Vaginal Microbicide Products Research Articles

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. 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.

P3.364 Does Tenofovir Gel - or Do Other Vaginal Microbicide Products - Affect Detection of Biomarkers of Semen Exposure?

BackgroundProstate Specific Antigen (PSA) and Y chromosome are used as biomarkers of semen exposure. There is currently no information on whether vaginal products evaluated in microbicide trials, in particular, tenofovir...

Intravaginal practices and microbicide acceptability in Papua New Guinea: implications for HIV prevention in a moderate-prevalence setting

BackgroundThe acceptability of female-controlled biomedical prevention technologies has not been established in Papua New Guinea, the only country in the Pacific region experiencing a generalised, moderate-prevalence HIV epidemic. Socio-cultural factors likely to impact on future product uptake and effectiveness, such as women’s ability to negotiate safer sexual choices, and intravaginal hygiene and menstrual practices (IVP), remain unclear in this setting.MethodsA mixed-method qualitative study was conducted among women and men attending a sexual health clinic in Port Moresby. During in-depth interviews, participants used copies of a hand-drawn template to indicate how they wash/clean the vulva and/or vagina. Interviewers pre-filled commercially available vaginal applicators with 2-3mL KY Jelly® to create a surrogate vaginal microbicide product, which was demonstrated to study participants.ResultsA total of 28 IDIs were conducted (women=16; men=12). A diverse range of IVP were reported. The majority of women described washing the vulva only with soap and water as part of their daily routine; in preparation for sex; and following sexual intercourse. Several women described cleaning inside the vagina using fingers and soap at these same times. Others reported cleaning inside the vagina using a hose connected to a tap; using vaginal inserts, such as crushed garlic; customary menstrual ‘steaming’ practices; and the use of material fragments, cloth and newspaper to absorb menstrual blood. Unprotected sex during menstruation was common. The majority of both women and men said that they would use a vaginal microbicide gel for HIV/STI protection, should a safe and effective product become available. Microbicide use was considered most appropriate in ‘high-risk’ situations, such as sex with non-regular, transactional or commercial partners. Most women felt confident that they would be able to negotiate vaginal microbicide use with male sexual partners but if necessary would be prepared to use product covertly.ConclusionsNotional acceptability of a vaginal microbicide gel for HIV/STI prevention was high among both women and men. IVP were diverse in nature, socio-cultural dimensions and motivators. These factors are likely to impact on the future acceptability and uptake of vaginal microbicides and other biomedical HIV prevention technologies in this setting.

Assessment of a Microbicide Candidate among a Diverse Cohort of Urban Southern US Women and their Male Sexual Partners

This mixed methods study reports on product acceptance from a Phase I clinical trial of a candidate non-nucleoside reverse transcriptase inhibitor (NNRTI) vaginal microbicide product (UC781). The product was evaluated in the context of a Phase I clinical trial in an area characterized by high HIV prevalence among minority women. The findings will inform the development of an acceptable microbicide that will address the needs of diverse women and their partners. This is a mixed methods study of 34 racially and ethnically diverse female participants and 10 male partners in Atlanta, Georgia. Chi-square tests for marginal homogeneity and kappa statistics were calculated to analyze differences between groups on product attributes and use intention. ANOVA was used to examine difference between the treatment groups. Qualitative data were analyzed via constant comparative methodology. Thirty-four out of the original female cohort of 36 completed the questionnaire. Approval of future microbicide development was high at 91.2% (n=31) despite a lack of enthusiasm for the placebo and UC781 formulations. Overall female acceptability was correlated with personal protection motivation (r=1.00, p<0.001). African American women indicated greater likelihood of post-licensure microbicide use (X2(3)=7.9, p=0.048) and ascribed greater importance to its potential protection against HIV (X2(4)=18.7, p=0.001) and its potential for dual protection (protective against STIs and/or pregnancy) compared to white women (X2(4)=11.3, p=0.024). Men and women supported development in the form of an intravaginal ring or suppository. Men were more likely to encourage female adoption of the method if it afforded HIV protection (r=0.935, p=0.001). Although most women agreed that the development of a microbicide was an important endeavor, quantitative and qualitative data indicated they would not use placebo or UC781 due to the objectionable viscosity, odor, and color. Male partners felt the potential protective benefit of a future microbicide product was its most important feature.

Development of a liposome microbicide formulation for vaginal delivery of octylglycerol for HIV prevention

The feasibility of using a liposome drug delivery system to formulate octylglycerol (OG) as a vaginal microbicide product was explored. A liposome formulation was developed containing 1% OG and phosphatidyl choline in a ratio that demonstrated in vitro activity against Neisseria gonorrhoeae, HSV-1, HSV-2 and HIV-1 while sparing the innate vaginal flora, Lactobacillus. Two conventional gel formulations were prepared for comparison. The OG liposome formulation with the appropriate OG/lipid ratio and dosing level had greater efficacy than either conventional gel formulation and maintained this efficacy for at least 2 months. No toxicity was observed for the liposome formulation in ex vivo testing in a human ectocervical tissue model or in vivo testing in the macaque safety model. Furthermore, minimal toxicity was observed to lactobacilli in vitro or in vivo safety testing. The OG liposome formulation offers a promising microbicide product with efficacy against HSV, HIV and N. gonorrhoeae.

A thermodynamic study of the cyclodextrin-UC781 inclusion complex using a HPLC method.

UC781, a very potent HIV-1 non-nucleoside reverse transcriptase inhibitor with extreme hydrophobicity and poor water solubility, is under development as a topical vaginal microbicide product to prevent HIV transmission. In this study, the thermodynamic behavior of the interaction between UC781 with three cyclodextrins (CDs): β-cyclodextrin (βCD), hydroxypropyl-β-cyclodextrin (HPβCD) and methyl-β-cyclodextrin (MβCD), was investigated using a reversed-phase HPLC method. A mobile phase consisting of acetonitrile: H2O (30:70) solution containing various CD concentrations was used. The retention time at different temperatures was determined to evaluate the inclusion process. The influence of βCDs on the solubility and hydrophobicity of UC781 was characterized by retention time values. The results showed that the inclusion capacity of cyclodextrins follows the order MβCD > βCD > HPβCD. An enthalpy-entropy compensation effect was also observed. In addition, the results revealed that the change of ΔH is greater than that of ΔS. These results suggested that the complexation of UC781 with βCDs is an enthalpy driven process. The modification on β-cyclodextrin will influence the inclusion process.

Using modeling to help understand vaginal microbicide functionality and create better products

A summary is presented of a range of mathematical models that relate to topical microbicidal molecules, applied vaginally to inhibit HIV transmission. These models contribute to the fundamental understanding of the functioning of those molecules, as introduced in different delivery systems. They also provide computational tools that can be employed in the practical design and evaluation of vaginal microbicide products. Mathematical modeling can be implemented, using stochastic principles, to understand the probability of infection by sexually transmitted HIV virions. This provides a frame of reference for the deterministic models of the various processes that underlie HIV transmission and its inhibition, including: the temporal and spatial history of HIV migration from semen to vaginal epithelial surfaces and thence to the underlying stroma; the time and spatial distribution of microbicidal drugs as delivered by various vehicles (e.g., gels, rings, films, and tablets)-this is central to understanding microbicide product pharmacokinetics; and the time and space history of the drug interactions with HIV directly and with host cells for HIV within the vaginal environment-this informs the understanding of microbicide pharmacodynamics. Models that characterize microbicide functionality and performance should and can interface with both in vitro and in vivo experimental studies. They can serve as a rapidly applied, inexpensive tool, to facilitate microbicide R&D, in advance of more costly and time consuming clinical trials.

Formulation Development of Retrocyclin 1 Analog RC-101 as an Anti-HIV Vaginal Microbicide Product

RC-101 is a synthetic microbicide analog of retrocyclin, which has shown in vitro activity against X4 and R5 HIV-1. In an effort to develop a safe and effective RC-101 vaginal microbicide product, we assessed safety in ex vivo macaque and human models and efficacy using in vitro and ex vivo models. A polyvinyl-alcohol vaginal film containing RC-101 (100 μg/film) was developed. Formulation assessment was conducted by evaluating disintegration, drug content, mechanical properties, and stability. Efficacy was evaluated by in vitro peripheral blood mononuclear cells (PBMC) assay and ex vivo human ectocervical tissue explant model. Ex vivo safety studies were conducted by exposing RC-101 to an excised monkey reproductive tract and excised human ectocervical tissue. RC-101 100 μg films were shown to be safe to human and monkey tissue and effective against HIV-1 in vitro and ex vivo in human ectocervical tissue. The 90% inhibitory concentration (IC90) for RC-101 films at 2,000 μg (IC90=57.5 μM) using an ex vivo model was 10-fold higher than the IC90 observed using an in vitro model (IC90=5.0 μM). RC-101 films were stable for 1 month at 25°C, with in vitro bioactivity maintained for up to 6 months. RC-101 was developed in a quick-dissolve film formulation that was shown to be safe in an ex vivo model and effective in in vitro and ex vivo models. RC-101 film formulations were shown to maintain bioactivity for a period of 6 months. Findings from the present study contribute to the development of a safe and effective topical microbicide product.

Effects of Physiological Fluids on Physical-Chemical Characteristics and Activity of Topical Vaginal Microbicide Products

The increased incidence of HIV infection in women has identified a need to develop a female controlled method to prevent sexually transmitted infections (STIs), including HIV. Formulations have been developed in our laboratory for two potential microbicide drug substances, 3-O-octyl-sn-glycerol (3-OG) and UC-781. A major concern for microbicide product development is dilution by vaginal fluids following application thereby reducing antimicrobial activity. We investigated the effect of product dilution on microbicidal activity and the product's chemical and physical properties by using vaginal fluid (VFS) and cervical mucus simulants (CMS). 3-OG and UC-781 were individually formulated into three semi-solid drug containing products: Hydroxyethylcellulose, Methylcellulose/Carbopol, and Liposome. Viscosity, osmolality, pH and in vitro activity against HIV-1 were evaluated. Results showed that pH was not affected when products were diluted with VFS; however, increases in pH were observed following CMS dilution. Viscosity was significantly decreased for all the dilutions tested excepted for some of the liposome products. Hydrogel products maintained greater activity against HIV-1 than Liposome products. The effect of dilution on anti-HIV activity varied based upon excipient choice and chemical characteristics of the active agent. These in vitro assessments can identify the potential for changes in product's physical-chemical characteristics in vivo which may result in diminished product performance.

Mucosal Irritation Potential of Personal Lubricants Relates to Product Osmolality as Detected by the Slug Mucosal Irritation Assay

The slug mucosal irritation assay has recently been used as a sensitive measure of mucus membrane tolerance for vaginal microbicide products and carriers. In the current study, it was determined whether musosal irritation potency of personal lubricants is related to varying product osmolalities. Five commercial lubricants with an osmolality range were evaluated using the previously validated slug mucosal irritation assay. Specifically, Arion lusitanicus were treated with lubricants over 5 days to quantify mucus production and tissue damage, allowing assignment of each product into an irritation potency category (none, mild, moderate, or severe). The irritation potency (assessed by the mucus production) of the lubricants showed a significant, quadratic relationship with the product osmolality (P = 0.001; R (2) = 0.99). Femglide, a hypo-osmotic lubricant (32 mOsm/kg), caused a negative mucus production. Pré, an iso-osmotic lubricant (316 mOsm/kg), caused no changes. Two moderately hyperosmotic lubricants, Replens and K-Y jelly (2143 and 2463 mOsm/kg), induced mild and moderate irritation, respectively. The highly hyperosmotic lubricant Astroglide (5848 mOsm/kg) resulted in severe irritation and tissue damage. Commonly used personal lubricants show a full range of mucosal irritation potential, which is related to product osmolality.

Vaginal microbicides for the prevention of HIV/AIDS: assessment of the potential market

This project, initiated and supervised by the European Commission’s AIDS programme for developing countries, has explored the potential demand for a vaginal microbicide product amongst women in the reproductive age group. The research was conducted in 11 European and developing countries chosen to be broadly representative of the total market area. One of the stated objectives of the project was to stimulate interest on the part of large pharmaceutical manufacturers. The study was designed and executed as a commercial new product development exercise rather than an academic or social study. The project has been structured around a market research study focused primarily on a representative sample of women in the age range 16–45 in the main urban centres of each country and on the healthcare professionals who might be expected to advise them. The findings reveal a very high level of interest in such a product. That interest, driven by personal concern, translates into a strong likelihood of purchase — even among women with very low levels of disposable income and even at price levels twice that of a condom. Calculations of theoretical demand based upon the results of the survey, although undoubtedly in excess of those which would be commercially achievable in practice, are extremely encouraging and justify proceeding to the next stage of the new product development process. They also support the case for increased public-private partnership in microbicide development.