Studies and methodologies on vaginal drug permeation

Development and validation of a stability-indicating method, structural elucidation of new degradation products from misoprostol by LC-MS time-of-flight, and an ex vivo study of vaginal permeation

Misoprostol (MSP) is commonly prescribed in obstetrics and gynecology clinical practice for labor induction, cervical ripening, first-trimester pregnancy termination, and the treatment of postpartum hemorrhage. Furthermore, there is a lack of comprehensive discussion evaluating how different commercially available formulations influence the overall efficacy of MSP, even though reports indicate issues with the quality of these formulations, particularly regarding stability and vaginal absorption processes. This study investigates the stability of MSP under acidic conditions and its in vitro permeation using swine vaginal mucosa. A forced degradation study was conducted using 0.2 M HCl, and a high-efficiency LC method was developed. Three degradation products were identified and characterized using electrospray ionization-high-resolution quadrupole-time-of-flight-MS, with respective m/z values of 391.2508, 405.2705, and 387.2259, respectively. These results suggest that the degradation mechanism involves dehydration of the β-hydroxy ketone moiety, followed by isomerization to its most resonance-stable form and de-esterification. Finally, the in vitro permeation study revealed that the esterified form of MSP was unable to permeate the mucosa and required prior degradation for any component to be detected in the receptor fluid.

Development of biopolymer films loaded with fluconazole and thymol for resistant vaginal candidiasis

Vulvovaginal candidiasis (VVC) is an opportunistic infection caused by a fungus of the Candida genus, affecting approximately 75 % of women during their lifetime. Fungal resistance cases and adverse effects have been the main challenges of oral therapies. In this study, the topical application of thin films containing fluconazole (FLU) and thymol (THY) was proposed to overcome these problems. Vaginal films based only on chitosan (CH) or combining this biopolymer with pectin (PEC) or hydroxypropylmethylcellulose acetate succinate (HPMCAS) were developed by the solvent casting method. In addition to a higher swelling index, CH/HPMCAS films showed to be more plastic and flexible than systems prepared with CH/PEC or only chitosan. Biopolymers and FLU were found in an amorphous state, contributing to explaining the rapid gel formation after contact with vaginal fluid. High permeability rates of FLU were also found after its immobilization into thin films. The presence of THY in polymer films increased the distribution of FLU in vaginal tissues and resulted in improved anti-Candida activity. A significant activity against the resistant C. glabrata was achieved, reducing the required FLU dose by 50 %. These results suggest that the developed polymer films represent a promising alternative for the treatment of resistant vulvovaginal candidiasis, encouraging further studies in this context.

Imiquimod-Loaded Nanosystem for Treatment Human Papillomavirus-Induced Lesions

Human papillomavirus (HPV)-associated cervical cancer is the most common cancer among women worldwide. The treatment options are strongly related to increased infertility in women. Imiquimod (IQ) is an imidazoquinoline, which has proven antiviral effects against persistent HPV infection by activating immune cells via Toll-like receptors 7/8 when formulated in carriers, like nanogels, for topical use. An effective alternative to conventional therapies is the nanoparticle drug delivery system. We studied lipidic nanoparticles with IQ (Lipo IQ) and functionalized them with a DNA aptamer, AT11 (Lipo IQ AT11), to improve the selectivity for cervical cancer cells combined with the efficacy of essential oils. The formulations showed that the physicochemical properties are adequate for vaginal drug delivery and have antimicrobial activity at higher concentrations (with MIC50 starting from 0.625%). The final formulations exhibited cytotoxicity in cancer cells, enhanced by essential oils without affecting healthy cells, resulting in less than 10% cell viability in HeLa cells and over 60% in NHDF cells. Essential oils potentiate Lipo IQ's effectiveness, while AT11 increases the selectivity for cervical cancer cells. As suggested by the results of the permeation assay, the formulations were internalized by the cancer cells. Overall, the obtained results suggested that the synergistic effect of the essential oils and the nanosystem potentiate the cytotoxic effect of Lipo IQ and that Lipo IQ AT11 promotes selectivity towards cancer cells.

Vaginal irritation testing-prospects of human organotypic vaginal tissue culture models

Personal lubricants intended for local or systemic delivery via the vaginal route can induce vaginal irritation, damage the vaginal epithelial barrier which can enhance microbial entry, induce inflammation, and alter the microbiome of the vaginal ecosystem. Therefore, manufacturers of personal lubricants and medical devices are required to show biocompatibility and safety assessment data to support regulatory decision-making within a specified context of use. Furthermore, due to ethical concerns and the introduction of the 7th amendment of the European Council Directive which bans animal testing for cosmetic ingredients and products coupled with the Food and Drug Administration modernization Act 2.0 guidelines, there is a wave of drive to develop alternative test methods to predict human responses to chemical or formulation exposure. In this framework, there is a potential to use three-dimensional organotypic human vaginal-ectocervical tissue models as a screening tool to predict the vaginal irritation potential of personal lubricants and medicaments. To be physiologically relevant, the in vitro tissue models need to be reconstructed using primary epithelial cells of the specific organ or tissue and produce organ-like structure and functionality that recapitulate the in vivo-like responses. Through the years, progress has been made and vaginal tissue models are manufactured under controlled conditions with a specified performance criterion, which leads to a high level of reproducibility and reliability. The utility of vaginal tissue models has been accelerated in the last 20 years with an expanded portfolio of applications ranging from toxicity, inflammation, infection to drug safety, and efficacy studies. This article provides an overview of the state of the art of diversified applications of reconstructed vaginal tissue models and highlights their utility as a tool to predict vaginal irritation potential of feminine care products.

Development and verification of mechanistic vaginal absorption and metabolism model to predict systemic exposure after vaginal ring and gel application

AIMS

The current work describes the development of mechanistic vaginal absorption and metabolism model within Simcyp Simulator to predict systemic concentrations following vaginal application of ring and gel formulations.

METHODS

Vaginal and cervix physiology parameters were incorporated in the model development. The study highlights the model assumptions including simulation results comparing systemic concentrations of 5 different compounds, namely, dapivirine, tenofovir, lidocaine, ethinylestradiol and etonogestrel, administered as vaginal ring or gel. Due to lack of data, the vaginal absorption parameters were calculated based on assumptions or optimized. The model uses release rate/in vitro release profiles with formulation characteristics to predict drug mass transfer across vaginal tissue into the systemic circulation.

RESULTS

For lidocaine and tenofovir vaginal gel, the predicted to observed AUC0-t and Cmax ratios were well within 2-fold error limits. The average fold error (AFE) and absolute AFE indicating bias and precision of predictions range from 0.62 to 1.61. For dapivirine, the pharmacokinetic parameters are under and overpredicted in some studies due to lack of formulation composition details and relevance of release rate used in ring model. The predicted to observed AUC0-t and Cmax ratios were well within 2-fold error limits for etonogestrel and ethinylestradiol vaginal ring (AFEs and absolute AFEs from 0.84 to 1.83).

CONCLUSION

The current study provides first of its kind physiologically based pharmacokinetic framework integrating physiology, population and formulation data to carry out in silico mechanistic vaginal absorption studies, with the potential for virtual bioequivalence assessment in the future.

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.

Experimental design approach for development of carboplatin loaded chitosan modified liposomal formulation with improved topical vaginal therapeutic potential

One of the most prevalent cancers affecting women globally is cervical cancer. Cervical cancer is thought to cause 570 000 new cases annually, and standard treatments can have serious side effects. In this work, the main aim is to design, fabrication, and evaluation of carboplatin loaded chitosan coated liposomal formulation (CCLF-I) for vaginal delivery in the treatment of cervical cancer. The particle size and polydispersity index of the CCLF-1 were observed at 269.33 ± 1.15 and 0.40 ± 0.002 nm, respectively. The in vitro mucin binding studies showed good adhesiveness of CCLF-I as compared to plain liposomes (CPLF-I), which was found at 23.49 and 10.80%, respectively. The ex-vivo percent drug permeation from plain liposomal formulation (CPLF-I) was found to be higher in comparison to chitosan coated liposomal formulation which was 56.33% while in CCLF-I it was observed 47.32% this is due to, higher retainability of delivery system (CCLF-I) on targeted site attained by coating of mucoadhesive polymer on liposomes. Ex vivo tissue retention studies exhibited 24.2% of CCLF-I in comparison to 10.34% from plain drug formulation (CPLF-I). The in vivo vaginal retention studies exhibited 14% of drug retention after 24 h from the novel formulation in comparison to 6% from the plain formulation. The developed CCLF-I formulation would open a new avenue in the cervical treatment.

Nanomaterials Solutions for Contraception: Concerns, Advances, and Prospects

Preventing unintentional pregnancy is one of the goals of a global public health policy to minimize effects on individuals, families, and society. Various contraceptive formulations with high effectiveness and acceptance, including intrauterine devices, hormonal patches for females, and condoms and vasectomy for males, have been developed and adopted over the last decades. However, distinct breakthroughs of contraceptive techniques have not yet been achieved, while the associated long-term adverse effects are insurmountable, such as endocrine system disorder along with hormone administration, invasive ligation, and slowly restored fertility after removal of intrauterine devices. Spurred by developments of nanomaterials and bionanotechnologies, advanced contraceptives could be fulfilled via nanomaterial solutions with much safer and more controllable and effective approaches to meet various and specific needs for women and men at different reproductive stages. Nanomedicine techniques have been extended to develop contraceptive methods, such as the targeted drug delivery and controlled release of hormone using nanocarriers for females and physical stimulation assisted vasectomy using functional nanomaterials via photothermal treatment or magnetic hyperthermia for males. Nanomaterial solutions for advanced contraceptives offer significantly improved biosafety, noninvasive administration, and controllable reversibility. This review summarizes the nanomaterial solutions to female and male contraceptives including the working mechanisms, clinical concerns, and their merits and demerits. This work also reviewed the nanomaterials that have been adopted in contraceptive applications. In addition, we further discuss safety considerations and future perspectives of nanomaterials in nanostrategy development for next-generation contraceptives. We expect that nanomaterials would potentially replace conventional materials for contraception in the near future.

Thermo-Responsive Sol-Gel-Based Nano-Carriers Containing Terbinafine HCl: Formulation, In Vitro and Ex Vivo Characterization, and Antifungal Activity

The current research aims to create a sol-gel-based nanocarrier containing terbinafine formulated for transdermal delivery of the drug into the skin. Sol-gel-based nanocarriers were prepared via the cold method using poloxamer-188, poloxamer-407, and distilled water. The prepared formulation was examined for pH, gelation temperature, Fourier transform infrared spectrophotometer (FTIR) analysis, thermal stability analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM), particle size analysis, zeta potential, and anti-microbial activity. The in-vitro drug release study of F1 was found to be 94%, which showed greater drug release as compared to F2 and F3. The pH of the formulation was found to be within the range applicable to the skin. The gelation temperature was detected at 28 °C. The SEM images of formulations have spotted various particles well-segregated from each other. Analysis of formulations showed a mean globule size diameter of 428 nm, zeta potential values of 0.04 mV, refractive index (1.329), and viscosity (5.94 cP). FTIR analysis confirmed various functional groups' presence in the prepared formulation. Thermal analysis has confirmed the stability of the drug within the prepared formulation. The growth of inhibition was found to be 79.2% in 60 min, which revealed that the prepared formulation has shown good permeation from the membrane. Hence, the sol-gel-based nanocarrier formulation of terbinafine was successfully developed and evaluated.

Repurposing Disulfiram as an Antifungal Agent: Development of a New Disulfiram Vaginal Mucoadhesive Gel

Alternative formulations need to be developed to improve the efficacy of treatments administered via the vaginal route. Mucoadhesive gels with disulfiram, a molecule that was originally approved as an antialcoholism drug, offer an attractive alternative to treat vaginal candidiasis. The aim of the current study was to develop and optimize a mucoadhesive drug delivery system for the local administration of disulfiram. Such formulations were composed of polyethylene glycol and carrageenan to improve the mucoadhesive and mechanical properties and to prolong the residence time in the vaginal cavity. Microdilution susceptibility testing showed that these gels had antifungal activity against Candida albicans, Candida parapsilosis, and Nakaseomyces glabratus. The physicochemical properties of the gels were characterized, and the in vitro release and permeation profiles were investigated with vertical diffusion Franz cells. After quantification, it was determined that the amount of the drug retained in the pig vaginal epithelium was sufficient to treat candidiasis infection. Together, our findings suggest that mucoadhesive disulfiram gels have the potential to be an effective alternative treatment for vaginal candidiasis.

Encapsulation and release of hydrocortisone from proliposomes govern vaginal delivery

Topical preparations of hydrocortisone can be used for the anti-inflammatory treatment of the female genital area. Although the drug is a low-strength corticosteroid, systemic absorption and distribution of the drug are the most common safety risks associated with this therapy. In the current investigation, we elucidate the physicochemical properties of lipid-based drug carrier systems that govern the local bioavailability of hydrocortisone for intravaginal administration. For this purpose, we compared various proliposome formulations with a commercial cream. Depending on the availability of physiological acceptors, encapsulation and drug release from the lipid phase were found to be the most important drivers of drug bioavailability. The high permeability of hydrocortisone leads to rapid transport of the drug across the mucosal cell layer as indicated by experiments using HEC-1-A and CaSki cell monolayer models. Under sink conditions, differences in the release from the liposomes as determined in the Dispersion Releaser were almost negligible. However, under non-sink conditions, the drug release plateaued at levels corresponding to the encapsulation efficiency. After redispersion, all liposomal formulations performed better than the commercial drug product indicating that the encapsulation into the lipid phase is the main driver sustaining the release.

In Silico Guided Nanoformulation Strategy for Circumvention of Candida albicans Biofilm for Effective Therapy of Candidal Vulvovaginitis

Candidal vulvovaginitis involving multispecies of Candida and epithelium-bound biofilm poses a drug-resistant pharmacotherapeutic challenge. The present study aims for a disease-specific predominant causative organism resolution for the development of a tailored vaginal drug delivery system. The proposed work fabricates a luliconazole-loaded nanostructured lipid carrier-based transvaginal gel for combating Candida albicans biofilm and disease amelioration. The interaction and binding affinity of luliconazole against the proteins of C. albicans and biofilm were assessed using in silico tools. A systematic QbD analysis was followed to prepare the proposed nanogel using a modified melt emulsification-ultrasonication-gelling method. The DoE optimization was logically implemented to ascertain the effect of independent process variables (excipients concentration; sonication time) on dependent formulation responses (particle size; polydispersity index; entrapment efficiency). The optimized formulation was characterized for final product suitability. The surface morphology and dimensions were spherical and ≤300 nm, respectively. The flow behavior of an optimized nanogel (semisolid) was non-Newtonian similar to marketed preparation. The texture pattern of a nanogel was firm, consistent, and cohesive. The release kinetic model followed was Higuchi (nanogel) with a % cumulative drug release of 83.97 ± 0.69% in 48 h. The % cumulative drug permeated across a goat vaginal membrane was found to be 53.148 ± 0.62% in 8 h. The skin-safety profile was examined using a vaginal irritation model (in vivo) and histological assessments. The drug and proposed formulation(s) were checked against the pathogenic strains of C. albicans (vaginal clinical isolates) and in vitro established biofilms. The visualization of biofilms was done under a fluorescence microscope revealing mature, inhibited, and eradicated biofilm structures.

Advanced Solid Formulations For Vulvovaginal Candidiasis

Vulvovaginal candidiasis (VVC) is an opportunistic and endogenous infection caused by a fungus of the Candida genus, which can cause pruritus, dysuria, vulvar edema, fissures and maceration of the vulva. The treatment of vaginal candidiasis is carried out mainly by antifungal agents of azole and polyene classes; however, fungal resistance cases have been often observed. For this reason, new therapeutic agents such as essential oils, probiotics and antimicrobial peptides are being investigated, which can be combined with conventional drugs. Local administration of antimicrobials has also been considered to allow greater control of drug delivery and reduce or avoid undesirable systemic adverse effects. Conventional dosage forms such as creams and ointments result in reduced residence time in the mucosa and non-sustained and variable drug delivery. Therefore, advanced solid formulations such as intravaginal rings, vaginal films, sponges and nanofibers have been purposed. In these systems, polymers in different ratios are combined aiming to achieve a specific drug release profile and high mucoadhesion. Overall, a more porous matrix structure leads to a higher rate of drug release and mucoadhesion. The advantages, limitations and technological aspects of each dosage form are discussed in detail in this review.

A systematic review of mucoadhesive vaginal tablet testing

Drug administration through the vaginal tract is one of the oldest modalities of pharmacotherapy, and it is also one of the most explored. Since the vaginal cavity has a wide surface area, a plentiful blood supply, and a complex network of blood arteries, it can evade hepatic first-pass metabolism and obtain high local drug concentrations. Vaginal pills look to be a good dose form since they are simple to use, portable, and can easily deliver the required amount of medicine. Vaginal formulations, on the other hand, are vulnerable to rapid expulsion due to the vaginal tract’s self-cleaning action, which reduces the formulation’s efficiency. Currently, there is an increasing amount of focus on mucoadhesive vaginal formulation research and development to fix the formulation at the place where the medicine can be released and/or absorbed. This article examines all of the strategies used by researchers to develop a mucoadhesive vaginal tablet that is safe, effective, and comfortable for the user.

In vitro and ex vivo models for evaluating vaginal drug delivery systems

Vaginal drug delivery systems are often preferred for treating a variety of diseases and conditions of the female reproductive tract (FRT), as delivery can be more targeted with less systemic side effects. However, there are many anatomical and biological barriers to effective treatment via the vaginal route. Further, biocompatibility with the local tissue and microbial microenvironment is desired. A variety of in vitro and ex vivo models are described herein for evaluating the physicochemical properties and toxicity profile of vaginal drug delivery systems. Deciding whether to utilize organoids in vitro or fresh human cervicovaginal mucus ex vivo requires careful consideration of the intended use and the formulation characteristics. Optimally, in vitro and ex vivo experimentation will inform or predict in vivo performance, and examples are given that describe utilization of a range of methods from in vitro to in vivo. Lastly, we highlight more advanced model systems for other mucosa as inspiration for the future in model development for the FRT.

Effect of Dexamethasone and Route of Administration on Sow Farrowing Behaviours, Piglet Delivery and Litter Performance

The inflammatory pain and stress some crated sows experience during farrowing has attendant risks of piglet-directed aggression, reduced teat exposure and hindered post-partum recovery. To counter this, the steroidal anti-inflammatory compound, dexamethasone, can be administered. To measure the potential for mucosal absorption as an alternative to injection, the permeability of porcine vaginal mucosa to dexamethasone was demonstrated using Franz cell diffusion. These studies found dexamethasone treatment diffused through vaginal mucosa at a constant rate, with 52.37 ± 5.54% permeation in 6 h. To examine in vivo effects on farrowing outcomes, dexamethasone was administered to gilts and parity one sows on the day of expected farrowing. We hypothesized that it would provide relief from farrowing discomfort and reduce behaviours threatening piglet survival. Sows were randomly assigned to receive dexamethasone as an intramuscular injection (n = 23); dexamethasone applied topically into the vagina (n = 20), or to receive no dexamethasone (n = 23). Sows (n = 66) and piglets (n = 593) were monitored for performance indicators during farrowing and early lactation. A subset of sows (n = 24) was also video monitored continuously over 24 h for behaviours associated with pain, postural changes and piglet interactions. No differences were observed between treatment for farrowing performance, piglet survival or behavioural changes for sows experiencing their first or second farrowing (p > 0.05), rejecting the hypothesis that corticosteroid administration will improve sow farrowing performance. This investigation did, however, show that dexamethasone can permeate through porcine vaginal mucosa and so can be administered as a non-injectable treatment.

Application of Sol–Gels for Treatment of Gynaecological Conditions—Physiological Perspectives and Emerging Concepts in Intravaginal Drug Delivery

Approaches for effective and sustained drug delivery to the female reproductive tract (FRT) for treating a range of gynaecological conditions remain limited. The development of versatile delivery platforms, such as soluble gels (sol–gels) coupled with applicators/devices, holds considerable therapeutic potential for gynaecological conditions. Sol–gel systems, which undergo solution-to-gel transition, triggered by physiological conditions such as changes in temperature, pH, or ion composition, offer advantages of both solution- and gel-based drug formulations. Furthermore, they have potential to be used as a suitable drug delivery vehicle for other novel drug formulations, including micro- and nano-particulate systems, enabling the delivery of drug molecules of diverse physicochemical character. We provide an anatomical and physiological perspective of the significant challenges and opportunities in attaining optimal drug delivery to the upper and lower FRT. Discussion then focuses on attributes of sol–gels that can vastly improve the treatment of gynaecological conditions. The review concludes by showcasing recent advances in vaginal formulation design, and proposes novel formulation strategies enabling the infusion of a wide range of therapeutics into sol–gels, paving the way for patient-friendly treatment regimens for acute and chronic FRT-related conditions such as bacterial/viral infection control (e.g., STDs), contraception, hormone replacement therapy (HRT), infertility, and cancer.

Recent advances in electrospun nanofiber vaginal formulations for women's sexual and reproductive health

Electrospinning is an innovative technique that allows production of nanofibers and microfibers by applying a high voltage to polymer solutions of melts. The properties of these fibers - which include high surface area, high drug loading capacity, and ability to be manufactured from mucoadhesive polymers - may be particularly useful in a myriad of drug delivery and tissue engineering applications. The last decade has witnessed a surge of interest in the application of electrospinning technology for the fabrication of vaginal drug delivery systems for the treatment and prevention of diseases associated with women's sexual and reproductive health, including sexually transmitted infections (e.g. infection with human immunodeficiency virus and herpes simplex virus) vaginitis, preterm birth, contraception, multipurpose prevention technology strategies, cervicovaginal cancer, and general maintenance of vaginal health. Due to their excellent mechanical properties, electrospun scaffolds are also being investigated as next-generation materials in the surgical treatment of pelvic organ prolapse. In this article, we review the latest advances in the field.

Nanoaggregate-forming lipid-conjugated AS1411 aptamer as a promising tumor-targeted delivery system of anticancer agents in vitro

Nanoparticles offer targeted delivery of drugs with minimal toxicity to surrounding healthy tissue and have great potential in the management of human papillomavirus (HPV)-related diseases. We synthesized lipid-modified AS1411 aptamers capable of forming nanoaggregates in solution containing Mg²⁺. The nanoaggregates presented suitable properties for pharmaceutical applications such as small size (100 nm), negative charge, and drug release. The nanoaggregates were loaded with acridine orange derivative C₈ for its specific delivery into cervical cancer cell lines and HPV-positive tissue biopsies. This improved inhibition of HeLa proliferation and cell uptake without significantly affecting healthy cells. Finally, the nanoaggregates were incorporated in a gel formulation with promising tissue retention properties aiming at developing a local delivery strategy of the nanoaggregates in the female genital tract. Collectively, these findings suggest that the nanoformulation protocol has great potential for the delivery of both anticancer and antiviral agents, becoming a novel modality for cervical cancer management.

Emulsion-Based Multicompartment Vaginal Drug Carriers: From Nanoemulsions to Nanoemulgels

In order to overcome the limitations associated with vaginal administration of drugs, e.g., the short contact time of the drug form with the mucosa or continuous carrier wash-out, the development of new carriers for gynecological use is necessary. Furthermore, high individual anatomical and physiological variability resulting in unsatisfactory therapeutic efficacy of lipophilic active substances requires application of multicompartment drug delivery systems. This manuscript provides an up-to-date comprehensive review of the literature on emulsion-based vaginal dosage forms (EVDF) including macroemulsions, microemulsions, nanoemulsions, multiple emulsions and self-emulsifying drug delivery systems. The first part of the paper discusses (i) the influence of anatomical-physiological conditions on therapeutic efficacy of drug forms after local and systemic administration, (ii) characterization of EVDF components and the manufacturing techniques of these dosage forms and (iii) methods used to evaluate the physicochemical and pharmaceutical properties of emulsion-based vaginal dosage forms. The second part of the paper presents (iv) the results of biological and in vivo studies as well as (v) clinical evaluation of EVDF safety and therapeutic efficacy across different indications.

Recent Advances in Polymer-Based Vaginal Drug Delivery Systems

The vagina has been considered a potential drug administration route for centuries. Most of the currently marketed and investigated vaginal formulations are composed with the use of natural or synthetic polymers having different functions in the product. The vaginal route is usually investigated as an administration site for topically acting active ingredients; however, the anatomical and physiological features of the vagina make it suitable also for drug systemic absorption. In this review, the most important natural and synthetic polymers used in vaginal products are summarized and described, with special attention paid to the properties important in terms of vaginal application. Moreover, the current knowledge on the commonly applied and innovative dosage forms designed for vaginal administration was presented. The aim of this work was to highlight the most recent research directions and indicate challenges related to vaginal drug administrations. As revealed in the literature overview, intravaginal products still gain enormous scientific attention, and novel polymers and formulations are still explored. However, there are research areas that require more extensive studies in order to provide the safety of novel vaginal products.

p-Coumaric acid loaded into liquid crystalline systems as a novel strategy to the treatment of vulvovaginal candidiasis

Vulvovaginal candidiasis (VVC) is an extremely common type of vaginal infection, which is mainly caused by Candida albicans. However, non-albicans Candida species are frequently more resistant to conventional antifungal agents and can represent up to 30% of cases. Due to side effects and increasing antifungal resistance presented by standard therapies, phenolic compounds, such as p-coumaric acid (p-CA), have been studied as molecules from natural sources with potential antifungal activity. p-CA is a poorly water-soluble compound, thus loading it into liquid crystals (LCs) may increase its solubility and effectiveness on the vaginal mucosa. Thereby, here we propose the development of mucoadhesive liquid crystalline systems with controlled release of p-CA, for the local treatment of VVC. Developed LCs consisted of fixed oily and aqueous phases (oleic acid and cholesterol (5:1) and poloxamer dispersion 16%, respectively), changing only the surfactant phase components (triethanolamine oleate (TEA-Oleate) or triethanolamine (TEA), the latter producing TEA-Oleate molecules when mixed with oleic acid). Systems were also diluted in artificial vaginal mucus (1:1 ratio) to mimic the vaginal environment and verify possible structural changes on formulations upon exposure to the mucosa. From the characterization assays, p-CA loaded TEA-Oleate systems presented mucoadhesive profile, liquid crystalline mesophases, well-organized structures and pseudoplastic behaviour, which are desirable parameters for topical formulations. Moreover, they were able to control the release of p-CA throughout the 12 h assay, as well as decrease its permeation into the vaginal mucosa. p-CA showed antifungal activity in vitro against reference strains of C. albicans (SC5314), C. glabrata (ATCC 2001) and C. krusei (ATCC 6258), and exhibited higher eradication of mature biofilms than amphotericin B and fluconazole. In vivo experiments demonstrated that the formulations reduced the presence of filamentous forms in the vaginal lavages and provided an improvement in swelling and redness present in the mice vaginal regions. Altogether, here we demonstrated the potential and feasibility of using p-CA loaded liquid crystalline systems as a mucoadhesive drug delivery system for topical treatment of VVC.

Optimization of Coumarins Extraction from Pterocaulon balansae by Box-Behnken Design and Anti-Trichomonas vaginalis Activity

Trichomonas vaginalis causes trichomoniasis, a nonviral sexually transmitted infection with a high prevalence worldwide. Oral metronidazole is the drug of choice for the treatment of this disease, although high levels of T. vaginalis resistance to this agent are well documented in the literature. This study describes the anti-T. vaginalis activity of an optimized coumarin-rich extract from Pterocaulon balansae. Optimization was performed to maximize extraction of total coumarins by means of a 3-level Box-Behnken design, evaluating the effect of three factors: extraction time, plant : solvent ratio, and ethanol concentration. Optimum conditions were found to be 5 h extraction time and a plant : solvent ratio of 1% (w/v) and 60% (v/v) ethanol, which resulted in approximately 30 mg of total coumarins/g of dry plant. The coumarin-enriched extract exhibited a minimum inhibitory concentration of 30 µg/mL and an IC₅₀ of 3.2 µg/mL against T. vaginalis, a low cytotoxicity, and a high selectivity index (18 for vaginal epithelial cells and 16 for erythrocytes). The coumarins permeation/retention profile through porcine vaginal mucosa was evaluated in Franz-type diffusion cells. After 8 h of kinetics, coumarins were detected in the tissue (4.93 µg/g) without detecting them in the receptor compartment. A significant increase of coumarins in the mucosa layers (8.18 µg/g) and receptor compartment (0.26 µg/g) was detected when a T. vaginalis suspension (2 × 10⁵ trophozoites/mL) was previously added onto the mucosa. No alterations were visualized in the stratified squamous non-keratinized epithelium of the porcine vaginal mucosa after contact with the extract. Overall, these results suggest that the P. balansae coumarin-rich extract may have potential as a treatment for trichomoniasis.

Clotrimazole-loaded N-(2-hydroxy)-propyl-3-trimethylammonium, O-palmitoyl chitosan nanoparticles for topical treatment of vulvovaginal candidiasis

Vulvovaginal candidiasis (VVC) represents a considerable health burden for women. Despite the availability of a significant array of antifungal drugs and topical products, the management of the infection is not always effective, and new approaches are needed. Here, we explored cationic N-(2-hydroxy)-propyl-3-trimethylammonium, O-palmitoyl chitosan nanoparticles (NPs) as carriers of clotrimazole (CLT) for the topical treatment of VVC. CLT-NPs with approximately 280 nm in diameter were obtained by self-assembly in water and subsequent stabilization by ionic crosslinking with tripolyphosphate. The nanosystem featured pH-independent sustained drug release up to 24 h, which affected both in vitro anti-Candida activity and cytotoxicity. The CLT-loaded nanostructured platform yielded favorable selectivity index values for a panel of standard strains and clinical isolates of Candida spp. and female genital tract cell lines (HEC-1-A, Ca Ski and HeLa), as compared to the free drug. CLT-NPs also improved in vitro drug permeability across HEC-1-A and Ca Ski cell monolayers, thus suggesting that the nanocarrier may provide higher mucosal tissue levels of the active compound. Overall, data support that CLT-NPs may be a valuable asset for the topical treatment of VVC. STATEMENT OF SIGNIFICANCE: Topical azoles such as clotrimazole (CLT) are first line antifungal drugs for the management of vulvovaginal candidiasis (VVC), but their action may be limited by issues such as toxicity and poor capacity to penetrate the genital mucosa. Herein, we report on the ability of a new cationic N-(2‑hydroxy)-propyl-3-trimethylammonium, O-dipalmitoyl chitosan derivative (DPCat35) to yield tripolyphosphate-reinforced micelle-like nanostructures that are suitable carriers for CLT. In particular, these nanosystems were able to improve the in vitro selectivity index of the drug and to provide enhanced epithelial drug permeability when tested in cell monolayer models. These data support that CLT-loaded DPCat35 nanoparticles feature favorable properties for the development of new nanomedicines for the topical management of VVC.

In vivo study of hypericin-loaded poloxamer-based mucoadhesive in situ gelling liquid crystalline precursor system in a mice model of vulvovaginal candidiasis

The present study reports the performance of the pigment hypericin (HYP)-loaded poloxamer-based mucoadhesive in situ gelling liquid crystalline precursor system (LCPS) for the treatment of vulvovaginal candidiasis (VVC) in mice. LCPS composed of 40% of ethoxylated and propoxylated cetyl alcohol, 30% of oleic acid and cholesterol (7:1), 30% of a dispersion of 16% poloxamer 407 and 0.05% of HYP (HYP-LCPS) was prepared and characterized by polarized light microscopy (PLM), small-angle X-ray scattering (SAXS) and ex vivo permeation and retention studies across vaginal porcine mucosa were performed. In addition, the antifungal properties of the HYP-LCPS were evaluated in a murine in vivo model; for this, infected C57BL female mice groups were treated with both HYP in solution and HYP-LCPS, and after 6 days colony forming unit (CFU)/ml count was performed. PLM and SAXS confirmed that HYP-LCPS is a microemulsion situated in boundary transition region confirming its action as an LCPS. When in contact with simulated vaginal fluid, HYP-LCPS became rigid and exhibited maltase crosses and bragg peaks characteristics of lamellar phase. Ex vivo permeation and retention studies showed that HYP-LCPS provides a localized treatment on the superficial layers of porcine vaginal mucosa. HYP-LCPS induced a significant reduction in the number of CFU/ml in the mice; thus this formulation indicated it is as effective as a commercial dosage form. It was concluded that LCPS maintains the biological activity of HYP and provides an adequate drug delivery system for this lipophilic molecule at the vaginal mucosa, being a promising option in cases of VVC.

Investigating natural antibiofilm components: a new therapeutic perspective against candidal vulvovaginitis

The rampant emergence of Candida albicans in the vagina and its ability to thrive as a biofilm has outstood the prevalence of candidal vulvovaginitis (CVV), a gender-based fungal infection approximately affecting 75% of the global female population. The biofilm represents a multidimensional microbial population, which often dictates prominent caveats of CVV such as increased fungal virulence, drug resistance and infection relapse/recurrence. Additionally, the conjugated issues of the ineffectiveness of conventional antifungals (azoles), prolonged treatment durations, compromised patient compliance, economic and social burden, exacerbates CVV complications as well. Henceforth, the current hypothesis narrates an investigational proposal for exploration and combination of naturally derived antibiofilm components with luliconazole (imidazole antifungal agent) as a new therapeutic paradigm against CVV. The purported hypothesis unravels a synergistic approach for fabricating Nanostructured Lipid Carriers, NLCs loaded transvaginal gel with dual APIs of natural (antibiofilm) as well as the synthetic (antifungal) origin to target high therapeutic efficacy, delivery, retention, controlled release and bioadhesion in a vaginal milieu. The multipronged effect of antibiofilm and antifungal agents will expectably enhance drug susceptibility thus, maintaining Minimum Inhibitory Concentration (MIC) against cells of C. albicans and targeting its biofilm in planktonic, adherent, and sessile phases. The effective disruption of a biofilm could further lower infection resistance and recurrence as well. In conclusion, the purported hypothesis could speed up the emergence of novel drug combinations and accelerates new product development with solid, synergistic, and complementary activities against C. albicans and its biofilm, making it amenable for generating pre-clinical and clinical results therebycreating a suitableroadmap for commercialization.

Thermosensitive hydrogels for vaginal delivery of secnidazole as an approach to overcome the systemic side-effects of oral preparations

Secnidazole (SEC) has been suggested as an alternative agent against Trichomonas vaginalis to overcome the adverse effects, antimicrobial resistance problems and poor adherence to the currently available therapy. Once no topical formulation may be found in the market until now, SEC was incorporated in thermosensitive bioadhesive systems to extend the contact time in the mucosa and to avoid a systemic drug disposition. Formulations containing 20% poloxamer 407, 1% poloxamer 188 and 1 or 2.5% chitosan showed suitable sol-gel transition temperature (> 30 °C), presenting a fast gelation time (100-115 s). Rheological, dynamic light scattering and infrared spectroscopy analysis suggested molecular interactions among polymers. Chitosan increased the mucoadhesion strength of the formulations. In addition, hydrogels showed a tendency to decrease the drug transport rate through mucosa when compared to the control. Mucin was also added onto mucosa for a more realistic simulation of permeability/retention. In the presence of this agent, hydrogels containing chitosan reduced the permeability/retention of the drug in approximately 2.0-fold when compared to the control. Therefore, the hydrogels presented suitable characteristics to remain in the vaginal environment, which would result in effective local treatment of trichomoniasis.

Vaginal Administration of Contraceptives

While contraceptive drugs have enabled many people to decide when they want to have a baby, more than 100 million unintended pregnancies each year in the world may indicate the contraceptive requirement of many people has not been well addressed yet. The vagina is a well-established and practical route for the delivery of various pharmacological molecules, including contraceptives. This review aims to present an overview of different contraceptive methods focusing on the vaginal route of delivery for contraceptives, including current developments, discussing the potentials and limitations of the modern methods, designs, and how well each method performs for delivering the contraceptives and preventing pregnancy.

Human Intestinal Tissue Explant Exposure to Silver Nanoparticles Reveals Sex Dependent Alterations in Inflammatory Responses and Epithelial Cell Permeability

Consumer products manufactured with antimicrobial silver nanoparticles (AgNPs) may affect the gastrointestinal (GI) system. The human GI-tract is complex and there are physiological and anatomical differences between human and animal models that limit comparisons between species. Thus, assessment of AgNP toxicity on the human GI-tract may require tools that allow for the examination of subtle changes in inflammatory markers and indicators of epithelial perturbation. Fresh tissues were excised from the GI-tract of human male and female subjects to evaluate the effects of AgNPs on the GI-system. The purpose of this study was to perform an assessment on the ability of the ex vivo model to evaluate changes in levels of pro-/anti-inflammatory cytokines/chemokines and mRNA expression of intestinal permeability related genes induced by AgNPs in ileal tissues. The ex vivo model preserved the structural and biological functions of the in-situ organ. Analysis of cytokine expression data indicated that intestinal tissue of male and female subjects responded differently to AgNP treatment, with male samples showing significantly elevated Granulocyte-macrophage colony-stimulating factor (GM-CSF) after treatment with 10 nm and 20 nm AgNPs for 2 h and significantly elevated RANTES after treatment with 20 nm AgNPs for 24 h. In contrast, tissues of female showed no significant effects of AgNP treatment at 2 h and significantly decreased RANTES (20 nm), TNF-α (10 nm), and IFN-γ (10 nm) at 24 h. Smaller size AgNPs (10 nm) perturbed more permeability-related genes in samples of male subjects, than in samples from female subjects. In contrast, exposure to 20 nm AgNPs resulted in upregulation of a greater number of genes in female-derived samples (36 genes) than in male-derived samples (8 genes). The ex vivo tissue model can distinguish sex dependent effects of AgNP and could serve as a translational non-animal model to assess the impacts of xenobiotics on human intestinal mucosa.

FbD directed fabrication and investigation of luliconazole based SLN gel for the amelioration of candidal vulvovaginitis: a 2 T (thermosensitive & transvaginal) approach

Candidal vulvovaginitis (CVV), is the second most leading vaginal infection (global prevalence > 75%), caused due to excessive growth of Candida spp., predominantly Candida albicans (>95% cases). The current treatment regimens for CVV are marred with the challenges of fungal resistance & infection recurrence, subsequently leading to the compromised therapeutic efficacy of anti-fungal drugs, prolonged treatment and low patient compliance. The core of the present research was the fabrication & investigation of 2 T-SLN (solid lipid nanoparticles) gel carrying luliconazole for the amelioration of CVV. '2T' symbolizes transvaginal & thermosensitive attributes of the present formulation. SLNs were prepared by a modified melt emulsification-ultra sonication method using a combination of solid lipids (Gelucire 50/13 & Precirol ATO 5), surfactant (Tween 80) and co-surfactant (Kolliphor). Formulation by design (FbD) approach was adopted to obtain appropriately screened and tailored SLNs. The optimized SLNs yielded a particle size, polydispersity index & entrapment efficiency of 62.18 nm, 0.263 & 81.5% respectively. To formulate the 2 T-gel, the final SLNs were loaded into Carbopol 971P-NF and Triethanolamine based gel. The 2 T-SLN gel was found to be easily spreadable and homogenous with mean extrudability (15 ± 0.4 g/cm²), viscosity (696.42 ± 2.34 Pa·s) and %drug content (93.24 ± 0.73%) values.. The pH of the prepared 2 T-SLN gel (4.5 ± 0.5) was in concordance with the vaginal pH (normal conditions). For in-vitro characterization of an optimized 2 T-SLN gel the release kinetics & anticandidal activity were assessed which offers a %cumulative drug release of 62 ± 0.5% in 72 h and 37.3 ± 1.5 mm zone of inhibition in 48 h. The visual appearance & dimensions were determined using fluorescent microscopy (spherical shape) & transmission electron microscopy (90-120 nm) respectively. The optimized 2 T-SLN gel showcases a skin-friendly profile with no significant signs of erythema and oedema and was found to be stable at room temperature for 2 months without any visual non-uniformity/cracking/breaking. In conclusion, the current research serves a new therapeutic perspective in assessing the activity of luliconazole for vaginal drug delivery using a 2 T-SLN gel system.

Sedative effects and pharmacokinetics of detomidine when administered intravenously and intravaginally as a gel in alpacas

OBJECTIVES

To evaluate the sedative effects and pharmacokinetics of detomidine gel administered intravaginally to alpacas in comparison with intravenously (IV) administered detomidine.

STUDY DESIGN

Randomized, crossover, blinded experiment.

ANIMALS

A group of six healthy adult female Huacaya alpacas (70.3 ± 7.9 kg).

METHODS

Alpacas were studied on two occasions separated by ≥5 days. Treatments were IV detomidine hydrochloride (70 μg kg^-1; treatment DET-IV) or detomidine gel (200 μg kg^-1; treatment DET-VAG) administered intravaginally. Sedation and heart rate (HR) were evaluated at intervals for 240 minutes. Venous blood was collected at intervals for 360 minutes after treatment for analysis of detomidine, carboxydetomidine and hydroxydetomidine using liquid chromatography-tandem mass spectrometry. Measured variables were compared between treatments and over time using mixed model analysis. Data are presented as the mean ± standard error of the mean, and a p value of <0.05 was considered significant.

RESULTS

Onset of sedation was faster in treatment DET-IV (1.6 ± 0.2 minutes) than in treatment DET-VAG (13.0 ± 2.5 minutes). Time to maximum sedation was shorter in treatment DET-IV (8.3 ± 1.3 minutes) than in treatment DET-VAG (25 ± 4 minutes). Duration of sedation was not different between treatments. There was a significant linear relationship between sedation score and plasma detomidine concentration. HR was less than baseline for 60 and 125 minutes for treatments DET-IV and DET-VAG, respectively. The maximal decrease in HR occurred at 15 minutes for both treatments. The mean maximum plasma concentration of detomidine, time to maximum concentration and bioavailability for treatment DET-VAG were 39.6 ng mL^-1, 19.9 minutes and 20%, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

Detomidine administration at the doses studied resulted in moderate sedation when administered IV or intravaginally to alpacas.

Self-Emulsified Nanoemulsion for Vaginal Administration: In Vitro Study of Effect on Lactobacillus acidophilus

Self-emulsified nanoemulsions (SENs), one of the promising lipid-based drug delivery systems may be used to deliver drugs through vaginal route. Vaginal cavity remains healthy because of the defensive action by its microflora against the pathogenic infections, and any disturbance to this microflora by the delivery systems gives invitation to the infections. In the present study, the growth inhibition and cytotoxic effects of two SENs and their components on L. acidophilus were evaluated. The two SENs showed inhibitory effects on the growth of L. acidophilus in a concentration-dependent manner when tested at the concentration range of 0.1-5.0%. The SEN composed of medium chain mono/di-glyceride had greater inhibitory effect than the one composed of long chain monoglyceride. The study on the effect by the individual lipids with the surfactant Kolliphor® RH40 further confirmed that the growth inhibitory and cytotoxic effects were in the order of Capmul® MCM > Maisine® CC > Miglyol® 810 > Kolliphor® RH40. Both OD₆₀₀ and CFU counting were used to measure the viability of the culture. The results from the two methods were in good correlation except when there was no growth, suggesting OD₆₀₀ can be used when there is no complete growth inhibition.

Progesterone loaded thermosensitive hydrogel for vaginal application: Formulation and in vitro comparison with commercial product

Progesterone (PGT) is a natural hormone that stimulates and regulates various important functions, such as the preparation of the female body for conception and pregnancy. Due to its low water solubility, it is administered in a micronized form and/or in vehicles with specific solvents requirements. In order to improve the drug solubility, inclusion complexes of PGT and β-cyclodextrins were obtained by the freeze-drying method. Two β-cyclodextrins (native and methylated) in two solvents (water and water:ethanol) and different molar ratio of the reagents were the variables tested for the selection of the best condition for the preparation of the complexes. The PGT/randomly methylated-β-cyclodextrin complexes were incorporated into chitosan thermosensitive hydrogels, as an alternative formulation for the vaginal administration of PGT. Neither the micro and macroscopic characteristics of the gels nor the transition time from solution to gel were modified after the complexes incorporation. In addition, chitosan gels with complexes resisted better the degradation in simulated vaginal fluid in comparison to commercial gel (Crinone®). The chitosan gel with inclusion complexes and Crinone® were tested in vitro in a diffusion assay to evaluate the delivery of the hormone and its diffusion through porcine epithelial mucosa obtained from vaginal tissue. Chitosan gel presented sustained diffusion similar to the exhibited by commercial gel. The use of chitosan gels with inclusion complexes based on cyclodextrins would be a viable alternative for vaginal administration of PGT.

Evaluation of the sedative effects and pharmacokinetics of detomidine gel administered intravaginally to horses

OBJECTIVES

To determine the sedative effects and pharmacokinetic profile of detomidine when administered intravaginally as a gel formulation to horses.

STUDY DESIGN

Randomized, crossover, masked experimental design.

ANIMALS

A group of six healthy adult mares (494 ± 56 kg).

METHODS

Mares were studied on two occasions and were administered either detomidine hydrochloride (10 μg kg^-1) intravenously (treatment IV) or detomidine gel (40 μg kg^-1) intravaginally (treatment IVG), separated by 1 week. Sedation, ataxia, muzzle-floor distance and heart rate (HR) were evaluated every 15 minutes for 240 minutes. Venous blood samples were collected at 15, 30, 45, 60, 90, 120, 150, 180, 240, 300 and 360 minutes postadministration and were analyzed for detomidine and metabolites using liquid chromatography-tandem mass spectrometry. Measured variables were compared over time and between treatments using mixed model analysis. Correlation between drug plasma concentrations and muzzle-floor distance, and sedation and ataxia scores was determined using the Spearman correlation coefficient. Data are presented as mean ± standard error of the mean and p value was set at <0.05.

RESULTS

Sedation was shorter with IV (119 ± 16 minutes) than with IVG (188 ± 22 minutes). Ataxia scores remained greater than baseline for 90 and 135 minutes for treatments IV and IVG, respectively. HR was lower than baseline for 45 and 30 minutes for IV and IVG, respectively, but did not differ between treatments. The mean maximum plasma concentration of detomidine, time to maximum concentration and bioavailability for treatment IVG was 8.57 ng mL^-1, 0.37 hour and 25%, respectively. There was a significant correlation (r = 0.68) between plasma detomidine concentrations and sedation score.

CONCLUSIONS AND CLINICAL RELEVANCE

Detomidine gel administered intravaginally resulted in clinically important sedation and is a viable method for detomidine gel delivery in mares.

Solid Lipid Nanoparticles Based on L-Cysteine for Progesterone Intravaginal Delivery

The present work has as its purpose the synthesis and characterization of a novel lipid material to be used in the preparation of solid lipid nanoparticles (SLNs) for the potential sustained release of progesterone in the vagina. For this reason, a material capable of ensuring the permanence of the formulation in the administration site for the time needed to guarantee the transmucosal absorption of the steroid was synthetized in order to reduce the number of administrations and to ensure an effective concentration of drug at the site of action. To this end, an ester, 2,3-dihydroxypropanoate of octadecyl (stearyl glycerine), containing two hydroxyl groups was initially synthesized. In particular, the hydroxyl group less sterically encumbered was functionalized with a thiol group, in a coupling reaction, with the amino acid L-cysteine. The obtained compound was characterized by FT-IR spectrometry and 1H-NMR. The functionalized lipid with L-cysteine was then used for the preparation of solid lipid nanoparticles that were loaded with progesterone. Finally, the release of progesterone from the lipid matrix based on newly synthesized ester, under conditions that simulate the vaginal physiological environment, was evaluated. All the obtained results suggest that the prepared nanoparticles could be used for the administration of progesterone, when its integration is essential, for example, in cases of threats of abortion or to increase fertility.

Design, Characterization, and Biopharmaceutical Behavior of Nanoparticles Loaded with an HIV-1 Fusion Inhibitor Peptide

New therapeutic alternatives to fight against the spread of HIV-1 are based on peptides designed to inhibit the early steps of HIV-1 fusion in target cells. However, drawbacks, such as bioavailability, short half-life, rapid clearance, and poor ability to cross the physiological barriers, make such peptides unattractive for the pharmaceutical industry. Here we developed, optimized, and characterized polymeric nanoparticles (NPs) coated with glycol chitosan to incorporate and release an HIV-1 fusion inhibitor peptide (E1) inside the vaginal mucosa. The NPs were prepared by a modified double emulsion method, and optimization was carried out by a factorial design. In vitro, ex vivo, and in vivo studies were carried out to evaluate the optimized formulation. The results indicate that the physicochemical features of these NPs enable them to incorporate and release HIV fusion inhibitor peptides to the vaginal mucosa before the fusion step takes place.

The role of mucus in cell-based models used to screen mucosal drug delivery

The increasing interest in developing tools to predict drug absorption through mucosal surfaces is fostering the establishment of epithelial cell-based models. Cell-based in vitro techniques for drug permeability assessment are less laborious, cheaper and address the concerns of using laboratory animals. Simultaneously, in vitro barrier models that thoroughly simulate human epithelia or mucosae may provide useful data to speed up the entrance of new drugs and new drug products into the clinics. Nevertheless, standard cell-based in vitro models that intend to reproduce epithelial surfaces often discard the role of mucus in influencing drug permeation/absorption. Biomimetic models of mucosae in which mucus production has been considered may not be able to fully reproduce the amount and architecture of mucus, resulting in biased characterization of permeability/absorption. In these cases, artificial mucus may be used to supplement cell-based models but still proper identification and quantification are required. In this review, considerations regarding the relevance of mucus in the development of cell-based epithelial and mucosal models mimicking the gastro-intestinal tract, the cervico-vaginal tract and the respiratory tract, and the impact of mucus on the permeability mechanisms are addressed. From simple epithelial monolayers to more complex 3D structures, the impact of the presence of mucus for the extrapolation to the in vivo scenario is critically analyzed. Finally, an overview is provided on several techniques and methods to characterize the mucus layer over cell-based barriers, in order to intimately reproduce human mucosal layer and thereby, improve in vitro/in vivo correlation.

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.

Ultrasound gel as an unrecognized source of exposure to phthalates and phenols among pregnant women undergoing routine scan

BACKGROUND

Systemic absorption of phthalates and parabens has been demonstrated after dermal application of body lotion, and medical devices such as intravenous bags and tubing have been identified as a source of exposure to di(2-ethylhexyl) phthalate (DEHP). However, use of products during medical procedures such as aqueous gel applied during obstetrical ultrasound in pregnancy has not been investigated as a potential source of endocrine disrupting chemical (EDC) exposure. Human studies have associated EDCs with various adverse pregnancy outcomes. There is a need to identify sources of inadvertent exposure to EDCs especially during vulnerable developmental periods such as pregnancy.

OBJECTIVES

We conducted a pilot study to determine whether use of gel during routine obstetrical ultrasound increased urinary concentrations of phthalate and phenol biomarkers.

METHODS

We recruited 13 women from the Massachusetts General Hospital who provided spot urine samples at the time of their second trimester anatomic survey. The first sample was collected prior to the procedure (pre-exposure, time 1), and two additional samples were obtained at approximately 1-2h (time 2) and 7-12h (time 3) post-exposure following the scan.

RESULTS

Urinary concentrations of several DEHP metabolites and metabolite of diisononyl cyclohexane-1,2-dicarboxylate (DINCH) increased across time. For example, the geometric mean concentrations of mono(2-ethyl-5-hydroxyhexyl) phthalate increased from 3.1ng/ml to 7.1ng/ml (p-value=0.03) between time 1 and time 3. We also observed significant differences in concentrations of metabolites of butylbenzyl phthalate (BBzP), di-n-butyl phthalate (DnBP), and di-isobutyl phthalate (DiBP). For example, mono-n-butyl phthalate (metabolite of DnBP) decreased from 3.5ng/ml to 1.8ng/ml (p-value=0.04) between time 1 and time 2, but then increased to 6.6ng/ml (p-value=0.002) at time 3. Propylparaben concentrations increased from 8.9ng/ml to 33.6ng/ml between time 1 and time 2 (p-value=0.005), followed by a decrease to 12.9ng/ml at time 3 (p-value=0.01). However, we cannot rule out the possibility that some of the observed differences are due to other sources of exposure to these compounds.

CONCLUSIONS

While additional research is needed, this pilot study potentially identifies a previously unknown source of phthalate and paraben exposure among pregnant women undergoing routine ultrasound examination.

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.

Microbicide vaginal rings: Technological challenges and clinical development

Vaginal rings (VRs) are flexible, torus-shaped, polymeric devices designed to sustain delivery of pharmaceutical drugs to the vagina for clinical benefit. Following first report in a 1970 patent application, several steroid-releasing VR products have since been marketed for use in hormone replacement therapy and contraception. Since 2002, there has been growing interest in the use of VR technology for delivery of drugs that can reduce the risk of sexual acquisition of human immunodeficiency virus type 1 (HIV-1), the causative agent of acquired immunodeficiency syndrome (AIDS). Although no vaginally-administered product has yet been approved for HIV reduction/prevention, extensive research efforts are continuing and a number of VR devices offering sustained release of so-called 'HIV microbicide' compounds are currently being evaluated in late-stage clinical studies. This review article provides an overview of the published scientific literature within this important field of research, focusing primarily on articles published within peer-reviewed journal publications. Many important aspects of microbicide-releasing VR technology are discussed, with a particular emphasis on the technological, manufacturing and clinical challenges that have emerged in recent years.