Pectosomes and chitosomes as delivery systems for metronidazole: the one-pot preparation method

Repurposing celecoxib for colorectal cancer targeting via pH-triggered ultra-elastic nanovesicles: Pronounced efficacy through up-regulation of Wnt/β-catenin pathway in DMH-induced tumorigenesis

Celecoxib (CLX), a selective inhibitor for cyclooxygenase 2 (COX-2), has manifested potential activity against diverse types of cancer. However, low bioavailability and cardiovascular side effects remain the major challenges that limit its exploitation. In this work, we developed ultra-elastic nanovesicles (UENVs) with pH-triggered surface charge reversal traits that could efficiently deliver CLX to colorectal segments for snowballed tumor targeting. CLX-UENVs were fabricated via a thin-film hydration approach. The impact of formulation factors (Span 80, Tween 80, and sonication time) on the nanovesicular features was evaluated using Box-Behnken design, and the optimal formulation was computed. The optimum formulation was positively coated with polyethyleneimine (CLX-PEI-UENVs) and then coated with Eudragit S100 (CLX-ES-PEI-UENVs). The activity of the optimized nano-cargo was explored in 1,2-dimethylhydrazine-induced colorectal cancer in Wistar rats. Levels of COX-2, Wnt-2 and β-catenin were assessed in rats' colon. The diameter of the optimized CLX-ES-PEI-UENVs formulation was 253.62 nm, with a zeta potential of -23.24 mV, 85.64% entrapment, and 87.20% cumulative release (24 h). ES coating hindered the rapid release of CLX under acidic milieu (stomach and early small intestine) and showed extended release in the colon section. In colonic environments, the ES coating layer was removed due to high pH, and the charge on the nanovesicular corona was shifted from negative to positive. Besides, a pharmacokinetics study revealed that CLX-ES-PEI-UENVs had superior oral bioavailability by 2.13-fold compared with CLX suspension. Collectively, these findings implied that CLX-ES-PEI-UENVs could be a promising colorectal-targeted nanoplatform for effective tumor management through up-regulation of the Wnt/β-catenin pathway.

Pectin nanoparticles loaded with nitric oxide donor drug: A potential approach for tissue regeneration

The process of wound healing and tissue regeneration involves several key mechanisms to ensure the production of new tissues with similar cellular functions. This study investigates the impact of pectin, a natural polysaccharide, and nebivolol hydrochloride (NBV), a nitric oxide (NO) donor drug, on wound healing. Utilizing ionotropic gelation, NBV-loaded pectin nanoparticles were developed following a 2231 full factorial design. The optimized formulation, determined using Design expert® software, exhibited an encapsulation efficiency percentage of 70.68%, zeta potential of -51.4 mV, and a particle size of 572 nm, characterized by a spherical, discrete morphology. An in vivo study was conducted to evaluate the effectiveness of the optimal formulation in wound healing compared to various controls. The results demonstrated the enhanced ability of the optimal formulation to accelerate wound healing. Moreover, histopathological examination further confirmed the formulation's benefits in tissue proliferation and collagen deposition at the wound site 15 days post-injury. This suggests that the developed formulation not only promotes faster healing but does so with minimal side effects, positioning it as a promising agent for effective wound healing and tissue regeneration.

The quest for nanoparticle-powered vaccines in cancer immunotherapy

Despite recent advancements in cancer treatment, this disease still poses a serious threat to public health. Vaccines play an important role in preventing illness by preparing the body's adaptive and innate immune responses to combat diseases. As our understanding of malignancies and their connection to the immune system improves, there has been a growing interest in priming the immune system to fight malignancies more effectively and comprehensively. One promising approach involves utilizing nanoparticle systems for antigen delivery, which has been shown to potentiate immune responses as vaccines and/or adjuvants. In this review, we comprehensively summarized the immunological mechanisms of cancer vaccines while focusing specifically on the recent applications of various types of nanoparticles in the field of cancer immunotherapy. By exploring these recent breakthroughs, we hope to identify significant challenges and obstacles in making nanoparticle-based vaccines and adjuvants feasible for clinical application. This review serves to assess recent breakthroughs in nanoparticle-based cancer vaccinations and shed light on their prospects and potential barriers. By doing so, we aim to inspire future immunotherapies for cancer that harness the potential of nanotechnology to deliver more effective and targeted treatments.

Preparation and Characterization of Novel Polyelectrolyte Liposomes Using Chitosan Succinate Layered over Chitosomes: A Potential Strategy for Colon Cancer Treatment

Chitosan succinate is distinguished by its ability to shield the loaded drug from the acidic environment, localize and keep the drug at the colon site, and release the drug over an extended time at basic pH. The current study attempts to develop polyelectrolyte liposomes (PEL), using chitosan and chitosan succinate (CSSC), as a carrier for liposomal-assisted colon target delivery of 5 fluorouracil (5FU). The central composite design was used to obtain an optimized formulation of 5FU-chitosomes. The chitosan-coated liposomes (chitosomes) were prepared by thin lipid film hydration technique. After that, the optimized formulation was coated with CSSC, which has several carboxylic (COOH) groups that produce an anionic charge that interacts with the cation NH2 in chitosan. The prepared 5FU-chitosomes formulations were evaluated for entrapment efficiency % (EE%), particle size, and in vitro drug release. The optimized 5FU-chitosomes formulation was examined for particle size, zeta potential, in vitro release, and mucoadhesive properties in comparison with the equivalent 5FU-liposomes and 5FU-PEL. The prepared 5FU-chitosomes exhibited high EE%, small particle size, low polydispersity index, and prolonged drug release. PEL significantly limited the drug release at acidic pH due to the deprotonation of carboxylate ions in CSSC, which resulted in strong repulsive forces, significant swelling, and prolonged drug release. According to a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay, PEL treatment significantly decreased the viability of HT-29 cells. When compared to 5FU-liposome and 5FU-chitosome, the in vivo pharmacokinetics characteristics of 5FU-PEL significantly (p < 0.05) improved. The findings show that PEL enhances 5FU permeability, which permits high drug concentrations to enter cells and inhibits the growth of colon cancer cells. Based on the current research, PEL may be used as a liposomal-assisted colon-specific delivery.

Effect of nanovesicular surface-functionalization via chitosan and/or PEGylation on cytotoxicity of tamoxifen in induced-breast cancer model

AIMS

The effect of surface-modification of Tamoxifen (Tam)-loaded-niosomes on drug cytotoxicity and bio-distribution, via functionalization with chitosan and/or PEGylation, was investigated.

MATERIALS AND METHODS

Tam-loaded hybrid-nanocarriers (Tam-loaded niosomes, chitosomes, PEGylated niosomes, and PEGylated chitosomes) were formulated and characterized.

KEY FINDINGS

Chitosanization with/without PEGylation proved to selectively enhance Tam-release at the cancerous-acidic micromilieu. Cytotoxic activity study showed that Tam-loaded PEGylated niosomes had a lower IC₅₀ value on MCF-7 cell line (0.39, 0.35, and 0.27 times) than Tam-loaded PEGylated chitosomes, Tam-loaded niosomes, and Tam-loaded chitosomes, respectively. Cell cycle analysis showed that PEGylation and/or Chitosanization significantly impact Tam efficiency in inducing apoptosis, with a preferential influence of PEGylation over chitosanization. The assay of Annexin-V/PI double staining revealed that chitosanized-nanocarriers had a significant role in increasing the incidence of apoptosis over necrosis. Besides, PEGylated-nanocarriers increased apoptosis, as well as total death and necrosis percentages more than what was shown from free Tam. Moreover, the average changes in both Bax/Bcl-2 ratio and Caspase 9 were best improved in cells treated by Tam-loaded PEGylated niosomes over all other formulations. The in-vivo study involving DMBA-induced-breast cancer rats revealed that PEGylation made the highest tumor-growth inhibition (84.9 %) and breast tumor selectivity, while chitosanization had a lower accumulation tendency in the blood (62.3 ng/ml) and liver tissues (103.67 ng/ml). The histopathological specimens from the group treated with Tam-loaded PEGylated niosomes showed the best improvement over other formulations.

SIGNIFICANCE

All these results concluded the crucial effect of both PEGylation and chitosan-functionalization of Tam-loaded niosomes in enhancing effectiveness, targetability, and safety.

Transdermal Glipizide Delivery System Based on Chitosan-Coated Deformable Liposomes: Development, Ex Vivo, and In Vivo Studies

The current study aimed to develop and evaluate a sustained-release transdermal Glipizide (GLP) film to overcome its oral administration problems. Chitosan (CS)-coated deformable liposomes (DLs) were utilized to enhance the drug transdermal delivery. The formulations were characterized in terms of particle size, zeta potential, entrapment efficiency (EE%), vesicle deformability, morphology, stability, and in vitro release. Transdermal films of chosen formulations were prepared by the solvent casting technique, and an ex vivo study throughout rat skin was also performed. Moreover, a pharmacokinetics (PK) study was carried out and blood glucose levels were estimated. All the liposomes were in the nanometer range and a high EE% was obtained from DLs compared to conventional liposomes (CL). The prepared formulations showed a high stability and the DLs exhibited a high deformability compared to CL. The in vitro release study confirmed the sustained release of GLP from both CL and DL and a more pronounced sustained release of GLP was detected after coating with CS. Moreover, GLP was shown to efficiently permeate through the rat skin from transdermal films by an ex vivo permeation test. The transdermal films showed a promising PK profile in the rat as compared with oral GLP. Most importantly, GLP-CS-DL1 demonstrated a higher hypoglycemic effect, confirming the possibility of systemic action by the local topical delivery of GLP.

Nanomedicines for the topical treatment of vulvovaginal infections: Addressing the challenges of antimicrobial resistance

Recent years have, surprisingly, witnessed an increase in incidence of sexually transmitted infections (STIs). At the same time, antimicrobial therapy came under the threat of ever rising antimicrobial resistance (AMR), resulting in STIs with extremely limited therapy options. In this review, we addressed the challenges of treating vaginal infections in an era of AMR. We focused on published work regarding nanomedicine destined for localized treatment of vaginal infections. Localized therapy offers numerous advantages such as assuring high drug concentration at the infection site, limiting systemic drug exposure that can lead to faster development of AMR reduction in the systemic side effects and potentially safe therapy in pregnancy. We provided a state-of-the-art overview of nanoformulations proposed to topically treat STIs, emphasizing the challenges and advantages of each type of nanocarriers, as well as issues of potential toxicity.

Lipid nanovesicles for biomedical applications: 'What is in a name'?

Vesicles, generally defined as self-assembled structures formed by single or multiple concentric bilayers that surround an aqueous core, have been widely used for biomedical applications. They can either occur naturally (e.g. exosomes) or be produced artificially and range from the micrometric scale to the nanoscale. One the most well-known vesicle is the liposome, largely employed as a drug delivery nanocarrier. Liposomes have been modified along the years to improve physicochemical and biological features, resulting in long-circulating, ligand-targeted and stimuli-responsive liposomes, among others. In this process, new nomenclatures were reported in an extensive literature. In many instances, the new names suggest the emergence of a new nanocarrier, which have caused confusion as to whether the vesicles are indeed new entities or could simply be considered modified liposomes. Herein, we discussed the extensive nomenclature of vesicles based on the suffix "some" that are employed for drug delivery and composed of various types and proportions of lipids and others amphiphilic compounds. New names have most often been selected based on changes of vesicle lipid composition, but the payload, structural complexity (e.g. multicompartment) and new/improved proprieties (e.g. elasticity) have also inspired new vesicle names. Based on this discussion, we suggested a rational classification for vesicles.

Formulation of Nanospanlastics as a Promising Approach for ‎Improving the Topical Delivery of a Natural Leukotriene Inhibitor (3-‎Acetyl-11-Keto-β-Boswellic Acid): Statistical Optimization, in vitro ‎Characterization, and ex vivo Permeation Study

Purpose

The current study aimed to discuss the potential of nanospanlastics as a surfactant-based vesicular system for improving the topical delivery of 3-acetyl-11-keto-β-boswellic acid (AKBA). AKBA is a potent anti-inflammatory drug, but it has poor oral bioavailability due to its poor aqueous solubility. Moreover, the topical delivery of AKBA is difficult due to its high lipophilicity. To overcome these drawbacks, AKBA was formulated as deformable elastic nanovesicles and nanospanlastics, for improving its topical delivery.

Materials and Methods

AKBA-loaded spanlastic nanovesicles (SNVs) were formulated by ethanol injection technique according to 2³ factorial design using Span 60 as a non-ionic surfactant and Tween 80 as edge activator (EA) to investigate the effect of different independent variables on entrapment efficiency (EE%), % drug released after 8 hr (Q_8h) and particle size (PS) using Design-Expert software. In vitro characterization, stability test and ex vivo permeation study of the optimized formula were performed.

Results

The choice of the optimized formula was based on the desirability criteria.‎ F7 was selected as the optimized formula because it has the highest desirability value of 0.648. F7 exhibited EE% of 90.04±0.58%, Q_8h of 96.87±2.67%, PS of 255.8±2.67 nm, and zeta potential of −49.56 mV. F7 appeared as spherical well-defined vesicles in both scanning electron microscope (SEM) and transmission electron microscope (TEM). The Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) studies investigated the absence of interaction between AKBA and ‎different excipients and good encapsulation of AKBA within SNVs. F7 retained both physical and chemical stability after storage for 3 months at 4–8 °C. Ex vivo permeation test exhibited significant enhancement of permeability of F7 across rat skin than the free drug.

Conclusion

Nanospanlastics could be a promising approach for improving the permeability and topical delivery of AKBA.

Bacterial vaginosis: Standard treatments and alternative strategies

Bacterial vaginosis (BV) affects many women and has a high influence on their self-esteem, being associated with huge discomfort and changes in the routines, especially the sexual life. International guidelines recommend the administration of metronidazole, clindamycin or tinidazole orally or intravaginally as the standard treatment. However, the treatment with these antibiotics is associated with high levels of failure and recurrence rates. These may be associated with antibiotic resistance, the inability to eradicate the polymicrobial biofilms, and failure to reestablish acidic pH and the lactobacillus-dominated commensal flora. Therefore, it is emergent to study alternative strategies to replace or to be combined with standard therapies in order to prevent and treat BV more efficiently. Alternative strategies may include antimicrobial substances (other antimicrobials, antiseptics and natural compounds) or substances that aim to reestablish the physiologic vaginal environment (probiotics, prebiotics and acidifying agents) while improving the local immunity response. Besides, the development of formulation strategies and new dosage forms and drug delivery systems can improve treatment efficacy and overcome some limitations associated with conventional products.

Carrageenan-Based Acyclovir Mucoadhesive Vaginal Tablets for Prevention of Genital Herpes

Women are the most affected by genital herpes, which is one of the most common sexually transmitted infections, affecting more than 400 million people worldwide. The application of vaginal microbicides could provide a safe method of protection. Acyclovir is a safe and effective medication for vaginal administration, and numerous benefits have been observed in the treatment of primary or recurrent lesions due to genital herpes. Vaginal tablets based on a combination of the polymers iota-carrageenan and hydroxypropyl methylcellulose were developed for the controlled release of acyclovir. Swelling, mucoadhesion and drug release studies were carried out in simulated vaginal fluid. The tablets, containing a combination of iota-carrageenan and hydroxypropyl methylcellulose, have an adequate uptake of the medium that allows them to develop the precise consistency and volume of gel for the controlled release of acyclovir. Its high mucoadhesive capacity also allows the formulation to remain in the vaginal area long enough to ensure the complete release of acyclovir. These promising formulations for the prevention of genital herpes deserve further evaluation.

Transdermal delivery of fluvastatin sodium via tailored spanlastic nanovesicles: mitigated Freund's adjuvant-induced rheumatoid arthritis in rats through suppressing p38 MAPK signaling pathway

The current study aimed to encapsulate fluvastatin sodium (FVS), a member of the statins family possessing pleiotropic effects in rheumatoid arthritis (RA), into spanlastic nanovesicles (SNVs) for transdermal delivery. This novel delivery could surmount FVS associated oral encumbrances such as apparent first-pass effect, poor bioavailability and short elimination half-life, hence, accomplishing platform for management of RA. To consummate this objective, FVS-loaded SNVs were elaborated by thin film hydration method, utilizing either Span 60 or Span 80, together with Tween 80 or Brij 35 as an edge activator according to full factorial design (2⁴). Applying Design-Expert^® software, the influence of formulation variables on SNVs physicochemical properties and the optimized formulation selection were explored. Additionally, the pharmacokinetic studies were scrutinized in rats. Furthermore, in Freund's adjuvant-induced arthritis, rheumatoid markers, TNF-α, IL-10, p38 MAPK, and antioxidant parameters were measured. The optimum SNVs were nano-scaled spherical vesicles (201.54 ± 9.16 nm), having reasonable entrapment efficiency (71.28 ± 2.05%), appropriate release over 8 h (89.45 ± 3.64%) and adequate permeation characteristics across the skin (402.55 ± 27.48 µg/cm²). The pharmacokinetic study disclosed ameliorated bioavailability of the optimum SNVs gel by 2.79- and 4.59-fold as compared to the oral solution as well as the traditional gel, respectively. Moreover, it elicited a significant suppression of p38 MAPK expression and also significant improvement of all other measured biomarkers. Concisely, the foregoing findings proposed that SNVs can be auspicious for augmenting FVS transdermal delivery for management of RA.

Rational Development of Liposomal Hydrogels: A Strategy for Topical Vaginal Antiretroviral Drug Delivery in the Context of HIV Prevention

HIV/AIDS stands as a global burden, and vaginal microbicides constitute a promising strategy for topical pre-exposure prophylaxis. Preceding the development of a microbicide containing tenofovir disoproxil fumarate (TDF) and emtricitabine (FTC), in silico and in vitro studies were performed to evaluate the physicochemical characteristics of both drugs, and to study their biophysical impact in lipid model systems. Results from these pre-formulation studies defined hydrogels as adequate vehicles to incorporate TDF-loaded liposomes and FTC. After studying interactions with mucin, zwitterionic liposomes with a mean diameter of 134 ± 13 nm, an encapsulation TDF efficiency of approximately 84%, and a transition temperature of 41 °C were selected. The chosen liposomal formulation was non-cytotoxic to HEC-1-A and CaSki cells, and was able to favor TDF permeation across polysulfone membranes (J_ss = 9.9 μg·cm^-2·h^-1). After the incorporation of TDF-loaded liposomes and FTC in carbomer hydrogels, the drug release profile was sustained over time, reaching around 60% for both drugs within 3-6 h, and best fitting the Weibull model. Moreover, liposomal hydrogels featured pseudoplastic profiles that were deemed suitable for topical application. Overall, the proposed liposomal hydrogels may constitute a promising formulation for the vaginal co-delivery of TDF/FTC.

Dapivirine Bioadhesive Vaginal Tablets Based on Natural Polymers for the Prevention of Sexual Transmission of HIV

Young sub-Saharan women are a group that is vulnerable to the sexual transmission of HIV. Pre-exposure prophylaxis through vaginal microbicides could provide them an option for self-protection. Dapivirine has been demonstrated to have topical inhibitory effects in HIV, and to provide protection against the sexual transmission of this virus. This paper reports on the studies into swelling behaviour, bioadhesion and release carried out on dapivirine tablets based on chitosan, locust bean gum and pectin, to select the most suitable formulation. The modified simulated vaginal fluid led to a high solubility of dapivirine and allowed the dapivirine release profiles to be characterized in sink conditions; this aqueous medium is an alternative to organic solvents, which are not a realistic option when evaluating systems whose behaviour varies in aqueous and organic media. Of the formulations evaluated, dapivirine/pectin tablets containing 290 mg of polymer and 30 mg of dapivirine present the most moderate swelling, making them the most comfortable dosage forms. Their high bioadhesive capacity would also allow the formulation to remain in the action zone and release the drug in a sustained manner, pointing to this formulation as the most promising candidate for future evaluations of vaginal microbicides for the prevention of HIV.

Chitosan-Based Mucoadhesive Vaginal Tablets for Controlled Release of the Anti-HIV Drug Tenofovir

Vaginal microbicides have the potential to give women at high risk of contracting HIV the option of self-protection by preventing the sexual transmission of the virus. In this paper, mucoadhesive vaginal tablets based on chitosan, alone and in combination with pectin and locust bean gum, were developed for the sustained release of tenofovir (an antiretroviral drug). The formulations were placed in simulant vaginal fluid (SVF) to swell, and Hg porosity and SEM microscopy were used for the microstructural characterization of the swelling witnesses. The results show that the association of pectin and chitosan generated polyelectrolyte complexes and produced a robust system able to maintain its structure during the swelling process, when small pores are formed. Drug release and bovine vaginal mucoadhesion studies were performed in SVF showing that tenofovir-controlled dissolution profiles and adhesion to the mucosa were conditioned by the swelling processes of the polymer/s in each formulation. Tablets based on chitosan/pectin have the most homogeneous tenofovir dissolution profiles and last up to 96 h, remaining attached to the vaginal mucosa for the same period. These formulations can therefore be considered a good option for the self-protection of women from the sexual transmission of HIV.

Gel in core carbosomes as novel ophthalmic vehicles with enhanced corneal permeation and residence

Carbopol is a good bio-adhesive polymer that increases the residence time in the eye. However, the effect of blinking and lacrimation still reduce the amount of polymer and the incorporated drug available for bioadhesion. Gel-core liposomes are advanced systems offering benefits making it a good tool for improved ocular drug delivery and residence time. Incorporation of carbopol in gel-core liposomes and their potential in ocular delivery have not so far been investigated. Fluconazole (FLZ) was selected as a challenging important ocular antifungal suffering from poor corneal permeation and short residence time. In this study, gel-core carbosomes have been elaborated as novel carbopol-based ophthalmic vehicles to solve ocular delivery obstacles of FLZ and to sustain its effect. Full in vitro appraisal was performed considering gel-core structure, entrapment efficiency, particle size and stability of the vesicles as quality attributes. Structure elucidation of the nanocarrier was performed using optical, polarizing and transmission electron microscopy before and after Triton-X100 addition. Ex-vivo ocular permeation and in vivo performance were investigated on male albino rabbits. Optimized formulation (CBS5) showed gel-core structure, nanosize (339.00 ± 5.50 nm) and not defined before (62.00% ± 1.73) entrapment efficiency. Cumulative amount of CBS5 permeated ex-vivo after 6 h, was 2.43 and 3.43 folds higher than that of conventional liposomes and FLZ suspension, respectively. In-vivo corneal permeation of CBS5 showed significantly higher AUC0-24 h (487.12 ± 74.80) compared to that of FLZ suspension (204.34 ± 7.46) with longer residence time in the eye lasts for more than 18 h. In conclusion, novel gel-core carbosomes could successfully be used as a promising delivery system for chronic ocular diseases.

A Chitosan-Based Liposome Formulation Enhances the In Vitro Wound Healing Efficacy of Substance P Neuropeptide

Currently, there is considerable interest in developing innovative biodegradable nanoformulations for controlled administration of therapeutic proteins and peptides. Substance P (SP) is a neuropeptide of 11 amino acids that belongs to the tachykinins family and it plays an important role in wound healing. However, SP is easily degradable in vivo and has a very short half-life, so the use of chitosan-based nanocarriers could enhance its pharmaceutical properties. In light of the above, the aim of this work was to produce and characterize chitosan-coated liposomes loaded with SP (SP-CH-LP) as novel biomaterials with potential application in mucosal wound healing. The loaded system’s biophysical properties were characterized by dynamic light scattering with non-invasive back scattering (DLS-NIBS), mixed mode measurements and phase analysis light scattering (M3-PALS) and high performance liquid chromatography with ultraviolet/visible light detection (HPLC-UV/VIS). Then, the efficacy of the obtained nanoformulations was examined via proof-of-principle experiments using in vitro cell assays. These assays showed an increment on cell motility and proliferation after treatment with free and encapsulated neuropeptides. Additionally, the effect of SP on wound healing was enhanced by the entrapment on CH-LP. Overall, the amenability of chitosan-based nanomaterials to encapsulate peptides and proteins constitutes a promising approach towards potential novel therapies to treat difficult wounds.

Chitosan-Based Nanomedicine to Fight Genital Candida Infections: Chitosomes

Vaginal infections are associated with high recurrence, which is often due to a lack of efficient treatment of complex vaginal infections comprised of several types of pathogens, especially fungi and bacteria. Chitosan, a mucoadhesive polymer with known antifungal effect, could offer a great improvement in vaginal therapy; the chitosan-based nanosystem could both provide antifungal effects and simultaneously deliver antibacterial drugs. We prepared chitosan-containing liposomes, chitosomes, where chitosan is both embedded in liposomes and surface-available as a coating layer. For antimicrobial activity, we entrapped metronidazole as a model drug. To prove that mucoadhesivness alone is not sufficient for successful delivery, we used Carbopol-containing liposomes as a control. All vesicles were characterized for their size, zeta potential, entrapment efficiency, and in vitro drug release. Chitosan-containing liposomes were able to assure the prolonged release of metronidazole. Their antifungal activity was evaluated in a C. albicans model; chitosan-containing liposomes exhibited a potent ability to inhibit the growth of C. albicans. The presence of chitosan was crucial for the system’s antifungal activity. The antifungal efficacy of chitosomes combined with antibacterial potential of the entrapped metronidazole could offer improved efficacy in the treatment of mixed/complex vaginal infections.

Chitosan and Kappa-Carrageenan Vaginal Acyclovir Formulations for Prevention of Genital Herpes. In Vitro and Ex Vivo Evaluation

Vaginal formulations for the prevention of sexually transmitted infections are currently gaining importance in drug development. Polysaccharides, such as chitosan and carrageenan, which have good binding capacity with mucosal tissues, are now included in vaginal delivery systems. Marine polymer-based vaginal mucoadhesive solid formulations have been developed for the controlled release of acyclovir, which may prevent the sexual transmission of the herpes simplex virus. Drug release studies were carried out in two media: simulated vaginal fluid and simulated vaginal fluid/simulated seminal fluid mixture. The bioadhesive capacity and permanence time of the bioadhesion, the prepared compacts, and compacted granules were determined ex vivo using bovine vaginal mucosa as substrate. Swelling processes were quantified to confirm the release data. Biocompatibility was evaluated through in vitro cellular toxicity assays, and the results showed that acyclovir and the rest of the materials had no cytotoxicity at the maximum concentration tested. The mixture of hydroxyl-propyl-methyl-cellulose with chitosan- or kappa-carrageenan-originated mucoadhesive systems that presented a complete and sustained release of acyclovir for a period of 8–9 days in both media. Swelling data revealed the formation of optimal mixed chitosan/hydroxyl-propyl-methyl-cellulose gels which could be appropriated for the prevention of sexual transmission of HSV.

Chitosan in mucoadhesive drug delivery: focus on local vaginal therapy

Mucoadhesive drug therapy destined for localized drug treatment is gaining increasing importance in today's drug development. Chitosan, due to its known biodegradability, bioadhesiveness and excellent safety profile offers means to improve mucosal drug therapy. We have used chitosan as mucoadhesive polymer to develop liposomes able to ensure prolonged residence time at vaginal site. Two types of mucoadhesive liposomes, namely the chitosan-coated liposomes and chitosan-containing liposomes, where chitosan is both embedded and surface-available, were made of soy phosphatidylcholine with entrapped fluorescence markers of two molecular weights, FITC-dextran 4000 and 20,000, respectively. Both liposomal types were characterized for their size distribution, zeta potential, entrapment efficiency and the in vitro release profile, and compared to plain liposomes. The proof of chitosan being both surface-available as well as embedded into the liposomes in the chitosan-containing liposomes was found. The capability of the surface-available chitosan to interact with the model porcine mucin was confirmed for both chitosan-containing and chitosan-coated liposomes implying potential mucoadhesive behavior. Chitosan-containing liposomes were shown to be superior in respect to the simplicity of preparation, FITC-dextran load, mucoadhesiveness and in vitro release and are expected to ensure prolonged residence time on the vaginal mucosa providing localized sustained release of entrapped model substances.