A study on the impact of hydroxypropyl methylcellulose on the viscosity of PEG melt suspensions using surface plots and principal component analysis

Degradation of hydroxypropyl methylcellulose (HPMC) by acoustic and hydrodynamic cavitation

The present study aims to investigate the degradation of HPMC on a laboratory scale by acoustic and hydrodynamic cavitation. The effects of temperature and the addition of an external oxidizing agent on the effectiveness of HPMC degradation were systematically investigated by SEC/MALS-RI, FTIR and 1H NMR. The results of the experiments without cavitation show that an external oxidizing agent alone reduces the weight-average molar mass at 60 °C in 30 min for 45.1 % (from 335 to 184 kg mol-1). However, the weight-average molar mass of HPMC decreased significantly more in the cavitation treatment, for 98.8 % (from 335 to 4 kg mol-1) in 30 min at optimal operating conditions of hydrodynamic cavitation (i.e. addition of external oxidant and 60 °C) with a concomitant narrowing of the molar mass distribution, as shown by the dispersity value, which decreased from 2.24 to 1.31. Compared to acoustic cavitation, hydrodynamic cavitation also proved to be more energy efficient. The FTIR spectra of the cavitated HPMC samples without the addition of H2O2 show negligible oxidation of the hydroxyl groups and the glycosidic bonds, confirming that mechanical effects predominate in HPMC degradation in these cases. In contrast, when H2O2 was added, FTIR and 1H NMR show typical signals for cellulose oxidation products, especially when the experiments were performed at 60 °C, confirming that chemical as well as mechanical effects are responsible for the extensive HPMC degradation in these cases. Since treatment methods that lead to lower molar masses and narrower molar mass distributions of the polymers are lacking or require longer treatment times (e.g. 24 h), mechanochemical treatment methods such as cavitation have great potential, as they enable faster polymer degradation (in our case 30 min) through a combination of mechanical and/or chemical degradation mechanisms.

Bulk Flow Optimisation of Amorphous Solid Dispersion Excipient Powders through Surface Modification

Particulate amorphous solid dispersions (ASDs) have been recognised for their potential to enhance the performance of various solid dose forms, especially oral bioavailability and macromolecule stability. However, the inherent nature of spray-dried ASDs leads to their surface cohesion/adhesion, including hygroscopicity, which hinders their bulk flow and affects their utility and viability in terms of powder production, processing, and function. This study explores the effectiveness of L-leucine (L-leu) coprocessing in modifying the particle surface of ASD-forming materials. Various contrasting prototype coprocessed ASD excipients from both the food and pharmaceutical industries were examined for their effective coformulation with L-leu. The model/prototype materials included maltodextrin, polyvinylpyrrolidone (PVP K10 and K90), trehalose, gum arabic, and hydroxypropyl methylcellulose (HPMC E5LV and K100M). The spray-drying conditions were set such that the particle size difference was minimised, so that it did not play a substantial role in influencing powder cohesion. Scanning electron microscopy was used to evaluate the morphology of each formulation. A combination of previously reported morphological progression typical of L-leu surface modification and previously unreported physical characteristics was observed. The bulk characteristics of these powders were assessed using a powder rheometer to evaluate their flowability under confined and unconfined stresses, flow rate sensitivities, and compactability. The data showed a general improvement in maltodextrin, PVP K10, trehalose and gum arabic flowability measures as L-leu concentrations increased. In contrast, PVP K90 and HPMC formulations experienced unique challenges that provided insight into the mechanistic behaviour of L-leu. Therefore, this study recommends further investigations into the interplay between L-leu and the physico-chemical properties of coformulated excipients in future amorphous powder design. This also revealed the need to enhance bulk characterisation tools to unpack the multifactorial impact of L-leu surface modification.

A Review on Physicochemical Properties of Polymers Used as Filaments in 3D-Printed Tablets

Three-dimensional (3D) printing technology has presently been explored widely in the field of pharmaceutical research to produce various conventional as well as novel dosage forms such as tablets, capsules, oral films, pellets, subcutaneous implants, scaffolds, and vaginal rings. The use of this innovative method is a good choice for its advanced technologies and the ability to make tailored medicine specifically for individual patient. There are many 3D printing systems that are used to print tablets, implants, and vaginal rings. Among the available systems, the fused deposition modeling (FDM) is widely utilized. The FDM has been regarded as the best choice of printer as it shows high potential in the production of tablets as a unit dose in 3D printing medicine manufacturing. In order to design a 3D-printed tablet or other dosage forms, the physicochemical properties of polymers play a vital role. One should have proper knowledge about the polymer's properties so that one can select appropriate polymers in order to design 3D-printed dosage form. This review highlighted the various physicochemical properties of polymers that are currently used as filaments in 3D printing. In this manuscript, the authors also discussed various systems that are currently adopted in the 3D printing.

Toward More Universal Prediction of Polymer Solution Viscosity for Solvent-Based Recycling

The viscosity of polymer solutions is important for both polymer synthesis and recycling. Polymerization reactions can become hampered by diffusional limitations once a viscosity threshold is reached, and viscous solutions complicate the cleaning steps during the dissolution–precipitation technique. Available experimental data is limited, which is more severe for green solvents, justifying dedicated viscosity data recording and interpretation. In this work, a systematic study is therefore performed on the viscosity of polystyrene solutions, considering different concentrations, temperatures, and conventional and green solvents. The results show that for the shear rate range of 1–1000 s^–1, the solutions with concentrations between 5 and 39 wt % display mainly Newtonian behavior, which is further confirmed by the applicability of the segment-based Eyring-NRTL and Eyring-mNRF models. Moreover, multivariate data analysis successfully predicts the viscosity of polystyrene solutions under different conditions. This approach will facilitate future data recording for other polymer–solvent combinations while minimizing experimental effort.

Preparation and optimization of multi-functional directly compressible excipient: an integrated approach of principal component analysis and design of experiments

Developing a new excipient and obtaining its market approval is an expensive, time-consuming, and complex process. The application of a multivariate analytical approach - principal component analysis (PCA) - in combination with the design of experiments (DoE) approach can make the process of developing co-processed excipient cost-effective and rapid. The present investigation was aimed to demonstrate the applicability of the DoE approach and PCA in developing a co-processed excipient by using the spray drying technique. The preliminary studies suggested a significant effect of inlet air temperature (X ₁) and polymer ratio [chitosan chlorhydrate (CC): mannitol - X ₂) on critical product characteristics so they were selected as independent variables in 3² full factorial design. The result of regression analysis suggested a significant effect of both independent variables on all response variables. The PCA of practically obtained value suggested a strong effect of all the selected response variables on the model. The prepared co-processed excipient had better tableting properties compared to the physical mixture of excipients and was able to accommodate more than 80% drug without compromising the flow property and compressibility. The present investigation successfully proved the applicability PCA and DoE approach as an effective and rapid tool for optimizing process parameters and formulation composition for preparing a directly compressible co-processed excipient.

Mucoadhesive Vaginal Discs based on Cyclodextrin and Surfactants for the Controlled Release of Antiretroviral Drugs to Prevent the Sexual Transmission of HIV

The strategies for developing vaginal microbicides to protect women against human immunodeficiency virus (HIV) sexual transmission are constantly changing. Although the initial dosage forms required daily administration to offer effective protection, the trend then moved towards sustained-release dosage forms that require less frequency of administration in order to improve women's compliance with the treatment. Nevertheless, another possible strategy is to design on-demand products that can be used in a coitally-dependent manner and only need to be administered immediately before intercourse to offer protection. Vaginal discs based on freeze-dried hydroxypropylmethyl cellulose gels have been developed for this purpose, containing two surfactants, i.e., sodium dodecyl sulphate and polysorbate 60, alone or in combination with 2-hydroxypropyl-β-cyclodextrin, to achieve a formulation capable of incorporating both hydrophilic and lipophilic drugs. Several studies have been carried out to evaluate how the inclusion of these substances modifies the structure of gels (viscosity and consistency studies) and the porosimetry of the freeze-dried discs (scanning electron microscopy micrographs, mechanical properties, swelling behaviour). The drug release and mucoadhesive properties of the discs have also been evaluated with a view to their clinical application. The systems combining sodium dodecyl sulphate and 2-hydroxypropyl-β-cyclodextrin were found to be adequate for the vaginal administration of both Tenofovir and Dapivirine and also offer excellent mucoadhesion to vaginal tissue; these discs could therefore be an interesting option for a coitally-dependent administration to protect women against HIV transmission.

Development of a topical tissue cross-linking solution using sodium hydroxymethylglycinate (SMG): viscosity effect

Hyperviscosity agents are commonly used in ophthalmic formulations for improving corneal drug penetration by increasing tissue contact time. One such viscosity agent is hydroxypropyl methylcellulose (HPMC). HPMC has been used in riboflavin solutions for photochemical UVA cross-linking (CXL). Sodium hydroxymethylglycinate (SMG) is a small molecule formaldehyde releaser that can function as a therapeutic tissue cross-linker for corneal and scleral applications. The present study was undertaken in order to study formulation factors using HPMC and SMG that could positively influence the cross-linking effect in these ocular tissues. Formulations containing 10 mM SMG and 100 mM sodium bicarbonate were prepared with varying HPMC concentrations from 0 to 4.4%. Their cross-linking effects on porcine and rabbit eyes were measured using differential scanning calorimetry (DSC), expressed as the change/difference in melting temperature (ΔT_m) compared with the control. SMG in 4.4% HPMC solution resulted in ΔT_m of 6.3 ± 1.21, while other concentration showed no differences in T_m shift on porcine cornea. In ex vivo rabbit cornea, there was a trend toward an increasing cross-linking effect with higher viscosity albeit mild differences. While a significant T_m shift was observed in porcine and rabbit sclera, there was no difference in effect of cross-linking between four HPMC concentrations. Increasing the HPMC concentration does not negatively affect the cross-linking efficacy attributed by SMG and could still be a positive cross-linking enhancer by virtue of increasing tissue contact time in a dynamic biological system. This information will be useful for planning further animal and human studies.

Bio- Fortification of Angelica gigas Nakai Nano-Powder Using Bio-Polymer by Hot Melt Extrusion to Enhance the Bioaccessibility and Functionality of Nutraceutical Compounds

Angelica gigas Nakai (AGN) is a popular traditional herbal medicine which has been used to alleviate various human diseases in Korea since ancient times. However, the low bioaccessibility of the nutraceutical compounds of AGN results in a poor water solubility, thereby limiting bioavailability. In this regard, a ternary AGN-biopolymer-plasticizer composite (AGNC) was developed to enhance the bioaccessibility of nutraceutical compounds from extrudate AGN formulations manufactured by hot melt extrusion (HME). The AGNC was prepared with extrudate AGN (EAGN) using different hydroxypropyl methylcellulose (HPMC) biopolymers (5% w/w) viz.: hypromellose phthalate (HP), hypromellose (AN), and hypromellose (CN) along with acetic acid (AA) (0.1 M, 20% w/v) as a plasticizer. The non-extrudate fresh AGN (FAGN) powder was used as a control. The physicochemical properties of the extrudate formulations and control were characterized by differential scanning calorimetry (DSC) and Fourier-transform infrared spectroscopy (FTIR). DSC analysis showed a lower enthalpy (ΔH) (12.22 J/g) and lower glass transition temperature (Tg) (41 °C) in HP-AA-EAGN compared to the control. FTIR confirmed the physical crosslinking between AGN and biopolymer in the extrudate composite and demonstrated that some functional groups formed viz., -OH and -CH2. The obtained result also shows that the particle size was reduced by 341 nm, and solubility was increased by 65.5% in HP-AA-EAGN compared to the control (1499 nm, 29.4%, respectively). The bioaccessibility of the total phenolic content and the total flavonoids-including decursin (D) and decursinol angelate (DA)-were significantly higher in HP-AA-EAGN compared to the control. The 2,2-diphenyl-1 picryl hydrazyl (DPPH) free radical scavenging capacity and ferric reducing antioxidant power assay (FRAP) indicated that the HP-AA-EAGN formulation preserves a greater antioxidant profile than the other formulations. Finally, it is summarized that the addition of acidified HP biopolymer increased the bioaccessibility, functionality, and improved the physicochemical properties of nutraceutical compounds in the extrudate AGN formulation.

Effects of Drug Particle Size and Lipid Additives on Drug Release from Paraffin Wax Formulations Prepared by Spray Congealing Technique

Paraffin wax is a hydrophobic meltable material that can be suitably used in spray congealing to develop drug-loaded microparticles for sustained release, taste-masking or stability enhancement of drugs. However, these functional properties may be impaired if the drug particles are not completely embedded. Moreover, highly viscous melts are unsuitable for spray dispersion. In this study, the effects of drug particle size and lipid additives, namely stearic acid (SA), cetyl alcohol (CA) and cetyl esters (CE), on melt viscosity and extent of drug particles embedment were investigated. Spray congealing was conducted on the formulations, and the resultant microparticles were analysed for their size, drug content, extent of drug particles embedment and drug release. The melt viscosity increased with smaller solid inclusions while lipid additives decreased the viscosity to varying extents. The spray-congealed microparticle size was largely dependent on the viscosity. The addition of lipid additives to paraffin wax enabled more complete embedment of the drug particles. CA produced microparticles with the lowest drug release, followed by SA and CE. The addition of CA and CE enhanced the drug release and showed potential for taste-masking. Judicious choice of drug particle size and matrix materials is important for successful spray congealing to produce microparticles with the desired characteristics.

Co-encapsulation of acyclovir and curcumin into microparticles improves the physicochemical characteristics and potentiates in vitro antiviral action: Influence of the polymeric composition

The present study developed and characterized microparticles formulations containing acyclovir and curcumin co-encapsulated in order to overcome the biopharmaceutical limitations and increase the antiviral effect of both drugs. The microparticles were prepared by a spray drying methodology following the ratio 1:3 (drug:polymer), which were made by hydroxypropylmethylcellulose (HPMC) and/or Eudragit® RS100 (EUD). The MP-1 formulation was composed of HPMC and EUD (1:1), MP-2 formulation was composed only of HPMC and MP-3 formulation was composed only of EUD. All formulations showed yielding around 50% and acceptable powder flowability. Drug content determination around 82.1-96.8% and 81.8-87% for acyclovir and curcumin, respectively. The microparticles had spherical shape, size within 11.5-15.3 μm, unimodal distribution and no chemical interactions among the components of the formulations. Of particular importance, the polymeric composition considerably influenced on the release profile of the drugs. The in vitro release experiment demonstrated that the microencapsulation provided a sustained release of acyclovir as well as increased the solubility of curcumin. Besides, mathematical modeling indicated that the experimental fit biexponential equation. Importantly, drugs microencapsulation promoted superior antiviral effect against BoVH-1 virus in comparison to their free form, which could be attributed to the improvement in the aforementioned physicochemical parameters. Therefore, these formulations could be promising technological drug carriers for acyclovir and curcumin, which highlight the great offering a potential alternative treatment for viral herpes.

Development of polyurethane foam dressing containing silver and asiaticoside for healing of dermal wound

Polyurethane foam dressings for dermal wounds were formulated with natural polyols in order to improve the foam characteristics and the release of 2 active agents, silver and asiaticoside (AS) as an antimicrobial agent and an herbal wound healing agent, respectively. The foam was instantly formed by interaction of polyols and diisocyanate. Hydroxypropyl methylcellulose, chitosan and sodium alginate were individually mixed with the main polyols, polypropylene glycol, in the formulation while the active components were impregnated into the obtained foam dressing sheets. Although the type and amount of the natural polyols slightly affected the pore size, water sorption-desorption profile and compression strength of the obtained foam sheets, a prominent effect was found in the release of both active components. Among natural polyols formulations, foam sheets with alginate showed the highest silver and AS release. Non-cytotoxicity of these foam sheets to human fibroblast cells was confirmed. Antimicrobial testing on four bacteria strains showed that 1 mg/cm2 silver in formulations with 6% of natural polyols and without natural polyols had sufficient content of the silver release with comparable inhibition zone and significantly larger zone than other formulations. In pig study, the foam dressing with 6% alginate, 1 mg/cm2 silver and 5% AS could improve wound healing in both the percentage of the wound closure and histological parameters of the dermal wound without any dermatologic reactions. In conclusion, this innovative foam dressing had potential to be a good candidate for wound treatment.