Performance of an in vitro mucoadhesion testing method for vaginal semisolids: Influence of different testing conditions and instrumental parameters

A Comparative Study and Prediction of the Ex Vivo Permeation of Six Vaginally Administered Drugs across Five Artificial Membranes and Vaginal Tissue

The theoretical interpretation of the vaginal permeability phenomenon, the evaluation of the suitability of five artificial membranes, and the prediction of the behaviors of vaginal drugs were the main objectives of this study. Franz vertical diffusion cells and different validated HPLC methods were used to measure the permeability of six vaginally administered drugs (econazole, miconazole, metronidazole, clindamycin, lidocaine, and nonoxynol-9). This study was performed (in vitro) on different membranes of polyvinylidene fluoride (PVDF), plain cellulose or cellulose impregnated with isopropyl myristate (IPM), and cellulose combined with PVDF or IPM. The results were compared with those obtained from cow vaginal tissue (ex vivo), where cellulose was proven to be the best simulant. According to the permeability profiles (Papp), the water solubility of the drugs was considered a necessary criterion for their transport in the membranes or in the tissue, while the size was important for their penetration. Furthermore, it was found that polar compounds show clear superiority when penetrating cellulose or tissue, while non-polar ones show superiority when penetrating the lipophilic PVDF membrane. Finally, a successful attempt was made to predict the Papp values (|Papp-predPapp| < 0.005) of the six drugs under study based on a PLS (Partial Least Squares) in silico simulation model.

Phase transforming in situ gels for sustained and controlled transmucosal drug delivery via the intravaginal route

Direct, reliable, controlled, and sustained drug delivery to female reproductive tract (FRT) remains elusive, with conventional dosage forms falling way short of the mark, leading to premature leakage, erratic drug delivery, and loss of compliance. Historically, the intravaginal route remains underserved by the pharmaceutical sector. To comprehensively address this, we turned our focus to phase-transforming sol-gels, using poloxamers, a thermosensitive polymer and, doxycycline (as hyclate salt, DOXH) as our model agent given its potential use in sexually transmitted infections (STIs). We further enhanced mucoadhesiveness through screening of differing viscosity grade hydroxypropyl methyl celluloses (HPMCs). The optimised sol-gels remained gelled at body temperature (<37 °C) and were prepared in buffer aligned to vaginal cavity pH and osmolality. Lead formulations were progressed based on their ability to retain key rheological properties, and acidic pH in the presence of simulated vaginal fluid (SVF). From a shelf-life perspective, DOXH stability, gelation temperature (Tsol-gel), and pH to three months (2-8 °C) was attained. In summary, the meticulously engineered, phase-transforming sol-gels provided sustained mucoretention despite dilution by vaginal fluid, paving the way for localised antimicrobial drug delivery at concentrations that potentially far exceed the minimum inhibitory concentration (MIC) for target STI-causing bacteria of the FRT.

Development of nanostructured environmentally responsive system containing hydroxypropyl methylcellulose for nose-to-brain administration of meloxicam

The intranasal administration of drugs using environmentally responsive formulations, employing a combination of hydroxypropyl methylcellulose (HPMC) and poloxamer 407 (P407), can result in release systems that may assist in the treatment of neurological diseases. Meloxicam, considered a potential adjuvant in the treatment of Alzheimer's disease, could be used in these platforms. The aim of this work was to develop a mucoadhesive, thermoresponsive, and nanostructured system containing HPMC for nose-to-brain administration of meloxicam. The initially selected systems were investigated for their rheological, mechanical, and micellar size characteristics. The systems were dilatant at 25 °C and pseudoplastic with a yield value at 37 °C, showing viscoelastic properties at both temperatures. The platform containing HPMC (0.1%, w/w) and P407 (17.5%, w/w) was selected and demonstrated good mucoadhesive properties, along with an appropriate in vitro release profile. HPMC could form a binary system with P407, displaying superior mucoadhesive and thermoresponsive properties for nose-to-brain meloxicam administration, indicating that the selected formulation is worthy of clinical studies.

Determination of Mucoadhesion of Polyvinyl Alcohol Films to Human Intestinal Tissue

The absorption of drugs with narrow absorption windows in the upper small intestine can be improved with a mucoadhesive drug delivery system such as enteric films. To predict the mucoadhesive behaviour in vivo, suitable in vitro or ex vivo methods can be performed. In this study, the influence of tissue storage and sampling site on the mucoadhesion of polyvinyl alcohol film to human small intestinal mucosa was investigated. Tissue from twelve human subjects was used to determine adhesion using a tensile strength method. Thawing of tissue frozen at -20 °C resulted in a significantly higher work of adhesion (p = 0.0005) when a low contact force was applied for one minute, whereas the maximum detachment force was not affected. When the contact force and time were increased, no differences were found for thawed tissue compared to fresh tissue. No change in adhesion was observed depending on the sampling location. Initial results from a comparison of adhesion to porcine and human mucosa suggest that the tissues are equivalent.

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.

Vaginal Sheets with Thymbra capitata Essential Oil for the Treatment of Bacterial Vaginosis: Design, Characterization and In Vitro Evaluation of Efficacy and Safety

We aimed to incorporate Thymbra capitata essential oil (TCEO), a potent antimicrobial natural product against bacterial vaginosis (BV)-related bacteria, in a suitable drug delivery system. We used vaginal sheets as dosage form to promote immediate relief of the typical abundant vaginal discharge with unpleasant odour. Excipients were selected to promote the healthy vaginal environment reestablishment and bioadhesion of formulations, while the TCEO acts directly on BV pathogens. We characterized vaginal sheets with TCEO in regard to technological characterization, predictable in vivo performance, in vitro efficacy and safety. Vaginal sheet D.O (acid lactic buffer, gelatine, glycerine, chitosan coated with TCEO 1% w/w) presented a higher buffer capacity and ability to absorb vaginal fluid simulant (VFS) among all vaginal sheets with EO, showing one of the most promising bioadhesive profiles, an excellent flexibility and structure that allow it to be easily rolled for application. Vaginal sheet D.O with 0.32 µL/mL TCEO was able to significantly reduce the bacterial load of all in vitro tested Gardnerella species. Although vaginal sheet D.O presented toxicity at some concentrations, this product was developed for a short time period of treatment, so this toxicity can probably be limited or even reversed when the treatment ends.

A novel nanotechnological mucoadhesive and fast-dissolving film for vaginal delivery of clotrimazole: design, characterization, and in vitro antifungal action

Pullulan (PUL) films containing pomegranate seed oil and Eudragit^® RS100 nanocapsules loaded with clotrimazole (CTZ-NC-PUL) were developed to treat vulvovaginal candidiasis (VVC). Our findings showed that the nanocapsule average diameter was around 163 ± 4 nm, with polydispersity index values of up to 0.1 ± 0.01 and positively charged zeta potential (+ 43.5 ± 0.7 mV). The pH was in the acid range (5.14 ± 0.12) and encapsulation efficiency was around 99.6%; CTZ nanoencapsulation promoted higher homogeneity values for the film (91%), and the stability studies displayed no changes in the drug content after 120 days for the CTZ-NC-PUL under refrigerated conditions. All formulations were considered non-irritant, and CTZ-NC-PUL promoted a controlled release of the drug (60% in 24 h) compared to CTZ-PUL (100% in 8 h). The permeation results corroborate the drug release, where higher CTZ amounts were found in the mucosa and receptor medium for CTZ-PUL (21.02 and 4.46 μg/cm²). The films were fast dissolving (10 min), and CTZ-NC-PUL presented higher mucoadhesive properties; the antifungal activity against Candida albicans was maintained, and the in vitro efficacy of the film was proved. In conclusion, CTZ-NC-PUL formulation was considered promising and suitable for vaginal application against candida-related infections.

Development and characterization of amphotericin B nanoemulsion-loaded mucoadhesive gel for treatment of vulvovaginal candidiasis

Despite being recognized as the "gold standard" for treating azole-resistant vulvovaginal candidiasis, amphotericin B (AmB), an amphoteric molecule, has not been widely used due to serious issues with solubility and permeability. In light of the aforementioned, the objective of the present study was to increase AmB's therapeutic efficacy by formulating it into an o/w nanoemulsion (AmB-NE) system. Furthermore, to facilitate AmB-NE's retention within the vaginal cavity, it was loaded into a mixture of Carbopol® 974P and Aloe vera-based gel (CA gel). Briefly, in the present study, a kinetically stable batch of formulated AmB-NE having a globule size of 76.52 ± 3.11 nm, PDI of 0.342 ± 0.032, and zeta potential of -22.32 ± 0.88 mV was incorporated into the CA gel base. This AmB-NE loaded gel (AmB-NE gel) exhibited a non-Fickian/anomalous diffusion from the hydrophilic matrix. The texture analysis of AmB-NE gel revealed that the prepared gel was a non-drip, soft, easy to spread, and sufficiently cohesive gel that could reside in the vaginal cavity, which was confirmed by our ex-vivo retention test, which revealed that AmB-NE loaded gel could stay in the vaginal cavity for approximately 11 h. Ex-vivo skin permeation studies revealed that AmB-NE is 4.26 times more permeable than AmB-coarse gel, implying that AmB-NE facilitates AmB entry into the vaginal epithelial layers. Furthermore, in-vivo vaginal lavage studies revealed that AmB-NE gel permeated 7.03-fold more than AmB-coarse gel. Prepared AmB-NE gel was stable in refrigerated condition and showed no histopathological toxicity. Thus, the present study suggests that AmB-NE gel could eliminate the existing problem of AmB and that it could serve as an alternative option to treat vulvovaginal candidiasis.

Mucoadhesive gellan gum hydrogel containing diphenyl diselenide-loaded nanocapsules presents improved anti-candida action in a mouse model of vulvovaginal candidiasis

The aim of this study was to evaluate the in vitro antifungal action of a diphenyl diselenide-loaded poly(ε-caprolactone) nanocapsules suspension (NC-1) and incorporate it into a gellan gum hydrogel formulation in order to assess its in vivo efficacy in an animal model of vulvovaginal candidiasis. Nanocapsules suspensions containing the compound (NC-1 ∼ 5 mg/mL) or not (NC-B) were prepared by the interfacial deposition of preformed polymer method. To estimate in vitro antifungal effect, the broth microdilution test was applied. The results showed that NC-1 had equal or lower MIC values when compared to free compound against fifteen Candida strains. Following, the hydrogel was prepared by direct thickening of the nanocapsules suspension by gellan gum addition. The animal model of vulvovaginal candidiasis was induced by infecting female Swiss mice with Candida albicans strains. The animals were topically treated with 20 µL of hydrogels (NC-1 and free compound - 0.1 mg of diphenyl diselenide/once a day for seven days) and then the total fungal burden was assessed after the euthanasia. The results showed that the hydrogels presented pH in the acidic range, compound content close to theoretical value, homogeneous particle distribution with nanometric size, high physicochemical and microbiological stability as well as great bioadhesive property. The nano-based presented superior pharmacological action in comparison to the hydrogel containing non-encapsulated diphenyl diselenide. The results demonstrated that the nanoencapsulation maintained the effective antifungal action of diphenyl diselenide. The nano-based hydrogel formulation may be considered a promising approach against vulvovaginal candidiasis.

Electrospun fibers for vaginal administration of tenofovir disoproxil fumarate and emtricitabine in the context of topical pre-exposure prophylaxis

Women are particularly vulnerable to sexual HIV-1 transmission. Oral pre-exposure prophylaxis (PrEP) with tenofovir disoproxil fumarate and emtricitabine (TDF/FTC) is highly effective in avoiding new infections in men, but protection has only been shown to be moderate in women. Such differences have been associated, at least partially, to poor drug penetration of the lower female genital tract and the need for strict adherence to continuous daily oral intake of TDF/FTC. On-demand topical microbicide products could help circumvent these limitations. We developed electrospun fibers based on polycaprolactone (PCL fibers) or liposomes associated to poly(vinyl alcohol) (liposomes-in-PVA fibers) for the vaginal co-delivery of TDF and FTC, and assessed their pharmacokinetics in mice. PCL fibers and liposomes-in-PVA fibers were tested for morphological and physicochemical properties using scanning electron microscopy, differential scanning calorimetry and X-ray diffractometry. Fibers featured organoleptic and mechanical properties compatible with their suitable handling and vaginal administration. Fluorescent quenching of mucin in vitro - used as a proxy for mucoadhesion - was intense for PCL fibers, but mild for liposomes-in-PVA fibers. Both fibers were shown safe in vitro and able to rapidly release drug content (15-30 min) under sink conditions. Liposomes-in-PVA fibers allowed increasing genital drug concentrations after a single intravaginal administration when compared to continuous daily treatment for five days with 25-times higher oral doses. For instance, the levels of tenofovir and FTC in vaginal lavage were around 4- and 29-fold higher, respectively. PCL fibers were also superior to oral treatment, although to a minor extent (approximately 2-fold higher drug concentrations in lavage). Vaginal tissue drug levels were generally low for all treatments, while systemic drug exposure was negligible in the case of fibers. These data suggest that proposed fibers may provide an interesting alternative or an ancillary option to oral PrEP in women.

Mucoadhesive hyaluronic acid-based films for vaginal delivery of metronidazole

Bacterial vaginosis is a prevalent women's health issue that affects millions of women worldwide every year; however, current treatments are often messy, inconvenient, and ineffective. Therefore, we developed a new hyaluronic acid-based film to deliver metronidazole that would be more effective, more convenient, and at a pH similar to that of the normal vaginal environment. Films were made by crosslinking modified hyaluronic acid to create a hydrogel, in which metronidazole or metronidazole benzoate and methylcellulose were incorporated, and the hydrogel was dried to a thin film. Through release testing, coupled with assessments of handleability, tensile strength, and mucoadhesion, it was determined that the films have the potential to remain in the vaginal environment for an extended time period and gradually release the drug for at least 6 days, which is a typical treatment length. As such, the films present a viable alternative to current treatment methods, allowing for both easy handling and a single treatment while eliminating the issues of pH and overall inconvenience.

Sodium bicarbonate gels: a new promising strategy for the treatment of vulvovaginal candidosis

Vulvovaginal candidosis (VVC), caused mainly by the yeast Candida albicans, is the second most prevalent vaginal infection. It has been found to have a large impact on women's quality of life, self-esteem and routines. The prevalence of recurrent vulvovaginal candidosis (RVVC) remains high so the development of alternative treatments is needed. The main objective of this study was to develop and characterize sodium bicarbonate gels to treat VVC. We described key formulation characteristics and analyzed their influence on in vitro performance evaluations. The potential to inhibit Candida albicans's growth, the pH, osmolality, viscosity and rheological performance in contact with vaginal fluid simulant and the bioadhesion's profile (using a vaginal ex vivo porcine model) were studied for all formulations. Among the formulations, formulation C (5% sodium bicarbonate, 1% carbomer and 94% water) was the most effective in inhibiting the C. albicans' growth. This gel presented the same potential (the same MIC 2.5%) to inhibit other etiological agents of VVC (C. glabrata, C. krusei, C. tropicalis and C. parapsilosis) for all species tested. Additionally, sensorial characteristics of gel C were in accord with users' preferences. This gel exhibited physicochemical characteristics acceptable for short term treatments, suggesting good overall performance for the treatment of VVC. Furthermore, Gel C was biocompatible with the HeLa cell line (MTT assay) and was classified as a non-severe irritant in the HET-CAM assay (irritation score 4 ± 1). Overall, gel C was deemed the best performing of the set tested, and suitable for further development.

Long lasting mucoadhesive membrane based on alginate and chitosan for intravaginal drug delivery

The intravaginal route of administration can be exploited to treat local diseases and for systemic delivery. In this work, we developed an alginate/chitosan membrane sufficiently stable in a simulated vaginal fluid and able to dissolve over time at a very slow and linear rate. The membrane demonstrated good mechanical properties both in its swollen and dry form. As a study case, we evaluated the viability of this potential drug delivery system for the treatment of bacterial vaginosis, a common disease affecting women in their reproductive age. Metronidazole was effectively included in the alginate/chitosan membrane and its bactericide effect was demonstrated against Staphylococcus aureus and Gardnerella vaginalis, simultaneously showing good biocompatibility with a cervix epithelial cell line. Since this alginate/chitosan membrane is stable in a simulated vaginal environment, is easy to fabricate and can be used for the controlled release of a model drug, it represents a promising drug delivery system for local intravaginal applications.

Mucoadhesive hydrogels for buccal drug delivery: In vitro-in vivo correlation study

AIM

It was the aim of this study to assess in vitro methods for the characterization of mucoadhesive hydrogels for their potential to predict the residence time on human buccal mucosa.

METHODS

Mixtures of hydrogels comprising hydroxyethyl cellulose (HEC), sodium carboxymethyl cellulose (CMC), xanthan gum (XTGM), hyaluronic acid sodium salt (HA), sodium alginate (ALG), carbopol (CP) as well as polycarbophil (PCP) and porcine mucus were analysed for relative rheological synergism. Furthermore, hydrogels were characterized for their texture and mechanical properties. For the assessment of mucoadhesive strength of formulations tensile studies were performed on porcine buccal mucosa. To facilitate a direct comparability of data the residence time of stained hydrogels was determined ex vivo on porcine buccal mucosa and in the oral cavity of volunteers.

RESULTS

The extent of relative rheological synergism was in good agreement with data from in vivo residence time studies. Results of tensile studies were further effected by textural properties of hydrogels leading to a restricted correlation with data from the in vivo experiment. The resistance towards removal by artificial saliva flow ex vivo revealed the highest correlation to the in vivo experiment with increasing mucosal residence time in the rank order CP < HEC, HA, ALG, PCP < CMC < XTGM.

CONCLUSIONS

This overview of measurement principles to predict the residence time of hydrogels for buccal application in humans may be a potent tool for the development of semisolid intraoral formulations.

Vaginal Suppositories with siRNA and Paclitaxel-Incorporated Solid Lipid Nanoparticles for Cervical Cancer: Preparation and In Vitro Evaluation

The objective of this study is to prepare vaginal suppository containing chemotherapeutic agent and genetic material that can be applied locally for cervical cancer. Cervical cancer is one of the most life-threatening types of cancer among women and is generally resistant to chemotherapy. Paclitaxel has been selected as chemotherapeutic agent, and siRNA that inhibits the Bcl-2 oncogene has been selected as the genetic material for simultaneous vaginal delivery. For this purpose, three different solid lipid nanoparticles (SLNs) were prepared that include Bcl-2 siRNA and paclitaxel and paclitaxel/Bcl-2 siRNA combination separately, and these SLN formulations were dispersed in vaginal suppositories prepared with PEG 6000. First, the physicochemical properties of SLNs, their cytotoxicities on HeLa cell lines, and the transfection ability of siRNA-incorporated SLN on the cells have been examined. Afterward, the release of SLNs from the three different vaginal suppositories prepared has been determined via horizontal diffusion chamber system. The loaded amount to the SLNs and release amount from suppositories of paclitaxel have been determined via HPLC, whereas stability, loading, and release amount of siRNA has been determined via gel retardation system and UV spectrophotometer.

Development of a mucoadhesive delivery system for control release of doxepin with application in vaginal pain relief associated with gynecological surgery

The main purpose of this study was to develop a semisolid mucoadhesive formulation for the non-invasive vaginal administration of doxepin (DOX) for relief of pain derived from the scarring process after surgery. An orafix^® platform loading DOX was tested for adequate stability, rheology and vaginal mucoadhesion capacity. The formulation exhibited appropriate pH and was microbiologically stable. The rheological studies confirmed its pseudoplastic and thixotropic nature with prevalence of the elastic behavior component over the viscous one. Appropriate syringeability and spreadability results were also confirmed. Different experiments showed adequate mucoadhesion capacity even in the presence of simulated vaginal fluid. Finally, DOX release, permeation and retention in vaginal mucosa studies were also accomplished with promising results. DOX release kinetics followed the modified Higuchi model and the permeation studies did not render such high values as to suggest potential systemic absorption which could lead to undesirable systemic side effects. Therefore, we can hypostatize that the proposed formulation may assist to fill in the therapeutic gap regarding pure pain relief at local level in vagina.

Vaginal semisolid products: Technological performance considering physiologic parameters

Vaginal semisolid products are frequently used to treat vaginal infections and atrophy-related symptoms of menopause. Formulations composition and the methods for their characterization, especially those developed concerning the target epithelia, are key tools to predict in vivo results at early stages of product development. However, recent studies on this subject have been almost exclusively focused on anti-HIV preparations. The aim of this work consists on improving traditional characterization methods by using physiological parameters in order to construct predictive tools to characterize a new ideal vaginal semisolid formulation whatever target it may have. Ten vaginal antimicrobial and hormonal products already available in the market were studied (Gino-Canesten®, Sertopic®, Dermofix®, Gyno-pevaryl®, Lomexin®, Gino Travogen®, Dalacin V®, Ovestin®, Blissel®, Colpotrophine®). Furthermore, Universal Placebo gel and Replens® were used for comparison. Products were characterized in terms of: pH and buffering capacity in a vaginal fluid simulant (VFS); osmolality - directly and upon dilution in VFS; textural parameters (firmness, adhesiveness and bioadhesion) using vaginal ex vivo porcine epithelium; and viscosity (including VFS dilution at 37°C and after administration on an ex vivo model). Interestingly, the majority of the tested commercial vaginal formulations did not present technological characteristics close to the ideal ones when tested under target biological conditions. The inclusion of such methodologic adaptations is expected to optimize cost-efficiency of new formulations development by predicting efficacy and safety profiles at early stages of product development.

Biological Effects of Drug-Free Alginate Beads Cross-Linked by Copper Ions Prepared Using External Ionotropic Gelation

External ionotropic gelation offers a unique possibility to entrap multivalent ions in a polymer structure. The aim of this experimental study was to prepare new drug-free sodium alginate (ALG) particles cross-linked by Cu²⁺ ions and to investigate their technological parameters (particle size, sphericity, surface topology, swelling capacity, copper content, release of Cu²⁺ ions, mucoadhesivity) and biological activity (cytotoxicity and efficiency against the most common vaginal pathogens-Herpes simplex, Escherichia coli, Candida albicans) with respect to potential vaginal administration. Beads prepared from NaALG dispersions (3 or 4%) were cross-linked by Cu²⁺ ions (0.5 or 1.0 M CuCl₂) using external ionotropic gelation. Prepared mucoadhesive beads with particle size over 1000 μm exhibited sufficient sphericity (all ˃0.89) and copper content (214.8-249.07 g/kg), which increased with concentration of polymer and hardening solution. Dissolution behaviour was characterized by extended burst effect, followed by 2 h of copper release. The efficiency of all samples against the most common vaginal pathogens was observed at cytotoxic Cu²⁺ concentrations. Anti-HSV activity was demonstrated at a Cu²⁺ concentration of 546 mg/L. Antibacterial activity of beads (expressed as minimum inhibition concentration, MIC) was influenced mainly by the rate of Cu²⁺ release which was controlled by the extent of swelling capacity. Lower MIC values were found for E. coli in comparison with C. albicans. Sample ALG-3_1.0 exhibited the fastest copper release and was proved to be the most effective against both bacteria. This could be a result of its lower polymer concentration in combination with smaller particle size and thus larger surface area.

Preparation and in vitro evaluation of melatonin-loaded HA/PVA gel formulations

Melatonin-loaded hyaluronic acid (HA) and poly(vinyl alcohol) (PVA) gels were prepared by using freeze-thaw technique and an emulsion method followed by freeze-thaw technique to produce a new synergistic system for topical application. Freeze-thaw hydrogels and emulgels were characterized by means of Fourier transform infrared spectroscopy, rheology and swelling tests. The porous structure of the hydrogels was shown by scanning electron microscopy observations and thermal properties were tested by differential scanning calorimetry measurements. Bioadhesion and in vitro release characterization of formulations were performed by texture profile analysis and dialysis bag method, respectively. The pore size of both formulations was ranging from 900 nm to 30 μm. Melatonin showed a good compatibility with the polymeric matrices as the pores were smaller for the drug-loaded systems. In vitro release studies showed that the release was improved by emulgel formulations. After 24 h, the release percentage was found to be 13.240% ± 1.094 and 15.192% ± 2.270 for hydrogel and emulgel, respectively. Emulgels had better bioadhesion properties than simple freeze-thaw samples. As a conclusion, regarding the in vitro characterization studies HA and PVA hydrogel and emulgel formulations and their lyophilized forms could be promising systems for topical application of melatonin.

Preparation and in vitro evaluation of vaginal formulations including siRNA and paclitaxel-loaded SLNs for cervical cancer

Cervical cancer is one of the most life threatening types of cancer among women and is generally resistant to chemotherapy. The objective of this study was to prepare a vaginal suppository containing a chemotherapeutic agent and a genetic material that can be applied locally for cervical cancer. Paclitaxel was selected as the chemotherapeutic agent and siRNA which inhibits BCL-2 oncogene was selected as the genetic material. Bcl-2 siRNA, paclitaxel and paclitaxel/Bcl-2 siRNA combination were incorporated into solid lipid nanoparticles (SLNs) and were dispersed separately in vaginal suppositories prepared with PEG 6000. Physicochemical properties of SLNs, their cytotoxicities on HeLa cell lines and also the effect of SLNs on the total protein amount of the cells were examined followed by the investigation of release rates of the active materials from the SLNs prepared. Average diameters of all SLNs prepared were below 180nm with a positive zeta potential value between +22.20 and +48.16mV at the pH range of 4.2 and 7.4. The release of Bcl-2 siRNA from SLNs incorporated Bcl-2 siRNA and the release of paclitaxel (PTX) from PTX incorporated SLNs were completed within 12h and 36h. SLNs incorporating Bcl-2 siRNA and paclitaxel/Bcl-2 siRNA were found to be more toxic when compared to paclitaxel incorporated SLN and placebo SLN. The disintegration of the vaginal suppositories as well as the release of the SLNs was completed within 2 h. This study indicates that vaginal suppository containing SLNs can bring the advantages of the simultaneous delivery of paclitaxel and siRNA via vaginal route with no help from professionals.

Development and in vivo safety assessment of tenofovir-loaded nanoparticles-in-film as a novel vaginal microbicide delivery system

Topical pre-exposure prophylaxis (PrEP) with antiretroviral drugs holds promise in preventing vaginal transmission of HIV. However, significant biomedical and social issues found in multiple past clinical trials still need to be addressed in order to optimize protection and users' adherence. One approach may be the development of improved microbicide products. A novel delivery platform comprising drug-loaded nanoparticles (NPs) incorporated into a thin polymeric film base (NPs-in-film) was developed in order to allow the vaginal administration of the microbicide drug candidate tenofovir. The system was optimized for relevant physicochemical features and characterized for biological properties, namely cytotoxicity and safety in a mouse model. Tenofovir-loaded poly(lactic-co-glycolic acid) (PLGA)/stearylamine (SA) composite NPs with mean diameter of 127nm were obtained with drug association efficiency above 50%, and further incorporated into an approximately 115μm thick, hydroxypropyl methylcellulose/poly(vinyl alcohol)-based film. The system was shown to possess suitable mechanical properties for vaginal administration and to quickly disintegrate in approximately 9min upon contact with a simulated vaginal fluid (SVF). The original osmolarity and pH of SVF was not affected by the film. Tenofovir was also released in a biphasic fashion (around 30% of the drug in 15min, followed by sustained release up to 24h). The incorporation of NPs further improved the adhesive potential of the film to ex vivo pig vaginal mucosa. Cytotoxicity of NPs and film was significantly increased by the incorporation of SA, but remained at levels considered tolerable for vaginal delivery of tenofovir. Moreover, histological analysis of genital tissues and cytokine/chemokine levels in vaginal lavages upon 14days of daily vaginal administration to mice confirmed that tenofovir-loaded NPs-in-film was safe and did not induce any apparent histological changes or pro-inflammatory response. Overall, obtained data support that the proposed delivery system combining the use of polymeric NPs and a film base may constitute an exciting alternative for the vaginal administration of microbicide drugs in the context of topical PrEP.

STATEMENT OF SIGNIFICANCE

The development of nanotechnology-based microbicides is a recent but promising research field seeking for new strategies to circumvent HIV sexual transmission. Different reports detail on the multiple potential advantages of using drug nanocarriers for such purpose. However, one important issue being frequently neglected regards the development of vehicles for the administration of microbicide nanosystems. In this study, we propose and detail on the development of a nanoparticle-in-film system for the vaginal delivery of the microbicide drug candidate tenofovir. This is an innovative approach that, to our best knowledge, had never been tested for tenofovir. Results, including those from in vivo testing, sustain that the proposed system is safe and holds potential for further development as a vaginal microbicide product.

Nanoparticles-in-film for the combined vaginal delivery of anti-HIV microbicide drugs

Combining two or more antiretroviral drugs in one medical product is an interesting but challenging strategy for developing topical anti-HIV microbicides. We developed a new vaginal delivery system comprising the incorporation of nanoparticles (NPs) into a polymeric film base - NPs-in-film - and tested its ability to deliver tenofovir (TFV) and efavirenz (EFV). EFV-loaded poly(lactic-co-glycolic acid) NPs were incorporated alongside free TFV into fast dissolving films during film manufacturing. The delivery system was characterized for physicochemical properties, as well as genital distribution, local and systemic 24h pharmacokinetics (PK), and safety upon intravaginal administration to mice. NPs-in-film presented suitable technological, mechanical and cytotoxicity features for vaginal use. Retention of NPs in vivo was enhanced both in vaginal lavages and tissue when associated to film. PK data evidenced that vaginal drug levels rapidly decreased after administration but NPs-in-film were still able to enhance drug concentrations of EFV. Obtained values for area-under-the-curve for EFV were around one log10 higher than those for the free drugs in aqueous vehicle (phosphate buffered saline). Film alone also contributed to higher and more prolonged local drug levels as compared to the administration of TFV and EFV in aqueous vehicle. Systemic exposure to both drugs was low. NPs-in-film was found to be safe upon once daily vaginal administration to mice, with no significant genital histological changes or major alterations in cytokine/chemokine profiles being observed. Overall, the proposed NPs-in-film system seems to be an interesting delivery platform for developing combination vaginal anti-HIV microbicides.

Oleic Acid Coated Gelatin Nanoparticles Impregnated Gel for Sustained Delivery of Zaltoprofen: Formulation and Textural Characterization

PURPOSE

In the present study, we have formulated zaltoprofen loaded, surface decorated, biodegradable gelatin nanogel and evaluated its texture characterization.

METHODS

The method used to prepare gelatin nanoparticles (GNP) was 'two step desolvation' and its surface decoration was performed with oleic acid (OA). The GNP was optimized by DOE software. Nanogels were evaluated for particle size entrapment efficiency, texture properties, SEM, in-vitro, ex-vivo drug release studies, in-vitro characterization, stability and in vivo evaluation of nanogel for anti-inflammatory activity was carried out by carrageenan induced rat paw edema method as an anti-inflammatory experimental model.

RESULTS

The formulated GNP with particle size and entrapment efficiency of optimized batch was found to be 247.1 nm and 76.21% respectively. The SEM of GNP shows smooth and spherical shape. In-vitro and Ex-vivo drug release shows that there was 69.47% and 78.59% drug released within 48 hrs. It follows Ritger peppas model, which indicates sustained drug release. The good texture properties of nanogel were observed from texture analysis graphs.In vivo studies of our formulation give significant results compared to the marketed nanogel. Stability data revealed stability of nanogel formulation up to 3 months.

CONCLUSION

The present approach can provide us promising results of the sustained analgesic activity and the stability of drug within the GNP.

Design and evaluation of an intravesical delivery system for superficial bladder cancer: preparation of gemcitabine HCl-loaded chitosan-thioglycolic acid nanoparticles and comparison of chitosan/poloxamer gels as carriers

This study aimed to develop an intravesical delivery system of gemcitabine HCl for superficial bladder cancer in order to provide a controlled release profile, to prolong the residence time, and to avoid drug elimination via urination. For this aim, bioadhesive nanoparticles were prepared with thiolated chitosan (chitosan–thioglycolic acid conjugate) and were dispersed in bioadhesive chitosan gel or in an in situ gelling poloxamer formulation in order to improve intravesical residence time. In addition, nanoparticle-loaded gels were diluted with artificial urine to mimic in vivo conditions in the bladder and were characterized regarding changes in gel structure. The obtained results showed that chitosanthioglycolic acid nanoparticles with a mean diameter of 174.5±3.762 nm and zeta potential of 32.100±0.575 mV were successfully developed via ionotropic gelation and that the encapsulation efficiency of gemcitabine HCl was nearly 20%. In vitro/ex vivo characterization studies demonstrated that both nanoparticles and nanoparticle-loaded chitosan and poloxamer gels might be alternative carriers for intravesical administration of gemcitabine HCl, prolonging its residence time in the bladder and hence improving treatment efficacy. However, when the gel formulations were diluted with artificial urine, poloxamer gels lost their in situ gelling properties at body temperature, which is in conflict with the aimed formulation property. Therefore, 2% chitosan gel formulation was found to be a more promising carrier system for intravesical administration of nanoparticles.

Preparation and characterization of bioadhesive controlled-release gels of cidofovir for vaginal delivery

The aim of this study was to develop mucoadhesive and thermosensitive gels for vaginal delivery that would be able to provide a controlled release of the model drug, cidofovir. The study also monitored the drug's potential antiviral properties. Cidofovir was put into the form of a vaginal gel, using mucoadhesive and thermosensitive polymers such as chitosan, Carbopol 974P, HPMC, and poloxamer 407. The physicopharmaceutical properties and stability of the vaginal gel formulations were evaluated. The gel formulation which was prepared with HPMC K100M exhibited the highest viscosity, as well as maximum adhesiveness, cohesiveness, and mucoadhesion values. The results of antiviral activity studies, which used the bovine herpes virus type 1 virus infection in vitro model using Vero cells, demonstrated the antiherpetic effect of the cidofovir gel containing HPMC K100M, at least under in vitro conditions. The study found that a mucoadhesive vaginal gel containing cidofovir can be a promising and innovative alternative therapeutic system for the treatment of genital herpes simplex virus and human papilloma virus induced infections in women.

Mucoadhesive and thermogelling systems for vaginal drug delivery

This review focuses on two formulation approaches, mucoadhesion and thermogelling, intended for prolonging residence time on vaginal mucosa of medical devices or drug delivery systems, thus improving their efficacy. The review, after a brief description of the vaginal environment and, in particular, of the vaginal secretions that strongly affect in vivo performance of vaginal formulations, deals with the above delivery systems. As for mucoadhesive systems, conventional formulations (gels, tablets, suppositories and emulsions) and novel drug delivery systems (micro-, nano-particles) intended for vaginal administration to achieve either local or systemic effect are reviewed. As for thermogelling systems, poly(ethylene oxide-propylene oxide-ethylene oxide) copolymer-based and chitosan-based formulations are discussed as thermogelling systems. The methods employed for functional characterization of both mucoadhesive and thermogelling drug delivery systems are also briefly described.

Bioadhesive hydrogels for cosmetic applications

INTRODUCTION

The use of bioadhesive hydrogels for skin care presents important advantages such as long residence times on the application site and reduced product administration frequency.

OBJECT

The aim of the present work was to develop bioadhesive hydrogels for skin application, using caffeine as a model active ingredient.

METHODS

Eight hydrogels were formulated using binary combinations of a primary polymer (carbomer homopolymer type C (Carbopol(®) 980) or kappa carrageenan potassium salt (Gelcarin(®) GP-812 NF)) and a secondary polymer (carbomer copolymer type B (Pemulen(™) TR-1), xanthan gum or guar gum). Hydrogels were characterized by means of physico-chemical (dynamic rheological measurements, spreadability and adhesion measurements) and sensory methods (projective mapping in combination with a check-all-that-apply (CATA) question). Caffeine hydrogels were formulated using two of the most promising formulations regarding adhesion properties and sensory characteristics. In vitro active ingredient release studies were carried out.

RESULTS

Hydrogel formulations showed a prevalently elastic rheological behaviour. Complex viscosity of carbomer homopolymer type C hydrogels was higher than that of the kappa carrageenan hydrogels. Besides, complex viscosity values were dependent on the secondary polymer present in the formulation. Significant differences among hydrogels were found in detachment force, work of adhesion and spreading diameter results. Association of projective mapping with CATA allowed to determine similarities and dissimilarities among samples. Cluster analysis associated the samples in two groups. Two hydrogels were selected to study the release of caffeine. Both hydrogels presented similar release profiles which were well described by the Higuchi model. Caffeine release was exclusively controlled by a diffusive process.

CONCLUSION

Physico-chemical and sensory techniques enabled the identification of bioadhesive hydrogel formulations with positive characteristics for cosmetic applications. Formulations which combined carbomer homopolymer type C with xanthan gum or with carbomer copolymer type B were the most promising for bioadhesive skin products. Caffeine release profiles of selected formulations were not statistically different. Both hydrogels gradually released the active ingredient, reaching approximately 80% within the first 5 h, and their profiles were well described by the Higuchi model. In this context, it could be concluded that the selected hydrogels are suitable bioadhesive hydrogel formulations for cosmetic application on the skin.

Screening of mucoadhesive vaginal gel formulations

Rational design of vaginal drug delivery formulations requires special attention to vehicle properties that optimize vaginal coating and retention. The aim of the present work was to perform a screening of mucoadhesive vaginal gels formulated with carbomer or carrageenan in binary combination with a second polymer (carbomer, guar or xanthan gum). The gels were characterised using in vitroadhesion, spreadability and leakage potential studies, as well as rheological measurements (stress and frequency sweep tests) and the effect of dilution with simulated vaginal fluid (SVF) on spreadability. Results were analysed using analysis of variance and multiple factor analysis. The combination of polymers enhanced adhesion of both primary gelling agents, carbomer and carrageenan. From the rheological point of view all formulations presented a similar behaviour, prevalently elastic and characterised by loss tangent values well below 1. No correlation between rheological and adhesion behaviour was found. Carbomer and carrageenan gels containing the highest percentage of xanthan gum displayed good in vitro mucoadhesion and spreadability, minimal leakage potential and high resistance to dilution. The positive results obtained with carrageenan-xanthan gum-based gels can encourage the use of natural biocompatible adjuvants in the composition of vaginal products, a formulation field that is currently under the synthetic domain.

Bioadhesive emulsions for control release of progesterone resistant to vaginal fluids clearance

The aim of this study is to propose that mucoadhesive vaginal emulsions can be able to resist the clearance effect of vaginal fluid and to have an effective control release of progesterone. With this goal, silicon derivative, cyclomethicone pentamer, was selected as the bioadhesive and water resistant material. In order to obtain a system which is insensitive to the dilution of aqueous fluids, water in silicone (W/S) emulsions were prepared and different proportions of cyclomethicone as well as 8% or 15% w/w of progesterone were employed. The rheological, mechanical and mucoadhesive properties of emulsions were characterized and the drug release was measured for each formulation. Mucoadhesive behavior was determined and the influence of simulated vaginal fluid (SVF) at bioadhesion was assessed using three commercial mucoadhesive vaginal gels (Crinone(®), K-Y jelly(®) and Zidoval(®)) as the bioadhesive references. All assayed emulsions have good rheological and mechanical properties and their consistence and viscosity increase when the proportion of the internal phase increases. Related to mucoadhesion, in the absence of SVF, W/S emulsions showed similar bioadhesive levels like the commercial formulations. However, in the presence of SVF, W/S emulsions are able to keep their mucoadhesive properties while the marketed references drastically lose their consistency and adherence to the vaginal mucosa. Drug release profiles from W/S emulsion show that progesterone is released with pseudo-order zero kinetics and a constant release rate is maintained for at least two weeks. The results of the in vivo studies developed in rats show that after a single vaginal administration, bioadhesive W/S emulsions increase the uterine tissue progesterone levels in young and postmenopausal rats. Moreover in postmenopausal rats, they provide high uterine levels of progesterone compared to the bioadhesive-marketed gel used as a reference. Therefore, W/S emulsions have an interesting potential as bioadhesive vaginal delivery systems for drug administration.

Characterization of commercially available vaginal lubricants: a safety perspective

Vaginal lubricants are widely used by women to help solve intercourse difficulties or as enhancers, but recent reports raise questions about their safety. Twelve commercially available gel products were tested for pH value, pH buffering capacity, osmolality and cytotoxicity relevant to vaginal delivery. Obtained data were analyzed in light of the recent Advisory Note by the World Health Organization (WHO) for personal lubricants to be concomitantly used with condoms. Results showed that most products do not comply with pH and osmolality recommended standards, thus posing a potential hazard. Four products presented values of osmolality around three-times higher than the maximum acceptable limit of 1200 mOsm/kg. In vitro cell testing further identified substantial cytotoxicity even at 1:100 dilutions for three products, contrasting with no significant effect of up to at least a 1:5 dilution of a Universal Placebo gel. However, no direct correlation between these last results and pH or osmolality was found, thus suggesting that the individual toxicity of specific formulation components plays an important role in the outcome of a particular product. Although further assessment is required, these results highlight potential safety issues related to the formulation of commercially available vaginal lubricants.

Bioadhesive mini-tablets for vaginal drug delivery

Different non-ionic cellulose ethers (methyl cellulose, MC; hydroxyethyl cellulose, HEC; hydroxypropyl cellulose, HPC; hydroxypropylmethyl cellulose, HPMC) and microcrystalline cellulose (MCC) were investigated as matrix formers for preparation of mini-tablets targeting vaginal drug delivery. Hexyl aminolevulinat hydrochloridum (HAL) was used as a model drug. The mini-tablets were characterized with respect to their mechanical strength, bioadhesion towards cow vaginal tissue in two independent tests (rotating cylinder test, detachment test using texture analyzer), and dissolution rate in two media mimicking the pH levels of fertile, healthy and post-menopausal women (vaginal fluid simulant pH 4.5, phosphate buffer pH 6.8). Mini-tablets with a matrix of either HPMC or HPC were found to possess adequate mechanical strength, superior bioadhesive behavior towards vaginal tissue, and pH independent controlled release of the model drug, suggesting that both systems would be suited for the treatment of women regardless of age, i.e., respective of their vaginal pH levels. Bioadhesive mini-tablets offer a potential for improved residence time in the vaginal cavity targeting contact with mucosal tissue and prolonged release of the drug.

Novel topical formulations of Terbinafine-HCl for treatment of onychomycosis

Terbinafine hydrochloride (TBF-HCl) is an active substance that is using for treatment of onychomycosis. Onychomycosis is a fungal infection which is the most common disease of nail plate. The nail plate is a barrier which prevents effective topical treatment of ungual disorders. In this study, TBF-HCl loaded liposome and ethosome formulations and also gel form of these formulations were prepared. The formulations were characterized and in vitro and ex vivo release studies were performed. Nail characterization studies were also performed to examine the effect of formulations and experimental conditions on nail surface. As a result, all formulations can serve as efficient formulations for ungual application of TBF-HCl. By the way, the results of the accumulation studies suggested that liposome poloxamer gel formulation could be promising system for ungual drug delivery due to the better accumulation and easier application of the formulation.

Development and evaluation of an in vitro vaginal model for assessment of drug's biopharmaceutical properties: curcumin

Vaginal administration is a promising alternative to the per-oral route in achieving systemic or local therapeutic effects, when intestinal drug absorption is hindered by problematic biopharmaceutical drug properties. The aim of this study was to establish an in vitro vaginal model and use it to characterize biopharmaceutical properties of liposomally associated curcumin destined for vaginal delivery. The in vitro permeability, metabolism, and tissue retention of high/low permeable compounds were assessed on cow vaginal mucosa and compared to the permeabilities determined through Caco-2 cells and rat jejunum in vitro. The results showed that the intestinal mucosa was superior to the vaginal one in categorizing drugs based on their permeabilities in high/low permeable classes. Passive diffusion was found to be the main mechanism of drug penetration through vaginal mucosa and it was not affected by transporter-enzyme alliance, as their expression/activity was significantly reduced compared to the intestinal tract. Curcumin permeability from the solution form was the lowest of all tested substances due to its significant tissue retention and curcumin-mucus interactions. The permeability of liposomally associated curcumin was even lower but the binding of liposomally associated curcumin to the vaginal tissue was significantly higher. The permeability and tissue retention of liposomal curcumin were vesicle size dependent. Vaginal application of liposomally associated curcumin provides relatively high levels of curcumin in vaginal tissue, with limited systemic absorption.

Formulation of bioadhesive hexylaminolevulinate pellets intended for photodynamic therapy in the treatment of cervical cancer

Photodynamic therapy has a great potential in the treatment of cervical cancer. The aim of this study was to develop bioadhesive pellets containing hexylaminolevulinate (HAL), a precursor of the photoactive substance PpIX, with a fast release for vaginal drug delivery. Pellets were produced by extrusion/spheronization, and Carbopol(®) 934 was used to obtain bioadhesive properties. A 2(2)-factorial design with center point investigating the HAL content (1 and 10%, w/w) and Carbopol(®) 934 content (1 and 8%, w/w) was set up. The most suitable formulations were mechanically stable and showed bioadhesive properties toward vaginal tissue. The drug load was released within 20 min in phosphate buffer pH 4 and 6.8 in the in vitro dissolution test. The stability of HAL in the pellet formulations varied, but the most stable formulation showed 96-97% HAL remaining in the formulation after 6-7 weeks of storage at accelerated temperature conditions (40 °C). The investigated formulations seem promising for vaginal delivery of HAL.

Mollusk glue inspired mucoadhesives for biomedical applications

Chitosan (CH), partially N-deacetylated chitin, is a biodegradable and biocompatible polymer that has shown great potential in drug delivery and tissue engineering applications. Although bioadhesive, CH has limited mucoadhesion in wet conditions due to weak interactions with biological surfaces. DOPA (3,4-dihydroxy-L-phenylalanine), a catechol-containing molecule naturally present in marine mussel foot proteins, has been shown to increase the mucoadhesion of several polymers. We report here a simple and bioinspired approach to enhance CH mucoadhesion in wet conditions by preparing mixed hydrogels including CH and different catechol-containing compounds, namely DOPA, hydrocaffeic acid (HCA), and dopamine (DA). We characterized the hydrogels for their swelling, release kinetics of the catechol compounds, and mucoadhesive strength to rabbit small intestine. The swelling of the hydrogels was pH dependent with maximum swelling at pH 1. The hydrogel swelling was higher in the presence of the DOPA and DA but lower in the presence of HCA. HCA/CH hydrogel also showed the slowest catechol release, most likely due to electrostatic interactions between CH and HCA. Lower hydrogel swelling and slower HCA release resulted in increased mucoadhesion: HCA/CH showed more than 2-fold enhancement of mucoadhesion to rabbit small intestine compared to CH alone. Since it is known that catechol compounds can be oxidized, we analyzed the oxidation of DOPA, HCA, and DA at different pH values and its effect on mucoadhesion. We found that oxidation occurring before contact with the intestinal mucosa did not improve mucoadhesion, while oxidation occurring during the contact further increased the mucoadhesion of HCA/CH hydrogels. These results show that mucoadhesion of CH hydrogels can be increased with a simple bioinspired approach, which has the potential to be applied to other polymers since it does not require any chemical modification.