Increased Dapivirine tissue accumulation through vaginal film codelivery of dapivirine and Tenofovir

Vaginal drug delivery system: A promising route of drug administration for local and systemic diseases

Scientists around the globe have done cutting-edge research to facilitate the delivery of poorly absorbed drugs via various routes of administration and different delivery systems. The vaginal route of administration has emerged as a promising mode of drug delivery, attributed to its anatomy and physiology. Novel drug delivery systems overcome the demerits of conventional systems via nanobiotechnology. This review will focus on the disorders associated with women that are currently targeted by vaginal drug delivery systems. In addition, it will provide insights into innovations in drug formulations for the general benefit of women.

Transport and Permeation Properties of Dapivirine: Understanding Potential Drug-Drug Interactions

The dapivirine (DPV) vaginal ring was developed by the nonprofit International Partnership for Microbicides (IPM) for reducing the risk of HIV infection. A clinical study (IPM 028) showed that concomitant use of the DPV ring and miconazole (MIC) altered DPV pharmacokinetic profile. In this work, we investigated whether or not DPV transport and permeation contributed to the observed DPV-MIC interaction. Our study evaluated the interaction between DPV and several transporters that are highly expressed in the human female reproductive tract, including MRP1, MRP4, P-gp, BCRP, and ENT1, using vesicular and cellular systems. We also evaluated the impact of DPV/MIC on cellular tight junctions by monitoring transepithelial electrical resistance with the Ussing chamber. Lastly, we evaluated the effect of MIC on DPV permeability across human cervical tissue. Our findings showed that DPV was not a substrate of MRP1, MRP4, P-gp, BCRP, or ENT1 transporters. Additionally, DPV did not inhibit the activity of these transporters. DPV, MIC, and their combination also did not disrupt cellular tight junctions. MIC did not affect DPV tissue permeability but significantly reduced DPV tissue levels. Therefore, our results suggest that the DPV-MIC interaction is not due to these five transporters, altered tight junction integrity, or altered tissue permeability.

Comprehensive Study of Antiretroviral Drug Permeability at the Cervicovaginal Mucosa via an In Vitro Model

Modulation of drug transporter activity at mucosal sites of HIV-1 transmission may be exploited to optimize retention of therapeutic antiretroviral drug concentrations at target submucosal CD4+ T cells. Previously, we showed that darunavir was a substrate for the P-glycoprotein efflux drug transporter in colorectal mucosa. Equivalent studies in the cervicovaginal epithelium have not been reported. Here, we describe the development of a physiologically relevant model to investigate the permeability of antiretroviral drugs across the vaginal epithelium. Barrier properties of the HEC-1A human endometrial epithelial cell line were determined, in a dual chamber model, by measurement of transepithelial electrical resistance, immunofluorescent staining of tight junctions and bi-directional paracellular permeability of mannitol. We then applied this model to investigate the permeability of tenofovir, darunavir and dapivirine. Efflux ratios indicated that the permeability of each drug was transporter-independent in this model. Reduction of pH to physiological levels in the apical compartment increased absorptive transfer of darunavir, an effect that was reversed by inhibition of MRP efflux transport via MK571. Thus, low pH may increase the transfer of darunavir across the epithelial barrier via increased MRP transporter activity. In a previous in vivo study in the macaque model, we demonstrated increased MRP2 expression following intravaginal stimulation with darunavir which may further increase drug uptake. Stimulation with inflammatory modulators had no effect on drug permeability across HEC-1A barrier epithelium but, in the VK2/E6E7 vaginal cell line, increased expression of both efflux and uptake drug transporters which may influence darunavir disposition.

Hexavalent sperm-binding IgG antibody released from vaginal film for development of potent on-demand nonhormonal female contraception

Nearly half of all pregnancies in the United States are unintended due to millions of women avoiding available hormonal contraceptive methods as a result of real and/or perceived side effects associated with the use of exogenous hormones. Topical vaginal delivery of antisperm monoclonal antibodies that could agglutinate sperm into clusters too large to penetrate mucus and prevent sperm from reaching the egg represents a potentially safe and potent mechanism for nonhormonal contraception. We report here the engineering of a vaginal film loaded with hexavalent (i.e., 6 Fab) antisperm IgG, made using GMP manufacturing processes, that possesses significantly superior agglutination potency than the parent IgG, enabling potent on-demand nonhormonal contraception via effectively agglutinating all human sperm within minutes.

Nonhormonal products for on-demand contraception are a global health technology gap; this unmet need motivated us to pursue the use of sperm-binding monoclonal antibodies to enable effective on-demand contraception. Here, using the cGMP-compliant Nicotiana-expression system, we produced an ultrapotent sperm-binding IgG antibody possessing 6 Fab arms per molecule that bind a well-established contraceptive antigen target, CD52g. We term this hexavalent antibody “Fab-IgG-Fab” (FIF). The Nicotiana-produced FIF had at least 10-fold greater sperm-agglutination potency and kinetics than the parent IgG, while preserving Fc-mediated trapping of individual spermatozoa in mucus. We formulated the Nicotiana-produced FIF into a polyvinyl alcohol–based water-soluble contraceptive film and evaluated its potency in reducing progressively motile sperm in the sheep vagina. Two minutes after vaginal instillation of human semen, no progressively motile sperm were recovered from the vaginas of sheep receiving FIF Film. Our work supports the potential of multivalent contraceptive antibodies to provide safe, effective, on-demand nonhormonal contraception.

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.

Lactoferrin nanoparticles coencapsulated with curcumin and tenofovir improve vaginal defense against HIV-1 infection

Aim: We report here the development of tenofovir- and curcumin-loaded lactoferrin nanoparticles (TCNPs) as an HIV-microbicide. Materials & methods: TCNPs were subjected to various physicochemical characterization experiments, followed by in vitro and in vivo experiments to assess their efficacy. Results: TCNPs had a diameter of 74.31 ± 2.56 nm with a gross encapsulation of more than 61% for each drug. Nanoparticles were effective against HIV-1 replication, with an IC₅₀ of 1.75 μM for curcumin and 2.8 μM for tenofovir. TCNPs provided drug release at the application site for up to 8-12 h, with minimal leakage into the systemic circulation. TCNPs showed spermicidal activity at ≥200 μM and induced minimal cytotoxicity and inflammation in the vaginal epithelium as revealed by histopathological and ELISA studies. Conclusion: We demonstrated that TCNPs could serve as a novel anti-HIV microbicidal agent in rats. [Formula: see text].

Mucoadhesive Vaginal Discs based on Cyclodextrin and Surfactants for the Controlled Release of Antiretroviral Drugs to Prevent the Sexual Transmission of HIV

The strategies for developing vaginal microbicides to protect women against human immunodeficiency virus (HIV) sexual transmission are constantly changing. Although the initial dosage forms required daily administration to offer effective protection, the trend then moved towards sustained-release dosage forms that require less frequency of administration in order to improve women's compliance with the treatment. Nevertheless, another possible strategy is to design on-demand products that can be used in a coitally-dependent manner and only need to be administered immediately before intercourse to offer protection. Vaginal discs based on freeze-dried hydroxypropylmethyl cellulose gels have been developed for this purpose, containing two surfactants, i.e., sodium dodecyl sulphate and polysorbate 60, alone or in combination with 2-hydroxypropyl-β-cyclodextrin, to achieve a formulation capable of incorporating both hydrophilic and lipophilic drugs. Several studies have been carried out to evaluate how the inclusion of these substances modifies the structure of gels (viscosity and consistency studies) and the porosimetry of the freeze-dried discs (scanning electron microscopy micrographs, mechanical properties, swelling behaviour). The drug release and mucoadhesive properties of the discs have also been evaluated with a view to their clinical application. The systems combining sodium dodecyl sulphate and 2-hydroxypropyl-β-cyclodextrin were found to be adequate for the vaginal administration of both Tenofovir and Dapivirine and also offer excellent mucoadhesion to vaginal tissue; these discs could therefore be an interesting option for a coitally-dependent administration to protect women against HIV transmission.

Rational Design of a Multipurpose Bioadhesive Vaginal Film for Co-Delivery of Dapivirine and Levonorgestrel

Human immunodeficiency virus (HIV) infection and unintended pregnancy, which can lead to life-threatening complications, are two major burdens for female reproductive health. To address these pressing health issues, multipurpose prevention technologies (MPTs) are proposed to deliver two or more drugs simultaneously. MPTs could offer several benefits for users such as improved convenience, increased effectiveness, reduced cost, and decreased environmental burden. Here, we report the development, and in vitro and in vivo assessment of a bioadhesive vaginal film as a coitally-independent MPT dosage form for delivering dapivirine (DPV) and levonorgestrel (LNG) to prevent HIV infection and unintended pregnancy, respectively. After confirming the feasibility of bioadhesive film use for weekly drug delivery in vivo through colpophotography and MRI evaluation, the pharmacokinetics (PK) of DPV/LNG single entity and combination bioadhesive films was investigated in pigtailed macaques (n = 5). Both drugs from single entity or combination films were able to provide sustained drug release in vivo. The combination film showed lower local tissue clearance for DPV and exhibited significantly increased plasma concentration for LNG as compared to the single entity film. This proof-of-concept study demonstrates the ability of this novel bioadhesive film platform to deliver LNG and DPV simultaneously as an MPT product for the prevention of HIV infection and unintended pregnancy.

Development of mucoadhesive vaginal films based on HPMC and zein as novel formulations to prevent sexual transmission of HIV

Although vaginal films were initially developed for a fast release of the drug, with the adequate formulation they can also be useful for sustained release. The latest strategies for the prevention of the sexual transmission of HIV have moved towards sustained-release dosage forms, so films may be an effective strategy that could also improve the patient's comfort. A hydrophilic polymer (hydroxypropylmethyl cellulose) and an amphiphilic polymer (zein) have been evaluated for the development of Tenofovir sustained-release vaginal films. The modification of the film's properties by the inclusion of polar (glycerol and polyethylene glycol 400 (PEG)) and amphiphilic (tributyl citrate and oleic acid) plasticisers was also evaluated. The films' physicochemical and mechanical properties were determined. The in vitro release of Tenofovir from the films and their bioadhesive capacity and behaviour in simulated vaginal fluid were also assessed. The combination of hydroxypropylmethyl cellulose and zein in films (ratio 1:5), with the inclusion of PEG (40% w/w) proved not only to have excellent mechanical properties, but was also able to release TFV in a sustained manner for 120 h and remain attached to biological tissues throughout this time. This film could be an interesting option for the prevention of sexual transmission of HIV.

Reverse Transcriptase Inhibitors Nanosystems Designed for Drug Stability and Controlled Delivery

An in-depth analysis of nanotechnology applications for the improvement of solubility, distribution, bioavailability and stability of reverse transcriptase inhibitors is reported. Current clinically used nucleoside and non-nucleoside agents, included in combination therapies, were examined in the present survey, as drugs belonging to these classes are the major component of highly active antiretroviral treatments. The inclusion of such agents into supramolecular vesicular systems, such as liposomes, niosomes and lipid solid NPs, overcomes several drawbacks related to the action of these drugs, including drug instability and unfavorable pharmacokinetics. Overall results reported in the literature show that the performances of these drugs could be significantly improved by inclusion into nanosystems.

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

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

User input in iterative design for prevention product development: leveraging interdisciplinary methods to optimize effectiveness

The development of HIV-preventive topical vaginal microbicides has been challenged by a lack of sufficient adherence in later stage clinical trials to confidently evaluate effectiveness. This dilemma has highlighted the need to integrate translational research earlier in the drug development process, essentially applying behavioral science to facilitate the advances of basic science with respect to the uptake and use of biomedical prevention technologies. In the last several years, there has been an increasing recognition that the user experience, specifically the sensory experience, as well as the role of meaning-making elicited by those sensations, may play a more substantive role than previously thought. Importantly, the role of the user-their sensory perceptions, their judgements of those experiences, and their willingness to use a product-is critical in product uptake and consistent use post-marketing, ultimately realizing gains in global public health. Specifically, a successful prevention product requires an efficacious drug, an efficient drug delivery system, and an effective user. We present an integrated iterative drug development and user experience evaluation method to illustrate how user-centered formulation design can be iterated from the early stages of preclinical development to leverage the user experience. Integrating the user and their product experiences into the formulation design process may help optimize both the efficiency of drug delivery and the effectiveness of the user.

On-demand microbicide products: design matters

Sexual intercourse (vaginal and anal) is the predominant mode of human immunodeficiency virus (HIV) transmission. Topical microbicides used in an on-demand format (i.e., immediately before or after sex) can be part of an effective tool kit utilized to prevent sexual transmission of HIV. The effectiveness of prevention products is positively correlated with adherence, which is likely to depend on user acceptability of the product. The development of an efficacious and acceptable product is therefore paramount for the success of an on-demand product. Acceptability of on-demand products (e.g., gels, films, and tablets) and their attributes is influenced by a multitude of user-specific factors that span behavioral, lifestyle, socio-economic, and cultural aspects. In addition, physicochemical properties of the drug, anatomical and physiological aspects of anorectal and vaginal compartments, issues relating to large-scale production, and cost can impact product development. These factors together with user preferences determine the design space of an effective, acceptable, and feasible on-demand product. In this review, we summarize the interacting factors that together determine product choice and its target product profile.

Full depth measurement of tenofovir transport in rectal mucosa using confocal Raman spectroscopy and optical coherence tomography

The prophylactic activity of antiretroviral drugs applied as microbicides against sexually transmitted HIV is dependent upon their concentrations in infectable host cells. Within mucosal sites of infection (e.g., vaginal and rectal mucosa), those cells exist primarily in the stromal layer of the tissue. Traditional pharmacokinetic studies of these drugs have been challenged by poor temporal and spatial specificity. Newer techniques to measure drug concentrations, involving Raman spectroscopy, have been limited by laser penetration depth into tissue. Utilizing confocal Raman spectroscopy (RS) in conjunction with optical coherence tomography (OCT), a new lateral imaging assay enabled concentration distributions to be imaged with spatial and temporal specificity throughout the full depth of a tissue specimen. The new methodology was applied in rectal tissue using a clinical rectal gel formulation of 1% tenofovir (TFV). Confocal RS revealed diffusion-like behavior of TFV through the tissue specimen, with significant partitioning of the drug at the interface between the stromal and adipose tissue layers. This has implications for drug delivery to infectable tissue sites. The new assay can be applied to rigorously analyze microbicide transport and delineate fundamental transport parameters of the drugs (released from a variety of delivery vehicles) throughout the mucosa, thus informing microbicide product design.

Nanoparticle-releasing nanofiber composites for enhanced in vivo vaginal retention

Current approaches for topical vaginal administration of nanoparticles result in poor retention and extensive leakage. To overcome these challenges, we developed a nanoparticle-releasing nanofiber delivery platform and evaluated its ability to improve nanoparticle retention in a murine model. We individually tailored two components of this drug delivery system for optimal interaction with mucus, designing (1) mucoadhesive fibers for better retention in the vaginal tract, and (2) PEGylated nanoparticles that diffuse quickly through mucus. We hypothesized that this novel dual-functioning (mucoadhesive/mucus-penetrating) composite material would provide enhanced retention of nanoparticles in the vaginal mucosa. Equivalent doses of fluorescent nanoparticles were vaginally administered to mice in either water (aqueous suspension) or fiber composites, and fluorescent content was quantified in cervicovaginal mucus and vaginal tissue at time points from 24 h to 7d. We also fabricated composite fibers containing etravirine-loaded nanoparticles and evaluated the pharmacokinetics over 7d. We found that our composite materials provided approximately 30-fold greater retention of nanoparticles in the reproductive tract at 24 h compared to aqueous suspensions. Compared to nanoparticles in aqueous suspension, the nanoparticles in fiber composites exhibited sustained and higher etravirine concentrations after 24 h and up to 7d, demonstrating the capabilities of this new delivery platform to sustain nanoparticle release out to 3d and drug retention out to one week after a single administration. This is the first report of nanoparticle-releasing fibers for vaginal drug delivery, as well as the first study of a single delivery system that combines two components uniquely engineered for complementary interactions with mucus.

Multipurpose tenofovir disoproxil fumarate electrospun fibers for the prevention of HIV-1 and HSV-2 infections in vitro

Sexually transmitted infections affect hundreds of millions of people worldwide. Both human immunodeficiency virus (HIV-1 and -2) and herpes simplex virus-2 (HSV-2) remain incurable, urging the development of new prevention strategies. While current prophylactic technologies are dependent on strict user adherence to achieve efficacy, there is a dearth of delivery vehicles that provide discreet and convenient administration, combined with prolonged-delivery of active agents. To address these needs, we created electrospun fibers (EFs) comprised of FDA-approved polymers, poly(lactic-co-glycolic acid) (PLGA) and poly(DL-lactide-co-ε-caprolactone) (PLCL), to provide sustained-release and in vitro protection against HIV-1 and HSV-2. PLGA and PLCL EFs, incorporating the antiretroviral, tenofovir disoproxil fumarate (TDF), exhibited sustained-release for up to 4 weeks, and provided complete in vitro protection against HSV-2 and HIV-1 for 24h and 1 wk, respectively, based on the doses tested. In vitro cell culture and EpiVaginal tissue tests confirmed the safety of fibers in vaginal and cervical cells, highlighting the potential of PLGA and PLCL EFs as multipurpose next-generation drug delivery vehicles.

Vaginal film for prevention of HIV: using visual and tactile evaluations among potential users to inform product design

Topical prevention of HIV and other STIs is a global health priority. To provide options for users, developers have worked to design safe, effective and acceptable vaginal dissolving film formulations. We aimed to characterize user experiences of vaginal film size, texture and color, and their role in product-elicited sensory perceptions (i.e. perceptibility), acceptability and willingness to use. In the context of a user-centered product evaluation study, we elicited users' 'first impressions' of various vaginal film formulation designs via visual and tactile prototype inspection during a qualitative user evaluation interview. Twenty-four women evaluated prototypes. Participants considered size and texture to be important for easy insertion. Color was more important following dissolution than prior to insertion. When asked to combine and balance all properties to arrive at an ideal film, previously stated priorities for individual characteristics sometimes shifted, with the salience of some individual characteristics lessening when multiple characteristics were weighted in combination. While first impressions alone may not drive product uptake, users' willingness to initially try a product is likely impacted by such impressions. Developers should consider potential users' experiences and preferences in vaginal film design. This user-focused approach is useful for characterizing user sensory perceptions and experiences relevant to early design of prevention technologies.

Historical development of vaginal microbicides to prevent sexual transmission of HIV in women: from past failures to future hopes

Infection with human immunodeficiency virus (HIV) remains a global public health concern and is particularly serious in low- and middle-income countries. Widespread sexual violence and poverty, among other factors, increase the risk of infection in women, while currently available prevention methods are outside the control of most. This has driven the study of vaginal microbicides to prevent sexual transmission of HIV from men to women in recent decades. The first microbicides evaluated were formulated as gels for daily use and contained different substances such as surfactants, acidifiers and monoclonal antibodies, which failed to demonstrate efficacy in clinical trials. A gel containing the reverse transcriptase inhibitor tenofovir showed protective efficacy in women. However, the lack of adherence by patients led to the search for dosage forms capable of releasing the active principle for longer periods, and hence to the emergence of the vaginal ring loaded with dapivirine, which requires a monthly application and is able to reduce the sexual transmission of HIV. The future of vaginal microbicides will feature the use of alternative dosage forms, nanosystems for drug release and probiotics, which have emerged as potential microbicides but are still in the early stages of development. Protecting women with vaginal microbicide formulations would, therefore, be a valuable tool for avoiding sexual transmission of HIV.

Preformulation and Vaginal Film Formulation Development of Microbicide Drug Candidate CSIC for HIV prevention

PURPOSE

5-chloro-3-[phenylsulfonyl] indole-2-carboxamide (CSIC) is a highly potent non-nucleoside reverse transcriptase inhibitor (NNRTI) of HIV-1 which has been shown to have a more desirable resistance profile than other NNRTIs in development as HIV prevention strategies. This work involves generation of preformulation data for CSIC and systematic development of a cosolvent system to effectively solubilize this hydrophobic drug candidate. This system was then applied to produce a polymeric thin film solid dosage form for vaginal administration of CSIC for use in prevention of sexual acquisition of HIV.

METHODS

Extensive preformulation, formulation development, and film characterization studies were conducted. An HPLC method was developed for CSIC quantification. Preformulation tests included solubility, crystal properties, stability, and drug-excipient compatibility. Cytotoxicity was evaluated using both human epithelial and mouse macrophage cell lines. Ternary phase diagram methodology was used to identify a cosolvent system for CSIC solubility enhancement. Following preformulation evaluation, a CSIC film formulation was developed and manufactured using solvent casting technique. The developed film product was assessed for physicochemical properties, anti-HIV bioactivity, and Lactobacillus biocompatibility during 12-month stability testing period.

RESULTS

Preformulation studies showed CSIC to be very stable. Due to its hydrophobicity, a cosolvent system consisting of polyethylene glycol 400, propylene glycol, and glycerin (5:2:1, w/w/w) was developed, which provided a uniform dispersion of CSIC in the film formulation. The final film product met target specifications established for vaginal microbicide application.

CONCLUSIONS

The hydrophobic drug candidate CSIC was successfully formulated with high loading capacity in a vaginal film by means of a cosolvent system. The developed cosolvent strategy is applicable for incorporation of other hydrophobic drug candidates in the film platform.

Influence of Chitosan Swelling Behaviour on Controlled Release of Tenofovir from Mucoadhesive Vaginal Systems for Prevention of Sexual Transmission of HIV

The main challenges facing efforts to prevent the transmission of human immunodeficiency virus (HIV) are the lack of access to sexual education services and sexual violence against young women and girls. Vaginal formulations for the prevention of sexually transmitted infections are currently gaining importance in drug development. Vaginal mucoadhesive tablets can be developed by including natural polymers that have good binding capacity with mucosal tissues, such as chitosan or guar gum, semisynthetic polymers such as hydroxypropylmethyl cellulose, or synthetic polymers such as Eudragit^® RS. This paper assesses the potential of chitosan for the development of sustained-release vaginal tablets of Tenofovir and compares it with different polymers. The parameters assessed were the permanence time of the bioadhesion—determined ex vivo using bovine vaginal mucosa as substrate—the drug release profiles from the formulation to the medium (simulated vaginal fluid), and swelling profiles in the same medium. Chitosan can be said to allow the manufacture of tablets that remain adhered to the vaginal mucosa and release the drug in a sustained way, with low toxicity and moderate swelling that ensures the comfort of the patient and may be useful for the prevention of sexual transmission of HIV.

Griffithsin-Modified Electrospun Fibers as a Delivery Scaffold To Prevent HIV Infection

Despite current prophylactic strategies, sexually transmitted infections (STIs) remain significant contributors to global health challenges, spurring the development of new multipurpose delivery technologies to protect individuals from and treat virus infections. However, there are few methods currently available to prevent and no method to date that cures human immunodeficiency virus (HIV) infection or combinations of STIs. While current oral and topical preexposure prophylaxes have protected against HIV infection, they have primarily relied on antiretrovirals (ARVs) to inhibit infection. Yet continued challenges with ARVs include user adherence to daily treatment regimens and the potential toxicity and antiviral resistance associated with chronic use. The integration of new biological agents may avert some of these adverse effects while also providing new mechanisms to prevent infection. Of the biologic-based antivirals, griffithsin (GRFT) has demonstrated potent inhibition of HIV-1 (and a multitude of other viruses) by adhering to and inactivating HIV-1 immediately upon contact. In parallel with the development of GRFT, electrospun fibers (EFs) have emerged as a promising platform for the delivery of agents active against HIV infection. In the study described here, our goal was to extend the mechanistic diversity of active agents and electrospun fibers by incorporating the biologic GRFT on the EF surface rather than within the EFs to inactivate HIV prior to cellular entry. We fabricated and characterized GRFT-modified EFs (GRFT-EFs) with different surface modification densities of GRFT and demonstrated their safety and efficacy against HIV-1 infection in vitro We believe that EFs are a unique platform that may be enhanced by incorporation of additional antiviral agents to prevent STIs via multiple mechanisms.

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.

Will dapivirine redeem the promises of anti-HIV microbicides? Overview of product design and clinical testing

Microbicides are being developed in order to prevent sexual transmission of HIV. Dapivirine, a non-nucleoside reverse transcriptase inhibitor, is one of the leading drug candidates in the field, currently being tested in various dosage forms, namely vaginal rings, gels, and films. In particular, a ring allowing sustained drug release for 1month is in an advanced stage of clinical testing. Two parallel phase III clinical trials are underway in sub-Saharan Africa and results are expected to be released in early 2016. This article overviews the development of dapivirine and its multiple products as potential microbicides, with particular emphasis being placed on clinical evaluation. Also, critical aspects regarding regulatory approval, manufacturing, distribution, and access are discussed.

Safety and Pharmacokinetics of Quick-Dissolving Polymeric Vaginal Films Delivering the Antiretroviral IQP-0528 for Preexposure Prophylaxis

For human immunodeficiency virus (HIV) prevention, microbicides or drugs delivered as quick-dissolving films may be more acceptable to women than gels because of their compact size, minimal waste, lack of an applicator, and easier storage and transport. This has the potential to improve adherence to promising products for preexposure prophylaxis. Vaginal films containing IQP-0528, a nonnucleoside reverse transcriptase inhibitor, were evaluated for their pharmacokinetics in pigtailed macaques. Polymeric films (22 by 44 by 0.1 mm; providing 75% of a human dose) containing IQP-0528 (1.5%, wt/wt) with and without poly(lactic-co-glycolic acid) (PLGA) nanoparticle encapsulation were inserted vaginally into pigtailed macaques in a crossover study design (n = 6). With unencapsulated drug, the median (range) vaginal fluid concentrations of IQP-0528 were 160.97 (2.73 to 2,104), 181.79 (1.86 to 15,800), and 484.50 (8.26 to 4,045) μg/ml at 1, 4, and 24 h after film application, respectively. Median vaginal tissue IQP-0528 concentrations at 24 h were 3.10 (0.03 to 222.58) μg/g. The values were similar at locations proximal, medial, and distal to the cervix. The IQP-0528 nanoparticle-formulated films delivered IQP-0528 in vaginal tissue and secretions at levels similar to those obtained with the unencapsulated formulation. A single application of either formulation did not disturb the vaginal microflora or the pH (7.24 ± 0.84 [mean ± standard deviation]). The high mucosal IQP-0528 levels delivered by both vaginal film formulations were between 1 and 5 log higher than the in vitro 90% inhibitory concentration (IC90) of 0.146 μg/ml. The excellent coverage and high mucosal levels of IQP-0528, well above the IC90, suggest that the films may be protective and warrant further evaluation in a vaginal repeated low dose simian-human immunodeficiency virus (SHIV) transmission study in macaques and clinically in women.

Drug transporters in tissues and cells relevant to sexual transmission of HIV: Implications for drug delivery

Efflux and uptake transporters of drugs are key regulators of the pharmacokinetics of many antiretroviral drugs. A growing body of literature has revealed the expression and functionality of multiple transporters in female genital tract (FGT), colorectal tissue, and immune cells. Drug transporters could play a significant role in the efficacy of preventative strategies for HIV-1 acquisition. Pre-exposure prophylaxis (PrEP) is a promising strategy, which utilizes topically (vaginally or rectally), orally or other systemically administered antiretroviral drugs to prevent the sexual transmission of HIV to receptive partners. The drug concentration in the receptive mucosal tissues and target immune cells for HIV is critical for PrEP effectiveness. Hence, there is an emerging interest in utilizing transporter information to explain tissue disposition patterns of PrEP drugs, to interpret inter-individual variability in PrEP drug pharmacokinetics and effectiveness, and to improve tissue drug exposure through modulation of the cervicovaginal, colorectal, or immune cell transporters. In this review, the existing literature on transporter expression, functionality and regulation in the transmission-related tissues and cells is summarized. In addition, the relevance of transporter function for drug delivery and strategies that could exploit transporters for increased drug concentration at target locales is discussed. The overall goal is to facilitate an understanding of drug transporters for PrEP optimization.

Drug delivery strategies and systems for HIV/AIDS pre-exposure prophylaxis and treatment

The year 2016 will mark an important milestone - the 35th anniversary of the first reported cases of HIV/AIDS. Antiretroviral Therapy (ART) including Highly Active Antiretroviral Therapy (HAART) drug regimens is widely considered to be one of the greatest achievements in therapeutic drug research having transformed HIV infection into a chronically managed disease. Unfortunately, the lack of widespread preventive measures and the inability to eradicate HIV from infected cells highlight the significant challenges remaining today. Moving forward there are at least three high priority goals for anti-HIV drug delivery (DD) research: (1) to prevent new HIV infections from occurring, (2) to facilitate a functional cure, i.e., when HIV is present but the body controls it without drugs and (3) to eradicate established infection. Pre-exposure Prophylaxis (PrEP) represents a significant step forward in preventing the establishment of chronic HIV infection. However, the ultimate success of PrEP will depend on achieving sustained antiretroviral (ARV) tissue concentrations and will require strict patient adherence to the regimen. While first generation long acting/extended release (LA/ER) DD Systems (DDS) currently in development show considerable promise, significant DD treatment and prevention challenges persist. First, there is a critical need to improve cell specificity through targeting in order to selectively achieve efficacious drug concentrations in HIV reservoir sites to control/eradicate HIV as well as mitigate systemic side effects. In addition, approaches for reducing cellular efflux and metabolism of ARV drugs to prolong effective concentrations in target cells need to be developed. Finally, given the current understanding of HIV pathogenesis, next generation anti-HIV DDS need to address selective DD to the gut mucosa and lymph nodes. The current review focuses on the DDS technologies, critical challenges, opportunities, strategies, and approaches by which novel delivery systems will help iterate towards prevention, functional cure and eventually the eradication of HIV infection.

Development and characterization of a solid dispersion film for the vaginal application of the anti-HIV microbicide UAMC01398

The purpose of this work was to design and evaluate a vaginal film delivery system for UAMC01398, a novel non-nucleoside reverse transcriptase inhibitor currently under investigation for use as an anti-HIV microbicide. UAMC01398 (1mg) films consisting of hydroxypropylmethylcellulose (HPMC) and polyethylene glycol 400 (PEG400) in different ratios were prepared by solvent evaporation. Based on its flexibility, softness and translucent appearance, the 30% PEG400 and 70% HPMC containing film was selected for further assessment. The vaginal film formulation was fast-dissolving (<10 min in 1 mL of vaginal fluid simulant), stable up to at least one month and safe toward epithelial cells and lactobacilli. Furthermore, formulating UAMC01398 into the film dosage form did not influence its antiviral activity. Powder X-ray diffraction revealed the amorphous nature of the UAMC01398 film, resulting in enhanced compound permeation across the epithelial HEC-1A cell layer, presumably owing to the induction of supersaturation. The in vivo vaginal tissue uptake of UAMC01398 in rabbits, as measured by systemic concentrations, was increased compared to the previously established non-solubilizing gel (significant difference) and sulfobutyl ether-β-cyclodextrin (5%) containing gel. To conclude, we identified a film formulation suitable for the vaginal delivery of UAMC01398.