been applied to organic hard materials, defect engineering is rarely used in soft matter design. In this review, we present a survey on investigations on defects and/or defect engineering in nine classes of soft matter composed of liquid crystals, colloids, linear polymers with moderate degree of branching, hyperbranched polymers and dendrimers, conjugated polymers, polymeric networks, self-assembled amphiphiles and proteins, block copolymers and supramolecular polymers. This overview proposes a promising role of this approach for tuning the properties of soft matter.

Taste-masked nanoparticles containing Saquinavir for pediatric oral administration

This research has aimed to improve the stability and taste-masking properties by developing nanostructured dosage forms containing Saquinavir. Liquid formulations were developed using Eudragit RS100® and Pullulan as polymers. The physicochemical characteristics, stability, in vitro drug release, morphology, mucoadhesion and taste masking capacity were evaluated. The Saquinavir-nanoparticles had average diameters between 136 and 158 nm, with a Span below 1.4. These formulations presented a drug content above 80%, a high encapsulation efficiency (>97%), slightly acidic pH levels, low dynamic viscosity and controlled drug release. Electron microscopy revealed irregular spherical nanoparticles. The formulations prepared with higher amounts of Eudragit RS100® had greater mucoadhesion. Both polymers were able to improve drug stabilization, taste-masking properties and protection against drug cytotoxicity. The Saquinavir-nanoparticles exhibited stability and control releasing properties, thus making it a promising liquid dosage form with taste-masking properties intended for application in pediatric treatment.

Pharmaceutical Application of Tablet Film Coating

Tablet film coating is a common but critical process providing various functionalities to tablets, thereby meeting diverse clinical needs and increasing the value of oral solid dosage forms. Tablet film coating is a technology-driven process and the evolution of coated dosage forms relies on advancements in coating technology, equipment, analytical techniques, and coating materials. Although multiple coating techniques are developed for solvent-based or solvent-free coating processes, each method has advantages and disadvantages that may require continuous technical refinement. In the film coating process, intra- and inter-batch coating uniformity of tablets is critical to ensure the quality of the final product, especially for active film coating containing active pharmaceutical ingredients in the coating layer. In addition to experimental evaluation, computational modeling is also actively pursued to predict the influence of operation parameters on the quality of the final product and optimize process variables of tablet film coating. The concerted efforts of experiments and computational modeling can save time and cost in optimizing the tablet coating process. This review provides a brief overview of tablet film coating technology and modeling approaches with a focus on recent advancements in pharmaceutical applications.

Predicting the Miscibility and Rigidity of Poly(lactic-co-glycolic acid)/Polyethylene Glycol Blends via Molecular Dynamics Simulations

The addition of polyethylene glycol (PEG) chains to poly(lactic-co-glycolic acid) (PLGA) matrices is extensively used to modulate the biodegradation, drug loading and release, mechanical properties, and chemical stability of the original system. Multiple parameters, including the molecular weight, relative concentration, polarity, and solubility, affect the physicochemical properties of the polymer blend. Here, molecular dynamics simulations with the united-atom 2016H66 force field are used to model the behavior of PLGA and PEG chains and thus predict the overall physicochemical features of the resulting blend. First, the model accuracy is validated against fundamental properties of pure PLGA and PEG samples. In agreement with previous experimental and theoretical observations, the PLGA solubility results to be higher in acetonitrile than in water, with Flory parameters ν_ACN = 0.63 ± 0.01 and ν_W = 0.21 ± 0.02, and the Young’s modulus of PLGA and PEG equal to Y = 2.0 ± 0.43 and 0.32 ± 0.34 GPa, respectively. Next, four PEG/PLGA blending regimes are identified by varying the relative concentrations and molecular weights of the individual polymers. The computational results demonstrate that at low PEG concentrations (<8% w/w), homogeneous blends are generated for both low and high PEG molecular weights. In contrast, at comparable PEG and PLGA concentrations (∼50% w/w), short PEG chains are only partially miscible whereas long PEG chains segregate within the PLGA matrix. This behavior has been confirmed experimentally via differential scanning calorimetry and is in agreement with previous observations. Finally, the computed Young’s modulus of PLGA/PEG blends is observed to decrease with the PEG content returning the lowest values for the partial and fully segregated regimens (Y ≈ 1.3 GPa). This work proposes a computational scheme for predicting the physicochemical properties of PLGA/PEG blends paving the way toward the rational design of polymer mixtures for biomedical applications.

The Effect of Polydimethylsiloxane-Ethylcellulose Coating Blends on the Surface Characterization and Drug Release of Ciprofloxacin-Loaded Mesoporous Silica

In this study, we obtained novel solid films composed of ciprofloxacin-loaded mesoporous silica materials (CIP-loaded MCM-41) and polymer coating blends. Polymer coating blends were composed of ethylcellulose (EC) with various levels of polydimethylsiloxane (PDMS, 0, 1, 2% (v/v)). The solid films were prepared via the solvent-evaporation molding method and characterized by using scanning electron microscopy (SEM), optical profilometry, and wettability analyses. The solid-state of CIP present in the solid films was studied using X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The release profiles of CIP were examined as a function of PDMS content in solid films. The surface morphology analysis of solid films indicated the progressive increase in surface heterogeneity and roughness with increasing PDMS content. The contact angle study confirmed the hydrophobicity of all solid films and significant impact of both PDMS and CIP-loaded MCM-41 on surface wettability. DSC and XRD analysis confirmed the presence of amorphous/semi-crystalline CIP in solid films. The Fickian diffusion-controlled drug release was observed for the CIP-loaded MCM-41 coated with PDMS-free polymer blend, whereas zero-order drug release was noticed for the CIP-loaded MCM-41 coated with polymer blends enriched with PDMS. Both the release rate and initial burst of CIP decreased with increasing PDMS content.

An Update of Moisture Barrier Coating for Drug Delivery

Drug hydrolytic degradation, caused by atmospheric and inherent humidity, significantly reduces the therapeutic effect of pharmaceutical solid dosages. Moisture barrier film coating is one of the most appropriate and effective approaches to protect the active pharmaceutical ingredients (API) from hydrolytic degradation during the manufacturing process and storage. Coating formulation design and process control are the two most commonly used strategies to reduce water vapor permeability to achieve the moisture barrier function. The principles of formulation development include designing a coating formulation with non-hygroscopic/low water activity excipients, and formulating the film-forming polymers with the least amount of inherent moisture. The coating process involves spraying organic or aqueous coating solutions made of natural or synthetic polymers onto the surface of the dosage cores in a drum or a fluid bed coater. However, the aqueous coating process needs to be carefully controlled to prevent hydrolytic degradation of the drug due to the presence of water during the coating process. Recently, different strategies have been designed and developed to effectively decrease water vapor permeability and improve the moisture barrier function of the film. Those strategies include newly designed coating formulations containing polymers with optimized functionality of moisture barrier, and newly developed dry coating processes that eliminate the usage of organic solvent and water, and could potentially replace the current solvent and aqueous coatings. This review aims to summarize the recent advances and updates in moisture barrier coatings.

Real time MRI to elucidate the functionality of coating films intended for modified release

Polymer films based on mixtures of ethyl cellulose (EC) and hydroxypropyl cellulose (HPC) have been widely used to coat pellets and tablets to modify the release profile of drugs. For three different EC/HPC films we used ¹H and ¹⁹F MRI in combination with a designed release cell to monitor the drug, polymer and water in 5 dimensional (5D) datasets; three spatial, one diffusion or relaxation and a temporal dimension, in real time. We observed that the water inflow through the films correlated with the initiation of the dissolution of the drug in the tablet beneath the film. Leaching of the pore forming HPC further accelerated water penetration and resulted in a drug release onset after a hydrostatic pressure was generated below the film indicated by positional changes of the film. For the more permeable film, both water ingress and drug egress showed a large variability of release over the film surface indicating the heterogeneity of the system. Furthermore, the ¹H diffusion dataset revealed the formation of a gel layer of HPC at the film surface. We conclude that the setup presented provides a significant level of details, which are not achieved with traditional methods.

Controlled Release Film Forming Systems in Drug Delivery: The Potential for Efficient Drug Delivery

Despite many available approaches for transdermal drug delivery, patient compliance and drug targeting at the desired concentration are still concerns for effective therapies. Precise and efficient film-forming systems provide great potential for controlling drug delivery through the skin with the combined advantages of films and hydrogels. The associated disadvantages of both systems (films and hydrogels) will be overcome in film-forming systems. Different strategies have been designed to control drug release through the skin, including changes to film-forming polymers, plasticizers, additives or even model drugs in formulations. In the current review, we aim to discuss the recent advances in film-forming systems to provide the principles and review the methods of these systems as applied to controlled drug release. Advances in the design of film-forming systems open a new generation of these systems.

Light-regulated molecular diffusion in a liquid crystal network

Photo-responsive liquid crystal polymer networks offer promising means to generate useful functional devices, but many of them focus on their mechanical response so as to generate surface features or shape change. Here, we investigate the photomechanical effect of the polymer network for molecular transport purposes. Dual wavelength illumination of an azobenzene-functionalized cholesteric liquid crystal polymer film produces excess free volume within the film, which results in an accelerated molecular diffusion through the film. Moreover, the polarization of the UV light exposure on the cholesteric network plays an important role in a remarkable enhancement of molecular diffusion. When linearly polarized UV light rotates along with the twist of the helical axis of the cholesteric polymer, excess free volume forms sequentially from the diffusion network toward the dry network in the polymer. It works in concert with the concentration gradient of the diffusant and greatly improves the diffusion through the film.

The effects of the treatment conditions on the dissolution profile of ethylcellulose coated pellets

Due to the additional particle coalescence in the coating, changes in the dissolution profile occur over time in the formulations coated by aqueous ethylcellulose latex. Dry thermal treatment (DT) of the coating can be used as a prevention of this process. Alternatively, it is advisable to take advantage of the synergistic effect of high humidity during wet treatment (WT), which substantially accelerates the film formation. This can be a problem for time-controlled systems, which are based on the coating rupture due to the penetration of water into the core causing the increase in the system volume. This process can begin already during the WT, which may affect the coating adversely. The submitted work was focused on the stability testing of two pellet core compositions: pellets containing swelling superdisintegrant sodium carboxymethyl starch (CMS) and pellets containing osmotically active polyethylene glycol (PEG). Another objective was to identify the treatment/storage condition effects on the pellet dissolution profiles. These pellets are intended to prevent hypoglycemia for patients with diabetes mellitus and therefore, besides the excipients, pellet cores contain 75% or 80% of glucose. The pellet coating is formed by ethylcellulose-based latex, which provides the required lag time (120-360 min). The sample stability was evaluated depending on the pellet core composition (PEG, CMS) for two types of final pellet coating treatment (DT or WT). Scanning electron microscopy and Raman microspectroscopy revealed the penetration of glucose and polyethylene glycol from the core to the PEG pellet surface after WT. For the CMS sample, significant pellet swelling after WT (under the conditions of elevated humidity) was statistically confirmed by the means of stereomicroscopic data evaluation. Therefore, the acceleration of dissolution rate during the stress tests is caused by the soluble substance penetration through the coating in the case of PEG pellets or by dosage form volume increase in the case of CMS pellets. The observed mechanisms can be generally anticipated during the stability testing of the ethylcellulose coated dosage forms. The aforementioned processes do not occur after DT and the pellets are stable in the environment without increased humidity.

Development of a "Dual Gates" Locked, Target-Triggered Nanodevice for Point-of-Care Testing with a Glucometer Readout

Developing a facile and sensitive sensing platform is of importance for point-of-care testing (POCT). Herein, a sensitive and portable POCT platform based on "dual gates" aminated magnetic mesoporous silica nanocomposites (AMMS) bearing polydopamine (PDA)-aptamer (Apt) two-tier shells, as a novel nanodevice, is designed for target detection through a target-triggered glucose (GO) release from AMMS with personal glucometer (PGM) readout. In the absence of target, GO can be firmly captured in pores by the designed "dual gates", which would decrease the high background signal of this system and ensure the accuracy of the detection results. Upon the introduction of the target molecules under acidic conditions (pH 5.5), the subsequent PDA self-degradation and the specific Apt-target reaction can cause the departure of "dual gates" and the opening of pores to release the loaded GO molecules, which could be quantitatively monitored by a portable PGM. It has been demonstrated that such POCT platform shows high sensitivity and excellent selectivity for aflatoxin B1 (AFB1) detection, accompanied by the well-presented reproducibility and stability. Importantly, this sensing platform was further validated by assaying contaminated samples, where the obtained results were well matched with that by HPLC. Regarding the features of portability, high sensitivity, and high throughput detection, the developed platform might find wide applications in POCT.

Polymer Distribution and Mechanism Conversion in Multiple Media of Phase-Separated Controlled-Release Film-Coating

Phase-separated films of water-insoluble ethyl cellulose (EC) and water-soluble hydroxypropyl cellulose (HPC) can be utilized to tailor drug release from coated pellets. In the present study, the effects of HPC levels and the pH, type, ionic strength and osmolarity of the media on the release profiles of soluble metoprolol succinates from the EC/HPC-coated pellets were investigated, and the differences in drug-release kinetics in multiple media were further elucidated through the HPC leaching and swelling kinetics of the pellets, morphology (SEM) and water uptake of the free films and the interaction between the coating polymers and the media compositions. Interestingly, the drug release rate from the pellets in different media was not in agreement with the drug solubility which have a positive correlation with the drug dissolution rate based on Noyes–Whitney equation law. In particular, the drug release rate in acetate buffer at pH 4.5 was faster than that in other media despite the solubility of drug was relatively lower, regardless of the HPC levels. It may be attributed to the mutual effect between the EC and acetate buffer, which improved the permeability of the film. In contrast, the release of drug in HCl solution was dependent on the HPC levels. Increasing the levels of HPC increased the effects of hydrogen ions on the polymer of HPC, which resulted in a lower viscosity and strength of the gel, forming the larger size of pores in polymer films, thus increasing the drug diffused from the coating film. Further findings in phosphate buffer showed a reduction in the drug release compared to that in other media, which was only sensitive to the osmolarity rather than the HPC level and pH of the buffer. Additionally, a mathematical theory was used to better explain and understand the experimentally measured different drug release patterns. In summary, the study revealed that the effects of the media overcompensated that of the drug solubility to some extent for controlled-release of the coating polymers, and the drug release mechanism in multiple media depend on EC and HPC rather than on HPC alone, which may have a potential to facilitate the optimization of ideally film-coated formulations.