Vaginal safety after use of a bioadhesive, acid-buffering, microbicidal contraceptive gel (ACIDFORM) and a 2% nonoxynol-9 product

Lactic acid, citric acid and potassium bitartrate non-hormonal prescription vaginal pH modulator (VPM) gel for the prevention of pregnancy

INTRODUCTION

A non-hormonal prescription vaginal pH modulator (VPM) gel (Phexxi®), with active ingredients lactic acid, citric acid and potassium bitartrate, has recently been approved for prevention of pregnancy in the United States. The objective of this review is to compile the evidence available from published preclinical and clinical trials to support its use.

AREAS COVERED

PubMed was searched for published literature on VPM gel. Two Phase III trials were found on clinicaltrials.gov database. The results demonstrated that VPM gel is safe, with minimal side effects, and effective (cumulative 6-7 cycle pregnancy rate of 4.1-13.65%, (Pearl Index 27.5) as a contraceptive. Microbicidal effects suggest potential for the prevention of sexually transmitted infections (STIs); currently a Phase III clinical trial is being conducted to evaluate prevention of chlamydia and gonorrhea.

EXPERT OPINION

Non-hormonal reversible contraceptive options have been limited to the highly effective copper-releasing intrauterine device that requires insertion by a trained clinician, and less effective coitally-associated barrier and spermicide options which are typically available over-the-counter. Spermicides, which improve efficacy of barrier devices, may increase the risk of HIV/STIs. VPM gel provides a new safe, effective non-hormonal contraceptive option, with potential for prevention of STIs.

Role of Immunity and Vaginal Microbiome in Clearance and Persistence of Human Papillomavirus Infection

Cervical cancer disproportionately affects women of reproductive age, with 80% of cases occurring in low- and middle-income countries. Persistent infection with high-risk human papillomavirus (HPV) genotypes has been described as the most common non-systemic biological risk factor for the development of cervical cancer. The mucosal immune system plays a significant role in controlling HPV infection by acting as the first line of host defense at the mucosal surface. However, the virus can evade host immunity using various mechanisms, including inhibition of the antiviral immune response necessary for HPV clearance. Pro-inflammatory cytokines and the vaginal microbiome coordinate cell-mediated immune responses and play a pivotal role in modulating immunity. Recently, diverse vaginal microbiome (associated with bacterial vaginosis) and genital inflammation have emerged as potential drivers of high-risk HPV positivity and disease severity in women. The potential role of these risk factors on HPV recurrence and persistence remains unclear. This article reviews the role of cellular or cytokine response and vaginal microbiome dysbiosis in the clearance, persistence, and recurrence of HPV infection.

Baseline and time-updated factors in preclinical development of anionic dendrimers as successful anti-HIV-1 vaginal microbicides

Although a wide variety of topical microbicides provide promising in vitro and in vivo efficacy, most of them failed to prevent sexual transmission of human immunodeficiency virus type 1 (HIV‐1) in human clinical trials. In vitro, ex vivo, and in vivo models must be optimized, considering the knowledge acquired from unsuccessful and successful clinical trials to improve the current gaps and the preclinical development protocols. To date, dendrimers are the only nanotool that has advanced to human clinical trials as topical microbicides to prevent HIV‐1 transmission. This fact demonstrates the importance and the potential of these molecules as microbicides. Polyanionic dendrimers are highly branched nanocompounds with potent activity against HIV‐1 that disturb HIV‐1 entry. Herein, the most significant advancements in topical microbicide development, trying to mimic the real‐life conditions as closely as possible, are discussed. This review also provides the preclinical assays that anionic dendrimers have passed as microbicides because they can improve current antiviral treatments' efficacy.

This article is categorized under:

Nanotechnology Approaches to Biology > Nanoscale Systems in Biology

Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease

Toxicology and Regulatory Issues in Nanomedicine > Regulatory and Policy Issues in Nanomedicine

Safety of G2-S16 Polyanionic Carbosilane Dendrimer as Possible HIV-1 Vaginal Microbicide

The UNAIDS objective for 2020 was 500,000 new HIV-1 infections per year; however, the latest annual reported data confirmed 1.7 million new HIV-1 infections in that year. Those data evidences the need for new prevention strategies and prophylactic treatments. This prevention crisis occurred in spite of the knowledge and availability of efficient prevention strategies. The G2-S16 is a microbicidal polyanionic carbosilane dendrimer currently being tested for topical vaginal application, which has been shown to be efficient in the prevention of HIV-1 infection. However, safety tests were lacked. For this purpose, we injected intravenously G2-S16 dendrimer to CD1 mice, thereby analyzing the hemogram, blood biochemical markers of systemic damage, accumulation in the organs and organ-tissue damage in heart, spleen, kidney, liver and brain. This work shows that even if the G2-S16 dendrimer penetrates the epithelial tissue, it does not cause vaginal irritation or tissue damage. Moreover, the i.v. injection of the G2-S16 dendrimer did not cause a damaging effect on the studied organs and it did not modify the hemogram or the biochemical plasma markers. In conclusion, the G2-S16 dendrimer has a very good safety profile, indicating that this molecule can be a very safe and efficient vaginal microbicide.

A trifunctional contraceptive gel enhances the safety and quality of sexual intercourse

Current contraceptive methods come with a number of drawbacks, including low efficacy, in the case of commercial contraceptive gels, and a reduction in the quality of sexual intercourse, in the case of condoms. Adding pharmacologically-active agents to contraceptive gels holds the potential to improve sexual experience, and hardbor safety and hygiene. In this study, we fabricated a Carbomer-based contraceptive gel consisting of three agents: tenofovir, gossypol acetate, and nitroglycerin (TGN), with pH adjusted to 4.5 (to be compatible with the vagina). In vitro, the gossypol component of the contraceptive gel proved to be a significantly effective spermicide. When the concentration of gossypol acetate was 10 mg/ml, the spermicidal ability reached 100% after 30s. In addition, tenofovir in the gel significantly inhibited lentiviral transfection efficiency in cell-containing media. In 6 pairs of rats, the gel successfully prevented all females from conceiving after successful mating. Moreover, increased sexual frequency and enhanced erection, which were promoted by the nitroglycerin in the components, were observed in male rats that had the gel applied to their penises. This novel TGN contraceptive gel yielded a higher contraceptive success rate than that of the commercial contraceptive gel (Contragel®). In addition, it has the added benefits to prevent sexually transmitted diseases and improve male libido and erection function during sexual intercourse. Combining three FDA-approved and marketed agents together, our trifunctional TGN gel has a great potential for further translation and commercialization.

A novel vaginal pH regulator: results from the phase 3 AMPOWER contraception clinical trial

Objective

The objective was to evaluate the contraceptive effectiveness, safety, and acceptability of a novel vaginal pH regulator over seven cycles of use.

Study design

A single-arm, open-label, phase 3 study was conducted across 112 sites in the United States in sexually active 18–35-year-old women at risk of pregnancy. Women administered the study treatment ≤ 1 h before each episode of intercourse. Women recorded use of study drug, coital information, and any symptoms experienced in electronic diaries. The primary outcome was the seven-cycle cumulative pregnancy rate as calculated using the Kaplan–Meier methodology; secondary outcomes included safety. Overall satisfaction was assessed via written questionnaires.

Results

A total of 1384 women were enrolled in the study from July 2017 to November 2018. Mean age was 27.7 ± 4.4 years; most women were white (69.0%). The seven-cycle cumulative pregnancy percentage was 13.7% [95% confidence interval (CI): 10.0%–17.5%], meeting the prespecified primary endpoint of having the upper bound 95% CI ≤ 21%. Most common adverse events (AEs) occurring in ≥ 2% of women were vulvovaginal burning sensation, vulvovaginal pruritus, urinary tract infection, vulvovaginal pain, mycotic infection, bacterial vaginosis, and nasopharyngitis. Of 1330 women who used the study drug at least once, fewer than 2% of women discontinued due to any AEs, and < 1% of women discontinued due to genitourinary symptoms. Overall, > 80% of women reported being “very satisfied” or “satisfied” with study treatment.

Conclusions

In this phase 3 study, the novel vaginal pH regulator demonstrated 86.3% contraceptive effectiveness, was safe and well tolerated, and was highly acceptable.

Implications

This novel vaginal pH regulator is a safe, nonhormonal, woman-controlled method of contraception that expands women's options.

An overview of properties of Amphora (Acidform) contraceptive vaginal gel

INTRODUCTION

Although only a minority of contracepting women rely solely on spermicides, they may soon be the only ongoing female method available without a prescription in the United States. Spermicides are also combined with other methods for additional pregnancy protection and/or lubrication. Nonoxynol-9 (N-9), the active ingredient in most spermicides, is cytotoxic and may increase risk of transmission of HIV and other sexually transmitted infections, especially in high-risk women. Amphora (previously called Acidform) is a noncytotoxic spermicide composed of a series of generally regarded as safe compounds, which maintains the acidity of the vagina following coitus to immobilize and kill sperm. Amphora is currently Food and Drug Administration-approved as a vaginal lubricant. Amphora is currently being tested in a multicenter Phase III contraceptive trial.

AREAS COVERED

This paper describes key properties of Amphora, including its acid-buffering abilities, viscosity, stability, bioadhesiveness, and tolerability.

EXPERT OPINION

Amphora is a nontoxic spermicide that maintains the pH within the vagina at levels less than 5.0 for hours, which immobilizes and kills sperm as well as many sexually transmitted pathogens. If the current clinical trial demonstrates safety, efficacy, and tolerability of Amphora as a contraceptive, it would represent a viable alternative to N-9. Its potential as a microbicide warrants further investigation.

Progress and Perspectives on HIV-1 microbicide development

The majority of HIV-1 infections occur via sexual intercourse. Women are the most affected by the epidemic, particularly in developing countries, due to their socio-economic dependence on men and the fact that they are often victims of gender based sexual violence. Despite significant efforts that resulted in the reduction of infection rates in some countries, there is still need for effective prevention methods against the virus. One of these methods for preventing sexual transmission in women is the use of microbicides. In this review we provide a summary of the progress made toward the discovery of affordable and effective HIV-1 microbicides and suggest future directions. We show that there is a wide range of compounds that have been proposed as potential microbicides. Although most of them have so far failed to show protection in humans, there are many promising ones currently in pre-clinical studies and in clinical trials.

ACIDFORM: a review of the evidence

OBJECTIVE

ACIDFORM is a candidate microbicide with spermicidal properties. A large Phase 3 trial is underway, and it is anticipated that this product will be approved for contraceptive use and marketed soon in the United States. The goal of this article is to critically review the evidence supporting the properties, safety profile and different uses of ACIDFORM gel.

STUDY DESIGN

We searched PubMed and Medline for any published literature on ACIDFORM.

RESULTS

ACIDFORM is an acidifying agent that works by lowering the vaginal pH to enhance the normal vaginal defenses. In addition to strong acid-buffering properties, ACIDFORM has high bioadhesive and viscosity-retaining properties. Several Phase 1 clinical trials have demonstrated the vaginal safety of ACIDFORM used alone or in combination with a diaphragm, although dose-dependent side effects appear to be present. Studies investigating the efficacy of ACIDFORM against sexually transmitted infections (STIs) are promising, but further trials are needed.

CONCLUSIONS

The properties of ACIDFORM offer many advantages for use, either alone or in combination with another active ingredient, such as Tenofovir. Potential applications for ACIDFORM include use as a personal lubricant, a vaginal contraceptive (alone or with a barrier method) and a microbicidal product or as a formulation vehicle for an active ingredient.

IMPLICATIONS

ACIDFORM is a candidate female-controlled vaginal preparation with microbicidal and spermicidal properties. A dual protection method could prevent unwanted pregnancies and reduce the risk of STI acquisition.

Vaginal microbicides to prevent human immunodeficiency virus infection in women: perspectives on the female genital tract, sexual maturity and mucosal inflammation

Topically applied vaginal microbicides to protect against human immunodeficiency (HIV) virus infection offer an important female-controlled prevention strategy. Microbicides have been in development for more than 2 decades, and have included various agents that disrupt cellular and microbial membranes (surfactants), restore the natural acidic protective pH of the vagina (acid buffers), and those that interfere with interactions between HIV envelope proteins and cellular receptors (anionic polymers). Although none of these candidate microbicides have shown significant protection against HIV in clinical trials, a topical gel, including the antiretroviral drug tenofovir (TFV) 1% was the first microbicide to be tested to show some protection against HIV infection. This review explores the effect of female genital tract biology and anatomy, mucosal inflammation, and age on the effectiveness of microbicides to prevent HIV infection.

HIV sexual transmission and microbicides

Pathogens often rely on the contacts between hosts for transmission. Most viruses have adapted their transmission mechanisms to defined behaviours of their host(s) and have learned to exploit these for their own propagation. Some viruses, such as HIV, the human papillomavirus (HPV), HSV-2 and HCV, cause sexually transmitted infections (STIs). Understanding the transmission of particular viral variants and comprehending the early adaptation and evolution is fundamental to eventually inhibiting sexual transmission of HIV. Here, we review the current understanding of the mechanisms of sexual transmission and the biology of the transmitted HIV. Next, we present a timely overview of candidate microbicides, including past, ongoing and future clinical trials of HIV topical microbicides.

Safety analysis of the diaphragm in combination with lubricant or acidifying microbicide gels: effects on markers of inflammation and innate immunity in cervicovaginal fluid

OBJECTIVE

Diaphragms are being considered for use with vaginal microbicide gels to provide enhanced protection against sexually transmitted pathogens. The purpose of this study was to determine whether use of a diaphragm with microbicide or placebo gel causes cervicovaginal inflammation or perturbations in cervicovaginal immune defense.

METHOD OF STUDY

Eighty-one non-pregnant women were randomized into three groups and instructed to use Milex (CooperSurgical, Inc., Trumbull, CT, USA)diaphragms overnight for 14 days in combination with one of the two acid-buffering microbicide gels [ACIDFORM (Instead Inc., La Jolla, CA, USA) or BufferGel(trade mark) (BG; ReProtect Inc., Baltimore, Maryland)] or placebo gel (K-Y Jelly); Personal Products Inc., Raritan, NJ, USA). Cervicovaginal lavages (CVLs) were performed prior to study entry and on days 8 and 16. Nine soluble mediators of vaginal inflammation or immune defense were measured in CVLs by Bio-Plex or ELISA.

RESULTS

Use of diaphragms with placebo or microbicide gel was not associated with increased levels of inflammation markers. Concentrations of secretory leukocyte protease inhibitor (SLPI) were markedly reduced in the BG group.

CONCLUSION

Daily use of a diaphragm with placebo or acidifying microbicide gel did not cause cervicovaginal inflammation. However, diaphragm/BG use was associated with markedly reduced levels of SLPI, an important mediator of innate immune defense. Further studies are warranted to establish the safety of diaphragm/microbicide gel combinations.

Vaginal microbicides and the prevention of HIV transmission

Worldwide, nearly half of all individuals living with HIV are now women, who acquire the virus largely by heterosexual exposure. With an HIV vaccine likely to be years away, topical microbicide formulations applied vaginally or rectally are being investigated as another strategy for HIV prevention. A review of preclinical and clinical research on the development of microbicides formulated to prevent vaginal HIV transmission yielded 118 studies: 73 preclinical and 45 clinical. Preclinical research included in-vitro assays and cervical explant models, as well as animal models. Clinical research included phase I and II/IIb safety studies, and phase III efficacy studies. Whereas most phase I and phase II clinical trials have found microbicide compounds to be safe and well tolerated, phase III trials completed to date have not demonstrated efficacy in preventing HIV transmission. Topical microbicides are grouped into five classes of agents, based on where they disrupt the pathway of sexual transmission of HIV. These classes include surfactants/membrane disruptors, vaginal milieu protectors, viral entry inhibitors, reverse transcriptase inhibitors, and a fifth group whose mechanism is unknown. The trajectory of microbicide development has been toward agents that block more specific virus-host cell interactions. Microbicide clinical trials face scientifically and ethically complex issues, such as the choice of placebo gel, the potential for viral resistance, and the inclusion of HIV-infected participants. Assessment of combination agents will most likely advance this field of research.

Vaginal microbicide and diaphragm use for sexually transmitted infection prevention: a randomized acceptability and feasibility study among high-risk women in Madagascar

BACKGROUND

In preparation for a randomized controlled trial (RCT), we conducted a pilot RCT of the acceptability and feasibility of diaphragms and candidate vaginal microbicide for sexually transmitted infection prevention among high-risk women in Madagascar.

METHODS

Participants were randomized to four arms: (1) diaphragm (worn continuously) with Acidform applied in the dome; (2) diaphragm (worn continuously) with placebo gel hydroxyethylcellulose (HEC) in the dome; (3) HEC applied intravaginally before sex; (4) Acidform applied intravaginally before sex. All women were given condoms. Participants were followed weekly for 4 weeks. We fit unadjusted negative binomial regression models with robust variance estimators to generate the proportion of sex acts with casual partners where condoms and experimental study products were used.

RESULTS

Retention was 98% among 192 participants. Experimental product use with casual partners was high, reported in 85%, 91%, 74%, and 81% of sex acts for women in the Acidform-diaphragm, HEC-diaphragm, HEC-alone, and Acidform-alone arms, respectively. However, the proportion reporting product use during 100% of acts with casual partners over the full follow-up period was much lower: 28% to 29% in the gel-diaphragm arms and 6% to 10% in gel-alone arms. Women used condoms in 62% to 67% of sex acts with casual partners, depending on the randomization arm. Participants found diaphragms easy to insert (97%) and remove (96%). Acidform users (with or without the diaphragm) reported more genitourinary symptoms than HEC users (14% vs. 5% of visits).

CONCLUSIONS

A sexually transmitted infection prevention RCT of candidate microbicide with and without the diaphragm appears acceptable and feasible in this population.

Phase I safety trial of two vaginal microbicide gels (Acidform or BufferGel) used with a diaphragm compared to KY jelly used with a diaphragm

OBJECTIVES

To assess the safety and acceptability of 2 vaginal microbicide gels (Acidform and BufferGel) used with a diaphragm compared to KY Jelly used with a diaphragm among low-risk, sexually abstinent women.

STUDY DESIGN

Eighty-one women enrolled in a randomized, masked, phase I safety study using a diaphragm with Acidform, BufferGel, or KY Jelly for 6 to 10 hours nightly for 14 nights. Physical examination, colposcopy, and lab studies were performed after 1 and 2 weeks of use. Diaries and questionnaires were used to assess user acceptability.

RESULTS

Sixty-nine participants (85%) completed the study. Safety and acceptability appeared similar among the 3 study groups and no serious adverse events related to the study products were reported. Adverse events were mild and anticipated.

CONCLUSIONS

Acidform and BufferGel compared to KY Jelly, when used with diaphragm daily for 14 days, appeared to be safe and acceptable in a small study of low-risk abstinent women.

Reversible female contraception: current options and new developments

Uncontrolled fertility results in significant infant and maternal mortality and morbidity. Contraception has the potential to reduce this disease burden. Although a rich array of reversible contraceptive methods exists, the need for more effective and user-friendly methods remains. Access to methods and affordability are major barriers in many parts of the world. However, in other areas, successful utilization is limited by convenience factors or a lack of appreciation of fertility risk. To address these issues, new products that require little user effort have been developed. To encourage correct and consistent use of other methods, noncontraceptive benefits are being popularized and new protocols to initiate contraceptive use immediately are being introduced. This review briefly discusses existing contraceptive methods and new developments that are under investigation.

Microbicide drug candidates to prevent HIV infection

25 years after the first HIV/AIDS cases emerged in 1981, the disease continues to spread worldwide, with about 15 000 new infections every day. Although highly active antiretroviral therapy (HAART) has greatly reduced the rate of HIV infection, and the spread of the epidemic, this effect has largely been seen in developed countries. More than 90% of HIV-infected people live in developing countries, most of whom do not have access to this treatment. The development of efficient, widely available, and low-cost microbicides (gels and creams can be applied topically before sex) to prevent sexually transmitted HIV infections should be given high priority. We review different categories of microbicide drugs and lead compounds, their mechanism of action, current status of development, and progress in phase III trials.

Microbicides: a new frontier in HIV prevention

Microbicides are products that can be applied to vaginal or rectal mucosal surfaces with the goal of preventing, or at least significantly reducing, the transmission of sexually transmitted infections (STIs) including HIV-1. Despite more than two decades of HIV-1 vaccine research, there is still no efficacious HIV-1 vaccine, and the scientific community appears skeptical about the short or long-term feasibility of developing a vaccine that has the ability to induce sterilizing immunity against HIV-1. In this setting, microbicide research has gathered momentum. Currently, 16 candidate microbicides are in clinical development and five products are being evaluated in large-scale Phase 2B/3 effectiveness studies. Initial data from these trials will be available within the next 2-3 years, and it is feasible that there could be one or more licensed microbicides by the end of the decade. The first generation of surfactant microbicides had a non-specific mechanism of action. However, subsequent candidate microbicides have been developed to target specific steps in the process of viral transmission. The purpose of this article is to provide an overview of microbicide development and an update on the candidate pipeline.

Role of seminal plasma in the anti-HIV-1 activity of candidate microbicides

Background

Evaluation of microbicides for prevention of HIV-1 infection in macaque models for vaginal infection has indicated that the concentrations of active compounds needed for protection by far exceed levels sufficient for complete inhibition of infection in vitro. These experiments were done in the absence of seminal plasma (SP), a vehicle for sexual transmission of the virus. To gain insight into the possible effect of SP on the performance of selected microbicides, their anti-HIV-1 activity in the presence, and absence of SP, was determined.

Methods

The inhibitory activity of compounds against the X4 virus, HIV-1 IIIB, and the R5 virus, HIV-1 BaL was determined using TZM-bl indicator cells and quantitated by measuring β-galactosidase induced by infection. The virucidal properties of cellulose acetate 1,2-benzene-dicarboxylate (CAP), the only microbicide provided in water insoluble, micronized form, in the presence of SP was measured.

Results

The HIV-1 inhibitory activity of the polymeric microbicides, poly(naphthalene sulfonate), cellulose sulfate, carrageenan, CAP (in soluble form) and polystyrene sulfonate, respectively, was considerably (range ≈ 4 to ≈ 73-fold) diminished in the presence of SP (33.3%). Formulations of micronized CAP, providing an acidic buffering system even in the presence of an SP volume excess, effectively inactivated HIV-1 infectivity.

Conclusion

The data presented here suggest that the in vivo efficacy of polymeric microbicides, acting as HIV-1 entry inhibitors, might become at least partly compromised by the inevitable presence of SP. These possible disadvantages could be overcome by combining the respective polymers with acidic pH buffering systems (built-in for formulations of micronized CAP) or with other anti-HIV-1 compounds, the activity of which is not affected by SP, e.g. reverse transcriptase and zinc finger inhibitors.