Vaginal rings for delivery of HIV microbicides

Polymer Delivery Systems for Long-Acting Antiretroviral Drugs

The success of long-acting (LA) drug delivery systems (DDSs) is linked to their biocompatible polymers. These are used for extended therapeutic release. For treatment or prevention of human immune deficiency virus type one (HIV-1) infection, LA DDSs hold promise for improved regimen adherence and reduced toxicities. Current examples include Cabenuva, Apretude, and Sunlenca. Each is safe and effective. Alternative promising DDSs include implants, prodrugs, vaginal rings, and microarray patches. Each can further meet patients' needs. We posit that the physicochemical properties of the formulation chemical design can optimize drug release profiles. We posit that the strategic design of LA DDS polymers will further improve controlled drug release to simplify dosing schedules and improve regimen adherence.

Disulfiram 3D printed film produced via hot-melt extrusion techniques as a potential anticervical cancer candidate

Cervical cancer is known globally as one of the most common health problems in women. Indeed, one of the most convenient approaches for its treatment is an appropriate bioadhesive vaginal film. This approach provides a local treatment modality, which inevitably decreases dosing frequency and improves patient compliance. Recently, disulfiram (DSF) has been investigated and demonstrated to possess anticervical cancer activity; therefore, it is employed in this work. The current study aimed to produce a novel, personalized three-dimensional (3D) printed DSF extended-release film using the hot-melt extrusion (HME) and 3D printing technologies. The optimization of the formulation composition and the HME and 3D printing processing temperatures was an important factor for overcoming the DSF heat-sensitivity issue. In addition, the 3D printing speed was specifically the most crucial parameter for alleviating heat-sensitivity concerns, which led to the production of films (F1 and F2) with an acceptable DSF content and good mechanical properties. The bioadhesion film study using sheep cervical tissue indicated a reasonable adhesive peak force (N) of 0.24 ± 0.08 for F1 and 0.40 ± 0.09 for F2, while the work of adhesion (N.mm) for F1 and F2 was 0.28 ± 0.14 and 0.54 ± 0.14, respectively. Moreover, the cumulative in vitro release data indicated that the printed films released DSF for up to 24 h. HME-coupled 3D printing successfully produced a patient-centric and personalized DSF extended-release vaginal film with a reduced dose and longer dosing interval.

Manufacturing and Examination of Vaginal Drug Delivery System by FDM 3D Printing

Vaginal drug delivery systems can provide a long-term and constant liberation of the active pharmaceutical ingredient even for months. For our experiment, FDM 3D printing was used to manufacture the vaginal ring samples from thermoplastic polyurethane filament, which enables fast manufacturing of complex, personalized medications. 3D printing can be an excellent alternative instead of industrial manufacturing, which is complicated and time-consuming. In our work, the 3D printed vaginal rings were filled manually with jellified metronidazole or chloramphenicol for the treatment of bacterial vaginosis. The need for manual filling was certified by the thermogravimetric and heatflow assay results. The manufactured samples were analyzed by an Erweka USP type II Dissolution Apparatus, and the dissolution profile can be distinguished based on the applied jellifying agents and the API's. All samples were considered non-similar based on the pairwise comparison. The biocompatibility properties were determined by prolonged MTT assay on HeLa cells, and the polymer could be considered non-toxic. Based on the microbiological assay on E. coli metronidazole and chitosan containing samples had bactericidal effects while just metronidazole or just chitosan containing samples bacteriostatic effect. None of these samples showed a fungistatic or fungicide effect against C. albicans. Based on our results, we successfully manufactured 3D printed vaginal rings filled with jellified metronidazole.

Women-specific routes of administration for drugs: A critical overview

The woman's body presents a number of unique anatomical features that can constitute valuable routes for the administration of drugs, either for local or systemic action. These are associated with genitalia (vaginal, endocervical, intrauterine, intrafallopian and intraovarian routes), changes occurring during pregnancy (extra-amniotic, intra-amniotic and intraplacental routes) and the female breast (breast intraductal route). While the vaginal administration of drug products is common, other routes have limited clinical application and are fairly unknown even for scientists involved in drug delivery science. Understanding the possibilities and limitations of women-specific routes is of key importance for the development of new preventative, diagnostic and therapeutic strategies that will ultimately contribute to the advancement of women's health. This article provides an overview on women-specific routes for the administration of drugs, focusing on aspects such as biological features pertaining to drug delivery, relevance in current clinical practice, available drug dosage forms/delivery systems and administration techniques, as well as recent trends in the field.

Development of Hormonal Intravaginal Rings: Technology and Challenges

Intravaginal rings (IVRs) are minimally invasive polymeric devices specifically designed to be used for the sustained and prolonged release of various type of drugs such as hormones. One of the benefits of using topical drug delivery systems (e.g., IVRs) is the fact that systemic drug delivery may cause drug resistance due to elevated drug levels. Topical drug delivery also provides higher concentrations of the drug to the target site and has fewer side effects. In addition, when a drug is administered vaginally, the hepatic first-pass effect is avoided, resulting in higher absorption. Contraception and treatments for specific diseases such as endometriosis and hormone deficiencies can be improved by the administration of hormones via an IVR. This article aims to classify and compare various designs of commercially available and non-commercial hormonal IVRs and to analyze their performance. Current challenges affecting the development of IVRs are investigated, and proposed solutions are discussed. A comprehensive search of publications in MEDLINE/PubMed and of commercial product data of IVRs was performed, and the materials, designs, performance, and applications (e.g., contraception, endometriosis, estrogen deficiency and urogenital atrophy) of hormonal IVRs were thoroughly evaluated. Most hormonal IVRs administer female sex hormones, i.e., estrogen and progestogens. In terms of material, IVRs are divided into 3 main groups: silicone, polyurethane, and polyethylene-co-vinyl acetate IVRs. As regards their design, there are 4 major designs for IVRs which strongly affect their performance and the timing and rate of hormone release. Important challenges include reducing the burst release and maintaining the bioavailability of hormones at their site of action over a prolonged period of administration as well as lowering production costs. Hormonal IVRs are a promising method which could be used to facilitate combination therapies by administering multiple drugs in a single IVR while eliminating the side effects of conventional drug administration methods. IVRs could considerably improve womenʼs quality of life all over the world within a short period of time.

Use of simulated vaginal and menstrual fluids to model in vivo discolouration of silicone elastomer vaginal rings

Vaginal rings releasing antiretrovirals – either alone or in combination with contraceptive progestins – are being developed for prevention of human immunodeficiency virus (HIV) transmission via vaginal sex. Following Phase I trials, significant discolouration was observed on the surface of investigational silicone elastomer antiretroviral-contraceptive matrix-type vaginal rings containing either 25 mg dapivirine or 200 mg dapivirine plus levonorgestrel. In this study, potential causes of the discolouration have been assessed in vitro using simulated vaginal and menstrual fluids (SVF and SMF, respectively) to model in vivo exposure. The fluid compositions also included hydrogen peroxide (H₂O₂), hydrogen peroxide plus a copper intrauterine device (IUD), or synthetic dyes (representing personal care and household cleaning products). No discolouration was observed for rings exposed to SVF + hydrogen peroxide (with or without an IUD). However, the SVF + dye compositions showed significant ring discolouration, with staining patterns similar to those observed with rings that had been exposed to highly-coloured personal care and household cleaning products during clinical trial use. Exposure of rings to SMF compositions invariably caused yellow surface discolouration, dark spotting and markings, similar to the staining patterns observed following clinical use. The darker marks on the ring surface were identified as blood debris derived from the SMF. The study indicates that surface discolouration of rings in vivo can be attributed to exposure to menstrual fluid or highly coloured personal care or household cleaning products. Discolouration of the rings was not associated with any specific safety risks for the user, though severe discolouration could potentially impact acceptability and adherence.

Colloidal Nanocarriers as Versatile Targeted Delivery Systems for Cervical Cancer

BACKGROUND

The second most common malignant cancer of the uterus is cervical cancer, which is present worldwide, has a rising death rate and is predominant in developing countries. Different classes of anticancer agents are used to treat cervical carcinoma. The use of these agents results in severe untoward side-effects, toxicity, and multidrug resistance (MDR) with higher chances of recurrence and spread beyond the pelvic region. Moreover, the resulting clinical outcome remains very poor even after surgical procedures and treatment with conventional chemotherapy. Because of the nonspecificity of their use, the agents wipe out both cancerous and normal tissues. Colloidal nano dispersions have now been focusing on site-specific delivery for cervical cancer, and there has been much advancement.

METHODS

This review aims to highlight the problems in the current treatment of cervical cancer and explore the potential of colloidal nanocarriers for selective delivery of anticancer drugs using available literature.

RESULTS

In this study, we surveyed the role and potential of different colloidal nanocarriers in cervical cancer, such as nanoemulsion, nanodispersions, polymeric nanoparticles, and metallic nanoparticles and photothermal and photodynamic therapy. We found significant advancement in colloidal nanocarrier-based cervical cancer treatment.

CONCLUSION

Cervical cancer-targeted treatment with colloidal nanocarriers would hopefully result in minimal toxic side effects, reduced dosage frequency, and lower MDR incidence and enhance the patient survival rates. The future direction of the study should be focused more on the regulatory barrier of nanocarriers based on clinical outcomes for cervical cancer targeting with cost-effective analysis.

Long-acting approaches for delivery of antiretroviral drugs for prevention and treatment of HIV: a review of recent research

INTRODUCTION

Despite significant advances in treatment and prevention of HIV-1 infection, poor adherence to daily combination antiretroviral therapy (ART) regimens remains a major obstacle toward achieving sustained viral suppression and prevention. Adherence to ART could also be compromised by adverse drug reactions and societal factors that limit access to therapy. Therefore, medicines that aim to improve adherence by limiting ART side effects, frequency of dosing and socially acceptable regimens are becoming more attractive.

AREAS COVERED

This review highlights recent advances and challenges in the development of long-acting drug delivery strategies for HIV prevention and treatment. Approaches for extended oral and transdermal deliveries, microbicides, broadly neutralizing antibodies, and long-acting implantable and injectable deliveries are reviewed.

EXPERT OPINION

Emerging approaches on long-acting antiretroviral therapies and broadly neutralizing antibody technologies are currently at various stages of development. Such efforts, if successful and become broadly accepted by clinicians and users, will provide newer and simpler options for prevention and treatment of HIV infection.

Matrix Vaginal Rings for Female Dogs-Effect of Altering Dimensions on Mechanical Properties and Dissolution Characteristics, and In vivo Safety Study

The vaginal rings research is almost exclusively focused on rings for human medicine, although the dosage form offers improvement of therapeutic effect in other mammals as well. This contribution studied an effect of varying dimension parameters (diameter 20, 30 or 40 mm; height 3, 4 or 5 mm; width of annulus 5, 7.5 or 10 mm) on mechanical properties and dissolution behaviour of silicone vaginal rings with constant drug amount, intended for use in dogs. Results showed that altering dimensions influenced mechanical properties (compressive force, tensile strength and resistance of removal thread), in vitro drug release and water uptake. The removal thread resistance was increasing with increasing height and width. Compression force was higher for the rings with smaller diameter. The total drug release was increasing with decreasing height and rising diameter, surface area and water uptake during dissolution test. The initial dissolution rate was slower for the rings with higher width. As the best candidate for use in model dog subjects, the ring with 30 mm diameter, 3 mm height and 7.5 mm width was found. These drug-free vaginal rings were further tested in in vivo safety study. The results did not show any major deviation from the physiological conditions. Graphical abstract.

Montmorillonite-based polyacrylamide hydrogel rings for controlled vaginal drug delivery

Vaginal drug delivery is regarded as a promising route against women-related health issues such as unwanted pregnancies and sexually transmitted infections. However, only a very few studies have been reported on the use of hydrogel rings with low cytotoxicity for vaginal drug delivery applications. Moreover, the effect of nanoparticles on hydrogel vaginal rings has not been clearly evaluated. To overcome these challenges, we hereby developed nanocomposite hydrogel rings based on polyacrylamide-sodium carboxymethyl cellulose-montmorillonite nanoparticles in the ring-shaped aluminum mold for controlled drug delivery. The hydrogel rings were synthesized by using N,N'-methylene bisacrylamide, N,N,N',N'-tetramethyl ethylene diamine, and ammonium persulfate, as a crosslinker, accelerator, and initiator, respectively. The obtained rings were 5.5 cm in diameters and 0.5 cm in rims. Chemical structures of the nanocomposite rings were confirmed by Fourier transform infrared, and Nuclear Magnetic Resonance spectroscopies. Additionally, the swelling ratio of hydrogels was appeared to be adjusted by the introduction of nanoparticles. In vitro release experiment of methylene blue, as a hydrophilic model drug, revealed that the nanocomposite rings could not only reduce burst effect (almost more than twice), but also achieve prolonged release for 15 days in the vaginal fluid simulant which mimic the vaginal conditions at pH of almost 4.2, and a temperature of 37 °C. Importantly, the resultant hydrogel rings with or without various concentrations of montmorillonite showed low cytotoxicity toward human skin fibroblasts. Furthermore, different antibacterial activities against Escherichia coli were observed for various concentrations of montmorillonite in hydrogels. These results suggest the great potential of montmorillonite-based hydrogel rings for vaginal drug delivery.

In vitro release testing methods for drug-releasing vaginal rings

Drug-releasing vaginal rings are torus-shaped devices, generally fabricated from thermoplastic polymers or silicone elastomers, used to administer pharmaceutical drugs to the human vagina for periods typically ranging from three weeks to twelve months. One of the most important product performance tests for vaginal rings is the in vitro release test. Although it has been fifty years since a vaginal ring device was first described in the scientific literature, and despite seven drug-releasing vaginal rings having been approved for market, there is no universally accepted method for testing in vitro drug release, and only one non-compendial shaking incubator method (for the estradiol-releasing ring Estring®) is described in the US Food and Drug Administration's Dissolution Methods Database. Here, for the first time, we critically review the diverse range of test methods that have been described in the scientific literature for testing in vitro release of drug-releasing vaginal rings. Issues around in vitro-in vivo correlation and modelling of in vitro release data are also discussed.

The development of a silicone vaginal ring with a prostaglandin analogue for potential use in the treatment of canine reproductive disorders

In veterinary medicine, vaginal rings (VRs) are rarely used. However, there are diseases of female dogs' reproductive system which represent a suitable possibility for their usage. An example of such a disease is canine pyometra which can be treated by lipophilic prostaglandin drugs, unfortunately with harmful side effects after systemic administration. The aim of the study was to prove that the matrix VR based on silicone and channel-forming substance can be successfully used as a carrier for a three-day delivery of prostaglandin E₂ (PGE₂). Based on an in-vitro release study, an optimum channel-forming substance and its concentration were selected. The results were implemented during the construction of VR from the medical grade silicone DDU-4840 with PGE₂ (5 mg). Glucose anhydrous in the 30% concentration was chosen as the most functional channel-forming substance due to synergism of osmotic activity and solubility. The DDU-VR containing PGE₂ and 30% of glucose anhydrous exhibited excellent mechanical characteristics and ensured 29% drug release through water-filled channels in first-order kinetic manner. This is eight times higher than a sample without glucose where molecular diffusion through the silicone matrix was dominating the release mechanism. Moreover, drug-free VRs were tested for mechanical resistance and the design of removal thread.

Advances in contraceptive vaginal rings: what does the future hold?

INTRODUCTION

Contraceptive vaginal rings (CVRs) are good contraceptive options because they do not require skilled providers, are self-administered, and show a higher stability of drug diffusion.

AREAS COVERED

This article provides a review of the developments made with CVRs over the past number of years, while giving focus to the latest CVRs that have gone through clinical development. The author of the article also provides an expert perspective on the future of these useful therapeutic options.

EXPERT OPINION

Pharmacokinetic studies have shown that segesterone, an absorbable progestin that is used alone or in combination with ethinyl estradiol (EE) or E_2, is the CVR of choice at this present time. Indeed, segesterone has demonstrated safety and efficacy as a CVR and is also an appropriate option for lactating women, as they are not absorbed orally. However, good cycle control is important for improved CVR adherence. CVRs that allow the combination of more than one drug may unravel another multi-purpose use when combined with microbicides and could provide combined protection to women who wish to protect themselves from pregnancy and sexually transmitted infection.

Impact of ring size and drug loading on the pharmacokinetics of a combination dapivirine-darunavir vaginal ring in cynomolgus macaques

This work investigates the impact of vaginal ring size and drug loading on the in vitro release, safety, ease of fit, and pharmacokinetics in cynomolgus macaques of matrix-type silicone elastomer vaginal rings containing a combination of the non-nucleoside reverse transcriptase inhibitor dapivirine and the protease inhibitor darunavir. Drug-free and drug-loaded vaginal rings having three different geometries were manufactured by reaction injection molding. In vitro drug release was assessed using both a solvent/water mixture and a vaginal fluid simulant. Macaques fitted with drug-free vaginal rings for 28 days were assessed by colposcopy, cytological evaluation of cervico-vaginal lavage and histological evaluation of tissue after ring removal. The 20 × 4.5 mm combination ring, deemed most appropriate for vaginal fit and comfort in the macaques, was evaluated for pharmacokinetics over 28 days. Substantial differences were observed in the in vitro release profiles between the three ring sizes. However, these differences were not manifest in vivo, where measured drug concentrations after 20 × 4.5 mm ring use were not significantly different from those reported previously with a 25 × 6 mm ring. These results suggest that ring placement and fit is an important species-specific study parameter that should be optimised prior to pharmacokinetic testing.

Solid state 13C NMR spectroscopy provides direct evidence for reaction between ethinyl estradiol and a silicone elastomer vaginal ring drug delivery system

Steroid molecules have a long history of incorporation into silicone elastomer materials for controlled release drug delivery applications. Previously, based on in vitro release testing and drug content analysis, we demonstrated indirectly that the contraceptive progestin levonorgestrel (LNG) chemically and irreversibly binds to addition cure silicone elastomers, presumably via a hydrosilylation reaction between the levonorgestrel ethynyl group and the hydrosilane groups in the poly(dimethylsiloxane-co-methylhydrosiloxane) crosslinker of the silicone elastomer. Here, for the first time, we report that solid state ¹³C nuclear magnetic resonance (NMR) spectroscopy provides direct evidence for the irreversible binding of ethinyl estradiol (EE) - an estrogenic steroid molecule also containing an ethynyl functional group - to an addition cure silicone elastomer. By preparing silicone elastomer samples containing ¹³C-labelled EE, signals in the NMR spectra could readily be assigned to both the free and bound EE. Additional depolymerisation studies, performed on an addition cure silicone elastomer system from which the unbound EE fraction was completely extracted, further confirmed the presence of bound EE through the formation of coloured reaction mixtures resulting from the reaction of bound EE and trifluoroacetic acid (TFA). These methods will be particularly useful in the ongoing development of new steroid-releasing silicone drug delivery devices, including various vaginal ring devices for contraception, HIV prevention and multipurpose prevention technology applications.

Vaginal drug delivery for the localised treatment of cervical cancer

Cervical cancer is usually treated by surgery, with the more advanced cancers requiring adjuvant chemotherapy or radiotherapy. The location of the cervix makes it easily accessible through the vagina for the localised delivery of chemotherapeutic drugs. Localised delivery has the advantage of direct delivery to the site of action resulting in a lower dose having to be required and a reduction in systemic side effects. This approach would be advantageous for fertility sparing surgery, whereby localised delivery could be used to reduce tumour size allowing for a much smaller tumour to be removed, reducing the risk of preterm birth. Furthermore, localised delivery could be used after surgery to reduce the risk of recurrence, which is significantly higher in fertility sparing surgery compared to standard surgery. In this paper, we discuss the number of vaginal dosage forms that have investigated for this purpose, including tablets, rings, bioadhesive and cervical caps. APIs under investigation have ranged from well-established chemotherapeutic drugs to more experimental compounds.

Sexual behavior experiences and characteristics of male-female partnerships among HIV positive adolescent girls and young women: Qualitative findings from Zimbabwe

Background

New HIV infections among sub-Saharan Africa's adolescent girls and young women (AGYW, ages 15–24) greatly exceed those of their male peers. In addition, AGYW tend to acquire HIV at a much earlier age. Understanding the factors associated with HIV infection in AGYW could inform effective prevention and treatment interventions for these populations and their male sexual partners.

Methods

This qualitative study, conducted October-November 2016, was a follow on to a quantitative survey that sought to characterize male sexual partners and sexual behaviors of sexually active HIV positive AGYW in Zimbabwe. The qualitative study explored sexual behavior experiences and characteristics of male-female partnerships among the same participants. We conducted in-depth interviews with purposively sampled AGYW (16–24 years). Audio recorded qualitative data were transcribed, translated into English, and thematically coded using NVivo.

Results

28 AGYW (n = 14 urban, n = 14 rural) took part in the in-depth interviews. 50% were 16–19 years old. Discussions with 10/11 (91%) AGYW who were reportedly infected through sex suggested that they had acquired HIV from their husbands or romantic partners. Accounts also suggested that the age difference between respondents and their male sexual partners was ≥5 years. Overall, respondents described two types of male partners: those older (''sugar daddies'', men ≥35 years old) and younger (<35 years). Respondents felt unable to suggest condom use to both older and younger partners. Evident in respondents' accounts was a general low HIV risk perception, particularly with younger men, which was largely due to poor HIV knowledge. Discussions suggested that an AGYW's relationship with either male partner was characterized by some form of violence.

Conclusions

Discussions highlighted the nature and characteristics of relationships between AGYW and their male sexual partners. Findings could inform interventions to engender risk perception among AGYW, promote female-controlled HIV prevention efforts and, foster risk-reduction among men.

Sustained release of the candidate antiretroviral peptides T-1249 and JNJ54310516-AFP from a rod insert vaginal ring

Administration of biomacromolecular drugs in effective quantities from conventional vaginal rings is hampered by poor drug permeability in the polymers from which rings are commonly constructed. Here, we report the formulation development and testing of rod insert rings for sustained release of the candidate antiretroviral peptides T-1249 and JNJ54310516-AFP (JNJ peptide), both of which have potential as HIV microbicides. Rod inserts were prepared comprising antiviral peptides T-1249 or JNJ peptide in combination with a hydrophilic excipient (sodium chloride, sodium glutamate, lactose or zinc acetate) dispersed at different loadings within a medical grade silicone elastomer. The inserts were tested for weight change and swelling when immersed in simulated vaginal fluid (SVF). Dye migration into the inserts was also assessed visually over 28 days. In vitro release of T-1249 and JNJ peptide from rings containing various insert types was tested. Weight change and degree of swelling of rods immersed in SVF was dependent on the type and concentration of excipient present. The rods displayed the following rank order in terms of weight change: sodium glutamate > zinc acetate ≈ sodium chloride > lactose. The weight change and degree of swelling of the inserts did not correlate with the level of dye uptake observed. In vitro release of T-1249 was improved through addition of lactose, sodium chloride and sodium glutamate, while release of JNJ peptide was improved through addition of sodium chloride or sodium glutamate. Sustained release of hydrophobic peptides can be achieved using a rod insert ring design formulated to include a hydrophilic excipient. Release rates were dependent upon the type of excipient used. The degree of release improvement with different inserts partially reflects their ability to imbibe surrounding fluid and swell in aqueous environments.

Long-Acting Antiretrovirals: Where Are We now?

PURPOSE OF REVIEW

Current HIV treatment options require daily use of combination antiretroviral drugs. Many persons living with HIV experience treatment fatigue and suboptimal adherence as a result. Long-acting antiretroviral drugs are being developed to expand options for HIV treatment. Here, we review the agents in development, and evaluate data from recent clinical trials. In addition, we anticipate challenges to successful widespread use of long-acting antiretrovirals.

RECENT FINDINGS

Parenteral nanosuspensions of cabotegravir and rilpivirine, and dapivirine vaginal ring are the farthest in clinical development. Long-acting modalities in earlier development stages employ drug-loaded implants, microparticles, or targeted mutagenesis, among other innovations. Long-acting antiretroviral drugs promise new options for HIV prevention and treatment, and ways to address poor adherence and treatment fatigue. Further studies will identify the long-acting agents or combinations that are suitable for routine use. Creative solutions will be needed for anticipated implementation challenges.

Association of vaginal dysbiosis and biofilm with contraceptive vaginal ring biomass in African women

We investigated the presence, density and bacterial composition of contraceptive vaginal ring biomass and its association with the vaginal microbiome. Of 415 rings worn by 120 Rwandese women for three weeks, the biomass density was assessed with crystal violet and the bacterial composition of biomass eluates was assessed with quantitative polymerase chain reaction (qPCR). The biomass was visualised after fluorescence in situ hybridisation (FISH) and with scanning electron microscopy (SEM). The vaginal microbiome was assessed with Nugent scoring and vaginal biofilm was visualised after FISH. All vaginal rings were covered with biomass (mean optical density (OD) of 3.36; standard deviation (SD) 0.64). Lactobacilli were present on 93% of the rings, Gardnerella vaginalis on 57%, and Atopobium vaginae on 37%. The ring biomass density was associated with the concentration of A. vaginae (OD +0.03; 95% confidence interval (CI) 0.01–0.05 for one log increase; p = 0.002) and of G. vaginalis (OD +0.03; (95% CI 0.01–0.05; p = 0.013). The density also correlated with Nugent score: rings worn by women with a BV Nugent score (mean OD +0.26), and intermediate score (mean OD +0.09) had a denser biomass compared to rings worn by participants with a normal score (p = 0.002). Furthermore, presence of vaginal biofilm containing G. vaginalis (p = 0.001) and A. vaginae (p = 0.005) correlated with a denser ring biomass (mean OD +0.24 and +0.22 respectively). With SEM we observed either a loose network of elongated bacteria or a dense biofilm. We found a correlation between vaginal dysbiosis and the density and composition of the ring biomass, and further research is needed to determine if these relationships are causal. As multipurpose vaginal rings to prevent pregnancy, HIV, and other sexually transmitted diseases are being developed, the potential impact of ring biomass on the vaginal microbiota and the release of active pharmaceutical ingredients should be researched in depth.

Packing Polymorphism of Dapivirine and Its Impact on the Performance of a Dapivirine-Releasing Silicone Elastomer Vaginal Ring

A silicone elastomer vaginal ring providing sustained release over 28 days of the anti-retroviral microbicide dapivirine has recently completed phase III clinical testing and showed moderate protection against HIV acquisition. In support of the product licensure program, we report the impact of dapivirine packing polymorphism on the thermal and solubility characteristics of dapivirine and on the in vitro performance of the 25 mg dapivirine ring product. This is the first time that polymorphism has been reported for a drug-releasing vaginal ring product. Thermal, particle size, powder X-ray diffraction, and thermodynamic solubility analyses of dapivirine polymorphic forms I and IV, both of which are persistent at room temperature and with form I being the thermodynamically stable form, were conducted for both micronized and non-micronized materials. No significant differences in solubility between DPV forms I and IV were observed in media commonly used for in vitro release testing. Matrix-type silicone elastomer vaginal rings were manufactured and the impact of dapivirine polymorphism on key in vitro parameters (compression and tensile behavior; content assay; in vitro release; residual content assay) was investigated. The data demonstrate that dapivirine packing polymorphism has no significant impact on in vitro performance of the 25 mg dapivirine vaginal ring.

Evaluation of poly(lactic-co-glycolic acid) and poly(dl-lactide-co-ε-caprolactone) electrospun fibers for the treatment of HSV-2 infection

More diverse multipurpose prevention technologies are urgently needed to provide localized, topical pre-exposure prophylaxis against sexually transmitted infections (STIs). In this work, we established the foundation for a multipurpose platform, in the form of polymeric electrospun fibers (EFs), to physicochemically treat herpes simplex virus 2 (HSV-2) infection. To initiate this study, we fabricated different formulations of poly(lactic-co-glycolic acid) (PLGA) and poly(dl-lactide-co-ε-caprolactone) (PLCL) EFs that encapsulate Acyclovir (ACV), to treat HSV-2 infection in vitro. Our goals were to assess the release and efficacy differences provided by these two different biodegradable polymers, and to determine how differing concentrations of ACV affected fiber efficacy against HSV-2 infection and the safety of each platform in vitro. Each formulation of PLGA and PLCL EFs exhibited high encapsulation efficiency of ACV, sustained-delivery of ACV through one month, and in vitro biocompatibility at the highest doses of EFs tested. Additionally, all EF formulations provided complete and efficacious protection against HSV-2 infection in vitro, regardless of the timeframe of collected fiber eluates tested. This work demonstrates the potential for PLGA and PLCL EFs as delivery platforms against HSV-2, and indicates that these delivery vehicles may be expanded upon to provide protection against other sexually transmitted infections.

Intravaginal immunisation using a novel antigen-releasing ring device elicits robust vaccine antigen-specific systemic and mucosal humoral immune responses

The generation of effective levels of antigen-specific immunity at the mucosal sites of pathogen entry is a key goal for vaccinologists. We explored topical vaginal application as an approach to initiate local antigen-specific immunity, enhance previously existing systemic immunity or re-target responses to the mucosae. To deliver a protein vaccine formulation to the vaginal mucosal surface, we used a novel vaginal ring device comprising a silicone elastomer body into which three freeze-dried, rod-shaped, hydroxypropylmethylcellulose inserts were incorporated. Each rod contained recombinant HIV-1 CN54gp140 protein (167μg)±R848 (167μg) adjuvant. The inserts were loaded into cavities within each ring such that only the ends of the inserts were initially exposed. Sheep received a prime-boost vaccination regime comprising intramuscular injection of 100μg CN54gp140+200μg R848 followed by three successive ring applications of one week duration and separated by one month intervals. Other sheep received only the ring devices without intramuscular priming. Serum and vaginal mucosal fluids were sampled every two weeks and analysed by CN54gp140 ELISA and antigen-specific B cells were measured by flow cytometry at necropsy. Vaccine antigen-specific serum antibody responses were detected in both the intramuscularly-primed and vaginal mucosally-primed groups. Those animals that received only vaginal vaccinations had identical IgG but superior IgA responses. Analysis revealed that all animals exhibited mucosal antigen-specific IgG and IgA with the IgA responses 30-fold greater than systemic levels. Importantly, very high numbers of antigen-specific B cells were detected in local genital draining lymph nodes. We have elicited local genital antigen-specific immune responses after topical application of an adjuvanted antigen formulation within a novel vaginal ring vaccine release device. This regimen and delivery method elicited high levels of antigen-specific mucosal IgA and large numbers of local antigen-reactive B cells, both likely essential for effective mucosal protection.

Adherence and Acceptability of a Multidrug Vaginal Ring for HIV Prevention in a Phase I Study in the United States

We evaluated the adherence and acceptability of a vaginal ring containing dapivirine, maraviroc, or both drugs for 28 days during a Phase I placebo-controlled trial in 48 HIV-negative sexually abstinent U.S. women aged 18-40. Adherence was assessed weekly by clinical interview and computer-assisted self-interviewing; acceptability assessment occurred at the last product-use visit. Study retention was 98 % (47/48); 94 % (45/48) reported being fully adherent with ring use during the 28-day period. Two participants experienced the ring partially coming out. Analysis was blinded and behavioral data were combined across study groups. Most women reported being very comfortable having the ring in their vagina; 44 % preferred continuous use, whereas 51 % had no preference compared to episodic use. Although a range of minor ring concerns were expressed, few were actually experienced. High adherence to and acceptability of this vaginal ring in this Phase I trial contributes to its promise as a sustained mechanism for multidrug vaginal microbicide delivery.

Development and evaluation of accelerated drug release testing methods for a matrix-type intravaginal ring

Accelerated drug release testing is a valuable quality control tool for long-acting non-oral extended release formulations. Currently, several intravaginal ring candidates designed for the long-term delivery of steroids or anti-infective drugs are being in the developing pipeline. The present article addresses the demand for accelerated drug release methods for these formulations. We describe the development and evaluation of accelerated release methods for a steroid releasing matrix-type intravaginal ring. The drug release properties of the formulation were evaluated under real-time and accelerated test conditions. Under real-time test conditions drug release from the intravaginal ring was strongly affected by the steroid solubility in the release medium. Under sufficient sink conditions that were provided in release media containing surfactants drug release was Fickian diffusion driven. Both temperature and hydro-organic dissolution media were successfully employed to accelerate drug release from the formulation. Drug release could be further increased by combining the temperature effect with the application of a hydro-organic release medium. The formulation continued to exhibit a diffusion controlled release kinetic under the investigated accelerated conditions. Moreover, the accelerated methods were able to differentiate between different prototypes of the intravaginal ring that exhibited different release profiles under real-time test conditions. Overall, the results of the present study indicate that both temperature and hydro-organic release media are valid parameters for accelerating drug release from the intravaginal ring. Variation of either a single or both parameters yielded release profiles that correlated well with real-time release.

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.

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.

Matrix and reservoir-type multipurpose vaginal rings for controlled release of dapivirine and levonorgestrel

A matrix-type silicone elastomer vaginal ring providing 28-day continuous release of dapivirine (DPV) - a lead candidate human immunodeficiency virus type 1 (HIV-1) microbicide compound - has recently demonstrated moderate levels of protection in two Phase III clinical studies. Here, next-generation matrix and reservoir-type silicone elastomer vaginal rings are reported for the first time offering simultaneous and continuous in vitro release of DPV and the contraceptive progestin levonorgestrel (LNG) over a period of between 60 and 180days. For matrix-type vaginal rings comprising initial drug loadings of 100, 150 or 200mg DPV and 0, 16 or 32mg LNG, Day 1 daily DPV release values were between 4132 and 6113μg while Day 60 values ranged from 284 to 454μg. Daily LNG release ranged from 129 to 684μg on Day 1 and 2-91μg on Day 60. Core-type rings comprising one or two drug-loaded cores provided extended duration of in vitro release out to 180days, and maintained daily drug release rates within much narrower windows (either 75-131μg/day or 37-66μg/day for DPV, and either 96-150μg/day or 37-57μg/day for LNG, depending on core ring configuration and ignoring initial lag release effect for LNG) compared with matrix-type rings. The data support the continued development of these devices as multi-purpose prevention technologies (MPTs) for HIV prevention and long-acting contraception.

Post-use assay of vaginal rings (VRs) as a potential measure of clinical trial adherence

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Simulated use of dapivirine VRs showed no content changes after storage at RT or −20 °C.

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On average, about 4 mg of dapivirine is released in vivo after 28 days of VR use.

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Both in vivo and in vitro drug release conform to the Higuchi equation.

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Residual ring data should be used in conjunction with other PK measures for modeling adherence.

Adherence measurement for microbicide use within the clinical trial setting remains a challenge for the HIV prevention field. This paper describes an assay method used for determining residual dapivirine levels in post-use vaginal rings from clinical trials conducted with the Dapivirine Vaginal Matrix Ring-004 developed by the International Partnership for Microbicides to prevent male to female HIV transmission. Post-use assay results from three Ring-004 clinical trials showed that of the 25 mg drug load, approximately 4 mg of dapivirine is released from the matrix ring over a 28-day use period. Data obtained by both in vitro and in vivo studies indicate that dapivirine is released according to a diffusion mechanism, as determined by conformance of both data sets to the Higuchi equation. This, coupled with the low variability associated with batch production over two manufacturing sites and 20 batches of material, provides evidence that post-use ring analysis can contribute to the assessment of adherence to ring use. Limitations of this method include the potential of intra-participant and inter-participant variability and uncertainty associated with measuring the low amount of dapivirine actually released relative to the drug load. Therefore, residual drug levels should not serve as the only direct measurement for microbicide adherence in vaginal ring clinical trials but should preferably be used as part of a multi-pronged approach towards understanding and assessing adherence to vaginal ring use.

Controlling levonorgestrel binding and release in a multi-purpose prevention technology vaginal ring device

Despite a long history of incorporating steroids into silicone elastomers for drug delivery applications, little is presently known about the propensity for irreversible drug binding in these systems. In this study, the ability of the contraceptive progestin levonorgestrel to bind chemically with hydrosilane groups in addition-cure silicone elastomers has been thoroughly investigated. Cure time, cure temperature, levonorgestrel particle size, initial levonorgestrel loading and silicone elastomer type were demonstrated to be key parameters impacting the extent of levonorgestrel binding, each through their influence on the solubility of levonorgestrel in the silicone elastomer. Understanding and overcoming this levonorgestrel binding phenomenon is critical for the ongoing development of a number of drug delivery products, including a multi-purpose technology vaginal ring device offering simultaneous release of levonorgestrel and dapivirine - a lead candidate antiretroviral microbicide - for combination HIV prevention and hormonal contraception.

Recent work on vaginal rings containing antiviral agents for HIV prevention

PURPOSE OF REVIEW

In response to the need for strategies women can use to protect themselves from HIV infection, a new class of product commonly referred to as vaginal 'microbicides' has been under development for the past few decades. Several leading products currently in development contain antiviral agents delivered in a vaginal ring.

RECENT FINDINGS

Research published over the past year reports advances in identification and continued formulation of specific antiviral agents that have potential for delivery in vaginal rings, including drug combinations for HIV, other sexually transmitted infections and contraception. Most products are antiretroviral reverse transcriptase inhibitors. Advances in vaginal ring design have also been reported; some of these are designed to release specific antiviral agents, while other designs could be used for multiple drugs. This review focuses both on antiviral agents and vaginal ring designs.

SUMMARY

Over the past year, advances continued to be made in the development of vaginal rings to deliver antiviral agents for prevention of HIV. An array of antiviral agents and vaginal ring designs to deliver these products are at various stages in the product pipeline process. Results from the first efficacy trials of an antiretroviral-containing vaginal ring are expected soon and will inform the continued development of this important product class.

Addressing gaps in the contraceptive method mix: methods in development

Despite the availability of a variety of contraceptive methods, millions of women still have an unmet need for contraceptive choices. Short-acting methods are plagued by issues with adherence, leading to imperfect or inconsistent use and subsequent unintended pregnancy. Long-acting contraceptive methods such as intrauterine devices and contraceptive implants, while providing highly effective and safe contraception, do not meet the needs of all women, often due to cost, access or acceptability issues. Several new methods are in various stages of development and are designed to address the shortcomings of current methods. Providers should be aware of these future options and how they might better meet women's needs.

Recent advances on anti-HIV vaginal delivery systems development

A review of the recent outcomes regarding technologies to prevent vaginal transmission of HIV, mainly by using antiretroviral (ARV) drugs formulated as microbicides. An introduction about the HIV transmission mechanisms by the vaginal route is included, together with the recent challenges faced for development of successful microbicide products. The outcomes of clinical evaluations are mentioned, and the different formulation strategies studied to-date, with the requirements, advantages, disadvantages and limitations of each dosage-form type, are presented. Finally, the recent attempts to apply various types of nanotechnologies in order to develop advanced microbicide-products and overcome existing limitations, are discussed.

Acceptability and preferences for vaginal dosage forms intended for prevention of HIV or HIV and pregnancy

This paper reviews key issues found to affect acceptability and preferences for vaginal products to prevent HIV infection or HIV and pregnancy. We focus on the interplay between the biological and physico-chemical aspects of formulation and the social and behavioral issues that may affect use. The need for an HIV prevention product that women can use is driven by women's increased biological and social vulnerability to HIV infection, and thus social and behavioral research on microbicide acceptability has been conducted alongside, as well as separate from, the earliest product development efforts. Some acceptability and preference issues are specific to a product's dosage form, use-requirements, and/or use indications, while others pertain to any vaginal product used for prevention of HIV or pregnancy. Although most of the work cited here was published since 2010, it draws on a much longer trajectory of research.

A temperature-monitoring vaginal ring for measuring adherence

BACKGROUND

Product adherence is a pivotal issue in the development of effective vaginal microbicides to reduce sexual transmission of HIV. To date, the six Phase III studies of vaginal gel products have relied primarily on self-reporting of adherence. Accurate and reliable methods for monitoring user adherence to microbicide-releasing vaginal rings have yet to be established.

METHODS

A silicone elastomer vaginal ring prototype containing an embedded, miniature temperature logger has been developed and tested in vitro and in cynomolgus macaques for its potential to continuously monitor environmental temperature and accurately determine episodes of ring insertion and removal.

RESULTS

In vitro studies demonstrated that DST nano-T temperature loggers encapsulated in medical grade silicone elastomer were able to accurately and continuously measure environmental temperature. The devices responded quickly to temperature changes despite being embedded in different thickness of silicone elastomer. Prototype vaginal rings measured higher temperatures compared with a subcutaneously implanted device, showed high sensitivity to diurnal fluctuations in vaginal temperature, and accurately detected periods of ring removal when tested in macaques.

CONCLUSIONS

Vaginal rings containing embedded temperature loggers may be useful in the assessment of product adherence in late-stage clinical trials.

Precise engineering of dapivirine-loaded nanoparticles for the development of anti-HIV vaginal microbicides

Polymeric nanoparticles (NPs) have the potential to provide effective and safe delivery of antiretroviral drugs in the context of prophylactic anti-HIV vaginal microbicides. Dapivirine-loaded poly(d,l-lactic-co-glycolic acid) (PLGA) NPs were produced by an emulsion-solvent evaporation method, optimized for colloidal properties using a 3-factor, 3-level Box-Behnken experimental design, and characterized for drug loading, production yield, morphology, thermal behavior, drug release, in vitro cellular uptake, cytotoxicity and pro-inflammatory potential. Also, drug permeability/membrane retention in well-established HEC-1-A and CaSki cell monolayer models as mediated by NPs was assessed in the absence or presence of mucin. Box-Behnken design allowed optimizing monodisperse 170nm drug-loaded NPs. Drug release experiments showed an initial burst effect up to 4h, followed by sustained 24h release at pH 4.2 and 7.4. NPs were readily taken up by different genital and macrophage cell lines as assessed by fluorescence microscopy. Drug-loaded NPs presented lower or at least similar cytotoxicity as compared to the free drug, with up to around one-log increase in half-maximal cytotoxic concentration values. In all cases, no relevant changes in cell pro-inflammatory cytokine/chemokine production were observed. Dapivirine transport across cell monolayers was significantly decreased when mucin was present at the donor side with either NPs or the free drug, thus evidencing the influence of this natural glycoprotein in membrane permeability. Moreover, drug retention in cell monolayers was significantly higher for NPs in comparison with the free drug. Overall, obtained dapivirine-loaded PLGA NPs possess interesting technological and biological features that may contribute to their use as novel safe and effective vaginal microbicides.

The ring plus project: safety and acceptability of vaginal rings that protect women from unintended pregnancy

BACKGROUND

Research is ongoing to develop multipurpose vaginal rings to be used continuously for contraception and to prevent Human Immunodeficiency Virus (HIV) infection. Contraceptive vaginal rings (CVRs) are available in a number of countries and are most of the time used intermittently i.e. three weeks out of a 4-week cycle. Efficacy trials with a dapivirine-containing vaginal ring for HIV prevention are ongoing and plans to develop multi-purpose vaginal rings for prevention of both HIV and pregnancy have been elaborated. In contrast with the CVRs, multi-purpose vaginal rings will have to be used continuously. Women who continuously use a CVR will no longer have menses. Furthermore, some safety aspects of CVR use have never been studied in-depth in the past, such as the impact of the vaginal ring on the vaginal microbiota, biofilm formation and induction of inflammation. We studied acceptability and these novel aspects of safety in Rwandan women. Although significant progress has been made over the past decade, Rwanda still has a high unmet need for contraception (with 47% unplanned births) and a generalized HIV epidemic, and CVRs are not yet available.

METHODS

We will conduct an open label, single centre, randomized controlled trial. A total of 120 HIV-negative women will be randomized to intermittent CVR use (to allow menstruation) or continuous CVR use. Women will be followed for a maximum of 14 weeks. In parallel, we will conduct a qualitative study using in-depth interview and focus group discussion methodology.

DISCUSSION

In addition to evaluating the safety and acceptability of intermittent and continuous CVR use in Rwandan women, we hope that our findings will inform the development of future multipurpose vaginal rings, will prepare Rwandan study populations for future clinical trials of multipurpose vaginal rings, and will pave the way for introduction of CVRs on African markets.

TRIAL REGISTRATION

Clinicaltrials.gov NCT01796613 . Registered 14 February 2013.

The road ahead: working towards effective clinical translation of biomedical HIV prevention strategies

ABSTRACT 

Emerging evidence from several randomized controlled trials show that antiretroviral-based biomedical HIV prevention interventions are efficacious in preventing HIV if they are taken as directed, and could potentially reduce the number of new HIV infections globally. Strategies such as treatment as prevention and use of oral pre-exposure prophylaxis for HIV prevention have shown great promise, yet have raised important implementation concerns around awareness and acceptance, delivery, adherence, side effects, risk compensation, cost–effectiveness and drug resistance. In order to address these issues, a number of treatment as prevention and pre-exposure prophylaxis demonstration projects have been initiated to assess the feasibility of introducing these interventions in ‘real-world’ settings. These projects will be instrumental in determining best practices for optimal delivery and sustainability of these HIV prevention interventions. The road to effective translation to clinical setting is promising, but comes with challenges which are not insurmountable.

Protein and oligonucleotide delivery systems for vaginal microbicides against viral STIs

Intravaginal delivery offers an effective option for localized, targeted, and potent microbicide delivery. However, an understanding of the physiological factors that impact intravaginal delivery must be considered to develop the next generation of microbicides. In this review, a comprehensive discussion of the opportunities and challenges of intravaginal delivery are highlighted, in the context of the intravaginal environment and currently utilized dosage forms. After a subsequent discussion of the stages of microbicide development, the intravaginal delivery of proteins and oligonucleotides is addressed, with specific application to HSV and HIV. Future directions may include the integration of more targeted delivery modalities to virus and host cells, in addition to the use of biological agents to affect specific genes and proteins involved in infection. More versatile and multipurpose solutions are envisioned that integrate new biologicals and materials into potentially synergistic combinations to achieve these goals.