Vaginal multipurpose prevention technologies: promising approaches for enhancing women's sexual and reproductive health

Phase 1 randomized trials to assess safety, pharmacokinetics, and vaginal bleeding associated with use of extended duration dapivirine and levonorgestrel vaginal rings

BACKGROUND

Vaginal rings formulated to deliver two drugs simultaneously have potential as user-controlled, long-acting methods for dual prevention of HIV and pregnancy.

METHODS

Two phase 1 randomized trials (MTN-030/IPM 041 and MTN-044/IPM 053/CCN019) respectively enrolled 24 and 25 healthy, HIV-negative participants to evaluate safety, pharmacokinetics, and vaginal bleeding associated with use of a vaginal ring containing 200mg dapivirine (DPV) and 320mg levonorgestrel (LNG) designed for 90-day use. MTN-030/IPM 041 compared the DPV/LNG ring to a DPV-only ring (200mg) over 14 days of use. MTN-044/IPM 053/CCN019 compared continuous or cyclic use of the DPV/LNG ring over 90 days of use. Safety was assessed by recording adverse events (AEs). DPV and LNG concentrations were quantified in plasma, cervicovaginal fluid, and cervical tissue. Vaginal bleeding was self-reported.

RESULTS

There were no differences in the proportion of participants with grade ≥2 genitourinary AEs or grade ≥3 AEs with DPV/LNG ring vs. DPV ring use (p = .22), or with DPV/LNG ring continuous vs. cyclic use (p = .67). Higher plasma DPV concentrations were observed in users of DPV/LNG compared to DPV-only rings (Cmax p = 0.049; AUC p = 0.091). Plasma DPV and LNG concentrations were comparable with continuous and cyclic use (Cmax p = 0.74; AUC p = 0.25). With cyclic use, median nadir plasma DPV concentration was approximately 300 pg/mL two days after removal and median t1/2 for cervicovaginal fluid DPV concentration was 5.76 hours (n = 3). Overall bleeding experiences did not differ between continuous and cyclic users (p = 0.12).

CONCLUSIONS

The extended duration DPV/ LNG rings were well tolerated and the observed DPV concentrations in plasma and cervicovaginal fluid when used continuously exceeded concentrations observed in previous DPV ring efficacy studies. LNG concentrations in plasma were comparable with other efficacious LNG-based contraceptives. Genital DPV concentrations had a short half-life and were thus not well sustained following ring removal.

Hypotonic, gel-forming delivery system for vaginal drug administration

Vaginal drug delivery is often preferred over systemic delivery to reduce side effects and increase efficacy in treating diseases and conditions of the female reproductive tract (FRT). Current vaginal products have drawbacks, including spontaneous ejection of drug-eluting rings and unpleasant discharge from vaginal creams. Here, we describe the development and characterization of a hypotonic, gel-forming, Pluronic-based delivery system for vaginal drug administration. The rheological properties were characterized with and without common hydrogel polymers to demonstrate the versatility. Both qualitative and quantitative approaches were used to determine the Pluronic F127 concentration below the critical gel concentration (CGC) that was sufficient to achieve gelation when formulated to be hypotonic to the mouse vagina. The hypotonic, gel-forming formulation was found to form a thin, uniform gel layer along the vaginal epithelium in mice, in contrast to the rapidly forming conventional gelling formulation containing polymer above the CGC. When the hypotonic, gel-forming vehicle was formulated in combination with a progesterone nanosuspension (ProGel), equivalent efficacy was observed in the prevention of chemically-induced preterm birth (PTB) compared to commercial Crinone® vaginal cream. Further, ProGel showed marked benefits in reducing unpleasant discharge, reducing product-related toxicity, and improving compatibility with vaginal bacteria in vitro. A hypotonic, gel-forming delivery system may be a viable option for therapeutic delivery to the FRT.

Long-acting injectable multipurpose prevention technology for prevention of HIV and unplanned pregnancy

Only condoms are proven to protect against both HIV and unplanned pregnancy, however, poor user acceptability and lack of partner cooperation impede effectiveness. We developed an injectable ultra-long-acting, biodegradable, and removable in-situ forming implant (ISFI) as multipurpose prevention technology (MPT). MPT ISFIs co-formulated an antiretroviral (dolutegravir (DTG)) or cabotegravir (CAB)), and a hormonal contraceptive (etonogestrel (ENG) or medroxyprogesterone acetate (MPA)). All formulations were well-tolerated in mice with no signs of chronic local or systemic inflammation. Plasma CAB and DTG concentrations were above 4× PA-IC90 for 90 days with zero-order and diffusion-controlled absorption, respectively, and no differences when co-formulated with either hormone. Plasma ENG and MPA concentrations were quantifiable for 90 days. Complete removal of CAB/MPA ISFIs resulted in MPA concentrations falling below the limit of quantification after 24 h post-removal, but incomplete CAB elimination from plasma. Collectively, we demonstrated the ability to co-formulate antiretrovirals with contraceptives in an ISFI that is well-tolerated with sustained plasma concentrations up to 90 days.

pH-triggered polymeric nanoparticles in gel for preventing vaginal transmission of HIV and unintended pregnancy

Human Immunodeficiency Virus/Acquired Immunodeficiency Syndrome (HIV/ AIDS) and unplanned pregnancy affect female reproductive health globally. A single product providing a dual purpose of HIV prophylaxis and contraception may improve adherence to the therapy. Thus, we formulated a female-centric multipurpose prevention technology (MPT) comprising of nanoparticle loaded vaginal gel formulation acting as a contraceptive and microbicide. Eudragit® S100 nanoparticles of Atazanavir sulphate (ATZ; antiviral) and Fluoxetine hydrochloride (FLX; repurposed spermicide) were prepared for pH dependent drug release and loaded in carrageenan and HPMC K200M gel. The particle size of ATZ and FLX nanoparticles was 396.7 ± 20.64 nm and 226.5 ± 2.08 nm respectively. The in vitro release of the gel formulation in simulated seminal fluid (pH 7.6) showed 96.16% and 95.98% release of ATZ and FLX respectively at the end of 8 h. The in vitro anti-HIV and spermicidal activity of the formulation was above 80% for low drug concentrations. In vivo studies on murine model showed no signs of inflammation or vaginal epithelial injury. Curcumin based imaging confirmed the retention of the formulation in the reproductive tract of mice with minimal leakage. Nanoparticles in gel enabled non-invasive and localised delivery with minimal side effects and can be an effective prophylactic therapy.

A Brief History and Advancement of Contraceptive Multipurpose Prevention Technology (cMPT) Products

The high incidence of HIV and other sexually transmitted infections (STIs), and an unmet need for modern contraception resulting in a high unintended pregnancy rate, are major problems in reproductive health. The concept of multipurpose prevention technology (MPT) was introduced following the failure of several leading microbicide candidates to prevent human immunodeficiency virus type 1 (HIV-1) transmission in large clinical trials in the early 2000s. MPTs are defined as products designed to simultaneously prevent at least two of the following conditions: unintended pregnancy, HIV-1, or other major STIs. The goal of contraceptive MPT products (cMPTs) is to provide contraception and protection against one or more major STI pathogen (eg, HIV-1, herpes simplex virus (HSV) type 2, Neisseria gonorrhoeae (gonorrhea), Treponema pallidum (syphilis), Trichomonas vaginalis, Chlamydia trachomatis (Chlamydia). This new field has great potential and will benefit from lessons learned from the early microbicide trials. The cMPT field includes candidates representing various categories with different mechanisms of action including pH modifiers, polyions, microbicidal peptides, monoclonal antibodies, and other peptides that target specific reproductive and infectious processes. More preclinical research is being conducted to ensure minimal side effects and maximum efficacy in vivo. Effective proven and novel candidates are being combined to maximize efficacy, minimize side effects, and avoid drug resistance. More attention is being paid to acceptability and new delivery systems. cMPTs have a very promising future if adequate resources can be mobilized to sustain the effort from preclinical research to clinical trials to bring effective, acceptable, and affordable products to market.

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

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

Multipurpose Prevention Technologies: Oral, Parenteral, and Vaginal Dosage Forms for Prevention of HIV/STIs and Unplanned Pregnancy

There is a high global prevalence of HIV, sexually transmitted infections (STIs), and unplanned pregnancies. Current preventative daily oral dosing regimens can be ineffective due to low patient adherence. Sustained release delivery systems in conjunction with multipurpose prevention technologies (MPTs) can reduce high rates of HIV/STIs and unplanned pregnancies in an all-in-one efficacious, acceptable, and easily accessible technology to allow for prolonged release of antivirals and contraceptives. The concept and development of MPTs have greatly progressed over the past decade and demonstrate efficacious technologies that are user-accepted with potentially high adherence. This review gives a comprehensive overview of the latest oral, parenteral, and vaginally delivered MPTs in development as well as drug delivery formulations with the potential to advance as an MPT, and implementation studies regarding MPT user acceptability and adherence. Furthermore, there is a focus on MPT intravaginal rings emphasizing injection molding and hot-melt extrusion manufacturing limitations and emerging fabrication advancements. Lastly, formulation development considerations and limitations are discussed, such as nonhormonal contraceptive considerations, challenges with achieving a stable coformulation of multiple drugs, achieving sustained and controlled drug release, limiting drug-drug interactions, and advancing past preclinical development stages. Despite the challenges in the MPT landscape, these technologies demonstrate the potential to bridge gaps in preventative sexual and reproductive health care.

The Promise of the Dual Prevention Pill: A Framework for Development and Introduction

Women of reproductive age need multipurpose prevention technology (MPT) products to address two overlapping health risks: unintended pregnancy and HIV. Currently, condoms are the only available MPT, however male condoms are not within the control of a woman, and the use of female condoms has been limited by low acceptability and cost. Oral pre-exposure prophylaxis (PrEP) is highly effective for HIV prevention, yet uptake and adherence among women have been low to date. Women globally need more options for HIV and pregnancy prevention. Several MPTs for simultaneous HIV and pregnancy prevention are in various stages of development and clinical testing, although most are many years away from market launch. A dual prevention pill (DPP), a daily oral pill combining oral contraceptives and PrEP, both of which are licensed, approved products in many low- and middle-income countries (LMIC), is likely to be the fastest route to getting an MPT product into the hands of women. The DPP is one option that could enhance method choice, particularly for women who are already using oral contraceptives. By leveraging the oral contraceptive market and reaching women currently using condoms or with an unmet need for contraception, the DPP has the potential to increase the uptake of PrEP. The successful rollout of the DPP will require careful consideration of user-, provider-, and product-centered factors during product development and introduction. Early attention to these interrelated factors can help ensure that the DPP has the ideal characteristics for maximum product acceptability, that effective and quality services are designed and implemented, and that users can make informed choices, demand the product, and use it effectively. The proposed framework outlines key considerations for the effective development and introduction of the DPP, which could also facilitate integration models for future MPTs.

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.