Equivalence assessment of creams with quali-quantitative differences in light of the EMA and FDA regulatory framework.

EMA and FDA are upgrading guidelines on assessing the quality and the equivalence of topically applied drug products for developing copies of originator products and supporting post-marketing variations. For topical products having remarkably similar composition, both EMA and FDA accept the equivalence on the bases of the comparison of rheological properties and in vitro drug release constant (k) and skin permeation flux (J) values, instead of clinical studies. This work aims to evaluate the feasibility to expand this approach to variations of the composition of complex semi-solid preparations. Ibuprofen (IB) creams at two different strengths (i.e., 1 % and 10 %) were used as a model formulation. Two formulative changes were performed: (a) the addition of the humectant to simulate a minor post-marketing variation; (b) the substitution of the emulsifying system to simulate a major one. These variations impacted only in 1 % IB formulations where both the equivalences of rheological data and J-values failed. At the highest concentration, the presence of IB crystals broke down the differences in rheological patterns and lead the IB thermodynamic activity at the maximum figuring out an overlapping of the J-values. Such data suggest the combination of these studies, which are thought mainly for the development of copies, could be also applied to the management of post-marketing variations that involve product composition.

3D printed mucoadhesive orodispersible films manufactured by direct powder extrusion for personalized clobetasol propionate based paediatric therapies.

The aim of this work is the development and production by Direct Powder Extrusion (DPE) 3D printing technique of novel oral mucoadhesive films delivering Clobetasol propionate (CBS), useful in paediatric treatment of Oral Lichen Planus (OLP), a rare chronic disease. The DPE 3D printing of these dosage forms can allow the reduction of frequency regimen, the therapy personalization, and reduction of oral cavity administration discomfort. To obtain suitable mucoadhesive films, different polymeric materials, namely hydroxypropylmethylcellulose or polyethylene oxide blended with chitosan (CS), were tested and hydroxypropyl-ß-cyclodextrin was added to increase the CBS solubility. The formulations were tested in terms of mechanical, physico-chemical, and in vitro biopharmaceutical properties. The film showed a tenacious structure, with drug chemical-physical characteristics enhancement due to its partial amorphization during the printing stage and owing to cyclodextrins multicomponent complex formation. The presence of CS enhanced the mucoadhesive properties leading to a significant increase of drug exposure time on the mucosa. Finally, the printed films permeation and retention studies through porcine mucosae showed a marked retention of the drug inside the epithelium, avoiding drug systemic absorption. Therefore, DPE-printed films could represent a suitable technique for the preparation of mucoadhesive film potentially usable for paediatric therapy including OLP.

Micelles-in-Liposome Systems Obtained by Proliposomal Approach for Cannabidiol Delivery: Structural Features and Skin Penetration.

Deformable liposomes represent valuable drug carriers for cutaneous administration. Nevertheless, the fluid lipid membrane can favor the drug leakage during storage. Proliposomes may represent a suitable strategy to solve this issue. As an alternative, a novel carrier, which encloses hydrophobic drugs in the inner core of vesicles, namely, a drug-in-micelles-in-liposome system (DiMiL), has been proposed. In this work, we investigated the possible advantages of combining these two approaches to obtain a formulation able to enhance the skin penetration of cannabidiol (CBD). Proliposomes were prepared by spray-drying or slurry method testing lactose, sucrose, and trehalose as carriers at different sugar/lipid weight ratios. The ratio between soy-phosphatidylcholine (main lipid) and Tween 80 was instead fixed at 85:15 w/w. DiMiL systems were extemporaneously obtained by the hydration of proliposomes with a Kolliphor HS 15 micellar dispersion (containing CBD, when appropriate). Based on the technological properties, sucrose and trehalose at 2:1 sugar/lipid ratio resulted in the best carriers for spray-dried and "slurried" proliposomes, respectively. Cryo-EM images clearly showed the presence of micelles in the aqueous core of lipid vesicles and the presence of sugars did not alter the structural organization of DiMiL systems, as demonstrated by SAXS analyses. All formulations were highly deformable and able to control CBD release regardless of the presence of sugar. The permeation through human epidermis of CBD carried by DiMiL systems was significantly improved compared to that obtained loading the drug in conventional deformable liposomes with the same lipid composition or in an oil solution. Furthermore, the presence of trehalose led to a further slight increase of the flux. Altogether, these results demonstrated that proliposomes may be a valuable intermediate for the preparation of deformable liposome-based cutaneous dosage forms, improving the stability without compromising the overall performances.

Spotlight on Calcipotriol/Betamethasone Fixed-Dose Combination in Topical Formulations: Is There Still Room for Innovation?

Psoriasis is a lifelong disease which requires treatment adherence for successful management. Considering the complexity of this pathology, the combination of active pharmaceutical ingredients with a synergistic mechanism of action can improve the safety and efficacy of the treatment with respect to the conventional monotherapy. Moreover, a fixed dose of therapeutic agents in a topical formulation offers the possibility to simplify administration, reduce the doses of each active ingredient, and improve patient's compliance. Among the first-line treatments in mild to moderate psoriasis, the formulation of calcipotriol (Cal) and betamethasone dipropionate (BD) in a single vehicle is challenging due to their chemical incompatibility in an aqueous environment and the formation of degradation products. Based on these considerations, this review aims to provide an overview on the biopharmaceutical properties of Cal/BD fixed-dose combination products available on the market (namely ointment, oleogel, foam, and O/W cream), highlighting also the novel approaches under evaluation. The main differences among topical formulations are discussed considering the different features of the anatomic districts involved in psoriasis and the patient's adherence. Moreover, since in vitro experiments are fundamental to evaluate the skin permeation profile during the development of an efficacious medicinal product, special emphasis is given to models proposed to mimic psoriatic lesions.

Caffeic Acid-Grafted PLGA as a Novel Material for the Design of Fluvastatin-Eluting Nanoparticles for the Prevention of Neointimal Hyperplasia.

Drug-eluting nanoparticles (NPs) administered by an eluting balloon represent a novel tool to prevent restenosis after angioplasty, even if the selection of the suitable drug and biodegradable material is still a matter of debate. Herein, we provide the proof of concept of the use of a novel material obtained by combining the grafting of caffeic acid or resveratrol on a poly(lactide-co-glycolide) backbone (g-CA-PLGA or g-RV-PLGA) and the pleiotropic effects of fluvastatin chosen because of its low lipophilic profile which is challenging for the encapsulation in NPs and delivery to the artery wall cells. NPs made of such materials are biocompatible with macrophages, human smooth muscle cells (SMCs), and endothelial cells (ECs). Their cellular uptake is demonstrated and quantified by confocal microscopy using fluorescent NPs, while their distribution in the cytoplasm is verified by TEM images using NPs stained with an Ag-PVP probe appositely synthetized. g-CA-PLGA assures the best control of the FLV release from NP sizing around 180 nm and the faster SMC uptake, as demonstrated by confocal analyses. Interestingly and surprisingly, g-CA-PLGA improves the FLV efficacy to inhibit the SMC migration, without altering its effects on EC proliferation and migration. The improved trophism of NPs toward SMCs, combined with the excellent biocompatibility and low modification of the microenvironment pH upon polymer degradation, makes g-CA-PLGA a suitable material for the design of drug-eluting balloons.

Design of Liposomal Lidocaine/Cannabidiol Fixed Combinations for Local Neuropathic Pain Treatment.

The administration of drug fixed combinations by nanocarriers is a new attractive approach since it can allow improvements in both the skin penetration of cargo compounds and their synergistic effects. The cutaneous administration of lidocaine (LD) and cannabidiol (CBD) combination can be useful for the local treatment of neuropathic pain. In fact, these drugs might exert a complementary effect on pain acting on sodium and calcium channels. In this study, the feasibility to deliver this combination in the deeper layers of the skin using deformable liposomes was studied. Based on a study of the drug affinity for lipid components performed by DSC, CBD was loaded in the lipid bilayer for limiting the leakage, while LD was loaded in the inner core by a pH gradient method (G-liposomes) or after previous encapsulation in micelle (DiMiL). The effect of the presence of Tween 80 in the liposome membrane was also evaluated. DiMiL increased both the skin permeation and the retention in the dermis of CBD and LD with respect to G-liposomes (R24dermis: 11.52 ± 2.4 against 4.51 ± 0.8 µg/cm2 for CBD; 19.6 ± 2.9 against 3.2 ± 0.1 µg/cm2 for LD). Moreover, both DiMiL and G-liposomes were more efficient than control formulations carrying free drugs in improving drug skin permeation. Interestingly, in the presence of a drug exerting a fluidizing effect such as CBD, the removal of Tween 80 from the composition led to an improved control of drug release and a higher extent of drug retention in the dermis layer.

Design and development of topical liposomal formulations in a regulatory perspective.

The skin is the absorption site for drug substances intended to treat loco-regional diseases, although its barrier properties limit the permeation of drug molecules. The growing knowledge of the skin structure and its physiology have supported the design of innovative nanosystems (e.g. liposomal systems) to improve the absorption of poorly skin-permeable drugs. However, despite the dozens of clinical trials started, few topically applied liposomal systems have been authorized both in the EU and the USA. Indeed, the intrinsic complexity of the topically applied liposomal systems, the higher production costs, the lack of standardized methods and the more stringent guidelines for assessing their benefit/risk balance can be seen as causes of such inefficient translation. The present work aimed to provide an overview of the physicochemical and biopharmaceutical characterization methods that can be applied to topical liposomal systems intended to be marketed as medicinal products, and the current regulatory provisions. The discussion highlights how such methodologies can be relevant for defining the critical quality attributes of the final product, and they can be usefully applied based on the phase of the life cycle of a liposomal product: to guide the formulation studies in the early stages of development, to rationally design preclinical and clinical trials, to support the pharmaceutical quality control system and to sustain post-marketing variations. The provided information can help define harmonized quality standards able to overcome the case-by-case approach currently applied by regulatory agencies in assessing the benefit/risk of the topically applied liposomal systems.

Rationalizing the Design of Hyaluronic Acid-Decorated Liposomes for Targeting Epidermal Layers: A Combination of Molecular Dynamics and Experimental Evidence.

This work provides information on the features of low molecular weight hyaluronic acid (HA)-decorated liposomes to target resveratrol (RSV) in the skin. Deformable liposomes were made of soy-phosphatidylcholine with Tween 80 as the fluidizing agent. For HA conjugation, three different phosphoethanolamines were tested: 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE), 1,2-dimyristoyl-sn-glycero-3-phosphoethanolamine (DMPE), and 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE). The different phosphoethanolamine-HA conjugates were inserted into the liposome bilayer by hydration (HA on both faces of the bilayer) or by the postinsertion method (HA only on the external face of the bilayer). The effect of these variables on deformability was experimentally assessed by an in-house method (K value, the lower the value, the higher the deformability) and molecular dynamics (MD) simulations. The results showed that the K values of HA-liposomes obtained by hydration were higher than the K values of HA-liposomes prepared by postinsertion, and both were at least 10-fold higher than the K values of the corresponding plain liposomes. The nature of the lipid anchor played a key role in deformability (DMPE > DOPE > DPPE) with high variability in the case of DOPE formulations. These data were justified by the trends found in silico for the bilayer bending modulus and the HA end-to-end distance. In addition to liposome flexibility, the HA extent seems to be the key factor governing the skin penetration of RSV. When the extent is higher, the amount of the drug retained in the skin is larger. Regarding skin permeation, a parabolic trend was recorded, and the optimal amount to favor skin permeation was an approximately 30 HA/phospholipid (µg/mmol) ratio. This study reports the first piece of evidence that it is possible to control drug delivery in the skin by tuning the amount of HA on the vesicle surface.

Design and development of plastic antibodies against SARS-CoV-2 RBD based on molecularly imprinted polymers that inhibit in vitro virus infection.

The present research study reports the development of plastic antibodies based on Molecularly Imprinted Polymers (MIPs) capable of selectively binding a portion of the novel coronavirus SARS-CoV-2 spike protein. Indeed, molecular imprinting represents a very promising and attractive technology for the synthesis of MIPs characterized by specific recognition abilities for a target molecule. Given these characteristics, MIPs can be considered tailor-made synthetic antibodies obtained by a templating process. After in silico analysis, imprinted nanoparticles were synthesized by inverse microemulsion polymerization and their ability to prevent the interaction between ACE2 and the receptor-binding domain of SARS-CoV-2 was investigated. Of relevance, the developed synthetic antibodies are capable of significantly inhibiting virus replication in Vero cell culture, suggesting their potential application in the treatment, prevention and diagnosis of SARS-CoV-2 infection.

Relevance of production method on the physical stability and in vitro biopharmaceutical performances of olanzapine orodispersible film.

This study assessed the relevance of the preparation process, namely solvent casting and hot-melt ram printing, on the biopharmaceutical performances of olanzapine orodispersible films (ODF) made of maltodextrins. Beside the clinical rationale, olanzapine was selected since it is subjected to polymorphism which impacts on its bioavailability. All ODF disintegrated in less than 3 min and showed content uniformity within the acceptable values. Dissolution testing in 3 mL of artificial saliva at pH = 6.8 evidenced that cast and printed ODF released after 5 min about 2% and 100%, respectively; at higher volume, a yellow precipitate was formed after disintegration of the cast ODF. At pH = 1.2, the t85% for cast ODF was reached after about 20 min and only the 90% olanzapine was dissolved increasing the pH to 6.8. These differences were explained by DSC, TGA and X-ray diffraction data which demonstrated that the casting method, which included the preparation of an aqueous slurry, favours the conversion from Form I to a hydrated one. Since extruded ODF resulted physically stable after 30 months, this suggests the potentiality of this technique to load in ODF drugs undergoing solid-state modification after exposure to aqueous media.

Extemporaneous printing of diclofenac orodispersible films for pediatrics.

OBJECTIVE: The possible application of a hot-melt ram extrusion printing to the preparation of diclofenac orodispersible films (ODF) made of maltodextrin was studied focusing the attention on the effects of taste-masking agents (i.e. namely mint, licorice-mint, and sucralose) and an opacifier (titanium dioxide [TiO2]). SIGNIFICANCE: This is a proof-of-concept of the feasibility to print ODF loaded with a thermosensitive drug substance by hot-melt technologies. METHODS: Diclofenac sodium (DNa) ODF made of maltodextrin (dextrose equivalent (DE) = 6 ) plasticized with glycerol were prepared by hot-melt extrusion printing. ODF were characterized for disintegration time, drug content, and solid state, in vitro dissolution in deionized water and simulated salivary fluid at pH 5.7, tensile, and adhesive properties. Moreover, the stability of ODF was assessed in accelerated conditions over six months. RESULTS: After the preparation, no variation in drug solid state was evident and the formation of impurity A of DNa was detected, even if it remained below the Pharmacopoeia (Ph. Eur.) limits (< 0.2%). Only the addition of DNa significantly improved the ODF tensile properties: the tensile strength increased from 0.17 ± 0.03 MPa (placebo ODF) to 2.21 ± 0.54 MPa (p ≤ 0.03). All ODF disintegrated in about 1 min, and the t80% was lower than 3 min. TiO2 reduced the static and dynamic peel forces (p ≤ 0.006) favoring the ODF detachment from the primary packaging material. During the accelerated stability study, ODF were easy to handle without fracture; the drug content, impurity A, and dissolution profiles remained superimposable. CONCLUSION: Hot-melt printing can be suitable to prepare palatable ODF loaded with bitter thermosensitive drugs.

Transplantation of autologous extracellular vesicles for cancer-specific targeting.

Nano- and microsized extracellular vesicles (EVs) are naturally occurring cargo-bearing packages of regulatory macromolecules, and recent studies are increasingly showing that EVs are responsible for physiological intercellular communication. Nanoparticles encapsulating anti-tumor theranostics represent an attractive "exosome-interfering" strategy for cancer therapy. Methods: Herein, by labeling plasma-derived EVs with indocyanine green (ICG) and following their biodistribution by in vivo and ex vivo imaging, we demonstrate the existence of nanoparticles with a highly selective cancer tropism in the blood of colorectal cancer (CRC) patients but not in that of healthy volunteers. Results: In CRC patient-derived xenograft (PDX) mouse models, we show that transplanted EVs recognize tumors from the cognate nanoparticle-generating individual, suggesting the theranostic potential of autologous EVs encapsulating tumor-interfering molecules. In large canine breeds bearing spontaneous malignant skin and breast tumors, the same autologous EV transplantation protocol shows comparable safety and efficacy profiles. Conclusions: Our data show the existence of an untapped resource of intercellular communication present in the blood of cancer patients, which represents an efficient and highly biocompatible way to deliver molecules directly to the tumor with great precision. The novel EV-interfering approach proposed by our study may become a new research direction in the complex interplay of modern personalized cancer therapy.

Trends in the Characterization Methods of Orodispersible Films.

The recent increased interest in orodispersible films (ODF) stems from their ideal potential to circumvent several pharmacotherapy-related problems, such as improved medication compliance and adherence, especially in children, elderly and uncooperative patients. Their administration is well accepted by the majority of patients because ODF dissolve upon contact with the saliva in the oral cavity without the need for water intake. ODF application in personalized pharmacotherapy is currently being exploited. Moreover, innovative preparation methods and characterization technologies have been evolving in recent years, highlighting a promising future both from the technological and clinical standpoints. However, the key obstacles to the attainment of full potential of ODF in the pharmaceutical field is the lack of harmonized and well-defined quality characterization procedures, standard evaluation parameters, guidance on appropriate final product properties and specifications. This review provides an appraisal on the ODF characterization methods from slurries to the finished medicinal products with a specific focus on the technologies suitable for identification, quantification, and quality evaluation of extemporaneously prepared ODF on small batches in individualized pharmacotherapy. Generally, there is a paradigm shift from the use of the conventional quality evaluation tools and/or protocols for oral solid dosage forms to characterize ODF to more specific equipment and procedures that suit the peculiarities of the ODF.

Echinacea angustifolia DC. Lipophilic Extract Patch for Skin Application: Preparation, In Vitro and In Vivo Studies.

Dodeca-2E,4E,8Z,10E/Z-tetraenoic isobutylamide (tetraene) is the main component of Echinacea angustifolia DC. lipophilic extract, the bioavailability and immunomodulatory effect after oral administration in soft gel capsules in healthy volunteers of which we have already demonstrated. In the present work, we assessed the transdermal administration as an alternative route of administration of such an alkamide. The first step, therefore, encompassed the preparation of a drug-in-adhesive patch with an area of 868 mm2 and containing a dose of 0.64 mg of tetraene. In vitro skin permeation studies in Franz-type diffusion chambers resulted in a tetraene flux of (103 ± 10) ng × cm-2 × h-1 with a very good linearity (r = 0.99). The relatively low lag time of just 13 min indicates low binding and the accumulation of tetraene in the skin. Finally, the patch was administered to six healthy volunteers, and the pharmacokinetic analysis was performed by nonlinear mixed effects modelling with soft gel oral capsules serving as the reference formulation. The in vivo results correlated well with the in vitro permeation and indicated an initial burst tetraene absorption from the patch that was in parallel with the zero-order kinetics of absorption. The rate of the latter process was in good agreement with the one estimated in vitro. The tetraene absorption rate was therefore slow and prolonged with time, resulting in a bioavailability of 39% relative to the soft gel capsules and a very flat plasma concentration profile.

Design of pressure-sensitive adhesive suitable for the preparation of transdermal patches by hot-melt printing.

This work aimed to design low-melting pressure sensitive adhesives and to demonstrate the feasibility of the preparation of (trans)dermal patches by hot-melt ram extrusion printing. This approach allows defining both the geometry of (trans)dermal patch and the drug strength easily according to patient needs. The preparation steps are the mixing of a poly-ammonium methacrylate polymer (i.e. Eudragit RL and RS) with a suitable amount of plasticizer (triacetin or tributyl citrate) and drug (ketoprofen or nicotine), the melting in the ram extruder, and the printing on the backing layer foil. The formulations were characterized in terms of rheological and adhesive properties, in vitro drug release and skin permeation profiles. The (trans)dermal patches made of Eudragit RL or Eudragit RS plasticized with the 40% triacetin could be printed at 90 °C giving formulations with suitable adhesive properties and without cold flow after 1 month of storage at 40 °C. Furthermore, the overall results showed that the performances of printed (trans)dermal patches overlapped those made by solvent casting, suggesting that the proposed solvent-free technology can be useful to treat cutaneous pathologies when the availability of (trans)dermal patches with size and shape that perfectly fit with the skin area affected by the disease improves the safety of the pharmacological treatment.

Preserving the Integrity of Liposomes Prepared by Ethanol Injection upon Freeze-Drying: Insights from Combined Molecular Dynamics Simulations and Experimental Data.

The freeze-drying of complex formulations, such as liposomes, is challenging, particularly if dispersions contain residual organic solvents. This work aimed to investigate the effects of possible protectants, namely sucrose, trehalose and/or poly(vinyl pyrrolidone) (PVP), on the main features of the dried product using a 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC)-based liposomal dispersion prepared by ethanol injection and containing ethanol up to 6%, as a model. The interactions among vesicles and protectants were preliminary screened by Molecular Dynamics (MD) simulations, which have been proved useful in rationalizing the selection of protectant(s). The freeze-drying protocol was based on calorimetric results. Overall data suggested a stronger cryo-protectant effect of trehalose, compared with sucrose, due to stronger interactions with the DPPC bilayer and the formation of highly ordered clusters around the lipids. The effect further improved in the presence of PVP. Differently from the other tested protectants, the selected trehalose/PVP combination allows to preserve liposome size, even in the presence of 6% ethanol, as demonstrated by Nanoparticle Tracking Analysis (NTA). Nevertheless, it should be also underlined that cakes blew out at an ethanol concentration higher than 1% v/v, probably due to the poor cohesion within the cake and solvent vapour pressure upon sublimation.

SEBS block copolymers as novel materials to design transdermal patches.

Styrene-block-(ethylene-co-butylene)-block-styrene (SEBS) copolymers are biocompatible elastomers with outstanding stability to UV radiation. This work addresses the potentialities of this class of elastomers for the development of transdermal patches. The influence of SEBS molecular weight, plasticizer and tackifier type on rheological pattern, debonding mechanisms, adhesive properties (i.e., tack, shear and peel adhesion) as well as on the in vitro biopharmaceutical performances (i.e., drug release and skin permeability) was investigated using ibuprofen as model drug. The relationships between the linear and non-linear rheological properties and the main adhesive and biopharmaceutical properties of the prepared patches have been demonstrated. The higher the viscous component of the matrix, the lower its cohesiveness and the faster the drug release rate. The in vitro skin permeability of ibuprofen was not limited by the polymeric matrix, even if compared to the commercial reference product. In conclusion, SEBS copolymers are suitable materials to design drug in-adhesive patches. In particular, SEBS-low molecular weight is the polymer worthy of consideration because of its favorable viscoelastic behavior.

Trends in the production methods of orodispersible films.

Interest in orodispersible films (ODF) is growing day-by-day, since this dosage form overcomes some therapeutic obstacles, such as impaired swallowing, and offers several benefits, such as the possibility to adapt the dosing requirements for a subset of patients. As a consequence, technologies to produce ODF have risen attention for possible applications in the development of patient-centric formulations. This review critically discusses current trends in the technology platforms proposed to manufacture ODF, including the innovation and opportunities to produce very small batches in a pharmacy setting. Although the main Pharmacopoeias recommend testing customized dosage forms for quality assurance, pharmaceutical assays are a matter of debate due to the complexity and high cost of conventional methods. Alternatively, non-disruptive online analytic methods can be proposed to assay ODF properties, above all to assure the uniformity of drug content.

Regulatory aspects and quality controls of polymer-based parenteral long-acting drug products: the challenge of approving copies.

To assure the safety and the efficacy of a medicinal product, quality and batch-to-batch reproducibility need to be guaranteed. In the case of parenteral long-acting products, the European Union (EU) and US Regulatory Authorities provide different indications, from the classification to the in vitro release assays related to such products. Despite their relevance, there are few in vitro experimental set-ups enabling researchers to discriminate among products with different in vivo behaviors. Consequently, most copies are authorized through hybrid instead of generic applications. Here, we review the actual regulatory frameworks to evaluate the in vitro release of drugs from polymer-based long-acting parenterals to highlight the directions followed by the Regulatory Agencies in the USA and EU.

Lysozyme Mucoadhesive Tablets Obtained by Freeze-Drying.

Lysozyme is particularly attractive for the local treatment of oral pathologies related to microbiological infections. However, the requirement of a prolonged release is difficult to achieve because of saliva swallowing and of the protein denaturation which can occur during production and storage of a dosage form. This work demonstrates the feasibility to prepare lysozyme mucoadhesive tablets by freeze-drying. Tablets were prepared by using alginate (ALG) physically "cross-linked" with calcium ion and different grades of hydroxypropyl methylcellulose (HPMC) (i.e., E5, E50, or K100). The tablets were characterized in terms of swelling or erosion behavior, in vitro mucoadhesive properties, lysozyme activity (Micrococcus lysodeikticus), drug release and ability to inactivate Staphylococcus aureus. The formulations prepared with HPMC K100 were discarded because of the fast erosion. All other formulations allowed a sustained release over at least 6 h. Independently of composition, lysozyme activity (78,311 ± 1873 Units/mg) significantly decreased in the case of tablets containing 5% and 10% w/w of protein (55,000 Units/mg and 33,000 Units/mg, respectively). Conversely, no modifications occurred in the case of tablets containing 1% w/w lysozyme. The formulation prepared by ALG/HPMC E5 7/3 ratio was efficacious against S. aureus. After 3 months of storage at 5 ± 3°C, no significant decrease in lysozyme activity was observed.