Chitosan for improved encapsulation of thyme aqueous extract in alginate-based microparticles

Ionotropic gelation is a low-cost, easy and green microencapsulation technique. However, the encapsulation of highly soluble compounds is challenging because of the wide loss of material into the external water phase by passive diffusion and the consequent low encapsulation efficiency. In this work an important increase of encapsulation efficiency for Thymus vulgaris L. aqueous extract in alginate-based microparticles has been obtained. A formulation with the proper thyme extract/alginate ratio (30:70) was used as reference and then optimized by adding different co-carrier excipients. Microparticles obtained by dropping a solution containing thyme extract and alginate into a chitosan/calcium-chloride/acid acetic solution lead to a high encapsulation efficiency (70.43 ± 5.28 %). After drying, microparticles had a particle size of 1096 ± 72 μm, 20.087 ± 1.487 % of extract content, 6.2 % of residual water, and showed a complete release of thyme extract within one hour. Combining alginate and chitosan as polymeric co-carrier was a valuable option for efficiently encapsulating an aqueous extract by ionotropic gelation.

Spray-Dried Powder Containing Cannabigerol: A New Extemporaneous Emulgel for Topical Administration

Cannabigerol (CBG), a cannabinoid from Cannabis sativa L., recently attracted noteworthy attention for its dermatological applications, mainly due to its anti-inflammatory, antioxidant, and antimicrobial effectiveness similar to those of cannabidiol (CBD). In this work, based on results from studies of in vitro permeation through biomimetic membranes performed with CBG and CBD in the presence and in the absence of a randomly substituted methyl-β-cyclodextrin (MβCD), a new CBG extemporaneous emulgel (oil-in-gel emulsion) formulation was developed by spray-drying. The powder (SDE) can be easily reconstituted with purified water, leading to a product with chemical-physical and technological characteristics that are comparable to those of the starting emulgels (E). Thermogravimetric analysis (TGA), attenuated total reflection-Fourier transformed infrared spectroscopy (ATR-FTIR), x-ray powder diffraction (XRPD), and high-performance liquid chromatography (HPLC) analyses demonstrated that the spray-drying treatment did not alter the chemical properties of CBG. This product can represent a metered-dosage form for the localized treatment of cutaneous afflictions such as acne and psoriasis.

Mesenchymal stem cell secretome and extracellular vesicles for neurodegenerative diseases: Risk-benefit profile and next steps for the market access

Neurodegenerative diseases represent a growing burden on healthcare systems worldwide. Mesenchymal stem cells (MSCs) have shown promise as a potential therapy due to their neuroregenerative, neuroprotective, and immunomodulatory properties, which are, however, linked to the bioactive substances they release, collectively known as secretome. This paper provides an overview of the most recent research on the safety and efficacy of MSC-derived secretome and extracellular vesicles (EVs) in clinical (if available) and preclinical models of Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, multiple sclerosis, Huntington's disease, acute ischemic stroke, and spinal cord injury. The article explores the biologically active substances within MSC-secretome/EVs, the mechanisms responsible for the observed therapeutic effects, and the strategies that may be used to optimize MSC-secretome/EVs production based on specific therapeutic needs. The review concludes with a critical discussion of current clinical trials and a perspective on potential future directions in translating MSC-secretome and EVs into the clinic, specifically regarding how to address the challenges associated with their pharmaceutical manufacturing, including scalability, batch-to-batch consistency, adherence to Good Manufacturing Practices (GMP) guidelines, formulation, and storage, along with quality controls, access to the market and relative costs, value for money and impact on total expenditure.

Microencapsulation of a Pickering Oil/Water Emulsion Loaded with Vitamin D3

The ionotropic gelation technique was chosen to produce vitamin D3-loaded microparticles starting from oil-in-water (O/W) Pickering emulsion stabilized by flaxseed flour: the hydrophobic phase was a solution of vitamin D3 in a blend of vegetable oils (ω6:ω3, 4:1) composed of extra virgin olive oil (90%) and hemp oil (10%); the hydrophilic phase was a sodium alginate aqueous solution. The most adequate emulsion was selected carrying out a preliminary study on five placebo formulations which differed in the qualitative and quantitative polymeric composition (concentration and type of alginate selected). Vitamin D3-loaded microparticles in the dried state had a particle size of about 1 mm, 6% of residual water content and excellent flowability thanks to their rounded shape and smooth surface. The polymeric structure of microparticles demonstrated to preserve the vegetable oil blend from oxidation and the integrity of vitamin D3, confirming this product as an innovative ingredient for pharmaceutical and food/nutraceutical purposes.

Silk Fibroin Bioink for 3D Printing in Tissue Regeneration: Controlled Release of MSC extracellular Vesicles

Sodium alginate (SA)-based hydrogels are often employed as bioink for three-dimensional (3D) scaffold bioprinting. They offer a suitable environment for cell proliferation and differentiation during tissue regeneration and also control the release of growth factors and mesenchymal stem cell secretome, which is useful for scaffold biointegration. However, such hydrogels show poor mechanical properties, fast-release kinetics, and low biological performance, hampering their successful clinical application. In this work, silk fibroin (SF), a protein with excellent biomechanical properties frequently used for controlled drug release, was blended with SA to obtain improved bioink and scaffold properties. Firstly, we produced a printable SA solution containing SF capable of the conformational change from Silk I (random coil) to Silk II (β-sheet): this transition is a fundamental condition to improve the scaffold's mechanical properties. Then, the SA-SF blends' printability and shape fidelity were demonstrated, and mechanical characterization of the printed hydrogels was performed: SF significantly increased compressive elastic modulus, while no influence on tensile response was detected. Finally, the release profile of Lyosecretome-a freeze-dried formulation of MSC-secretome containing extracellular vesicles (EV)-from scaffolds was determined: SF not only dramatically slowed the EV release rate, but also modified the kinetics and mechanism release with respect to the baseline of SA hydrogel. Overall, these results lay the foundation for the development of SA-SF bioinks with modulable mechanical and EV-release properties, and their application in 3D scaffold printing.

Solid Lipid Microparticles by Spray Congealing of Water/Oil Emulsion: An Effective/Versatile Loading Strategy for a Highly Soluble Drug

Spray congealing technique was exploited to produce solid lipid microparticles (SLMp) loaded with a highly water-soluble drug (metoclopramide hydrochloride) dissolved in the aqueous phase of a water in oil (W/O) emulsion. The use of an emulsion as starting material for a spray congealing treatment is not so frequent. Moreover, for this application, a W/O emulsion with a drug dissolved in water is a totally novel path. A ternary diagram was built to optimize the emulsion composition, a factorial design was used to identify the factors affecting the properties of the microparticles and a Design of Experiment strategy was applied to define the impact of process conditions and formulation variables on the SLMp properties. SLMp were characterized by particle size distribution, morphology, residual moisture, drug content, release behavior, FT-IR analysis and XRPD. The obtained microparticles presented a spherical shape, particle size distribution between 54-98 µm depending on atomizing pressure used during the production step and 2-5% residual moisture 4 days after the preparation. XRPD analysis revealed that lipid polymorphic transition alfa-beta occurs depending on the presence of water. In vitro drug release tests highlighted that all the formulations had a reduced release rate compared to the drug alone. These results suggest that spray congealing of a W/O emulsion could be proposed as a good strategy to obtain SLMp with a high loading of a hydrophilic drug and able to control its release rate.

Three-Dimensional Bioprinted Controlled Release Scaffold Containing Mesenchymal Stem/Stromal Lyosecretome for Bone Regeneration: Sterile Manufacturing and In Vitro Biological Efficacy

Recently, 3D-printed scaffolds for the controlled release of mesenchymal stem cell (MSC) freeze-dried secretome (Lyosecretome) have been proposed to enhance scaffold osteoinduction and osteoconduction; coprinting of poly(ε-caprolactone) (PCL) with alginate hydrogels allows adequate mechanical strength to be combined with the modulable kinetics of the active principle release. This study represents the feasibility study for the sterile production of coprinted scaffolds and the proof of concept for their in vitro biological efficacy. Sterile scaffolds were obtained, and Lyosecretome enhanced their colonization by MSCs, sustaining differentiation towards the bone line in an osteogenic medium. Indeed, after 14 days, the amount of mineralized matrix detected by alizarin red was significantly higher for the Lyosecretome scaffolds. The amount of osteocalcin, a specific bone matrix protein, was significantly higher at all the times considered (14 and 28 days) for the Lyosecretome scaffolds. Confocal microscopy further confirmed such results, demonstrating improved osteogenesis with the Lyosecretome scaffolds after 14 and 28 days. Overall, these results prove the role of MSC secretome, coprinted in PCL/alginate scaffolds, in inducing bone regeneration; sterile scaffolds containing MSC secretome are now available for in vivo pre-clinical tests of bone regeneration.

Freeze-Dried Mesenchymal Stem Cell-Secretome Pharmaceuticalization: Optimization of Formulation and Manufacturing Process Robustness

Producing mesenchymal stem cell (MSC)-secretome for dose escalation studies and clinical practice requires scalable and good manufacturing practice (GMP)-compliant production procedures and formulation into a standardized medicinal product. Starting from a method that combines ultrafiltration and freeze-drying to transform MSC-secretome into a pharmaceutical product, the lyosecretome, this work aims to: (i) optimize the lyosecretome formulation; (ii) investigate sources of variability that can affect the robustness of the manufacturing process; (iii) modify the ultrafiltration step to obtain a more standardized final product. Design of experiments and principal component analysis of the data were used to study the influence of batch production, lyophilization, mannitol (M)/sucrose (S) binary mixture, selected as cryoprotectant excipients, and the total amount of excipients on the extracellular vesicles (EV) particle size, the protein and lipid content and the in vitro anti-elastase. The different excipients ratios did not affect residual moisture or EV particle size; simultaneously, proteins and lipids were better preserved in the freeze-dried product using the maximum total concentration of excipients (1.5% w/v) with a M:S ratio of about 60% w/w. The anti-elastase activity was instead better preserved using 0.5% w/w of M as excipient. The secretome batch showed to be the primary source of variability; therefore, the manufacturing process has been modified and then validated: the final product is now concentrated to reach a specific protein (and lipid) concentration instead of cell equivalent concentration. The new standardization approach led to a final product with more reproducible quali-quantitative composition and higher biological activity.

Effect of Methyl-β-Cyclodextrin and Trehalose on the Freeze-Drying and Spray-Drying of Sericin for Cosmetic Purposes

Sericin is a protein extracted from Bombyx mori silk cocoons. Over the last decade, this wastewater product of the textile industry has shown many interesting biological properties. This protein is widely used in the cosmetic and biomedical fields. In this study, sericin has been obtained via a High–Temperature High–Pressure degumming process, and was dried using the freeze–drying (fd) and spray–drying (sd) techniques. Proteins tend to collapse during drying, hence, sericin has been dried in the presence of two selected carrier agents: methyl–β–cyclodextrin and trehalose. The obtained powders have been analyzed using thermal investigation, microscopy (optical, SEM), and granulometric and spectroscopic analyses. Moreover, the percentage yield of the spray–drying process has been calculated. Both the agents were able to significantly improve the drying process, without altering the physico–chemical properties of the protein. In particular, the co–spray–drying of sericin with methyl–β–cyclodextrin and trehalose gave good process yields and furnished a powder with low moisture content and handling properties that are better than those of the other studied dried products. These characteristics seem to be appropriate and fruitful for the manufacturing of cosmetic raw materials.

Glargine insulin loaded lipid nanoparticles: Oral delivery of liquid and solid oral dosage forms

BACKGROUND AND AIMS

The oral administration of insulin has so far been precluded by gastro-intestinal enzyme degradation and poor intestinal absorption. Preliminary evidence for peptide uptake by the gut has recently been obtained, by our research group, following the administration of nanostructured lipid-carrier suspensions loaded with glargine insulin in healthy animal models.

METHODS AND RESULTS

In this experimental study, glargine insulin-loaded nanostructured lipid carriers have been converted into solid oral dosage forms (tablets, capsules), that are more suitable for administration in humans and have prolonged shelf-life. The liquid and solid oral dosage forms were tested for glargine insulin uptake and glucose responsivity in healthy and streptozotocin-induced diabetic rats (6 animals in each group). A suitable composition gave redispersible solid oral dosage forms from glargine insulin-loaded carriers, using both spray-drying and freeze-drying. It was observed that the liquid and solid formulations had relevant hypoglycaemic effects in healthy rats, while only capsules were efficacious in diabetic rats; probably because of gut alterations in these animal models. Detected glargine insulinaemia was consistent with a glycaemic profile.

CONCLUSION

The formulations under study showed their potential as oral glucose-lowering agents, particularly when used as capsules. However, further study is needed to produce a useful orally-active insulin preparation.

Formulation and Coating of Alginate and Alginate-Hydroxypropylcellulose Pellets Containing Ranolazine

The formulation and the coating composition of biopolymeric pellets containing ranolazine were studied to improve their technological and biopharmaceutical properties. Eudragit L100 (EU L100) and Eudragit L30 D-55-coated alginate and alginate-hydroxypropylcellulose (HPC) pellets were prepared by ionotropic gelation using 3 concentrations of HPC (0.50%, 0.65%, and 1.00% wt/wt) and applying different percentages (5%, 10%, 20%, and 30% wt/wt) of coating material. The uncoated pellets were regular in shape and had mean diameter between 1490 and 1570 μm. The rate and the entity of the swelling process were affected by the polymeric composition: increasing the HPC concentration, the structure of the pellets became more compact and slowed down the penetration of fluids. Coated alginate-HPC formulations were able to control the drug release at neutral pH: a higher quantity of HPC in the system determined a slower release of the drug. The nature of the coating polymer and the coating level applied affected the drug release in acidic environment: EU L100 gave better performance than Eudragit L30 D-55 and the best coating level was 20%. The pellets containing 0.65% of HPC and coated with 20% EU L100 represented the best formulation, able to limit the drug release in acidic environment and to control it at pH 6.8.

Calcium Alginate and Calcium Alginate-Chitosan Beads Containing Celecoxib Solubilized in a Self-Emulsifying Phase

In this work alginate and alginate-chitosan beads containing celecoxib solubilized into a self-emulsifying phase were developed in order to obtain a drug delivery system for oral administration, able to delay the drug release in acidic environment and to promote it in the intestinal compartment. The rationale of this work was linked to the desire to improve celecoxib therapeutic effectiveness reducing its gastric adverse effects and to favor its use in the prophylaxis of colon cancer and as adjuvant in the therapy of familial polyposis. The systems were prepared by ionotropic gelation using needles with different diameters (400 and 600 μm). Morphology, particle size, swelling behavior, and in vitro drug release performance of the beads in aqueous media with different pH were investigated. The experimental results demonstrated that the presence of chitosan in the formulation caused an increase of the mechanical resistance of the bead structure and, as a consequence, a limitation of the bead swelling ability and a decrease of the drug release rate at neutral pH. Alginate-chitosan beads could be a good tool to guarantee a celecoxib colon delivery.

Preparation of multiparticulate systems for oral delivery of a micronized or nanosized poorly soluble drug

The purpose of the present work was to prepare multiparticulate drug delivery systems for oral administration of a poorly soluble drug such as itraconazole. Multiparticulate systems were prepared by extrusion/spheronization technique using a mix of crospovidone, low viscosity hypromellose, microcrystalline cellulose, micronized drug and water. In order to improve the release performance of the multiparticulate systems, the micronized drug was suspended in water with polysorbate 20 and nanonized by a high-pressure homogenization. The suspension of drug nanoparticles was then spray-dried for enabling an easy handling of the drug and for preventing the over-wetting of the powders during extrusion/spheronization processing. Both multiparticulate units prepared with micronized or nanonized drug showed acceptable disintegrating properties. The nanosizing of micronized drug powder provided a significant improvement of drug dissolution rates of the multiparticulates.

Thermogravimetric investigation of the hydration behaviour of hydrophilic matrices

This article proposes thermogravimetric analysis (TGA) as a useful method to investigate the hydration behaviour of hydrophilic matrix tablets containing hydroxypropylmethylcellulose (HPMC), sodium carboxymethylcellulose (NaCMC) or a mixture of these two polymers and four drugs with different solubility. The hydration behaviour of matrix systems was studied as a function of the formulation composition and of the dissolution medium pH. TGA results suggest that the hydration of matrices containing HPMC is pH-independent and not affected by the characteristics of the loaded drug; this confirms HPMC as a good polymer to formulate controlled drug delivery systems. On the other hand, the performances of NaCMC matrix tablets are significantly affected by the medium pH and the hydration and swelling of this ionic polymer is influenced by the loaded drug. For systems containing the two polymers, HPMC plays a dominant role in the hydration/dissolution process at acidic pH, while at near neutral pH both the cellulose derivatives exert a significant influence on the hydration performance of systems. The results of this work show that TGA is able to give quantitative highlights on the hydration behaviour of polymeric materials; thus this technique could be a helpful tool to support conventional hydration/swelling/dissolution studies.

Matrices containing NaCMC and HPMC

The aim of the present study is an investigation of the swelling behaviour of matrix systems containing a mixture of hydroxypropylmethylcellulose (HPMC) and sodium carboxymethylcellulose (NaCMC) with a model soluble drug to find the correlation between the morphological behaviour and the drug release performance. The swelling study was conducted on tablets containing only the drug and the two polymers mixture (MB) and on reference tablets containing each polymer and the same drug, at three different pHs. MB matrices show a similar swelling trend at pH 4.5 and 6.8, while they have different behaviour in acidic fluid. At pH 1 the gel layer formed by NaCMC is characterized by a rigid structure of a partially chemically crosslinked hydrogel while HPMC and MB matrices form a physical not crosslinked gel. At pH 4.5 and 6.8, all the systems show the typical morphological behaviour of a swellable matrix in which the macromolecular chains in the gel network are held together by weak bondings (physical gel). In these buffers, MB systems maintain a constant drug release rate coupling diffusion and erosion mechanism: the gel and infiltrated layers thicknesses are maintained constant and a zero-order release kinetics can be achieved.

Matrices containing NaCMC and HPMC 1. Dissolution performance characterization

In this study hydroxypropylmethylcellulose (HPMC) and sodium carboxymethylcellulose (NaCMC) were used as polymeric carriers to improve controlled release performances of matrix tablets containing a soluble drug. The drug release behaviour of the systems containing these two polymers mixture and each material separately was investigated. To evaluate the effect of the dissolution medium pH, on the drug release performance, release tests were conducted at pH 1, 4.5 and 6.8. In vitro release studies demonstrated that the mixture of the two cellulose derivatives enables a better control of the drug release profiles at pH 4.5 and at 6.8 both in term of rate and mechanism. Texture analysis on the swollen tablets helps to understand drug release kinetic and mechanism. In fact, the results obtained confirm that a gel, which is characterized by high strength and consistence is less susceptible to erosion and chains disentanglement and the drug release mechanism is mainly governed by diffusion. On the contrary, gels, which show a low strength and texture, have low resistance to the fluid erosion action and the release of the active molecule is manly due to polymer relaxation and chains disentanglement moving the drug delivery kinetic towards an erosion/relaxation mechanism.

Preparation and evaluation of release characteristics of 3TabGum, a novel chewing device

A new chewing gum device in the form of a three layers tablet (3TabGum) has been developed. The new drug delivery system is obtained, at room temperature, by direct compression using conventional pharmaceutical equipment. Basically, the resulting chewing gum tablets comprise a gum core combined with two protective antiadherent external layers, which prevent gum adhesion to the punches of the tableting machine. Drug release from a dosage form is the critical step in drug absorption and bioavailability, thus an experimental protocol has been designed to evaluate the efficiency of this kind of therapeutic system by verifying its capability to release the drug dose and by assessing the delivery rate. Simple diffusion into the medium causes the release of only a small percentage of the drug contained in the medicated chewing gum, while the delivery of the major part of the dose occurs during mastication. The results obtained in this study suggest that water soluble drugs are freely and easily released by chewing gums, while for actives characterized by reduced water solubility the release rate depends on the chewing time although all the drugs tested are completely released after a reasonable mastication time.

Polymers-gamma ray interaction. Effects of gamma irradiation on modified release drug delivery systems for oral administration

The aim of this work is to verify the efficiency of two kinds of matrix tablets formulations containing PEO or PVA as retarding polymer. Moreover, since in the last years the exposure to ionizing radiation is a more and more used method to reduce bacterial charge in pharmaceutical products, the effects of gamma irradiation on these two kinds of polymers has been evaluated. The study is performed on matrix tablets containing diltiazem HCl, as model drug, and polyethylene oxides (PEO) of two different molecular weights or polyvinylalchool (PVA) of medium degree of hydrolysis, as drug release modulators. Dissolution of the matrices, release of diltiazem and morphological behaviour of the samples, before and after exposure to increasing doses of gamma irradiation, are investigated in order to verify their stability. The results show that the ionizing radiation does not modify significantly the dissolution trend of the PVA samples; on the contrary, the dissolution and the morphological behaviour of the PEO matrices is strongly affected by the radiation dose received. In particular, the dissolution rate of the irradiated PEO tablets dramatically increases as a function of the irradiation dose and the swelling process, which characterised the non-irradiated PEO samples, was replaced by a rapid erosion process responsible for the quickly dissolution of the matrices. The changes of the dissolution and morphological PEO tablets performances could be explained by a breaking of the polymeric chains (shown by EPR studies) as a consequence of the exposure to gamma rays. These chemical-structural modifications of the polymers are responsible for the reduced efficacy of the PEO systems in controlling the drug release rate.

Chemical and physical stability of hydroxypropylmethylcellulose matrices containing diltiazem hydrochloride after gamma irradiation

In recent years, the exposure to gamma-radiation is an increasingly used method to sterilize or to reduce bacterial charge in drug-delivery devices. The aim of this study was to investigate whether the ionizing radiation may be responsible for drug inactivation or for the alteration of the functional excipient used to modulate drug release from a controlled-release delivery system. In this work, we investigated the physical and dissolution stability of prolonged release matrix tablets containing diltiazem hydrochloride, as a model drug, and hydroxypropylmethylcellulose (HPMC) of two different viscosity grades, as the retarding polymer, before and after exposure to increasing doses of gamma-rays. The results show that gamma-irradiation induces chemical modifications in the structure of the active agent, and also of the hydrophilic polymer. The electronic paramagnetic resonance analysis of gamma-irradiated diltiazem has afforded evidence of carbon radicals stemming from C-H bond ruptures and sulphur radicals, the latter being formed mainly after admission of air at room temperature. The major radical products in the HPMC polymer radiolysis have been reckoned with chain scission events in agreement with the results of viscosity measurements that show a progressive decrease of the average molecular weight with increasing the radiation dose. The elaboration of the viscosity data has led to linear relationships between the eta(o)/eta ratio and the radiation dose D which were rationalized with the following equation under the assumption of a Mark-Houwink Sakurada coefficient a approximately equal 1: eta(o)/eta = (1 + uy(o) D)(a). In this equation, D is gamma-radiation dose, eta(o) and eta are the reduced viscosities before and after the irradiation respectively, u is the number average degree of polymerization, and y(o) is the chain scission radiolytic yield. From the linear relationships G(chain scissions) = 1.2 x 10(-6) and 1.4 x 10(-6) moles/J have been obtained for the two HPMC polymer samples M100 and M4 of different molecular weight used in the experiments. These changes could be responsible for the alteration of the drug-release mechanism and reduced polymer efficacy in controlling drug release.

Photostability of extended-release matrix formulations

The photostability of drugs has been widely studied while less attention is devoted to the possible modifications that UV light may induce on the excipients of a dosage form, in particular, on the functional polymers used to modulate drug delivery. In this work we have evaluated the effect of UV light on the release characteristics of extended-release matrix tablets containing hydroxypropylmethylcellulose (HPMC) or polyethylene oxide (PEO) as retarding polymers. Two different model drugs have been used: nifedipine (insoluble and photolabile drug) and diltiazem (soluble and photostable drug). Photodecomposition of nifedipine was evaluated and the formation of the photoproducts was followed during the dissolution process. Regarding the dissolution stability, the matrix tablets containing HPMC exposed to UV light have not shown significant differences in drug release profiles compared to the same non-irradiated formulation, while the matrix tablets containing PEO and exposed to the same conditions of UV light have shown a remarkable increase of drug release rate within the first minutes of the dissolution test (burst effect) which is particularly critical because it can cause the loss of the desired therapeutic control.

Dissolution behaviour of hydrophilic matrix tablets containing two different polyethylene oxides (PEOs) for the controlled release of a water-soluble drug. Dimensionality study

Hydrophilic matrix tablets containing polyethylene oxides as the retarding polymer have been successfully employed in the controlled release of drugs. To evaluate the relative influence of drug diffusion and polymer erosion mechanisms in the drug delivery process, we studied the hydration behaviour of matrix tablets containing a water-soluble drug and PEOs of two different molecular weights: Polyox WSRN 1105 (Mw = 0.9 x 10(6)) and Polyox WSRN 301 (Mw = 4 x 10(6)). The hydration rate, the extent of swelling, and the erosion rate of matrices containing the polymer, the drug and tableting excipients were evaluated in comparison to tablets made of pure polymer. The results of these studies on function of the release behaviour were then discussed. The results show that the higher molecular weight PEO swells to a greater extent and tends to form, upon hydration, a stronger gel, which is therefore less liable to erosion, if compared to the lower molecular weight PEO. This difference in the erosion behaviour can explain the different efficiencies of the two polymeric products in modulating the delivery rate of the water-soluble drug. Moreover, the presence of other soluble components (drug and excipients) in the dosage form enhances the erosion trend of the tablets with a consequent reduction of the efficiency of the polymer in drug release control.