Chitosan and liposomal delivery systems for epicatechin or propyl gallate targeting localized treatment of vulvovaginal candidiasis.

Natural polyphenols are promising alternatives to antifungals for novel treatments of vulvovaginal candidiasis (VVC) in an era of antimicrobial resistance. However, polyphenols are poorly soluble and prone to degradation. To overcome their limitations, we propose incorporation in liposomes. The study aimed to develop chitosan and liposome comprising delivery systems for epicatechin (EC) or propyl gallate (PG) as treatment of VVC. EC was selected for its antioxidative properties and PG as an ester of antifungal gallic acid. To improve formulation retention at vaginal site, mucoadhesive chitosan was introduced into formulation as liposomal surface coating or hydrogel due to intrinsic antifungal properties. These polyphenol-loaded liposomes exhibited an average size of 125 nm with a 64 % entrapment efficiency (for both polyphenols). A sustained in vitro polyphenol release was seen from liposomes, particularly in chitosan hydrogel (p < 0.01 or lower). Viscosity was evaluated since increased viscosity upon mucin contact indicated adhesive bond formation between chitosan and mucin confirming mucoadhesiveness of formulations. Antifungal activity was evaluated by the broth microdilution method on Candida albicans CRM-10231. Unlike PG, incorporation of EC in liposomes enabled antifungal activity. Fungicidal activity of chitosan was confirmed both when used as liposomal coating material and as hydrogel vehicle.

Azithromycin-loaded liposomal hydrogel: a step forward for enhanced treatment of MRSA-related skin infections.

Azithromycin (AZT) encapsulated into various types of liposomes (AZT-liposomes) displayed pronounced in vitro activity against methicillin-resistant Staphylococcus aureus (MRSA) (1). The present study represents a follow-up to this previous work, attempting to further explore the anti-MRSA potential of AZT-liposomes when incorporated into chitosan hydrogel (CHG). Incorporation of AZT-liposomes into CHG (liposomal CHGs) was intended to ensure proper viscosity and texture properties of the formulation, modification of antibiotic release, and enhanced antibacterial activity, aiming to upgrade the therapeutical potential of AZT-liposomes in localized treatment of MRSA-related skin infections. Four different liposomal CHGs were evaluated and compared on the grounds of antibacterial activity against MRSA, AZT release profiles, cytotoxicity, as well as texture, and rheological properties. To our knowledge, this study is the first to investigate the potential of liposomal CHGs for the topical localized treatment of MRSA-related skin infections. CHG ensured proper viscoelastic and texture properties to achieve prolonged retention and prolonged release of AZT at the application site, which resulted in a boosted anti-MRSA effect of the entrapped AZT-liposomes. With respect to anti-MRSA activity and biocompatibility, formulation CATL-CHG (cationic liposomes in CHG) is considered to be the most promising formulation for the treatment of MRSA-related skin infections.

A Novel Approach for the Treatment of Aerobic Vaginitis: Azithromycin Liposomes-in-Chitosan Hydrogel.

Biocompatible mucoadhesive formulations that enable a sustained drug delivery at the site of action, while exhibiting inherent antimicrobial activity, are of great importance for improved local therapy of vaginal infections. The aim of this research was to prepare and evaluate the potential of the several types of azithromycin (AZM)-liposomes (180-250 nm) incorporated into chitosan hydrogel (AZM-liposomal hydrogels) for the treatment of aerobic vaginitis. AZM-liposomal hydrogels were characterized for in vitro release, and rheological, texture, and mucoadhesive properties under conditions simulating the vaginal site of application. The role of chitosan as a hydrogel-forming polymer with intrinsic antimicrobial properties was explored against several bacterial strains typical for aerobic vaginitis as well as its potential effect on the anti-staphylococcal activity of AZM-liposomes. Chitosan hydrogel prolonged the release of the liposomal drug and exhibited inherent antimicrobial activity. Additionally, it boosted the antibacterial effect of all tested AZM-liposomes. All AZM-liposomal hydrogels were biocompatible with the HeLa cells and demonstrated mechanical properties suitable for vaginal application, thus confirming their potential for enhanced local therapy of aerobic vaginitis.

Toxicity Assessment of Resveratrol Liposomes-in-Hydrogel Delivery System by EpiVaginalTM Tissue Model.

The natural polyphenol resveratrol (RES) has shown great potential as an antimicrobial, including against microbes associated with vaginal infections. To fully exploit the activities of RES, an all-natural ingredients formulation for RES delivery at vaginal site has been developed, namely liposomes loaded with RES, incorporated into a chitosan hydrogel as secondary vehicle. Although considered non-toxic and safe on their own, the compatibility of the final formulation must be evaluated for its biocompatibility and non-irritancy to the vaginal mucosa. As a preclinical safety assessment, the impact of RES formulation on the tissue viability, the effect on barrier function and cell monolayer integrity, and cytotoxicity were evaluated using the cell-based vaginal tissue model, the EpiVaginal™ tissue. RES liposomes-in-hydrogel formulations neither affected the mitochondrial activity, nor the integrity of the cell monolayer in RES concentration up to 60 µg/mL. Moreover, the barrier function was maintained to a greater extent by RES in formulation, emphasizing the benefits of the delivery system. Additionally, none of the tested formulations expressed an increase in lactate dehydrogenase activity compared to the non-treated tissues. The evaluation of the RES delivery system suggests that it is non-irritant and biocompatible with vaginal tissue in vitro in the RES concentrations considered as therapeutic.

The Expanded Role of Chitosan in Localized Antimicrobial Therapy.

Chitosan is one of the most studied natural origin polymers for biomedical applications. This review focuses on the potential of chitosan in localized antimicrobial therapy to address the challenges of current rising antimicrobial resistance. Due to its mucoadhesiveness, chitosan offers the opportunity to prolong the formulation residence time at mucosal sites; its wound healing properties open possibilities to utilize chitosan as wound dressings with multitargeted activities and more. We provide an unbiased overview of the state-of-the-art chitosan-based delivery systems categorized by the administration site, addressing the site-related challenges and evaluating the representative formulations. Specifically, we offer an in-depth analysis of the current challenges of the chitosan-based novel delivery systems for skin and vaginal infections, including its formulations optimizations and limitations. A brief overview of chitosan's potential in treating ocular, buccal and dental, and nasal infections is included. We close the review with remarks on toxicity issues and remaining challenges and perspectives.

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.

Liposomes-In-Hydrogel Delivery System Enhances the Potential of Resveratrol in Combating Vaginal Chlamydia Infection.

Chlamydia trachomatis is the most common cause of bacterial sexually transmitted infections and causes serious reproductive tract complications among women. The limitations of existing oral antibiotics and treatment of antimicrobial resistance require alternative treatment options. We are proposing, for the first time, the natural polyphenol resveratrol (RES) in an advanced delivery system comprising liposomes incorporated in chitosan hydrogel, for the localized treatment of C. trachomatis infection. Both free RES and RES liposomes-in-hydrogel inhibited the propagation of C. trachomatis in a concentration-dependent manner, assessed by the commonly used in vitro model comprising McCoy cells. However, for lower concentrations, the anti-chlamydial effect of RES was enhanced when incorporated into a liposomes-in-hydrogel delivery system, with inhibition of 78% and 94% for 1.5 and 3 µg/mL RES, respectively for RES liposomes-in-hydrogel, compared to 43% and 72%, respectively, for free RES. Furthermore, RES liposomes-in-hydrogel exhibited strong anti-inflammatory activity in vitro, in a concentration-dependent inhibition of nitric oxide production in the LPS-induced macrophages (RAW 264.7). The combination of a natural substance exhibiting multi-targeted pharmacological properties, and a delivery system that provides enhanced activity as well as applicability for vaginal administration, could be a promising option for the localized treatment of C. trachomatis infection.

The Antimicrobial Properties of Chitosan Can be Tailored by Formulation.

Topical administration of drugs into the vagina can provide local therapy of vaginal infections, preventing the possible systemic side effects of the drugs. The natural polysaccharide chitosan is known for its excellent mucoadhesive properties, safety profile, and antibacterial effects, and thus it can be utilized in improving localized vaginal therapy by prolonging the residence time of a drug at the vaginal site while acting as an antimicrobial in synergy. Therefore, we aimed to explore the potential of chitosan, namely chitosan-coated liposomes and chitosan hydrogel, as an excipient with intrinsic antimicrobial properties. Liposomes were prepared by the thin-film hydration method followed by vesicle size reduction by sonication to the desired size, approximately 200 nm, and coated with chitosan (0.01, 0.03, 0.1, and 0.3%, w/v, respectively). The mucoadhesive properties of chitosan-coated liposomes were determined through their binding efficiency to mucin compared to non-coated liposomes. Non-coated liposomal suspensions were incorporated in chitosan hydrogels forming the liposomes-in-hydrogel formulations, which were further assessed for their texture properties in the presence of biological fluid simulants. The antibacterial effect of chitosan-coated liposomes (0.03%, 0.1% and 0.3%, w/v) and chitosan hydrogels (0.1% and 0.3%, w/w) on Staphylococcus epidermidis and Staphylococcus aureus was successfully confirmed.

Localized Therapy of Vaginal Infections and Inflammation: Liposomes-In-Hydrogel Delivery System for Polyphenols.

Natural polyphenols, such as resveratrol (RES) or epicatechin (EPI), are attractive for treatments of various diseases, including vaginal infections and inflammation, because of their strong anti-oxidative and anti-inflammatory properties. However, their low solubility and consequent poor bioavailability limit their therapeutic uses. To overcome these limitations, a vaginal delivery system comprising either RES or EPI liposomes-in-hydrogel was developed. This system permits therapeutic action of both liposomal polyphenol (RES or EPI) and chitosan-based hydrogel. Liposomes of around 200 nm and entrapment efficiency of 81% and 77% for RES and EPI, respectively, were incorporated into chitosan hydrogel, respectively. Medium molecular weight chitosan (2.5%, w/w) was found to have optimal texture properties and mucoadhesiveness in ex vivo conditions. The in vitro release studies confirmed the sustained release of polyphenols from the system. Both liposomal polyphenols and polyphenols-in-liposomes-in-hydrogel exhibited only minor effects on cell toxicity. EPI showed superior radical scavenging activity at lower concentrations compared to antioxidants vitamin C and E. Anti-inflammatory activity expressed as the inhibitory activity of formulations on the NO production in the LPS-induced macrophages (RAW 264.7) confirmed the superiority of EPI liposomes-in-hydrogel. The plain liposomes-in-hydrogel also exhibited potent anti-inflammatory activity, suggesting that chitosan hydrogel acts in synergy regarding anti-inflammatory effect of formulation.

PEGylated liposomes for topical vaginal therapy improve delivery of interferon alpha.

Recent studies regarding mucosal drug delivery indicate that nanosystems with surface-available polyethylene glycol (PEG) are able to penetrate mucus barrier, assure closer contact with the epithelium, and improve drug delivery to vagina. In the present work, we developed the mucus-penetrating PEGylated liposomes containing interferon alpha-2b (IFN α-2b), destined to provide localized therapy for human papilloma virus (HPV) vaginal infections. The PEGylated liposomes were of a mean size of 181±8nm, bearing a negative zeta potential of - 13mV and an entrapment efficiency of 81±10%. In vitro release experiments on model membrane showed a nearly non-existent IFN α-2b release from both the control and liposomally-associated IFN α-2b. However, the ex vivo penetration studies performed on the vaginal tissue obtained from pregnant sheep, showed the clear elevated IFN α-2b penetration from PEGylated liposomes as compared to the control. Furthermore, mucin studies confirmed the absence of interaction between the PEG-modified liposomes and mucin, confirming their ability to penetrate mucus and reach the deeper epithelium. The system holds a promise in improving topical delivery of IFN α-2b through enhanced efficacy of local anti-viral therapy.

Resveratrol-loaded liposomes for topical treatment of the vaginal inflammation and infections.

Resveratrol (RES), chemically known as 3,5,4'-trihydroxy-trans-stilbene, is a promising multi-targeted anti-oxidative and anti-inflammatory natural polyphenol. Preclinical studies showed its biological activities against the pathogens of sexually transmitted diseases causing vaginal inflammation and infections. Due to its low solubility and poor bioavailability, the optimal therapeutic uses are limited. Therefore, a clinically acceptable topical vaginal formulation of RES exhibiting optimal therapeutic effects is highly desirable. For this purpose, we prepared and optimized chitosan-coated liposomes with RES. The coated vesicles (mean diameter 200nm) entrapped up to 77% of RES, a sufficient load to assure required therapeutic outcome. In vitro drug release study showed the ability of liposomes to provide sustained release of RES. In vitro anti-oxidative activities of RES, namely DPPH and ABTS(•+) radicals scavenging assays, confirmed RES to be as potent as standard anti-oxidants, vitamins C and E. The anti-oxidative activities of RES and its corresponding liposomal formulation were also compared by measuring enhanced superoxide dismutase (SOD) activities in lipopolysaccharide (LPS)-induced J774A.1 cells. In vitro anti-inflammatory activities were compared by measuring nitric oxide (NO), tumor necrosis factor (TNF)-α and interleukin (IL)-1ß production in LPS-induced J774A.1 cells. Liposomal RES was found to exhibit stronger anti-oxidative and anti-inflammatory activities than RES solution.

Chitosan-coated liposomes for topical vaginal therapy: assuring localized drug effect.

The choice of drug therapy in pregnant patients suffering from vaginal infections is limited by the safety profile of the drug. Assuring the efficient topical therapy to avoid systemic absorption is considered the best therapy option. Chitosan-coated liposomes have been developed and optimized to assure localized therapy of clotrimazole. Chitosan was selected as mucoadhesive polymer both to prolong system's retention at the vaginal site and act on biofilms responsible for high recurrence of infections. Sonicated liposomes were coated with chitosan in three different concentrations, namely 0.1, 0.3 and 0.6% (w/v). Clotrimazole-containing (22 µg/mg lipid) chitosan-coated liposomes were in the size range of 100-200 nm. The in vitro release studies confirmed prolonged release of clotrimazole from both non-coated and chitosan-coated liposomes as compared to control. The ex vivo penetration experiments performed on the pregnant sheep vaginal tissue showed that coated liposomes assured increased clotrimazole tissue retention and reduced its penetration as compared to the control. Mucin studies revealed that the coating with lower chitosan concentration increased the system's mucoadhesive potential, as compared to coating with higher concentrations. These results provide a good platform for further in vivo animal studies on mucoadhesive liposomes destined to localized vaginal therapy.