The ins and outs of drug-releasing vaginal rings: a literature review of expulsions and removals

A multipurpose silicone elastomer vaginal ring releasing dapivirine and Cu2+/Zn2+ ions for HIV prevention and non-hormonal contraception

A dapivirine (DPV)-releasing vaginal ring (DapiRing®, containing 25 mg DPV) has been approved in various African countries for prevention of human immunodeficiency virus type 1 (HIV-1). Current research is focused on next-generation multipurpose prevention technology (MPT) vaginal rings that additionally provide contraception, and a combination dapivirine + levonorgestrel ring is in clinical development. However, hormonal contraceptives have numerous side effects and contraindications, and many women are interested in hormone-free contraceptive options. Copper and zinc have well documented spermicidal activity; for example, copper intrauterine devices-comprising a copper metal wire fitted to a polyethylene frame and releasing cupric (Cu2+) ions-have a long history of use as a long-actingreversible non-hormonal form of contraception. Here, we report a multipurpose vaginal ring offering sustained release of DPV, Cu2+ ions, and Zn2+ ions. Matrix-type silicone elastomer vaginal rings containing different combinations of DPV (25 mg) and various copper/zinc substances (copper nanopowders, zinc nanopowders, copper sulphate pentahydrate, and zinc acetate dihydrate) were successfully manufactured by injection molding. DPV and the metal nanopowders were stable during manufacturing; partial dehydration occurred with copper sulphate pentahydrate and zinc acetate dihydrate. Incorporation of copper/zinc substances had minimal impact on DPV release, and the formulations produced similar DPV release compared with DapiRing®. Rings containing metal salts released significantly more Cu2+/Zn2+ ions than those containing metal nanopowders, and greater quantities of Cu2+/Zn2+ ions compared with marketed copper IUDs or experimental copper-zinc IUDs. The results demonstrate that copper/zinc metals and salts can be effectively incorporated into and released from silicone elastomer vaginal rings and are compatible with DPV. The inclusion of copper/zinc offers potential as non-hormonal contraception and warrants further investigation in the context of MPTs.

Preference, adherence, and acceptability of 3 nonmedicated intravaginal rings of differing external diameters: a randomized, crossover trial

BACKGROUND

No empirical data support the 54 to 58 mm external diameter of intravaginal rings currently available and in development for contraception and other indications. Understanding how external diameter affects preference, adherence, and acceptability is critical for optimizing future product development.

OBJECTIVE

Our primary objectives were to determine which of 3 nonmedicated rings of differing external diameters was preferred and yielded the highest adherence. Secondary objectives were comparing acceptability, patterns of adherence, and safety of the 3 rings.

STUDY DESIGN

In an open-label, 3-way crossover trial, healthy, HIV-uninfected, monogamous, sexually active, nonpregnant, 18-year-old to 40-year-old cisgender women and their male partners in Atlanta, GA and the Bronx, NY were randomly assigned to the sequence of using 3 nonmedicated silicone rings (46 mm, 56 mm, and 66 mm external diameters) continuously for approximately 30 days each (90 days total; November 2021 to December 2022). We tested whether end-of-study preference for any of the 3 rings was greater than 0.33 (binomial proportion, exact test). We used mixed-effect regression models with random intercepts by participants to compare adherence (ring never out for more than 30 minutes in 24 hours) and probability of removals (including reasons for removal), expulsions, and the ring being out of the vagina all day, per ring, per day of use with the 56-mm ring as the reference group and to compare scores on a novel 19-item acceptability scale with items related to ease and experience of use and impact on sex.

RESULTS

Of 24 women, 23 completed the study (median age: 26.7 years [standard deviation: 3.78]). Most were college graduates (92%), White (63%), non-Hispanic (79%), single (79%), and nulliparous (92%). At the end of the study, 59% preferred the smallest (46 mm) ring versus 18% each for the 56-mm and 66-mm rings (P=.0045). The proportion of participants who were adherent did not differ by ring (46 mm, 78%; 56 mm, 75%; 66 mm, 59%; P=.30); however, odds of expulsion were higher for the 46-mm (odds ratio: 5.72; 95% confidence interval: 1.25-26.1) and 66-mm (odds ratio: 25.9; 95% confidence interval: 6.11-109) rings than for the 56-mm ring. The 66-mm ring also had greater odds of being out (removal or expulsion, any length of time) than the 56-mm ring (odds ratio: 6.50; 95% confidence interval: 3.46-12.2). Mean acceptability scale scores were identical (4.54/5) for the 46-mm and 56-mm (smallest and medium) rings and significantly higher than for the largest, 66-mm ring (3.94/5; P<.001).

CONCLUSION

Although the 46-mm ring was preferred by more women and had higher rates of adherence compared to the other 2 rings, the 56-mm ring was rated as equally acceptable with significantly fewer reports of expulsions/removals compared to the other 2 rings. These data confirm that the current 54 to 58 mm diameter of vaginal rings on the market and in development is acceptable and performs well. Future studies should explore the effect of other mechanical attributes, such as compressibility, on preference, adherence, and acceptability, as well as investigating ring characteristics in other populations.

3D printed reservoir-like vaginal rings for antibiotic delivery

Targeting the development of 3D printed reservoir-like vaginal rings (VRs) intended to fulfill the needs of precision medicine, prototypes ensuring prolonged release of metronidazole (MTZ) were preliminary manufactured and tested. Indeed, this drug represents the first-line therapy against bacterial vaginosis, which would especially benefit from convenient as well as easy dose adjustment and from more than 48 h continuous release, thus avoiding barely tolerated and repeated administrations. Starting from a soft thermoplastic elastomer (TPE), hollow ring structures were successfully printed at 190 °C and then extemporaneously filled with drug-loaded, in-situ-crosslinking hydrogel formulations based on alginate (ALG). 3 VR designs, differing in dimensions, number of open surfaces as well as in relevant areas were investigated, together with 9 drug-saturated hydrogel formulations containing extra suspended MTZ particles (20-50 %) and increasing ALG concentrations (2-6 %). Manufacturing of final rings was fine-tuned based on materials thermo-mechanical properties. For comparison purposes, hydrogels with analogous composition were either cast using purposely developed molds or 3D printed mimicking the ring design. VR release performance turned out dependent on the drug solubility and on the surface area available for hydrogel contact with vaginal fluids. Interestingly, this surface resulted correlated to both the outer and inner structure of the system. The data collected would provide an effective asset to increase the versatility of reservoir-like VRs, making them a powerful tool towards therapy customization.

Locally administered nanosuspension increases delivery of estradiol for the treatment of vaginal atrophy in mice

Vaginal atrophy affects up to 57% of post-menopausal women, with symptoms ranging from vaginal burning to dysuria. Estradiol hormone replacement therapy may be prescribed to alleviate these symptoms, though many vaginal products have drawbacks including increased discharge and local tissue toxicity due to their hypertonic nature. Here, we describe the development and characterization of a Pluronic F127-coated estradiol nanosuspension (NS) formulation for improved vaginal estradiol delivery. We compare the pharmacokinetics to the clinical comparator vaginal cream (Estrace) and demonstrate increased delivery of estradiol to the vaginal tissue. We utilized ovariectomized (OVX) mice as a murine model of post-menopausal vaginal atrophy and demonstrated equivalent efficacy in vaginal re-epithelialization when dosed with either the estradiol NS or Estrace cream. Further, we demonstrate compatibility of the estradiol NS with vaginal bacteria in vitro. We demonstrate that a Pluronic F127-coated estradiol NS may be a viable option for the treatment of post-menopausal vaginal atrophy.

Acceptability of a dapivirine levonorgestrel vaginal ring in two Phase 1 trials (MTN-030/IPM 041 and MTN-044/IPM 053/CCN019): Implications for multipurpose prevention technology development

End-user feedback early in product development is important for optimizing multipurpose prevention technologies for HIV and pregnancy prevention. We evaluated the acceptability of the 90-day dapivirine levonorgestrel ring (DPV-LNG ring) used for 14 days compared to a dapivirine-only ring (DVR-200mg) in MTN-030/IPM 041 (n = 23), and when used for 90 days cyclically or continuously in MTN-044/IPM 053/CCN019 (n = 25). We enrolled healthy, non-pregnant, HIV-negative women aged 18-45 in Pittsburgh, PA and Birmingham, AL (MTN-030 only). Self-reports of vaginal bleeding and adherence (ring removals, expulsions) were collected via daily short message service. Acceptability data were recorded in face-to-face interviews at study exit. We assessed differences in acceptability by product characteristics and adherence; and associations between baseline characteristics/demographics, number of bleeding days, adherence, and overall acceptability. Most (21/23) women in the 14-day MTN-030 study and about half (13/25) in the 90-day MTN-044 study liked their assigned rings. In MTN-030 there were no significant associations between any variables and overall acceptability of either ring. In MTN-044, women who disliked the DPV-LNG ring had a significantly higher incidence of unanticipated vaginal bleeding, and reporting that vaginal bleeding changes were unacceptable than those who liked it. Although we found no overall association between adherence and acceptability, significantly more women who disliked (versus liked) the DPV-LNG ring reported expulsions during toileting. The DPV-LNG ring could meet the needs of women seeking simultaneous protection from HIV and unintended pregnancy. Addressing issues related to vaginal bleeding and expulsions early in product development will likely enhance acceptability of the DPV-LNG ring. Trial registration: Clinical Trial Registration: MTN-030/IPM 041: ClinicalTrials.gov NCT02855346; MTN-044/IPM 053/CCN019: ClinicalTrials.gov NCT03467347.

Risk factors for and outcomes of ring expulsions with a 1-year contraceptive vaginal system

BACKGROUND

The US Food and Drug Administration-approved segesterone acetate and ethinyl estradiol ring-shaped contraceptive vaginal system, known as Annovera (Sever Pharma Solutions/QPharma, Malmö, Sweden), was inserted and removed under a woman's control for a 21 day in and 7 day out regimen for up to 13 cycles of use.

OBJECTIVE

We aimed to describe the patterns of ring expulsion over time, to identify potential predictors of expulsion, and to evaluate the impact of expulsions on method discontinuation and pregnancy risk.

STUDY DESIGN

Using data from 2064 participants who were enrolled in 2 multinational phase 3 clinical trials on the use of this contraceptive vaginal system, we examined data from participants' daily diaries for documentation of complete ring expulsion. We modeled the odds of reported expulsions over time with adjustment for background and demographic characteristics using mixed-effects logistic regression models with random intercepts. We compared the probability of continuation between those who did and those who did not report expulsions in the first cycle of use using survival analysis and hazards modeling. To determine if expulsions during the first cycle of use affected the risk for pregnancy, we calculated Pearl Indices.

RESULTS

Most participants (75%) never experienced any expulsions during any cycle of use, and 91% to 97% did not experience an expulsion during any 1 cycle. The incidence of expulsion was highest in cycle 1 (9%). The odds of experiencing expulsions decreased by half in cycles 2 to 8 when compared with cycle 1 (0.48; 95% confidence interval, 0.40-0.58), and in cycles 9 to 13, expulsions were about a third of that in cycle 1 (0.32; 95% confidence interval, 0.26-0.41). Of those who did experience expulsions, most (62%-84%) experienced ≤2 expulsions per cycle. Participants from study sites in Latin America vs those in the United States had higher odds of not experiencing an expulsion (odds ratio, 1.95; 95% confidence interval, 1.45-2.63). Women with a higher education level had higher odds of experiencing an expulsion. Notably, parity, age, and body mass index were not associated with expulsion. Participants who experienced any expulsions in cycle 1 were more likely to discontinue use early (hazard ratio, 1.28; 95% confidence interval, 1.14-1.43) than participants who did not have an expulsion. The Pearl Index for participants who had expulsions during cycle 1 was 3.99 (95% confidence interval, 1.29-9.31), which was higher than that among participants who reported no expulsions (Pearl Index, 2.39; 95% confidence interval, 1.61-3.41), but the overlapping confidence intervals indicate that there is not sufficient evidence to demonstrate an association between expulsions and pregnancy risk.

CONCLUSION

Expulsions were infrequent overall, decreased with subsequent cycles of use, and were not associated with body mass index or parity. Early discontinuation of product use was higher among participants who experienced an expulsion during cycle 1. Although it is unclear whether pregnancy risk was associated with expulsions, early recognition of expulsions among users may identify those at higher risk for discontinuation and may highlight when enhanced anticipatory counselling and guidance may be advantageous.

High adherence to intermittent and continuous use of a contraceptive vaginal ring among women in a randomized controlled trial in Kigali, Rwanda

Background

The introduction of female-initiated drug-delivery methods, including vaginal rings, have proven to be a promising avenue to address sexually transmitted infections and unintended pregnancies, which disproportionally affects women and girls in sub-Saharan Africa. Efficient uptake of existing and new technologies such as vaginal rings requires in depth understanding of product adherence. This remains a major challenge as data on adherence to vaginal rings from African countries is limited. In this study, we explored adherence of contraceptive vaginal ring (NuvaRing®) use in Kigali, Rwanda using a mixed methods approach.

Methods

We collected quantitative and qualitative data at multiple time points from women participating in a clinical trial exploring the safety and acceptability of either intermittent or continuous use of the NuvaRing®. Various adherence categories were used including monthly and cumulative adherence measurement. The quantitative data were analysed using R and the qualitative data were analysed using a deductive, content-analytical approach based on categories related to the quantitative adherence measures. All data were compared and triangulated.

Results

Data from 120 enrolled participants showed that self-reported adherence was high at every study visit in both study groups. At first study visit 80% of the intermittent ring users and 79.7% of the continuous ring users reported perfect adherence (assessed as "the ring was never out"). Reporting of ring expulsions and removals were highest (28.3%) at the beginning of the trial. Self-reported perfect ring adherence increased during the study and reports of ring expulsions and removals declined as familiarity with this contraceptive method increased. The percentage of women with perfect cumulative adherence was non-significantly higher in the intermittent (61.7%) than in the continuous use group (54.3%). The low rate of discrepant adherence data after triangulation (6%) is in line with the perception of the participants as adherent throughout the study.

Conclusions

Self-reported adherence in both study groups was high with removals and expulsions being within the expected product range. Comprehensive adherence data triangulation allowed for a deeper understanding of context-driven behaviour that shaped adherence patterns and challenges. Our data categorisation and triangulation approach has shown potential for implementation in future vaginal ring studies aiming to better understand and measure adherence.

Two into one does go: Formulation development of a multipurpose combination vaginal ring releasing dapivirine and metronidazole for prevention of HIV infection and treatment of bacterial vaginosis

Bacterial vaginosis (BV) is a common but often asymptomatic dysbiosis of the human vagina characterized by an imbalance in the normal vaginal microbiota due to loss of lactobacilli and an overgrowth of certain anaerobic bacteria. While BV itself is not a sexually transmitted infection, it is associated with an increased risk in women of various sexually acquired infections, including human immunodeficiency virus (HIV) infection. There is, therefore, a strong rationale for pursuing new multipurpose products that seek to treat or prevent BV alongside preventing HIV infection. With the dapivirine-releasing vaginal ring for HIV prevention now approved in several African countries, here we report formulation development of a next-generation ring product that releases both dapivirine (DPV) and the antibiotic drug metronidazole (MET). Following thermal analysis studies to characterize the phase behaviour of DPV-MET mixtures and rheological analysis to assess the cure characteristics of the active silicone elastomer mixes, matrix-type rings were manufactured containing 25 or 200 mg DPV in combination with 100, 250, 500, 1000 or 2000 mg MET. The results for drug content, in vitro release, mechanical testing, and Gardnerella vaginalis time-kill experiments demonstrate the feasibility of incorporating both DPV and MET in a matrix-type ring formulation and indicate that clinically effective release rates may be possible.

Three-Dimensionally Printed Vaginal Rings: Perceptions of Women and Gynecologists in a Cross-Sectional Survey

Three-dimensional printing technologies can be implemented for the fabrication of personalized vaginal rings (VRs) as an alternative approach to traditional manufacturing. Although several studies have demonstrated the potential of additive manufacturing, there is a lack of knowledge concerning the opinions of patients and clinicians. This study aimed to investigate the perception of women and gynecologists regarding VRs with personalized shapes. The devices were printed with different designs (traditional, "Y", "M", and flat circle) by Fused Deposition Modeling for a cross-sectional survey with 155 participants. Their anticipated opinion was assessed through a questionnaire after a visual/tactile analysis of the VRs. The findings revealed that most women would feel comfortable using some of the 3D-printed VR designs and demonstrated good acceptability for the traditional and two innovative designs. However, women presented multiple preferences when the actual geometry was assessed, which directly related to their age, previous use of the vaginal route, and perception of comfort. In turn, gynecologists favored prescribing traditional and flat circle designs. Overall, although there was a difference in the perception between women and gynecologists, they had a positive opinion of the 3D-printed VRs. Finally, the personalized VRs could lead to an increase in therapeutic adherence, by meeting women's preferences.

Biphasic drug release from electrospun structures

INTRODUCTION

Biphasic release, as a special drug-modified release profile that combines immediate and sustained release, allows fast therapeutic action and retains blood drug concentration for long periods. Electrospun nanofibers, particularly those with complex nanostructures produced by multi-fluid electrospinning processes, are potential novel biphasic drug delivery systems (DDSs).

AREAS COVERED

This review summarizes the most recent developments in electrospinning and related structures. In this review, the role of electrospun nanostructures in biphasic drug release was comprehensively explored. These electrospun nanostructures include monolithic nanofibers obtained through single-fluid blending electrospinning, core-shell and Janus nanostructures prepared via bifluid electrospinning, three-compartment nanostructures obtained via trifluid electrospinning, nanofibrous assemblies obtained through the layer-by-layer deposition of nanofibers, and the combined structure of electrospun nanofiber mats with casting films. The strategies and mechanisms through which complex structures facilitate biphasic release were analyzed.

EXPERT OPINION

Electrospun structures can provide many strategies for the development of biphasic drug release DDSs. However, many issues such as the scale-up productions of complex nanostructures, the in vivo verification of the biphasic release effects, keeping pace with the developments of multi-fluid electrospinning, drawing support from the state-of-the-art pharmaceutical excipients, and the combination with traditional pharmaceutical methods need to be addressed for real applications.

Color, Scent and Size: Exploring Women's Preferences Around Design Characteristics of Drug-Releasing Vaginal Rings

Steroid-releasing vaginal rings are available for contraception and estrogen replacement therapy, and a new antiretroviral-releasing ring was recently approved for HIV prevention. Marketed rings are white or transparent in appearance, non-scented, and supplied as one-size-fits-all devices with diameters ranging from 54 to 56 mm. In this study, drug-free silicone elastomer rings were manufactured in different sizes, colors and scents, and the opinions/preferences of 16 women (eThekwini District, South Africa; 20-34 years) assessed through focus group discussions and thematic analysis. Opinions varied on ring color and scent, with some women preferring specific colors or scent intensities, while for others these attributes were unimportant. Concerns about color and scent were linked to perceptions around vaginal health and safety related to chemical composition. There was greater agreement on preferred ring size; flexibility and width were considered important factors for insertion and comfort. Greater choice with ring products could facilitate acceptability and overall uptake.

Toward a new generation of vaginal pessaries via 3D-printing: concomitant mechanical support and drug delivery

To improve patient adherence, vaginal pessaries - polymeric structures providing mechanical support to treat stress urinary incontinence (SUI) - greatly benefit from 3D-printing through customization of their mechanics, e.g. infill modifications. However, currently only limited polymers provide both flawless printability and controlled drug release. The current study closes this gap by exploring 3D-printing, more specifically fused filament fabrication, of pharmaceutical grade thermoplastic polyurethanes (TPU) of different hardness and hydrophilicity into complex pessary structures. Next to the pessary mechanics, drug incorporation into such a device was addressed for the first time. Mechanically, the soft hydrophobic TPU was the most promising candidate for pessary customization, as pessaries made thereof covered a broad range of the key mechanical parameter, while allowing self-insertion. From the drug release point of view, the hydrophobic TPUs were superior over the hydrophilic one, as the release levels of the model drug acyclovir were closer to the target value. Summarizing, the fabrication of TPU-based pessaries via 3D-printing is an innovative strategy to create a customized pessary combination product that simultaneously provides mechanical support and pharmacological therapy.

Personalised urethra pessaries prepared by material extrusion-based additive manufacturing

Material extrusion-based additive manufacturing, commonly referred to as 3D-printing, is regarded as the key technology to pave the way for personalised medical treatment. This study explores the technique's potential in customising vaginal inserts with complex structures, so-called urethra pessaries. A novel, flawlessly 3D-printable and biocompatible polyester-based thermoplastic elastomer serves as the feedstock. Next to the smart selection of the 3D-printing parameters cross-sectional diameter and infill to tailor the pessary's mechanical properties, we elaborate test methods accounting for its application-specific requirements for the first time. The key property, i.e. the force the pessary exerts on the urethra to relief symptoms of urinary incontinence, is reliably adjusted within a broad range, including that of the commercial injection-moulded silicone product. The pessaries do not change upon long-term exposure to vaginal fluid simulant and compression (in-vivo conditions), satisfying the needs of repeated pessary use. Importantly, the vast majority of the 3D-printed pessaries allows for self-insertion and self-removal without any induced pessary rupture. Summarising, 3D-printed pessaries are not only a reasonable alternative to the commercial products, but build the basis to effectively treat inhomogeneous patient groups. They make the simple but very effective pessary therapy finally accessible to every woman.

Novel polyester-based thermoplastic elastomers for 3D-printed long-acting drug delivery applications

To improve patient compliance and personalised drug delivery, long-acting drug delivery devices (LADDDs), such as implants and inserts, greatly benefit from a customisation in their shape through the emerging 3D-printing technology, since their production usually follows a one-size-fits-most approach. The use of 3D-printing for LADDDs, however, is mainly limited by the shortage of flawlessly 3D-printable, yet biocompatible materials. The present study tackles this issue by introducing a novel, non-biodegradable material, namely a polyester-based thermoplastic elastomer (TPC) - a multi-block copolymer containing alternating semi-crystalline polybutylene terephthalate hard segments and poly-ether-terephthalate amorphous soft segments. Next to a detailed description of the material's 3D-printability by mechanical, rheological and thermal analyses, which was found to be superior to that of conventional polymers (ethylene-vinyl acetates (EVA)), this study establishes the fundamental understandings of the interactions between progesterone (P4) and TPC and drug-releasing properties of TPC for the first time. P4-loaded LADDDs based on TPC, prepared via an elaborated solvent-immersion technique, enable the release of P4 at pharmacologically relevant rates, similar to those of marketed formulations based on EVA and silicones. Additionally, TPC demonstrated an exceptional 3D-printability for a wide selection of implant sizes and complex geometries.