Bud-Poplar-Extract-Embedded Chitosan Films as Multifunctional Wound Healing Dressing.

Wounds represent a major global health challenge. Acute and chronic wounds are sensitive to bacterial infection. The wound environment facilitates the development of microbial biofilms, delays healing, and promotes chronic inflammation processes. The aim of the present work is the development of chitosan films embedded with bud poplar extract (BPE) to be used as wound dressing for avoiding biofilm formation and healing delay. Chitosan is a polymer with antimicrobial and hydrating properties used in wound dressing, while BPE has antibacterial, antioxidative, and anti-inflammatory properties. Chitosan-BPE films showed good antimicrobial and antibiofilm properties against Gram-positive bacteria and the yeast Candida albicans. BPE extract induced an immunomodulatory effect on human macrophages, increasing CD36 expression and TGFß production during M1/M2 polarization, as observed by means of cytofluorimetric analysis and ELISA assay. Significant antioxidant activity was revealed in a cell-free test and in a human neutrophil assay. Moreover, the chitosan-BPE films induced a good regenerative effect in human fibroblasts by in vitro cell migration assay. Our results suggest that chitosan-BPE films could be considered a valid plant-based antimicrobial material for advanced dressings focused on the acceleration of wound repair.

Promethazine-montmorillonite inclusion complex to enhance drug photostability.

The capability of montmorillonite as a matrix (MONT) to improve the photostability of photolabile drugs has been recently reported. Herein promethazine (PRO), which was chosen as a model drug because of its photodegradation mechanism, was intercalated into this inorganic matrix, and the effects on drug photoprotection were evaluated as well. The hybrid material (MONT-PRO) was successfully prepared with high drug loading and then was characterized by X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), and FTIR spectroscopy. The spectrophotometric measurements as a function of light exposure time showed that PRO intercalation into montmorillonite markedly improved the drug photostability because a 5-fold-slower degradation rate was determined compared to that measured for PRO in homogeneous solutions; nanosecond transient absorption measurements highlighted that the interaction with the inorganic matrix made negligible the photoionization process of the drug, and its efficiency in producing singlet oxygen was strongly reduced. The MONT-PRO intercalation compound could be easily formulated in gel or ointment media without losing its photostability.

Ozonated Sunflower Oil Embedded within Spray-Dried Chitosan Microspheres Cross-Linked with Azelaic Acid as a Multicomponent Solid Form for Broad-Spectrum and Long-Lasting Antimicrobial Activity.

Multicomponent solid forms for the combined delivery of antimicrobials can improve formulation performance, especially for poorly soluble drugs, by enabling the modified release of the active ingredients to better meet therapeutic needs. Chitosan microspheres incorporating ozonated sunflower oil were prepared by a spray-drying method and using azelaic acid as a biocompatible cross-linker to improve the long time frame. Two methods were used to incorporate ozonated oil into microspheres during the atomization process: one based on the use of a surfactant to emulsify the oil and another using mesoporous silica as an oil absorbent. The encapsulation efficiency of the ozonated oil was evaluated by measuring the peroxide value in the microspheres, which showed an efficiency of 75.5-82.1%. The morphological aspects; particle size distribution; zeta potential; swelling; degradation time; and thermal, crystallographic and spectroscopic properties of the microspheres were analyzed. Azelaic acid release and peroxide formation over time were followed in in vitro analyses, which showed that ozonated oil embedded within chitosan microspheres cross-linked with azelaic acid is a valid system to obtain a sustained release of antimicrobials. In vitro tests showed that the microspheres exhibit synergistic antimicrobial activity against P. aeruginosa, E. coli, S. aureus, C. albicans and A. brasiliensis. This makes them ideal for use in the development of biomedical devices that require broad-spectrum and prolonged antimicrobial activity.

Silver Nanoparticles and Simvastatin-Loaded PLGA-Coated Hydroxyapatite/Calcium Carbonate Scaffolds.

The need to develop synthetic bone substitutes with structures, properties, and functions similar to bone and capable of preventing microbial infections is still an ongoing challenge. This research is focused on the preparation and characterization of three-dimensional porous scaffolds based on hydroxyapatite (HA)-functionalized calcium carbonate loaded with silver nanoparticles and simvastatin (SIMV). The scaffolds were prepared using the foam replica method, with a polyurethane (PU) sponge as a template, followed by successive polymer removal and sintering. The scaffolds were then coated with poly(lactic-co-glycolic) acid (PLGA) to improve mechanical properties and structural integrity, and loaded with silver nanoparticles and SIMV. The scaffolds were characterized by X-ray powder diffraction (XRD), field emission scanning electron microscopy (FE-SEM), ATR FT-IR, and silver and SIMV loading. Moreover, the samples were analyzed by Brillouin and Raman microscopy. Finally, in vitro bioactivity, SIMV and silver release, and antimicrobial activity against Staphylococcus aureus and Staphylococcus epidermidis were evaluated. From the Brillouin spectra, samples showed characteristics analogous to those of bone tissue. They exhibited new hydroxyapatite growth, as evidenced by SEM, and good antimicrobial activity against the tested bacteria. In conclusion, the obtained results demonstrate the potential of the scaffolds for application in bone repair.

Alginate microparticles containing silver@hydroxyapatite functionalized calcium carbonate composites.

This paper focuses on the preparation and characterization of antibacterial alginate microparticles containing silver@hydroxyapatite functionalized calcium carbonate composites for tissue engineering. Microparticles were prepared by cross-linking a silver@composite sodium alginate dispersion with CaCl2. This method showed a very good silver efficiency loading and the presence of silver chloride nanoparticles was detected. Silver free microparticles, containing hydroxyapatite functionalized calcium carbonates and neat alginate microparticles were prepared as well. All microparticles were characterized for water absorption and for in vitro bioactivity by immersion in simulated body fluid (SBF). Finally, antimicrobial and antibiofilm activities as well as cytotoxicity were evaluated. Microparticles containing silver@composites exhibited good antimicrobial and antibiofilm activities against Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa and Candida albicans, but exerted a certain cytotoxicity against the tested cell models (fibroblasts and osteoblasts). Microparticles containing hydroxyapatite functionalized calcium carbonates were found to be always less cytotoxic, also in comparison to neat alginate microparticles, proving that the presence of the inorganic matrices exerts a protective effect on microparticle cytotoxicity.

A New Challenge for the Old Excipient Calcium Carbonate: To Improve the Dissolution Rate of Poorly Soluble Drugs.

Calcium carbonate is an excipient traditionally used in solid dosage forms with several functions such as a diluent, a quick dissolution agent, a buffer and an opacifier. Recently, many other challenges have arisen for calcium carbonate and, among them, the possibility of using it as an excipient for improving the dissolution rate of poorly soluble drugs. As a consequence of their poor solubility in biological fluids, many active ingredients suffer from low and erratic bioavailability when administered by the oral route and thus, many formulation strategies and excipients have been proposed to overcome this problem. Among them, calcium carbonate has been proposed as an excipient for improving dissolution rates. Calcium carbonate has many interesting characteristics, in fact it dissolves quickly in gastric fluid, is inexpensive and is safe. It exists in different polymorphic forms and in porous morphology and recently a porous functionalized calcium carbonate has been proposed as a new excipient. This review is the first overview on the use of calcium carbonate as an excipient for improving drug dissolution rates. The drug loading procedure, the physical characterization of the drug/CaCO3 samples and their dissolution profiles will be described. Moreover, the possible mechanisms of dissolution improvement, such as the presence of the drug in amorphous or polymorphic forms, in small crystals, and the effects of CaCO3 dissolution in acidic medium will be discussed. Different polymorphic forms of calcium carbonate and the presence of porosity and functionalization will be analyzed as well and their effects on dissolution rates will be discussed.

Ketorolac Loaded Poly(lactic-co-glycolic acid) Coating of AZ31 in the Treatment of Bone Fracture Pain.

Biodegradable metal alloys may be successfully used to support bone repair, avoiding second surgery commonly needed when inert metal alloys are used. Combining a biodegradable metal alloy with a suitable pain relief agent could improve patient quality of life. AZ31 alloy was coated using a poly(lactic-co-glycolic) acid (PLGA) polymer loaded with ketorolac tromethamine using the solvent casting method. The ketorolac release profile from the polymeric film and the coated AZ31 samples, the PLGA mass loss of polymeric film, and the cytotoxicity of the optimized coated alloy were assessed. The coated sample showed a ketorolac release that was prolonged for two weeks, which was slower than that of just the polymeric film, in simulated body fluid. PLGA mass loss was complete after a 45-day immersion in simulated body fluid. The PLGA coating was able to lower AZ31 and ketorolac tromethamine cytotoxicity observed in human osteoblasts. PLGA coating also prevents AZ31 cytotoxicity, which was identified in human fibroblasts. Therefore, PLGA was able to control ketorolac release and protect AZ31 from premature corrosion. These characteristics allow us to hypothesize that the use of ketorolac tromethamine-loaded PLGA coating on AZ31 in the management of bone fractures can favor osteosynthesis and relief pain.

Antimicrobial Oleogel Containing Sustainably Prepared Silver-Based Nanomaterials for Topical Application.

Oleogels containing silica-silver-based nanomaterials were prepared to be used as potential antimicrobial treatment for preventing and curing skin infections. Fumed silica was used as a bifunctional excipient able to offer support to silver-based nanoparticle growth and act as a gelling agent for oleogel formulation. First, silica-silver composites were prepared following a sustainable method by contact of fumed silica and silver nitrate in the presence of ethanol and successive UV irradiation. The composites were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), ATR FT-IR spectroscopy and UV-Vis spectrophotometry. The presence of 8-20 nm spherical nanoparticles, in addition to the silica aggregates and AgNO3 crystals, was detected. The composites showed good antimicrobial activity against the Gram-negative Pseudomonas aeruginosa and the Gram-positive bacteria Staphylococcus aureus and Staphylococcus epidermidis. Thus, they were formulated in an oleogel, obtained using fumed silica as a gelling agent. For comparison, oleogels containing AgNO3 were prepared according to two different formulative techniques. The silica-silver-based oleogels showed good antimicrobial activity and did not show cytotoxic effects for fibroblasts and keratinocytes.

Ag/Ag3PO4 Nanoparticle-Decorated Hydroxyapatite Functionalized Calcium Carbonate: Ultrasound-Assisted Sustainable Synthesis, Characterization, and Antimicrobial Activity.

Silver nanoparticles are usually prepared by the reduction of silver cations through chemical and non-sustainable procedures that involve the use of reducing chemical agents. Therefore, many efforts have been made in the search for sustainable alternative methods. Among them, an ultrasound-assisted procedure could be a suitable and sustainable method to afford well-dispersed and nanometric silver particles. This paper describes a sustainable, ultrasound-assisted method using citrate as a reducing agent to prepare silver@hydroxyapatite functionalized calcium carbonate composites. For comparison, an ultrasound-assisted reduction was performed in the presence of NaBH4. The composites obtained in the presence of these two different reducing agents were compared in terms of nanoparticle nature, antimicrobial activity, and cytotoxic activity. The nanoparticle nature was investigated by several techniques, including X-ray powder diffraction, field-emission scanning electron microscopy, transmission electron microscopy, UV-Vis spectroscopic measurements, and X-ray photoemission spectroscopy. Nanoparticles with a predominance of Ag or Ag3PO4 were obtained according to the type of reducing agent used. All composites were tested for antimicrobial and antibiofilm activities against Gram-positive and Gram-negative (Staphylococcus aureus and Pseudomonas aeruginosa, respectively) bacteria and for cytotoxicity towards human skin keratinocytes and human fibroblasts. The nature of the nanoparticles, Ag or Ag3PO4, and their predominance seemed to affect the in vitro silver release and the antimicrobial and antibiofilm activities. The composites obtained by the citrate-assisted reduction gave rise to the best results.

Alginate Ag/AgCl Nanoparticles Composite Films for Wound Dressings with Antibiofilm and Antimicrobial Activities.

Recently, silver-based nanoparticles have been proposed as components of wound dressings due to their antimicrobial activity. Unfortunately, they are cytotoxic for keratinocytes and fibroblasts, and this limits their use. Less consideration has been given to the use of AgCl nanoparticles in wound dressings. In this paper, a sustainable preparation of alginate AgCl nanoparticles composite films by simultaneous alginate gelation and AgCl nanoparticle formation in the presence of CaCl2 solution is proposed with the aim of obtaining films with antimicrobial and antibiofilm activities and low cytotoxicity. First, AgNO3 alginate films were prepared, and then, gelation and nanoparticle formation were induced by film immersion in CaCl2 solution. Films characterization revealed the presence of both AgCl and metallic silver nanoparticles, which resulted as quite homogeneously distributed, and good hydration properties. Finally, films were tested for their antimicrobial and antibiofilm activities against Staphylococcus epidermidis (ATCC 12228), Staphylococcus aureus (ATCC 29213), Pseudomonas aeruginosa (ATCC 15692), and the yeast Candida albicans. Composite films showed antibacterial and antibiofilm activities against the tested bacteria and resulted as less active towards Candida albicans. Film cytotoxicity was investigated towards human dermis fibroblasts (HuDe) and human skin keratinocytes (NCTC2544). Composite films showed low cytotoxicity, especially towards fibroblasts. Thus, the proposed sustainable approach allows to obtain composite films of Ag/AgCl alginate nanoparticles capable of preventing the onset of infections without showing high cytotoxicity for tissue cells.

Immobilization of Alendronate on Zirconium Phosphate Nanoplatelets.

Different amounts of sodium-alendronate (ALN) were loaded into layered zirconium phosphates of alpha and gamma type (αZP and γZP) by means of topotactic exchange reactions of phosphate with ALN. In order to extend the exchange process to the less accessible interlayer regions, ALN solutions were contacted with colloidal dispersions of the layered solids previously exfoliated in single sheets by means of intercalation reaction of propylamine (for αZP) or acetone (for γZP). The ALN loading degree was determined by liquid P-nuclear magnetic resonance (NMR) and inductively coupled plasma (ICP), and it was reported as ALN/Zr molar ratios (Rs). The maximum R obtained for γZP was 0.34, while αZP was able to load a higher amount of ALN, reaching Rs equal to 1. The synthesized compounds were characterized by X-ray powder diffractometry, scanning electron microscopy (SEM), solid-state NMR, and infrared spectroscopy. The way the grafted organo-phosphonate groups were bonded to the layers of the host structure was suggested. The effect of ZP derivatives was assessed on cell proliferation, and the results showed that after 7 days of incubation, none of the samples showed a decrease in cell proliferation.

Solid State Photoreduction of Silver on Mesoporous Silica to Enhance Antifungal Activity.

A solid-state Ultraviolet-photoreduction process of silver cations to produce Ag0 nanostructures on a mesoporous silica is presented as an innovative method for the preparation of efficient environmental anti-fouling agents. Mesoporous silica powder, contacted with AgNO3, is irradiated at 366 nm, where silica surface defects absorb. The detailed characterization of the materials enables us to document the silica assisted photo-reduction. The appearance of a Visible (Vis) band centered at 470 nm in the extinction spectra, due to the surface plasmon resonance of Ag0 nanostructures, and the morphology changes observed in transmission electron microscopy (TEM) images, associated with the increase of Ag/O ratio in energy dispersive X-ray (EDX) analysis, indicate the photo-induced formation of Ag0. The data demonstrate that the photo-induced reduction of silver cation occurs in the solid state and takes place through the activation of silica defects. The activation of the materials after UV-processing is then tested, evaluating their antimicrobial activity using an environmental filamentous fungus, Aspergillus niger. The treatment doubled inhibitory capacity in terms of minimal inhibitory concentration (MIC) and biofilm growth. The antimicrobial properties of silver-silica nanocomposites are investigated when dispersed in a commercial sealant; the nanocomposites show excellent dispersion in the silicon and improve its anti-fouling capacity.

PVC grafted zinc oxide nanoparticles as an inhospitable surface to microbes.

Antimicrobial Polyvinyl chloride (PVC) was obtained by covalent bonding of zinc oxide nanoparticles, which have gained important achievements in antimicrobial fields because of their auspicious properties. This was achieved by grafting mercaptopropyltrimethoxysilane onto PVC, followed by the growth of zinc oxide nanoparticles covalently bonded on the polymer surface. In this study, the relationship between the physicochemical features of modified-surface PVC and antimicrobial activity on Staphylococcus aureus and Candida albicans was investigated. Zinc oxide with controllable morphologies (rods, rod flowers, and petal flowers) was synthesized on the polymer surface by tuning merely base-type and concentration using a hydrothermal process. The antimicrobial activity was more pronounced for rod flower morphology, because of their differences in microscopic parameters such as specific Zn-polar planes. This work provides an important hint for the safe use of PVC for biomedical devices by the structure surface tuning without injuring polymer bulk properties and a reduced risk of the covalently bonded nanoparticle dispersion in the host and the environment.

Bioinspired Reactive Interfaces Based on Layered Double Hydroxides-Zn Rich Hydroxyapatite with Antibacterial Activity.

This work is focused on the preparation and multi-technique characterization of potentially biocompatible reactive interfaces obtained by combining layered double hydroxides (LDHs) and hydroxyapatite (HA). Antimicrobial and osteoinductive metallic ions as Zn2+ and Ga3+ were chosen as intralayer constituents of LDH to obtain ZnAl and ZnAlGa systems. These LDHs, exchanged with dihydrogenphosphate anions, promoted the precipitation of HA on the LDH surface yielding HA@LDH composites. X-ray diffraction quantitative analysis, through the Rietveld refinement method, coupled with elemental analysis and micro-Raman spectroscopy showed the formation of a mixed Ca-Zn HA phase. Scanning electron microscopy revealed that HA, in the presence of LDH, grew preferentially along its a-axis, thus crystallizing mainly in the form of flake crystals. LDH and HA@LDH composites showed antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa at not cytotoxic concentrations for human osteoblasts (hFob 1.19), especially when Ga cations were present in the LDH structure. The effect of the presence of HA in the composites on the bone-bonding ability and on human osteoblast proliferation was also investigated. The HA seemed to reduce the toxicity of the LDH toward human osteoblast while did not affect the bone-bonding ability. This multidisciplinary study provides the bio-chemical, structural characterization of new LDH and HA@LDH composites, evaluating also their bioactivity to be potentially applicable to titanium-based prostheses.

Hydroxyapatite Functionalized Calcium Carbonate Composites with Ag Nanoparticles: An Integrated Characterization Study.

In the present work, composite materials very promising for biomedical and pharma-ceutical applications were investigated. They are composed of silver nanoparticles (Ag NPs) in a matrix constituted of calcium carbonate functionalized with hydroxyapatite (HA-FCC). The composites were obtained by different synthesis methods, starting from a mixture of the silver acetate with HA-FCC (using adsorption or mixing in wet conditions methods) and then treating them by exposure to visible light or calcination to promote the silver reduction; a synthetic procedure based on ultrasound-assisted reduction with NaBH4 or citrate was also carried out. The characterization by X-ray photoelectron spectroscopy and reflected electron energy loss spectroscopy analysis also involved the reference sample of HA-FCC matrix. Then the morphology of the Ag NPs and the crystalline structure of HA-FCC were studied by transmission electron microscopy and X-ray diffraction, respectively. To assess the effectiveness of the different methods on silver reduction, the Auger parameters α' were calculated and compared. The use of this methodology based on the Auger parameter is neither trivial nor ordinary. We demonstrate its validity since the different values of this parameter allow to identify the oxidation state of silver and consequently to evaluate the formation yield of metallic Ag NPs in the HA-FCC matrix and the effectiveness of the different reduction methods used.

Use of calcium carbonate as an excipient for release of poorly water soluble drugs: The case of carbamazepine.

Carbamazepine (CBZ) is a poorly water soluble drug owing to the Biopharmaceutic Classification System (BCS) class II. It is characterized by a variable bioavailability and by the presence of different polymorphs. In this paper the effects of CaCO3 on the physicochemical properties of CBZ and its solubility and release were evaluated. CaCO3 is a naturally non-toxic biomineral and was chosen because it is a safe, cheap and eco-friendly excipient able to dissolve in an acidic environment. Composites with different CBZ loadings were prepared by ball milling and antisolvent method. The composites were characterized by X-ray powder diffraction, differential scanning calorimetry analysis and attenuated total reflectance FT-IR which revealed that both the presence of CaCO3 and the preparation procedure affect the polymorphic form crystallinity and intermolecular interactions among the drug molecules. Scanning electron microscopy showed that small drug crystals with different crystalline forms were deposited on the surface of the CaCO3 particles. Solubility and dissolution tests showed an increase in the apparent solubility of CBZ and improved drug release. These results demonstrated that CaCO3 affected the drug release properties likely due to its pH-sensitive characteristics.

Biocompatible alginate silica supported silver nanoparticles composite films for wound dressing with antibiofilm activity.

Alginate films containing pyrogenic silica supported silver nanoparticles were prepared as potential wound dressings. First silica supported silver nanoparticles (CAB-O-SIL-Ag) were prepared via solid state sintering route without the use of any solvent and reducing agent. The obtained composite was characterized by X-ray powder diffraction, transmission electron microscopy and UV-vis spectroscopy which evidenced the presence of 8-20 nm spherical silver nanoparticles uniformly distributed and grown on the silica surface. Then the CAB-O-SIL-Ag was used as filler to prepare alginate films by casting method and successive gelation. Films with two different silver concentrations were prepared. They showed good hydration properties and a very slow silver release. Films exhibited antimicrobial and antibiofilm activities against Staphylococcus aureus and Pseudomonas aeruginosa and showed no cytotoxicity towards human skin keratinocytes and human fibroblasts HuDe.

Formulation studies of benzydamine mucoadhesive formulations for vaginal administration.

BACKGROUND: Vaginal cavity represents a good site for drug administration and delivery. AIM: The aim of this work was the design of new mucoadhesive semisolid dosage forms for vaginal delivery of benzydamine. METHOD: Simple gels, obtained by using sodium carboxymethylcellulose (NaCMC) and hydroxyethylcellulose (HEC), were employed as water phase of an oil-in-water emulsion (O/W cream) to obtain emulgels, more stable and manageable than gels. Successively, in order to modify the emulgel consistency, the ingredient cetostearylic alcohol was replaced by the same amount of gel or vaseline. All the preparations were submitted to mucoadhesion and rheological, extrusion, and release studies and compared to market vaginal cream Tantum Rosa. RESULTS: HEC formulations showed good drug release profiles and good rheological behavior but low mucoadhesion strength, whereas NaCMC (4% gel) formulations had better drug release and very high mucoadhesive strength. However, the presence of NaCMC 4% conferred too much viscosity to the preparation. Taking into consideration all performances, the most suitable formulations for vaginal applications resulted in those containing NaCMC (3% gel) and with gel replacing cetostearylic alcohol as they showed good ex vivo performances in terms of manageability and high bioadhesion to vaginal mucosa.

Nanostructured zinc oxide on silica surface: Preparation, physicochemical characterization and antimicrobial activity.

Zinc oxide nanoparticles were synthesized using two silica supports largely used in pharmaceutical field as excipients, Cab-O-Sil-H5 and Syloid 244 FP characterized by high surface area and different porosity. In order to evaluate the effects of different silica on nanoparticle chemical physical properties, composites (ZnO-SiO2) containing different amounts of ZnO nanoparticles were obtained and characterized by X-ray Powder Diffraction (XRPD), Transmission Electron Microscopy (TEM), Attenuated Transmission Reflectance (ATR), UV-vis spectroscopy and finally Photoluminescence (PL). Composites showed the presence of quite uniformly distributed zinc nanostructures on the silica surface with size in the range of 30-50 nm with an estimated specific surface area ranged from ca. 20 to 70 m2/g. The formation of a Zn-O-Si interface in ZnO-SiO2 was observed as well. Photoluminescence studies revealed that ZnO-SiO2 samples based on Cab-O-Sil present a higher contribution of oxygen vacancies per unit volume. Finally, the resulting composites were tested for antibacterial and antifungal activities. Whereas silica supports did not show any antibacterial and antifungal activities, most of the prepared composites, both with Cab-O-Sil-5H and Syloid 244 FP supports, resulted active against both bacteria and fungi. In particular the contingency analysis showed that the amount of zinc oxide in the composites was partly related to MIC results in bacteria (p = 0.059), whereas it showed an interesting p = 0.022 in yeast in the case of low amount of ZnO (10%). Thus, the described ZnO-SiO2 composites can be proposed for the preparation of both pharmaceutical formulations and medical disposals with antibacterial and antifungal activities.

Chitosan and a modified chitosan as agents to improve performances of mucoadhesive vaginal gels.

New mucoadhesive formulations were designed and studied in order to improve local vaginal therapy by increasing formulation retention prolonging thus drug-mucosa contact time. Some gels were prepared using hydroxyethylcellulose (HEC) alone or mixed with chitosan (CS) or its derivative 5-methyl-pyrrolidinone-chitosan (MPCS) and were loaded with the antibacterial metronidazole (MET) (0.75%). All formulations showed pseudoplastic flow and viscosity increase was observed proportionally to chitosan content (CS>MPCS). Prepared gels showed better extrusion properties (yield stress) than market formulation Zidoval. Mucoadhesion force studies permitted to point out that: (i) CS decreases mucoadhesion force; (ii) MPCS addition increases the mucoadhesion force at high percentage; (iii) all gels containing chitosan showed better mucoadhesive performances than Zidoval. Gels containing MPCS showed higher and faster drug release than those containing CS. All the preparations were able to release higher drug amounts if compared to market formulation. In conclusion MPCS improved gel characteristics in terms of mucoadhesion force, rheological behaviour and drug release pointing out that this modified chitosan is very suitable to obtain manageable and more acceptable vaginal formulation.