Hydroxypropyl Methylcellulose Matrix Research Articles

Synthesis and characterization of hydroxy propyl methyl Cellulose/Copper nanobiocomposites for antibacterial and antioxidant smart materials

The synthesis of hydroxy propyl methyl cellulose (HPMC)/copper nanobiocomposites adopting a microwave treatment. In this study, HPMC and copper nitrate at various concentration were mixed and subjected to varying microwave treatment times (10, 20, 30, 40, 50 and 60 s). UV–Vis spectroscopy was employed to analyse the physicochemical characteristics of HPMC/copper nanobiocomposites, with a maximal absorbance at 380 nm, indicating the formation of copper nanoparticles within the HPMC matrix. The interaction between copper nanoparticles and HPMC was further confirmed through FT-IR analysis. The SEM analysis displayed microporous structures ranging from 5 to 14 µm in diameter, with an average pore size of 7.0 ± 2.0 nm. The compositional analysis was done with EDS mapping. TEM analysis revealed spherical shaped copper nanoparticles with an average particle size about 2.5 nm in HPMC matrix. Remarkably, these nanobiocomposites exhibited a broad-spectrum antibacterial activity, displaying minimal inhibitory concentrations against both Gram-negative and Gram-positive bacterium. Significantly, the assessment of antibacterial activity in HPMC/copper nanobiocomposites demonstrated their efficacy against both Escherichia coli and Staphylococcus aureus. In addition to the antioxidant property, the antibacterial properties holds significant implications for their potential applications of HPMC/ copper nanobiocomposites in the fields of food packaging and biomedicine.

Susceptibility of periodontal pathogens to a novel target-specific drug delivery system containing self-nanoemulsifying curcumin: An in vitro study.

Long-term use of many classic chemotherapeutic agents as adjuncts in the management of periodontitis has adverse complications, leading to seeking out naturopathic remedies. Although curcumin has been investigated in managing periodontitis, its therapeutic benefits have not been fully explored due to its limited solubility in an aqueous medium. This study aimed to develop a novel target-specific drug delivery system containing 1% self-nanoemulsifying curcumin (SNEC) in a hydroxypropylmethylcellulose (HPMC) matrix and evaluate the susceptibility of periodontal pathogens to this system in vitro. Its antibacterial activity against Tannerella forsythia, Porphyromonas gingivalis, Prevotella intermedia, and Aggregatibacter actinomycetemcomitans was evaluated and compared to pure nano-curcumin and SNEC alone by estimating their minimum inhibitory concentrations (MIC). The antibacterial activity of pure nano-curcumin, SNEC, and SNEC in HPMC against the four periodontal pathogens evaluated in terms of MIC was recorded in the range of 0.2‒0.4, 0.4‒0.8, and 0.2‒0.8 µg/mL, respectively. However, the MIC of all three curcumin formulations against the periodontal pathogens tested was higher than that of the standard moxifloxacin. While both pure nano-curcumin and SNEC showed increasing values of inhibition zones with increasing concentrations on disk diffusion assay, lower concentrations of SNEC in HPMC did not show a zone of inhibition against the tested pathogens. The novel delivery system containing SNEC in HPMC may be a potential adjunct in managing periodontitis due to its probable sustained antimicrobial activity against the tested periodontal pathogens.

Effect of the incorporation of liposomes loaded with rutin on the transport properties of edible film produced with hydroxypropyl methylcellulose: An in vitro release study

This work studied the effect of encapsulating rutin in liposomes on the transport properties of the edible film (EF) produced with hydroxypropyl methylcellulose (HPMC). Encapsulated rutin in liposomes were 106.1 ± 1.2 nm and there was high percentage of encapsulation (89.3 ± 0.5%). When incorporated into the HPMC matrix, the formulation did not show phase separation or agglomeration. Interestingly, the presence of the liposomes caused significant changes in the EF, modifying thickness, yellowness index, and mechanical properties. Less rigid and more deformable EF were obtained with the addition of liposomes and glycerol. The encapsulation of rutin in liposomes, loaded in the EF showed a delay in the liberation of the active compound when compared to non-encapsulated rutin; diffusion coefficients of 3.27*10−16 m2/s and 1.24*10−15 m2/s, respectively. In summary, the presence of liposomes loaded with rutin allows for the production of EF with improved physical characteristics desirable for food systems. Liposomes loaded with active compounds are a good ingredient/carrier for inclusion in EF providing a gradual release of antioxidant agents, with the added benefit of potentially providing a longer shelf life of the food.

Continuous Monitoring of the Hydration Behavior of Hydrophilic Matrix Tablets Using Time-Domain NMR.

Time-domain NMR (TD-NMR) was used for continuous monitoring of the hydration behavior of hydrophilic matrix tablets. The model matrix tablets comprised high molecular weight polyethylene oxide (PEO), hydroxypropyl methylcellulose (HPMC), and polyethylene glycol (PEG). The model tablets were immersed in water. Their T2 relaxation curves were acquired by TD-NMR with solid-echo sequence. A curve-fitting analysis was conducted on the acquired T2 relaxation curves to identify the NMR signals corresponding to the nongelated core remaining in the samples. The amount of nongelated core was estimated from the NMR signal intensity. The estimated values were consistent with the experiment measurement values. Next, the model tablets immersed in water were monitored continuously using TD-NMR. The difference in hydration behaviors of the HPMC and PEO matrix tablets was then characterized fully. The nongelated core of the HPMC matrix tablets disappeared more slowly than that of the PEO matrix tablets. The behavior of HPMC was significantly affected by the PEG content in the tablets. It is suggested that the TD-NMR method has potential to be utilized to evaluate the gel layer properties, upon replacement of the immersion medium: purified (nondeuterated) water is replaced with heavy (deuterated) water. Finally, drug-containing matrix tablets were tested. Diltiazem hydrochloride (a highly water-soluble drug) was employed for this experiment. Reasonable in vitro drug dissolution profiles, which were in accordance with the results from TD-NMR experiments, were observed. We concluded that TD-NMR is a powerful tool to evaluate the hydration properties of hydrophilic matrix tablets.

Effect of the combined addition of ultrasonicated kraft lignin and montmorillonite on hydroxypropyl methylcellulose bionanocomposites.

Although hydroxypropyl methylcellulose (HPMC) has been proposed as renewable substitute for traditional plastic, its barrier and active properties need to be improved. Thus, the combination of an organic residue such as kraft lignin (0-10% w/w) and a natural clay such as montmorillonite (3% w/w) by application of ultrasound can significantly improve HPMC properties. This is most likely due to the close interaction between lignin and montmorillonite, which leads to delamination of the clay and improves its dispersion within the HPMC matrix. Specifically, the addition of kraft lignin to the bionanocomposite films provided them with UV-shielding, antioxidant capacity and antibacterial activity. The incorporation of 3% montmorillonite resulted in reductions of 65.8% and 11.4% in oxygen (OP) and water vapor permeabilities (WVP), respectively. Moreover, a reduction of 43.8% in WVP was achieved when both lignin (1%) and montmorillonite (3%) were incorporated, observing a synergistic effect. Thus, the HPMC bionanocomposite with 1% lignin and 3% montmorillonite, presented good thermal stability and mechanical strength with significantly improved gas barrier permeability, as well as UV-shielding (maintaining a good transparency), antioxidant and antibacterial activities.

Cellulose derivative as protection coating: Effect of nanoparticle additives on load capacity

The cellulose derivative hydroxypropyl methylcellulose (HPMC) has recently been extensively studied and used in mechanical applications. However, the softness and susceptibility to deformation of HPMC limited its further applications. In this study, metal nanoparticles (nano-aluminum and nano-copper) and nano-metal oxide particles (nano-alumina and nano-copper oxide) were used as additives to HPMC to form a composite film with improved mechanical properties, particularly load capacity. The addition of high levels of additives provided a higher load capacity. Among the nano-additives used in the study, Cu (2 wt.%) provided the composite with the highest load capacity, improving the load capacity of pure HPMC by 250%. The surface treatment of strengthening additives is an important step. Adding specific high-strength and high-modulus metal and metal oxide additives to the soft HPMC matrix can effectively improve the load-bearing capacity of the composite material. This study proposes a simple evaluation method for the load-bearing capability of the coating as well.

Glycosyltransferases improve breadmaking quality by altering multiscale structure in gluten-free bread

In gluten-free bread (GFB), starch and its interplay with structural agents were vital for product quality due to the absence of gluten. During breadmaking, amylolytic enzymes modified starch in situ , and their reaction modes determined starch structure and hence how interactions occurred. Herein, based on the matrices of rice protein and hydroxypropyl methylcellulose (HPMC), α-amylase and multifunctional enzymes of glucan branching enzyme (GBE) and cyclodextrin glycosyltransferases (CGTase) were adopted, aiming to understand the mechanism of these enzymes on breadmaking quality of fresh bread from the multiscale structure of GFB. Results demonstrated that all enzymes, especially CGTase and GBE, markedly increased GFB specific volume to 107%–134% of Control. Compared with α-amylase, CGTase and GBE more depended on the structural changes rather than fermentation to improve GFB volume. Considering the texture, CGTase and GBE reduced crumb stickiness and still maintained a relatively softness and springiness crumb, while α-amylase induced a stick and less elastic crumb. Starch molecular changes enhanced the entanglement of starch and HPMC to form extended and bold fibril bundles and finally improved strength and pore size of gel network structure. Moreover, the starch structure modifications and specific enzymatic products of CGTase and GBE altered the microstructure and thus facilitated the even distribution of rice protein, which further improved GFB texture properties. Amylolytic enzymes, that acted both hydrolysis and glycosyl transfer, moderately hydrolyzed starch and generated specific enzymatic products, were more suitable to enhance GFB structure and eliminate the weak crumb texture. • α-amylase (α-Amy) and glycosyltransferases (GTases) were included. • Breadmaking quality of gluten-free bread (GFB) with α-Amy and GTases was compared. • GFB with GTases performed better in crumb structure and texture. • GTases depended more on structure rather than gas to improve volume. • Interactions of enzymatic starch and structural agents was crucial for GFB quality.

Synthesis of antibacterial hydroxypropyl methylcellulose and silver nanoparticle biocomposites via solution plasma using silver electrodes

The biocomposites of hydroxypropyl methylcellulose (HPMC)/silver nanoparticles (AgNPs) were synthesized using the solution plasma process (SPP). HPMC/AgNPs were synthesized in 1–5 % HPMC solutions using silver electrodes. UV–Vis spectroscopy showed a peak near 400 nm and the peak increased as the concentration of HPMC and discharge time increased. FTIR analysis indicated no change in the chemical structure of the HPMC based biocomposites. Spherical shaped AgNPs with size ranges about 2–18 nm and well dispersed in the porous HPMC matrices with fringed edges were observed by TEM and SEM/EDS analyses. The synthesized biocomposites were found to be thermo-stable by TGA analysis. The inhibition zones of bacterial growth formed by the HPMC/AgNPs biocomposites were in the range of 8–14.3 mm; minimal inhibition concentrations, in the range of 10–15 μg·mL−1 for Gram-negative bacteria; 25–30 μg·mL−1 for Gram-positive bacteria. The biocomposites were non-toxic to the HEK293 cells up to 125 μg·mL−1. The results indicated that the synthesis of antibacterial agents in the HPMC matrix using silver electrodes via SPP would be an efficient and safe way for the development of biopolymer based antimicrobials and wound healing biomaterials.

New Insight into the Impact of Effervescence on Gel Layer Microstructure and Drug Release of Effervescent Matrices Using Combined Mechanical and Imaging Characterisation Techniques

Gel layer characteristics play a crucial role in hydrophilic hydroxypropyl methylcellulose (HPMC) matrix development. Effervescent agents have the potential to affect the gel layer microstructures. This study aimed to investigate the influence of effervescence on the microstructure of the gel layer around HPMC matrices using a combination of texture analysis and imaging techniques. The relationship with drug release profile and release mechanisms were also examined. The high amounts of effervescent agents promoted a rapid carbonation reaction, resulting in a high gel layer formation with a low gel strength through texture analysis. This finding was ascribed to the enhanced surface roughness and porosity observed under digital microscopy and microporous structure of the gel layer under scanning electron microscopy. The reconstructed three-dimensional images from synchrotron radiation X-ray tomographic microscopy notably exhibited the interconnected pores of various sizes from the carbonation reaction of effervescent and microporous networks, indicating the gel layer on the tablet surface. Notably, effervescence promoted the increase in interconnected porosities, which directly influenced the strength of the gel layer microstructure, drug release patterns and release mechanism of the effervescent matrix tablet. Therefore, combined mechanical characterisation and imaging techniques can provide new insights into the role of effervescent agents on the gel layer microstructure, and describe the relationship of drug release patterns and release mechanism of matrix tablets.

Unexpected Stability of a Prodrug to Enzymatic Hydrolysis within a Hydrated HPMC Matrix Tablet.

The uptake of alkaline phosphate present in dissolution medium into a hydrating hydroxypropyl methylcellulose matrix tablet and that its activity was retained therein was demonstrated. This presents a risk to the stability of prodrugs that are substrates of this enzyme such as phosphonooxymethyl derivative prodrugs. It was found that fostemsavir, a phosphonooxymethyl derivative prodrug being developed for the treatment of HIV-1 infection, was unexpectedly resistant to hydrolysis within a hydrated HPMC matrix when subjected to drug release testing in media containing alkaline phosphatase. Studies indicated that this was not due to microenvironmental pH effects, osmolality effects or effective phosphate concentration effects associated with the presence of the prodrug. That the prodrug and not its parent could affect enzyme activity in a concentration dependent manner, and that another phosphate ester prodrug fosphenytoin did not inhibit alkaline phosphatase activity within a hydrated HPMC matrix suggested that the unexpected stability of the HIV-1 therapy prodrug may be associated with the ability of the phosphate group-containing compound itself to inhibit the enzyme at the concentrations it exists at in the hydrated dosage form and so enables the development of the compound in this type of dosage form.

Release Kinetics of Hydroxypropyl Methylcellulose Governing Drug Release and Hydrodynamic Changes of Matrix Tablet.

Hydrophilic Hydroxypropyl Methylcellulose (HPMC) matrix tablets are the standard role model of the oral controlled-release formulation. Nevertheless, the HPMC kinetics for the mechanistic understanding of drug release and hydrodynamic behaviors are rarely investigated. This study aims to investigate the release behaviors of both HPMC and paracetamol (model drug) from the hydrophilic matrix tablet. Two different viscosity grades of HPMC were used (Low viscosity: 6 cps, High viscosity: 4,000 cps). Three different ratios of drug/HPMC (H:38.08%, M:22.85%, and L:15.23% (w/w) of HPMC amounts in total weight) matrix tablets were prepared by wet granulation technique. The release profiles of the drug and HPMC in a matrix tablet were quantitatively analyzed by HPLC and 1H-Nuclear Magnetic Resonance (NMR) spectroscopy. The hydrodynamic changes of HPMC were determined by the gravimetric behaviors such as swelling and erosion rates, gel layer thickness, front movement data,and distributive Near-Infrared (NIR) chemical imaging of HPMC in a matrix tablet during the dissolution process. High viscosity HPMC tablets showed slower release of HPMC than the release rate of drug, suggesting that drug release preceded polymer release.Different hydration phenomenon was qualitatively identified and corresponded to the release profiles. The release behaviors of HPMC and drug in the tablet could be distinguished with the significant difference with fitted dissolution kinetics model (Low viscosity HPMC 6cps; Korsmeyer-Peppas model, High viscosity HPMC 4000cps; Hopfenberg model, Paracetamol; Weibull model) according to the weight of ingredients and types of HPMC. The determination of HPMC polymer release correlating with drug release, hydrodynamic behavior, and NIR chemical imaging of HPMC can provide new insights into the drug release- modulating mechanism in the hydrophilic matrix system.

Characterization of Natural Anthocyanin Indicator Based on Cellulose Bio-Composite Film for Monitoring the Freshness of Chicken Tenderloin.

Intelligent packaging with indicators that provide information about the quality of food products can inform the consumer regarding food safety and reduce food waste. A solid material for a pH-responsive indicator was developed from hydroxypropyl methylcellulose (HPMC) composited with microcrystalline cellulose (MCC). MCC at 5%, 10%, 20%, and 30% w/w was introduced into the HPMC matrix and the physical, barrier, thermal, and optical properties of the HPMC/MCC bio-composite (HMB) films were analyzed. At 5, 10, and 20% MCC, improved mechanical, transparency, and barrier properties were observed, where HMB with 20% of MCC (H20MB) showed the best performance. Therefore, H20MB was selected as the biodegradable solid material for fabricating Roselle anthocyanins (RA) pH sensing indicators. The performance of the RA-H20MB indicator was evaluated by monitoring its response to ammonia vapor and tracking freshness status of chicken tenderloin. The RA-H20MB showed a clear color change with respect to ammonia exposure and quality change of chicken tenderloin; the color changed from red to magenta, purple and green, respectively. These results indicated that RA-H20MB can be used as a biodegradable pH sensing indicator to determine food quality and freshness.

Raman-based real-time dissolution prediction using a deterministic permeation model

The purpose of this study was to develop a deterministic permeation model (DPM) that predicts the in vitro release profile of an active ingredient (API) embedded in hydroxypropyl-methylcellulose (HPMC) matrix tablets based on Raman spectra. So far in the literature, such mechanistic models were utilized only for formulation optimization (off-line dissolution prediction), while the real-time prediction of dissolution profiles based on Process Analytical Technology (PAT) data was performed by empirical methods such as Partial Least Squares (PLS) regression. Our work represents a novel conceptual approach that utilizes a mechanistic model to predict dissolution profiles based on data yielded by PAT tools. Tablets containing various API- and HPMC-amounts were produced using different compression pressures according to a 33 full factorial design, their Raman spectra were recorded before dissolution testing. The DPM was constructed using one-third of the measured dissolution profiles and is presented as a system of differential equations together with its analytical solution. The parameters of DPM were estimated by the training data set containing the spectroscopically determined API- and HPMC- amounts and the tableting pressures used, then the release profiles of the remaining two-thirds of the tablets were predicted. The Raman spectra-based predictions of DPM were compared with predictions of an Artificial Neural Network (ANN). It was found that the two methods yield similar results, however, the mechanistic approach has the benefit of requiring a lower amount of training samples. Although the model is based on a remarkable simplification of reality, it facilitates a deeper understanding of the behavior of the formulation.The DPM could improve our understanding of the effect of HPMC and tableting pressures on the release kinetics of the HPMC matrix tablets and participate in the development of PAT-based new surrogate dissolution methods for Real-Time Release testing (RTRt).

Gel polymer electrolyte based on hydroxypropyl methyl cellulose matrix composited with polyhedral oligomeric silsesquioxane

• POSS could hinder large anions transport and improve Li + ions conduction. • High Li + ion transference number. • Electrochemical stability window (4.74 V, vs. Li + /Li). High Li + ion transference number gel polymer electrolytes (GPEs) comprised of hydroxypropyl methyl cellulose (HPMC) matrix with adding hybrid nanoparticle polyhedral oligomeric silsesquioxane (POSS) are presented. POSS is a cage-type inorganic–organic nanoparticle which could hinder large anions transport and improve Li + ions conduction. An optimized GPE membrane is prepared by adding 10% POSS into HPMC. It achieves the best electrochemical performance, including high Li + ion transference number (0.81), remarkable ionic conductivity (9.05 × 10 −3 S cm −1 , 25 ℃) and electrochemical stability window (4.78 V, vs. Li + /Li). In addition, this system has the special ability to regulate lithium deposition/dissolution and exhibits overpotential stability for more than 460 h.

Management and control of intraocular pressure applying macitentan hydrogel film formulation: improved effect of surfactant and cosurfactant system.

Macitentan blocks endothelin receptors in order to control the pulmonary arterial hypertension (PAH). Oral administration of macitentan is associated with painful urination and troubled breathing. Formulated macitentan hydrogel film was used for examining the control of intraocular pressure, and the effect of surfactant and cosurfactant was studied. Macitentan ocular film formulation has been prepared in hydroxypropyl methylcellulose (HPMC) matrix system using different surfactant/co-surfactant system, and intraocular pressure was monitored on normotensive rabbit eyes after application in the cul-de-sac. The solid state characterization of the film indicated amorphisation of macitentan and no issues regarding major incompatibility was observed. Combination of surfactant, co-surfactant and hydrophilic co-solvent systems in the said films markedly improved the drug release and mucosal tissue permeation. Presence of PEG and Transcutol significantly improved ex vivo corneal permeation of MP and MT respectively compared to other films. Transcutol (MT) exhibited greatest difference among the formulations by improving the vesicular bilayer fluidity and reducing the mucosal tissue barrier facilitating the transcorneal diffusion. A combination of diffusion and erosion control behavior was observed in drug release and corneal permeation of the films due to the balanced liquid penetration and polymeric chain relaxation rate. MP and MT films were used for further in vivo studies to achieve possible effective and prolonged control of intraocular pressure. In vivo study has revealed the reduction in intraocular pressure upto about 23 % when tested on normotensive rabbit model. The films has managed to lower the IOP upto 3 h. Developed macitentan hydrogel film containing Transcutol (MT) could have a high potential for the control and management of ocular hypertension after topical application.

Aspirin-hydrogel ocular film for topical delivery and ophthalmic anti-inflammation

Ocular drug delivery in hydrogel forming film form has several benefits over conventional dosage forms. An ophthalmic anti-inflammation study was undertaken using topically applied aspirin in a hydrogel film formulation. A hydroxypropyl methylcellulose (HPMC) matrix film formulation was prepared by the solvent casting and evaporation technique by taking triethanolamine (TEA) as a plasticizer. Ex vivo corneal permeation as well as anti-inflammatory potential of aspirin was studied on carrageenan induced rabbit eye model. Moisture uptake was found to be in the range of 17.1 and 19.1 % for all the film formulations. The film with the higher HPMC content exhibited both increased moisture uptake and amount of swelling. Among the formulations, the swelling order was found to increase with increasing amount of HPMC in the film. Presence of the hydrogel matrix forming polymer sustained the drug release and corneal permeation for more than 6 h and controlled the process by the diffusion mechanism. The signs of carrageenan induced acute inflammation was inhibited completely within just 2 h of placing the film in the rabbit eye whilst the positive control continued showing redness and increased tear secretion. Aspirin ocular film formulation could be utilized for ocular anti-inflammation for an extended period of time with better patient compliance.

Gentamicin-Montmorillonite Intercalation Compounds as an Active Component of Hydroxypropylmethylcellulose Bionanocomposite Films with Antimicrobial Properties

The present study introduces an overview of gentamicin-clay mineral systems for applications in biomedicine and then focuses on the development of a series of gentamicin/clay hybrid materials to be used as the bioactive phase of hydroxypropylmethylcellulose (HPMC) to produce bionanocomposite membranes possessing antimicrobial activity of interest in wound-dressing applications. Gentamicin (Gt) was adsorbed from aqueous solutions into a montmorillonite (Cloisite®-Na+) to produce intercalation compounds with tunable content of the antibiotic. The hybrids were characterized by CHN chemical analysis, energy-dispersive X-ray analysis, X-ray diffraction, Fourier-transform infrared spectroscopy, and thermogravimetric analysis, confirming the intercalation of Gt by an ion-exchange mechanism. The release of Gt from the hybrids was tested in water and in buffer solution to check their stability. Hybrids with various amounts of Gt were incorporated into a HPMC matrix at various loadings and processed as films by the casting method. The resulting Gt-clay/HPMC bionanocomposites were characterized by means of field-emission scanning electron microscopy, and were also evaluated for their water-adsorption and mechanical properties to confirm their suitability for wound-dressing applications. The antimicrobial activity of the bionanocomposite films was tested in vitro toward various microorganisms (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus faecium, Acinetobacter baumannii, and Klebsiella pneumonia), showing a complete bacterial reduction even in films with small Gt contents.

Exploring the unexpected behavior of HPMC matrix tablets in dissolution media with SDS

In the case of poorly soluble drugs, a surfactant is often added to dissolution media to increase drug release. In this study, diclofenac sodium (DF-Na) release from hydroxypropyl methylcellulose (HPMC) matrix tablets was explored in dissolution media containing different sodium lauryl sulfate (SDS) concentrations. Drug release increased with increasing SDS concentration; however, an unexpected decrease in DF-Na release was noticed in the medium with pH 4 containing 0.03–0.08% SDS, which is just below the critical micelle concentration (CMC). In addition, an inverse correlation between swelling and release was noticed. Measurements of transmittance of multiple HPMC–SDS dispersions showed that with increasing HPMC concentration transmittances are lower at a wider SDS concentration interval. Thus, when using media with low SDS concentrations, especially those with concentrations lower than CMC (0.03–0.08%), DF-Na release from HPMC matrix tablets is decreased due to increased swelling and lack of SDS in the swelled layer, both possibly due to SDS binding to HPMC. However, when using media with a higher initial SDS concentration in the medium, there remains a high concentration of non-bound SDS in the bulk, which can solubilize incorporated drug and thus enhance its release from HPMC matrix tablets.

Cellulase as an “active” excipient in prolonged-release HPMC matrices: A novel strategy towards zero-order release kinetics

Hydrophilic matrices are of utmost interest for oral prolonged release of drugs. However, they show decreasing release rate over time, mainly due to lengthening of the diffusional pathway across the gel formed upon glass-rubber transition of the polymer. Therefore, achievement of zero-order release kinetics, which could reflect in constant drug plasma levels, is still an open issue. With the aim of improving the release performance of hydroxypropyl methylcellulose (HPMC) systems, the use of cellulolytic enzymes was proposed to aid erosion of the swollen matrix, thereby counteracting the release rate decrease particularly toward the end of the process. The effectiveness of this strategy was evaluated by studying the mass loss and drug tracer release from tableted matrices consisting of high-viscosity HPMC (Methocel® K4M), Acetaminophen and increasing amounts (0.5–10% on HPMC) of a cellulolytic product (Sternzym® C13030). A faster erosion and progressive shift to linearity of the overall release profiles were observed as a function of the enzyme concentration. Release was markedly linear from matrices containing 5 and 10% Sternzym® C13030. In partially coated matrices with these cellulase concentrations, such results were in agreement with data of erosion and swelling front movement, which exhibited early and long-lasting synchronization.

Microwave-induced diffusion method for solid dispersion of curcumin in HPMC matrix using water as hydration carrier

In this study, a possible way of dispersing curcumin on hydroxypropylmethylcellulose (HPMC) at a nanoscale level using microwave-induced diffusion method is reported to enhance its solubility, release control and oral bioavailability. Different weight ratios of 1:1, 1:2 and 1:4 curcumin-HPMC solid dispersions (SDs) were prepared and characterized. The results of XRD and DSC indicated that obtained 1:4 SDs exhibited less crystalline and less fusion enthalpy (13.72 ± 1.19 J/g) compared to pure curcumin and other SDs. FESEM confirmed that size reduced curcumin nanoparticles were uniformly dispersed in HPMC. Dispersed curcumin nanoparticles of 20–40 nm were embedded in HPMC for 1:4 SDs as shown by AFM and TEM analysis. In vitro release test showed that this method was successful in achieving a higher dissolution rate of curcumin at pH 6.8 and 1.2. This study proposes that the prepared SDs favorably enhanced the solubility and sustained high dissolution rate of water-insoluble curcumin.