Safety and tolerability of BufferGel, a novel vaginal microbicide, in women in the United States

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.

Mucoadhesive drug delivery systems: a promising noninvasive approach to bioavailability enhancement. Part II: formulation considerations

INTRODUCTION

Mucoadhesive drug delivery systems (MDDS) are specifically designed to interact and bind to the mucosal layer of the epithelium for localized, prolonged, and/or targeted drug delivery. Over the past 4 decades, several dosage forms have been developed for localized as well as systemic drug delivery at different anatomical sites.

AREAS COVERED

The objective of this review is to provide a detailed understanding of the different aspects of MDDS. Part II describes the origin and evolution of MDDS, followed by a discussion of the properties of mucoadhesive polymers. Finally, a synopsis of the different commercial aspects of MDDS, recent advances in the development of MDDS for biologics and COVID-19 as well as future perspectives are provided.

EXPERT OPINION

A review of the past reports and recent advances reveal MDDS as highly versatile, biocompatible, and noninvasive drug delivery systems. The rise in the number of approved biologics, the introduction of newer highly efficient thiomers, as well as the recent advances in the field of nanotechnology have led to several excellent applications of MDDS, which are predicted to grow significantly in the future.

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.

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

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

Impact of the griffithsin anti-HIV microbicide and placebo gels on the rectal mucosal proteome and microbiome in non-human primates

Topical microbicides are being explored as an HIV prevention method for individuals who practice receptive anal intercourse. In vivo studies of these microbicides are critical to confirm safety. Here, we evaluated the impact of a rectal microbicide containing the antiviral lectin, Griffithsin (GRFT), on the rectal mucosal proteome and microbiome. Using a randomized, crossover placebo-controlled design, six rhesus macaques received applications of hydroxyethylcellulose (HEC)- or carbopol-formulated 0.1% GRFT gels. Rectal mucosal samples were then evaluated by label-free tandem MS/MS and 16 S rRNA gene amplicon sequencing, for proteomics and microbiome analyses, respectively. Compared to placebo, GRFT gels were not associated with any significant changes to protein levels at any time point (FDR < 5%), but increased abundances of two common and beneficial microbial taxa after 24 hours were observed in HEC-GRFT gel (p < 2E-09). Compared to baseline, both placebo formulations were associated with alterations to proteins involved in proteolysis, activation of the immune response and inflammation after 2 hours (p < 0.0001), and increases in beneficial Faecalibacterium spp. after 24 hours in HEC placebo gel (p = 4.21E-15). This study supports the safety profile of 0.1% GRFT gel as an anti-HIV microbicide and demonstrates that current placebo formulations may associate with changes to rectal proteome and microbiota.

Pre-exposure prophylaxis (PrEP) in an era of stalled HIV prevention: Can it change the game?

Pre-exposure prophylaxis (PrEP) for HIV prevention has evolved significantly over the years where clinical trials have now demonstrated the efficacy of oral PrEP, and the field is scaling-up implementation. The WHO and UNAIDS have made PrEP implementation a priority for populations at highest risk, and several countries have developed guidelines and national plans accordingly, largely based on evidence generated by demonstration projects. PrEP presents the opportunity to change the face of HIV prevention by offering a new option for protection against HIV and disrupting current HIV prevention systems. Nevertheless, as with all new technologies, both practical and social requirements for implementation must be taken into account if there is to be sustained and widespread adoption, which will also apply to forthcoming prevention technologies. Defining and building success for PrEP within the scope of scale-up requires careful consideration. This review summarises where the PrEP field is today, lessons learned from the past, the philosophy and practicalities of how successful programming may be defined, and provides perspectives of costs and affordability. We argue that a successful PrEP programme is about effective intervention integration and ultimately keeping people HIV negative.

Exploring acceptability of oral PrEP prior to implementation among female sex workers in South Africa

INTRODUCTION

Female sex workers (FSWs) are at high-risk for HIV acquisition in South Africa, where the advent of new HIV prevention and treatment interventions represent the potential to significantly impact the epidemic. This paper focuses on aspects of PrEP acceptability as a new intervention within the context of a larger service delivery programme including the simultaneous rollout of early ART. This paper explores PrEP acceptability among the FGD participants as future potential users.

METHODS

FGDs were conducted in two clinic-based sites in Johannesburg and Pretoria. They aimed to explore community-level, multi-dimensional acceptability of PrEP within the context of imminent implementation alongside early ART in the TAPS Demonstration Project. Sex worker peer educators recruited participants from varying sex work locales. Facilitation was in English with adaptation by facilitators into local languages as needed. Transcripts were translated and transcribed into English. Thematic analysis was used to analyse the data.

RESULTS

Four FGDs were conducted in each site for a total of eight FDGs and 69 participants. Demographics were largely similar across the sites. Overall, there was strong acceptability of PrEP among participants and positive anticipation for the imminent delivery of PrEP in the local sex worker clinics. Themes arising from the discussions exploring aspects of PrEP acceptability included: awareness and understanding of PrEP; PrEP motivations including choice, control, and vulnerability, managing PrEP risks and worries; and, de-stigmatizing and empowering PrEP delivery. Participant discussions and recommendations highlighted the importance of developing clear education and messaging to accurately convey the concept of PrEP, and intervention integration into supportive and tailored services.

CONCLUSIONS

Through the course of these FGDs, PrEP became a positive and highly anticipated prevention option among the FSWs participants who endorsed implementation in their communities. Effective integration of PrEP into existing services will include comprehensive health programming where ART is also available, appropriate messaging, and support.

Evaluation of immunological markers of ovine vaginal irritation: Implications for preclinical assessment of non-vaccine HIV preventive agents

The presence of genital inflammatory responses and a compromised vaginal epithelial barrier have been linked to an increased risk of HIV acquisition. It is important to assure that application of candidate microbicides designed to limit HIV transmission will not cause these adverse events. We previously developed high resolution in vivo imaging methodologies in sheep to assess epithelial integrity following vaginal application of a model microbicide, however characterization of genital inflammation in sheep has not been previously possible. In this study, we significantly advanced the sheep model by developing approaches to detect and quantify inflammatory responses resulting from application of a nonoxynol-9-containing gel known to elicit vaginal irritation. Vaginal application of this model microbicide resulted in foci of disrupted epithelium detectable by confocal endomicroscopy. Leukocytes also infiltrated the treated mucosa and the number and composition of leukocytes obtained by cervicovaginal lavage (CVL) were determined by differential staining and flow cytometry. By 18h post-treatment, a population comprised predominantly of granulocytes and monocytes infiltrated the vagina and persisted through 44h post-treatment. The concentration of proinflammatory cytokines and chemokines in CVL was determined by quantitative ELISA. Concentrations of IL-8 and IL-1β were consistently significantly increased after microbicide application suggesting these cytokines are useful biomarkers for epithelial injury in the sheep model. Together, the results of these immunological assessments mirror those obtained in previous animal models and human trials with the same compound and greatly extend the utility of the sheep vaginal model in assessing the vaginal barrier and immune microenvironment.

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.

Repeated Vaccination of Cows with HIV Env gp140 during Subsequent Pregnancies Elicits and Sustains an Enduring Strong Env-Binding and Neutralising Antibody Response

An important feature of a potential vaccine against HIV is the production of broadly neutralising antibodies (BrNAbs) capable of potentially blocking infectivity of a diverse array of HIV strains. BrNAbs naturally arise in some HIV infected individuals after several years of infection and their serum IgG can neutralise various HIV strains across different subtypes. We previously showed that vaccination of cows with HIV gp140 AD8 trimers resulted in a high titre of serum IgG against HIV envelope (Env) that had strong BrNAb activity. These polyclonal BrNAbs concentrated into the colostrum during the late stage of pregnancy and can be harvested in vast quantities immediately after calving. In this study, we investigated the effect of prolonged HIV gp140 vaccination on bovine colostrum IgG HIV Env-binding and BrNAb activity over subsequent pregnancies. Repeated immunisation led to a maintained high titre of HIV Env specific IgG in the colostrum batches, but this did not increase through repeated cycles. Colostrum IgG from all batches also strongly competed with sCD4 binding to gp140 Env trimer and with human-derived monoclonal VRC01 and b12 BrNAbs that bind the CD4 binding site (CD4bs). Furthermore, competition neutralisation assays using RSC3 Env gp120 protein core and a derivative CD4bs mutant, RSC3 Δ371I/P363N, showed that CD4bs neutralising antibodies contribute to the neutralising activity of all batches of purified bovine colostrum IgG. This result indicates that the high IgG titre/avidity of anti-CD4bs antibodies with BrNAb activity was achieved during the first year of vaccination and was sustained throughout the years of repeated vaccinations in the cow tested. Although IgG of subsequent colostrum batches may have a higher avidity towards the CD4bs, the overall breadth in neutralisation was not enhanced. This implies that the boosting vaccinations over 4 years elicited a polyclonal antibody response that maintained the proportion of both neutralising and non-neutralising CD4bs antibodies.

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.

New candidate biomarkers in the female genital tract to evaluate microbicide toxicity

Vaginal microbicides hold great promise for the prevention of viral diseases like HIV, but the failure of several microbicide candidates in clinical trials has raised important questions regarding the parameters to be evaluated to determine in vivo efficacy in humans. Clinical trials of the candidate microbicides nonoxynol-9 (N9) and cellulose sulfate revealed an increase in HIV infection, vaginal inflammation, and recruitment of HIV susceptible lymphocytes, highlighting the need to identify biomarkers that can accurately predict microbicide toxicity early in preclinical development and in human trials. We used quantitative proteomics and RT-PCR approaches in mice and rabbits to identify protein changes in vaginal fluid and tissue in response to treatment with N9 or benzalkonium chloride (BZK). We compared changes generated with N9 and BZK treatment to the changes generated in response to tenofovir gel, a candidate microbicide that holds promise as a safe and effective microbicide. Both compounds down regulated mucin 5 subtype B, and peptidoglycan recognition protein 1 in vaginal tissue; however, mucosal brush samples also showed upregulation of plasma proteins fibrinogen, plasminogen, apolipoprotein A-1, and apolipoprotein C-1, which may be a response to the erosive nature of N9 and BZK. Additional proteins down-regulated in vaginal tissue by N9 or BZK treatment include CD166 antigen, olfactomedin-4, and anterior gradient protein 2 homolog. We also observed increases in the expression of C-C chemokines CCL3, CCL5, and CCL7 in response to treatment. There was concordance in expression level changes for several of these proteins using both the mouse and rabbit models. Using a human vaginal epithelial cell line, the expression of mucin 5 subtype B and olfactomedin-4 were down-regulated in response to N9, suggesting these markers could apply to humans. These data identifies new proteins that after further validation could become part of a panel of biomarkers to effectively evaluate microbicide toxicity.

Poly(ethylene glycol) (PEG)-lactic acid nanocarrier-based degradable hydrogels for restoring the vaginal microenvironment

Women with bacterial vaginosis (BV) display reduced vaginal acidity, which make them susceptible to associated infections such as HIV. In the current study, poly(ethylene glycol) (PEG) nanocarrier-based degradable hydrogels were developed for the controlled release of lactic acid in the vagina of BV-infected women. PEG-lactic acid (PEG-LA) nanocarriers were prepared by covalently attaching lactic acid to 8-arm PEG-SH via cleavable thioester bonds. PEG-LA nanocarriers with 4 copies of lactic acid per molecule provided controlled release of lactic acid with a maximum release of 23% and 47% bound lactic acid in phosphate buffered saline (PBS, pH7.4) and acetate buffer (AB, pH4.3), respectively. The PEG nanocarrier-based hydrogels were formed by cross-linking the PEG-LA nanocarriers with 4-arm PEG-NHS via degradable thioester bonds. The nanocarrier-based hydrogels formed within 20 min under ambient conditions and exhibited an elastic modulus that was 100-fold higher than the viscous modulus. The nanocarrier-based degradable hydrogels provided controlled release of lactic acid for several hours; however, a maximum release of only 10%-14% bound lactic acid was observed possibly due to steric hindrance of the polymer chains in the cross-linked hydrogel. In contrast, hydrogels with passively entrapped lactic acid showed burst release with complete release within 30 min. Lactic acid showed antimicrobial activity against the primary BV pathogen Gardnerella vaginalis with a minimum inhibitory concentration (MIC) of 3.6 mg/ml. In addition, the hydrogels with passively entrapped lactic acid showed retained antimicrobial activity with complete inhibition G. vaginalis growth within 48 h. The results of the current study collectively demonstrate the potential of PEG nanocarrier-based hydrogels for vaginal administration of lactic acid for preventing and treating BV.

Acceptability of optical coherence tomography and abstinence requirements among women participating in microbicide safety trials

BACKGROUND

Developing effective and safe microbicides requires study procedures (e.g., technology used, abstinence requirements, and product use) that are acceptable to participants.

METHODS

Thirty women completed 4 study visits including pelvic examination, colposcopy, optical coherence tomography (OCT), and semistructured, qualitative interviews. Additional requirements included abstinence (for approximately 16 days) and twice daily vaginal product use (for 5.5 days). Interviews were audio-recorded, transcribed, and analyzed using framework analysis. Themes addressing OCT experiences, acceptability of abstinence, and vaginal product use were examined.

RESULTS

OCT was viewed favorably as an imaging technology. Some women reported feeling the fiber-optic probe "poking" them and more than one-third spontaneously reported feeling pressure or pinching upon rotation of the speculum in connection with the OCT evaluation. Compliance with vaginal gel use was high, but for many women assigned to use a product containing nonoxynol-9 (vs. placebo), the postproduct use examination was more uncomfortable, relative to the initial examination or 1 week following product discontinuation. Nearly all women experienced product leakage; acceptability of leakage varied. Two women were not abstinent and several more found abstinence challenging. Some women involved their partner in decision making regarding trial enrollment. Strategies to remain abstinent included participating when the partner was away, avoiding early intimacy, and engaging in alternative sexual activities.

CONCLUSIONS

Qualitative interviews in early-phase studies provide insights and capture information that would be missed by behavioral inference alone. Understanding participant's experiences is important in order to provide anticipatory guidance and plan future microbicide studies that facilitate adherence with trial requirements.

Silencing sexually transmitted infections: topical siRNA-based interventions for the prevention of HIV and HSV

The global impact of sexually transmitted infections (STIs) is significant. The sexual transmission of viruses such as herpes simplex virus type-2 (HSV-2) and the human immunodeficiency virus type-1 (HIV-1), has been especially difficult to control. To date, no effective vaccines have been developed to prevent the transmission of these STIs. Although antiretroviral drugs have been remarkably successful in treating the symptoms associated with these viral infections, the feasibility of their widespread use for prevention purposes may be more limited. Microbicides might provide an attractive alternative option to reduce their spread. In particular, topically applied small inhibitory RNAs (siRNAs) have been shown to not only block transmission of viral STIs to mucosal tissues both in vitro and in vivo, but also confer durable knockdown of target gene expression, thereby circumventing the need to apply a microbicide around the time of sexual encounter, when compliance is mostly difficult. Despite numerous clinical trials currently testing the efficacy of siRNA-based therapeutics, they have yet to be approved for use in the treatment of viral STIs. While several obstacles to their successful implementation in the clinic still exist, promising preclinical studies suggest that siRNAs are a viable modality for the future prevention and treatment of HSV and HIV.

Microbicides: topical prevention against HIV

Microbicides represent a potential intervention strategy for preventing HIV transmission. Vaginal microbicides would meet the need for a discreet method that women could use to protect themselves against HIV. Although early-generation microbicides failed to demonstrate efficacy, newer candidates are based on more potent antiretroviral (ARV) products. Positive data from the CAPRISA 004 trial of tenofovir gel support use in women and represent a turning point for the field. This article reviews current progress in development of ARV-based microbicides. We discuss the consensus on selection criteria, the potential for drug resistance, rationale for drug combinations, and the use of pharmacokinetic (PK)/pharmacodynamic (PD) assessment in product development. The urgent need for continued progress in development of formulations for sustained delivery is emphasized. Finally, as the boundaries between different prevention technologies become increasingly blurred, consideration is given to the potential synergy of diverse approaches across the prevention landscape.

A phenyl-thiadiazolylidene-amine derivative ejects zinc from retroviral nucleocapsid zinc fingers and inactivates HIV virions

Background

Sexual acquisition of the human immunodeficiency virus (HIV) through mucosal transmission may be prevented by using topically applied agents that block HIV transmission from one individual to another. Therefore, virucidal agents that inactivate HIV virions may be used as a component in topical microbicides.

Results

Here, we have identified 2-methyl-3-phenyl-2H-[1,2,4]thiadiazol-5-ylideneamine (WDO-217) as a low-molecular-weight molecule that inactivates HIV particles. Both HIV-1 and HIV-2 virions pretreated with this compound were unable to infect permissive cells. Moreover, WDO-217 was able to inhibit infections of a wide spectrum of wild-type and drug-resistant HIV-1, including clinical isolates, HIV-2 and SIV strains. Whereas the capture of virus by DC-SIGN was unaffected by the compound, it efficiently prevented the transmission of DC-SIGN-captured virus to CD4⁺ T-lymphocytes. Interestingly, exposure of virions to WDO-217 reduced the amount of virion-associated genomic RNA as measured by real-time RT-qPCR. Further mechanism-of-action studies demonstrated that WDO-217 efficiently ejects zinc from the zinc fingers of the retroviral nucleocapsid protein NCp7 and inhibits the cTAR destabilization properties of this protein. Importantly, WDO-217 was able to eject zinc from both zinc fingers, even when NCp7 was bound to oligonucleotides, while no covalent interaction between NCp7 and WDO-217 could be observed.

Conclusion

This compound is a new lead structure that can be used for the development of a new series of NCp7 zinc ejectors as candidate topical microbicide agents.

Plant made anti-HIV microbicides--a field of opportunity

HIV remains a significant global burden and without an effective vaccine, it is crucial to develop microbicides to halt the initial transmission of the virus. Several microbicides have been researched with various levels of success. Amongst these, the broadly neutralising antibodies and peptide lectins are promising in that they can immediately act on the virus and have proven efficacious in in vitro and in vivo protection studies. For the purpose of development and access by the relevant population groups, it is crucial that these microbicides be produced at low cost. For the promising protein and peptide candidate molecules, it appears that current production systems are overburdened and expensive to establish and maintain. With recent developments in vector systems for protein expression coupled with downstream protein purification technologies, plants are rapidly gaining credibility as alternative production systems. Here we evaluate the advances made in host and vector system development for plant expression as well as the progress made in expressing HIV neutralising antibodies and peptide lectins using plant-based platforms.

Phase I randomized safety study of twice daily dosing of acidform vaginal gel: candidate antimicrobial contraceptive

Background

Acidform gel, an acid-buffering product that inactivates spermatozoa, may be an effective topical non-hormonal contraceptive. This study was designed to evaluate the safety of vaginal dosing and effects of Acidform on mucosal immune mediators, antimicrobial properties of genital secretions, and vaginal microbiota.

Methods

Thirty-six sexually abstinent U.S. women were randomized to apply Acidform or hydroxyethylcellulose (HEC) placebo gel twice daily for 14 consecutive days. Safety was assessed by symptoms and pelvic examination. The impact of gel on mucosal immunity was assessed by quantifying cytokines, chemokines, antimicrobial proteins and antimicrobial activity of genital secretions collected by cervicovaginal lavage (CVL) at screening, 2 hours after gel application, and on days 7, 14 and 21. Vaginal microbiota was characterized at enrollment and day 14 using species-specific quantitative PCR assays.

Results

The median vaginal and cervical pH was significantly lower 2 hours after application of Acidform and was associated with an increase in the bactericidal activity of CVL against E. coli. However, 65% of women who received Acidform had at least one local adverse event compared with 11% who received placebo (p = 0.002). While there was no increase in inflammatory cytokines or chemokines, CVL concentrations of lactoferrin and interleukin-1 receptor antagonist (IL-1ra), an anti-inflammatory protein, were significantly lower following Acidform compared to HEC placebo gel application. There were no significant changes in Lactobacillus crispatus or Lactobacillus jensenii in either group but there was a decrease in Gardnerella vaginalis in the Acidform group (p = 0.08).

Conclusions

Acidform gel may augment mucosal defense as evidenced by an increase in bactericidal activity of genital secretions against E. coli and a decrease in Gardnerella vaginalis colonization. However, Acidform was associated with more irritation than placebo and lower levels of antimicrobial (lactoferrin) and anti-inflammatory (IL-1ra) proteins. These findings indicate the need for additional safety studies of this candidate non-hormonal contraceptive.

Trial Registration

ClinicalTrials.gov NCT00850837

Utility of colposcopy in a phase 2 portion of a microbicide clinical trial of BufferGel and 0.5% PRO 2000 Gel

Background

The majority of new HIV infections are acquired through heterosexual transmission. There is urgent need for prevention methods to compliment behavior change and condom use. Topical microbicide represent a potential strategy for reduction of HIV transmission in women.

Methods

Monthly Colposcopy evaluations were performed during pelvic examinations among 299 women enrolled in the Phase 2 portion of HPTN 035 study at four sites (1 in USA, 3 in Southern Africa). This was a phase 2/2b, multisite, randomized, and controlled clinical trial with four arms: BufferGel, 0.5% PRO2000 Gel, placebo gel and no gel. At two of the sites, pelvic examinations were conducted by the use of naked eye without colposcopy.

Results

A colposcopy finding of any kind was detected in 48% of participants at baseline compared to 40% at 3 months (p =0.04). The lower rates were also observed in vaginal discharge (22% at baseline, 16% at 3 months, p=0.06), erythema (15% at baseline, 8% at 3 months, p=0.004). The trend towards significance at p=0.05 disappear when utilizing stringent statistical significance levels. A pelvic finding of any kind was detected in 71% of colposcopy participants compared to 41% of participants who had naked eye examination only conducted at two sites that performed both colposcopy and naked eye without colposcopy. Use of colposcopy yielded significantly higher rates of participants with deep epithelial disruption, erythema and ecchymosis. We observed no cases of incident Chlamydia, Gonorrhea, or Syphilis during the three month follow up. There were 2 cases of incident HIV during 3-month study period neither of which was associated with any abnormal colposcopy evaluation findings.

Conclusion

No safety signals were observed in the 4 study arms, allowing seamless transition from phase 2 to 2b. Colposcopy utility in microbicide clinical trials has minimal value given high rates of background noise findings of no relevant clinical significance.

An exploratory, randomized, crossover MRI study of microbicide delivery with the SILCS diaphragm compared to a vaginal applicator

BACKGROUND

Microbicide gels studied for HIV prevention often are delivered via a single-use vaginal applicator. Using a contraceptive diaphragm such as the SILCS diaphragm for gel delivery could have advantages, including lower cost and additional pregnancy prevention.

STUDY DESIGN

We performed an exploratory, nonblinded, randomized, crossover study among healthy, sexually active, nonpregnant women. Using BufferGel, we evaluated three microbicide delivery methods for gel distribution and retention: SILCS single-sided gel delivery, SILCS double-sided gel delivery and a vaginal applicator (without SILCS). Magnetic resonance images were taken at baseline, after gel insertion, and immediately and 6 h after simulated intercourse. Three women completed all gel delivery methods described in this article.

RESULTS

Magnetic resonance imaging analysis indicated similar gel spread in the vagina among all three methods. SILCS single-sided gel application resulted in the most consistent longitudinal coverage; SILCS double-sided gel application was the most consistent in the transverse dimension.

CONCLUSIONS

Gel coverage was similar with all three methods. These results suggest that the SILCS microbicide delivery system is comparable to vaginal applicators for delivery of gel products intravaginally.

Topical microbicides for prevention of sexually transmitted infections

BACKGROUND

Two decades of research on topical microbicides for prevention of sexually transmitted infections (STIs) have had limited success. However, new microbicide randomised controlled trial (RCT) data have recently been published; but these have not yet been the subject of a systematic review.

OBJECTIVES

To determine the effects of topical microbicides for prevention of the acquisition of STIs, including human immunodeficiency virus (HIV) infection, by women from men and by men who have sex with men (MSM).

SEARCH METHODS

In July 2011 we searched the Cochrane Central Register of Controlled Trials (CENTRAL), PubMed, EMBASE, Web of Science, NLM Gateway, CLIB, AIDS Education Global Information System, ClinicalTrials.gov and the World Health Organization (WHO) International Clinical Trials Registry Platform; handsearched reference lists of relevant articles and contacted relevant organisations and experts.

SELECTION CRITERIA

RCTs of topical microbicides (except Nonoxynol-9) in sexually active, HIV-negative women or MSM. We excluded Nonoxynol-9 because previous systematic reviews showed that it does not have a significant effect on HIV or STIs.

DATA COLLECTION AND ANALYSIS

We assessed study eligibility, extracted data and assessed risk of bias in duplicate; resolving differences by discussion and consensus. We then conducted fixed-effect meta-analysis, stratified by type of microbicide.

MAIN RESULTS

We found that by the end of 2011, nine microbicide RCTs had either been conducted to term (one BufferGel and 0.5% PRO 2000, one Carraguard and one tenofovir trial) or stopped early due to safety concerns (two cellulose sulphate trials) or insufficient rate of HIV infection and low likelihood of showing a protective effect (one 2% PRO 2000, one tenofovir and two SAVVY trials). The nine RCTs enrolled 31,941 sexually active women between 2004 and 2011; in Benin, Ghana, Malawi, Nigeria, South Africa, Tanzania, Uganda, Zambia, Zimbabwe, India, and the US. A small proof-of-concept RCT found that tenofovir (a nucleotide reverse transcriptase inhibitor) reduced the risk of HIV acquisition (one trial, 889 women; risk ratio (RR) 0.63; 95% CI 0.43 to 0.93). Effectiveness data are not yet available from the second tenofovir RCT that enrolled 5000 women and was stopped early due to low likelihood of showing a protective effect. We found no evidence of an effect on HIV acquisition for cellulose sulphate (2 trials, n = 3069; RR 1.20; 95% CI 0.74 to 1.95), SAVVY (two trials, n = 4295; RR 1.38; 95% CI 0.79 to 2.41), Carraguard (one trial, n = 6202; RR 0.89; 95% CI 0.71 to 1.11), PRO 2000 (two trials, n = 12,486; RR 0.93, 95% CI 0.77 to 1.14) and BufferGel (one trial, n = 1546; RR 1.05; 95% CI 0.73 to 1.52). Tenofovir reduced the incidence of herpes simplex virus type 2 (HSV-2) infection (one trial, 426 women; RR 0.55; 95% CI 0.37 to 0.83) and cellulose sulphate reduced the risk of chlamydia infection (two trials, n = 3069; RR 0.70, 95% CI 0.49 to 0.99). However, there was no evidence of an effect of any microbicide on the acquisition of gonorrhoea, syphilis, condyloma acuminatum, trichomoniasis, or human papillomavirus (HPV) infection. A substudy of the Carraguard trial found the prevalence of high-risk HPV infection (HR-HPV) to be 23.5% in women on Carraguard and 23.0% on placebo (n = 1718; RR 1.02; 95% CI 0.86 to 1.21). After controlling for HR-HPV risk factors, the authors found that compliant Carraguard users were 0.62 (95% CI 0.41 to 0.94) times as likely to be HR-HPV positive as compliant placebo users. Overall, there was no significant difference in the incidence of adverse events between microbicide and placebo groups.

AUTHORS' CONCLUSIONS

Limited evidence suggests that vaginal tenofovir microbicides may reduce the risk of acquisition of HIV and HSV-2 infections in women; but other types of topical microbicides have not shown evidence of an effect on HIV or STI acquisition. Therefore, there is not enough evidence to recommend topical microbicides for HIV or STI prevention at present. Further studies are needed to confirm the beneficial effects of tenofovir microbicide gel in vaginal sex. In addition, further research should continue on the development and testing of new microbicides. If the effectiveness of the tenofovir and/or other microbicides is confirmed in further studies, there will need to be a clear pathway to rapid regulatory approval. Successful launch of the effective gel would depend on having in place appropriate mechanisms for distribution to the women who need it, along with a strategy for ensuring that they use it correctly.

Vaginal film drug delivery of the pyrimidinedione IQP-0528 for the prevention of HIV infection

PURPOSE

Polymeric quick-dissolving films were developed as a solid dosage topical microbicide formulation for the vaginal delivery of the highly potent and non-toxic, dual-acting HIV nonnucleoside reverse transcriptase inhibitor (NNRTI) pyrimidinedione, IQP-0528.

METHODS

Formulated from approved excipients, a polyvinyl alcohol (PVA) based film was manufactured via solvent casting methods. The film formulations were evaluated based upon quantitative physicochemical evaluations defined by a Target Product Profile (TPP) RESULTS: Films dosed with 0.1% (w/w) of IQP-0528 disintegrated within 10 min with over 50% of drug released and near 100% total drug released after 30 min. The IQP-0528 films were found to be non-toxic in in vitro CEM-SS and PBMC cell-based assays and biologically active with sub-nanomolar efficacy against HIV-1 infection. In a 12 month stability protocol, the IQP-0528 films demonstrated no significant degradation at International Conference on Harmonization (ICH) recommended standard (25°C/65% relative humidity (R.H.)) and accelerated (40°C/75% R.H.) environmental conditions.

CONCLUSIONS

Based on the above evaluations, a vaginal film formulation has been identified as a potential solid dosage form for the vaginal delivery of the topical microbicide candidate IQP-0528.

Development of a combination microbicide gel formulation containing IQP-0528 and tenofovir for the prevention of HIV infection

In light of the increasing worldwide AIDS pandemic, there is a continuing need to develop new prevention strategies to inhibit the transmission of HIV-1. In the absence of a successful vaccine, topical microbicides represent the best strategies to reduce the epidemic. Following the success of HIV therapeutic cocktail strategies, combinations of microbicides including nucleotide reverse transcriptase inhibitors (NtRTIs) and nonnucleoside reverse transcriptase inhibitors (NNRTIs) may offer significant protection from infection over single agents. We have developed a combination microbicide gel formulation for the delivery of IQP-0528, a novel NNRTI, and tenofovir (TFV), a NtRTI. Gel formulations were evaluated based on quantitative viscoelastic and physiochemical evaluations defined by a target product profile (TPP). For the majority of the evaluations, the gel formulations behaved similarly; all showed shear thinning behavior, were stable, nontoxic, and active against HIV-1 infection. Gel formulation F2759 displayed increased drug release of 289 ± 100 µg/(cm(2) h(1/2) ) and a tissue permeability of 60 times the half maximal effective concentration (EC(50) ) of TFV and 800 times the EC(50) of IQP-0528. In addition, F2759 showed osmolality within TPP and the highest performance in gel spreading. We have identified a gel formulation to deliver a combination microbicide of IQP-0528 and TFV that has significant potential to prevent infection of HIV-1.

Vaginal irritation models: the current status of available alternative and in vitro tests

Mucosal surfaces, such as the vaginal epithelium, are natural barriers to infection that are constantly exposed to bacteria and viruses, and are therefore potential sites of entry for numerous pathogens. The vaginal epithelium can be damaged mechanically, e.g. by the incorrect use of objects such as tampons, and by chemicals that are irritating or corrosive. Consequently, this can lead to an increase in susceptibility to further damage or infection. Pharmaceutical, cosmetic and personal care products that are specifically formulated for application onto human external mucosae can occasionally induce undesirable local or systemic side-effects. Therefore, the compatibility of applied materials with this mucosal surface represents a key issue to be addressed by manufacturers. The most frequently used method for assessing vaginal mucosal irritation is the in vivo rabbit vaginal irritation test. However, the current emphasis in the field of toxicology is to use alternative in vitro methods that reduce, refine, and replace the use of animals, and which model and predict human, not animal, responses. Such an approach is of particular interest to the personal care and cosmetic industries in their effort to comply with European legislative measures, such as the 7th Amendment to the EU Cosmetics Directive that does not permit the marketing of cosmetic products if they, or their ingredients, have been tested for irritation responses in animals. The focus of this review is to provide an overview of the alternative and in vitro tests that are currently available for vaginal mucosal irritation assessment, and which are already used, or may become useful, to establish the safety of newly-designed products for human use.

Safety and effectiveness of BufferGel and 0.5% PRO2000 gel for the prevention of HIV infection in women

OBJECTIVE

To determine the safety and effectiveness of BufferGel and 0.5% PRO2000 microbicide gels for the prevention of male-to-female HIV transmission.

DESIGN

Phase II/IIb, randomized, placebo-controlled trial with three double-blinded gel arms and an open-label no gel arm.

METHODS

Study participants from Malawi, South Africa, Zambia, Zimbabwe, and the USA were instructed to apply study gel up to 1 h before each sex act and safety, sexual behavior, pregnancy, gel adherence, acceptability, and HIV serostatus were assessed during follow-up.

RESULTS

The 3101 enrolled women were followed for an average of 20.4 months with 93.6% retention and 81.1% self-reported gel adherence. Adverse event rates were similar in all study arms. HIV incidence rates in the 0.5% PRO2000 gel, BufferGel, placebo gel, and no gel arms were 2.70, 4.14, 3.91, and 4.02 per 100 women-years, respectively. HIV incidence in the 0.5% PRO2000 gel arm was lower than the placebo gel arm (hazard ratio = 0.7, P = 0.10) and the no gel arm (hazard ratio = 0.67, P = 0.06). HIV incidence rates were similar in the BufferGel and both placebo gel (hazard ratio = 1.10, P = 0.63) and no gel control arms (hazard ratio = 1.05, P = 0.78). HIV incidence was similar in the placebo gel and no gel arms (hazard ratio = 0.97, P = 0.89).

CONCLUSION

The 0.5% PRO2000 gel demonstrated a modest 30% reduction in HIV acquisition in women. However, these results were not statistically significant and subsequent findings from the Microbicide Development Programme (MDP) 301 trial have confirmed that 0.5% PRO2000 gel has little or no protective effect. BufferGel did not alter the risk of HIV infection. Both products were well tolerated.

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.

A phase I randomized placebo controlled trial of the safety of 3% SPL7013 Gel (VivaGel®) in healthy young women administered twice daily for 14 days

Objective

To assess the safety of VivaGel® used vaginally twice daily for 14 days among healthy, sexually-abstinent women, aged 18–24 years in the USA and Kenya.

Design

Randomized placebo controlled trial.

Methods

Participants were randomized 2∶1, VivaGel to placebo. Safety was assessed by comparing genitourinary (GU) adverse events (AEs), colposcopy findings, vaginal lactobacilli and laboratory abnormalities by arm.

Results

Fifty-four women were enrolled; 35 in the VivaGel arm and 19 in the placebo arm. Twenty-six (74%) and 10 (53%) women reported taking all doses of VivaGel and placebo, respectively. No grade 3 or 4 AEs, or serious AEs occurred. Twenty-five (71%) participants in the VivaGel arm compared to 10 (53%) participants in the placebo arm had at least one grade 1 or 2 GU AE associated with product use (RR = 1.4, 95% CI 0.8-2.2). All seven grade 2 GU AEs associated with product use occurred among four women in the VivaGel arm. Vulvar and cervical erythema, cervical lesions, symptomatic BV, urinary frequency and metrorrhagia were more common in the VivaGel arm than the placebo arm. Twenty-nine (83%) participants in the VivaGel arm had a colposcopic finding compared to 10 (53%) participants in the placebo arm (RR = 1.6, 95%CI = 1.0-2.5). Two women in the VivaGel arm prematurely discontinued product use themselves due to a reported GU AE. Persistence of H₂O₂-producing and non-producing lactobacilli did not differ by study arm.

Conclusions

GU AEs and colposcopic findings consistent with mild epithelial irritation and inflammation occurred more commonly among women in the VivaGel arm.

Trial Registration

ClinicalTrials.gov NCT003311032

Application of nanotechnologies for improved immune response against infectious diseases in the developing world

There is an urgent need for new strategies to combat infectious diseases in developing countries. Many pathogens have evolved to elude immunity and this has limited the utility of current therapies. Additionally, the emergence of co-infections and drug resistant pathogens has increased the need for advanced therapeutic and diagnostic strategies. These challenges can be addressed with therapies that boost the quality and magnitude of an immune response in a predictable, designable fashion that can be applied for wide-spread use. Here, we discuss how biomaterials and specifically nanoscale delivery vehicles can be used to modify and improve the immune system response against infectious diseases. Immunotherapy of infectious disease is the enhancement or modulation of the immune system response to more effectively prevent or clear pathogen infection. Nanoscale vehicles are particularly adept at facilitating immunotherapeutic approaches because they can be engineered to have different physical properties, encapsulated agents, and surface ligands. Additionally, nanoscaled point-of-care diagnostics offer new alternatives for portable and sensitive health monitoring that can guide the use of nanoscale immunotherapies. By exploiting the unique tunability of nanoscale biomaterials to activate, shape, and detect immune system effector function, it may be possible in the near future to generate practical strategies for the prevention and treatment of infectious diseases in the developing world.

Development of topical microbicides to prevent the sexual transmission of HIV

Women comprise almost 50% of the population of people living with HIV and the majority of these women contracted the virus through sexual transmission in monogamous relationships in the developing world. In these environments, where women are not empowered to protect themselves through the negotiation of condom use, effective means of preventing HIV transmission are urgently needed. In the absence of an approved and effective vaccine, microbicides have become the strategy of choice to provide women with the ability to prevent HIV transmission from their infected partners. Topical microbicides are agents specifically developed and formulated for use in either the vaginal or rectal environment that prevent infection by sexually transmitted infectious organisms, including pathogenic viruses, bacteria and fungi. Although a microbicidal product will have many of the same properties as other anti-infective agents and would be similarly developed through human clinical trials, microbicide development bears its own challenges related to formulation and delivery and the unique environment in which the product must act, as well as the requirement to develop a product that is acceptable to the user. Herein, perspectives based on preclinical and clinical microbicide development experience, which have led to an evolving microbicide development algorithm, will be discussed. This article forms part of a special issue of Antiviral Research marking the 25th anniversary of anti-retroviral drug discovery and development, Vol 85, issue 1, 2010.

Pharmaceutical development of microbicide drug products

HIV infection rates in the developing world remain a serious problem. One potential approach to reduce infection rates is to use products known as microbicides, referred to herein as microbicide drug products (MDPs). These are drugs capable of, when administered topically to the vagina (or rectum), interfering with infection by one or more mechanisms. This review article covers the latest pharmaceutical developments in the area of microbicides dosage forms and delivery systems. These products are principally designed for use in the developing world and must therefore address cultural and societal issues generally unknown in the developed world. The first-generation microbicides evaluated clinically were principally polyanions. These drugs, administered intravaginally as gels, were found to be ineffective in preventing transmission of HIV from men to women. Second-generation drugs such as tenofovir, dapivirine, and UC781 are reverse transcriptase inhibitors developed as gels formulations and intravaginal rings (IVRs). Gels are considered coitally-related products while IVRs are coitally-independent systems designed to release the drug over a four-week period or possibly longer (up to 3 or 4 months). Other dosage forms under development include fast dissolving films, tablets/capsules, and possibly vaginal sponges. Dual protection systems are also under development. These systems include formulations capable of preventing HIV infection along with a second drug capable of preventing conception or other viral infections such as HSV.

Microbicidal spermicide or spermicidal microbicide?

Vaginal contraception, the oldest method of fertility regulation that remained virtually forgotten for a few decades has recently come under focal review due to an increase in STDs and HIV infections worldwide. Today it is being considered very strongly that a conceptual microbicidal spermicide can tender protection against pregnancy as well as STDs (including AIDS), simultaneously. However the two activities (spermicidal and microbicidal) need to be integrated in vaginal preparations, as many women across the world may be concerned more about the unwanted pregnancy rather than the STI during a coital act. A strong detergent like nonoxynol-9 (N-9) has been used as a spermicide in many local contraceptive preparations and studies have shown that it also exhibits significant microbicidal activity in vitro. However, recent clinical trials have shown that detergent spermicides do not provide any protection against STDs and AIDS but may in fact even promote their transmission. This anomaly has largely been attributed to their surfactant nature that irritates the vagina and kills the normal vaginal flora making it more susceptible to STD infections. An urgent need for a suitable non-detergent spermicide has thus emerged to replace N-9 in local contraceptive preparations. Anticipating the potential of spermicide-based vaginal contraceptives in the reproductive health of women, a large number of synthetic, non-detergent molecules were designed and evaluated at this Institute over recent years. Simultaneously, a number of natural products from terrestrial plants and marine flora/fauna were also evaluated for spermicidal activity. A local contraceptive preparation incorporating the active ingredient from the fruit pericarp of Sapindus mukorossi has successfully completed Phase III clinical trials in India and is ready for marketing. Recent studies have indicated that in comparison to N-9, this ingredient is much less toxic to Lactobacillus spp. and effectively inhibits the growth of Trichomonas vaginalis in vitro. Other candidate spermicides/microbicides under development worldwide have been reviewed briefly.

Formulating a sulfonated antiviral dendrimer in a vaginal microbicidal gel having dual mechanisms of action

SPL7013 is the sodium salt of a sulfonated dendrimer that has potent antiviral properties. VivaGel, a topical gel containing 3% (wt/wt) SPL7013, is in development as a vaginal microbicide. BufferGel is a Carbopol-based acidic buffering gel that enhances the natural protective action of the vagina to produce a broad-spectrum microbicidal environment. The positive attributes of both gels were combined into a combination vaginal microbicidal gel having dual mechanisms of action. A 3% (wt/wt) SPL7013 combination gel, pH 3.7, was developed and fully characterized and was shown to have more than twofold greater acidic buffering capacity than BufferGel. Ultracentrifugation experiments demonstrated that SPL7013 was not sequestered or entropically trapped in the viscous gel, thereby confirming, along with viral challenge studies, that SPL7013 has sufficient mobility in the viscous gel to exert antiviral properties.

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 drug delivery systems for HIV prevention

Microbicides have become a principal focus for HIV prevention strategies. The successful design of drug delivery systems for vaginal microbicide drug candidates brings with it a multitude of challenges. It is imperative that the chemical and physical characteristics of the drug candidate and its mechanism of action be clearly understood and considered to successfully deliver and target drug candidates efficiently. In addition, an understanding of the dynamic nature of the vaginal environment, the tissue and innate barriers present, as well as patient preferences are critical considerations in the design of effective microbicide products. Although the majority of drug candidates clinically evaluated to date have been delivered using conventional semisolid aqueous-based gel dosage forms, drug delivery system design has recently been extended to include advanced delivery systems such as vaginal rings, quick-dissolve films, and tablets. Ultimately, it may be necessary to develop multiple dosage platforms for a single active agent to provide users with options that can be used within the constraints of their social environment, personal choice, and environmental conditions.

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.

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.

Preclinical evaluation of lime juice as a topical microbicide candidate

BACKGROUND

The continued growth of the global HIV epidemic highlights the urgent need to develop novel prevention strategies to reduce HIV transmission. The development of topical microbicides is likely to take a number of years before such a product would be widely available. This has resulted in a call for the rapid introduction of simpler vaginal intervention strategies in the interim period. One suggested practice would be vaginal douching with natural products including lime or lemon juice. Here we present a comprehensive preclinical evaluation of lime juice (LiJ) as a potential intervention strategy against HIV.

RESULTS

Pre-treatment of HIV with LiJ demonstrated direct virucidal activity, with 10% juice inactivating the virus within 5 minutes. However, this activity was significantly reduced in the presence of seminal plasma, where inactivation required maintaining a 1:1 mixture of neat LiJ and seminal plasma for more than 5 minutes. Additionally, LiJ demonstrated both time and dose-dependent toxicity towards cervicovaginal epithelium, where exposure to 50% juice caused 75-90% toxicity within 5 minutes increasing to 95% by 30 minutes. Cervicovaginal epithelial cell monolayers were more susceptible to the effects of LiJ with 8.8% juice causing 50% toxicity after 5 minutes. Reconstructed stratified cervicovaginal epithelium appeared more resilient to LiJ toxicity with 30 minutes exposure to 50% LiJ having little effect on viability. However viability was reduced by 75% and 90% following 60 and 120 minutes exposure. Furthermore, repeat application (several times daily) of 25% LiJ caused 80-90% reduction in viability.

CONCLUSION

These data demonstrate that the virucidal activity of LiJ is severely compromised in the presence of seminal plasma. Potentially, to be effective against HIV in vivo, women would need to apply a volume of neat LiJ equal to that of an ejaculate, and maintain this ratio vaginally for 5-30 minutes after ejaculation. Data presented here suggest that this would have significant adverse effects on the genital mucosa. These data raise serious questions about the plausibility and safety of such a prevention approach.

A Phase I study of the functional performance, safety and acceptability of the BufferGel Duet

BACKGROUND

The purpose of this study was to assess the functional performance of the BufferGel Duet, a buffering microbicide and spermicide gel applied to the cervix and vagina by a novel applicator that also serves as a mechanical barrier.

STUDY DESIGN

This was a noncomparative Phase I safety trial in 30 healthy couples, aged 20-50 years, at low risk for sexually transmitted infections, who agreed to use the gel-device combination twice in 1 week and respond to detailed questionnaires about their experience. The female participants were examined with colposcopy before and 6-18 h after using the second device.

RESULTS

Based on written instructions alone, 25 women successfully placed and 28 women successfully removed the device. Three women reported feeling the device dislodge around the time of intercourse. The product was equally acceptable to both men and women. Most users concluded that intercourse was the same or better with the device than with no product. About 73% would choose Duet over male condoms, and no one preferred the standard diaphragm. Colposcopic findings were noted in 79% of women with external genital findings (9) or cervicovaginal peeling (18) predominating. Only one finding breached the epithelium. Most product-related adverse events were mild (10/11) and confined to the genitourinary tract.

CONCLUSIONS

The successful placements and acceptability suggest that further product development is warranted and could target over-the-counter use. During increased duration of use or more frequent dosing, cervicovaginal monitoring is advised based on the extent of peeling and external colposcopic findings in this short-term study.

Microbicide research in developing countries: have we given the ethical concerns due consideration?

BACKGROUND

HIV prevention research has been fraught with ethical concerns since its inception. These concerns were highlighted during HIV vaccine research and have been elaborated in microbicide research. A host of unique ethical concerns pervade the microbicide research process from trial design to post-trial microbicide availability. Given the urgency of research and development in the face of the devastating HIV pandemic, these ethical concerns represent an enormous challenge for investigators, sponsors and Research Ethics Committees (RECs) both locally and internationally.

DISCUSSION

Ethical concerns relating to safety in microbicide research are a major international concern. However, in the urgency to develop a medically efficacious microbicide, some of these concerns may not have been anticipated. In the risk-benefit assessment of research protocols, both medical and psycho-social risk must be considered. In this paper four main areas that have a potential for medical and/or psycho-social harm are examined. Male partner involvement is controversial in the setting of covert use of microbicides. However, given the long-term exposure of men to experimental products, this may be methodologically, ethically and legally important. Covert use of microbicides may impact negatively on relationship dynamics leading to psychosocial harm to varying extents. The unexpectedly high rates of pregnancy during clinical trials raise important methodological and ethical concerns. Enrollment of adolescents without parental consent generates ethical and legal concerns that must be carefully considered by RECs and trial sites. Finally, paradoxical outcomes in recent trials internationally have advanced the debate on the nature of informed consent and responsibility of researchers to participants who become HIV positive during or after trials.

SUMMARY

Phase 3 microbicide trials are an undisputed research and ethical priority in developing countries. However, such trials must be conducted with attention to both methodological and ethical detail. It is imperative that guidelines are formulated to ensure that high ethical standards are maintained despite the scientific urgency of microbicide development. Given the controversy raised by emergent ethical issues during the course of microbicide development, it is important that international consensus is reached amongst the various ethics and regulatory agencies in developing and developed countries alike.

Lime Juice as a Candidate Microbicide? An Open-Label Safety Trial of 10% and 20% Lime Juice Used Vaginally

OBJECTIVE

Lime has a long history as a contraceptive and vaginal hygiene douche, and ongoing use in Africa is documented. We report on the first safety study on diluted lime juice to assess its potential as a candidate microbicide.

METHODS

Twenty-five sexually abstinent women were randomly assigned to apply a 10% or 20% concentration of lime juice or 0% (water-only) through a soaked tampon once daily for 14 consecutive days. Tests for genital infections, measurement of inflammatory biomarkers, and a colposcopy were performed before and after treatment.

RESULTS

No participant showed severe vaginal irritation. Two women developed a yeast infection after using lime juice. More than 70% of women in all groups reported side effects, most being singular, mild, and transient events. The users of 20% diluted lime juice experienced a significantly higher frequency of burning and dryness. Vaginal inflammatory biomarkers showed no significant change between preexposure and postexposure levels. The naturally low vaginal pH showed little change, and lactobacilli colonization did not decrease.

CONCLUSIONS

Lime juice up to 20% concentration has an acceptable safety profile for vaginal use. However, as new in vitro research shows that the effectiveness of lime juice to prevent HIV transmission in concentrations lower than >or=50% is unlikely and concentrations of 50% have been shown to be toxic, women should be discouraged from commencing or continuing the vaginal use of lime juice.

Contraceptive Efficacy of a Novel Spermicidal Microbicide Used With a Diaphragm

OBJECTIVE

Women need products that protect against both pregnancy and sexually transmitted infections, including human immunodeficiency virus (HIV). The acid buffering gel is a nondetergent spermicide that may provide this dual protection by reinforcing normal vaginal acidity to inactivate both sperm and acid-sensitive sexually transmitted pathogens. The objective of this study was to assess the gel's contraceptive effects, safety, and acceptability.

METHODS

We conducted a multicenter, randomized, double-masked, noninferiority study at 11 centers, comparing 621 women who used an acid buffering gel plus diaphragm with 300 women who used a nonoxynol-9 spermicide plus diaphragm for 6 months. A double-masked study extension followed 234 women for an additional 6 months of use.

RESULTS

The 6-month pregnancy rate per hundred women was 10.1% (95% confidence interval [CI] 7.1-13.1%) for acid buffering gel and 12.3 (95% CI 7.7-16.9) for nonoxynol-9 spermicide users. The difference in rates was -2.2% with a 95% CI -7.7 to 3.3%. Consistent and correct use 6-month pregnancy rates were 4.7% for acid buffering gel and 6.1% for nonoxynol-9 spermicide users, calculated from those cycles where diary entries indicated such use. Adverse events and acceptability were similar between the two groups. Pregnancy probabilities were similar between groups participating in the 12-month study extension.

CONCLUSION

An acid buffering gel used with a diaphragm is a safe, acceptable contraceptive with efficacy comparable to that of a common commercial spermicide with diaphragm.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, www.ClinicalTrials.gov, NCT00065858

LEVEL OF EVIDENCE

I.

Safety, tolerance and acceptability of the Invisible Condom® and its vaginal applicator in healthy women and their male sexual partners

OBJECTIVES

The study was conducted to evaluate the safety and acceptability of the Invisible Condom when applied once or twice daily for 14 days in healthy women and their male sexual partners.

STUDY DESIGN

Forty-one women and 23 men divided into three cohorts were enrolled. Cohort 1:14 sexually abstinent women applying gel twice daily for 14 days; Cohort 2:14 sexually active women with tubal ligation applying gel once daily for 14 days and their 14 sexual partners who did not use gel; Cohort 3:13 women on oral contraceptive applying gel once daily for 14 days and 9 of their sexual partners.

RESULTS

No serious adverse events (AEs) were reported. Colposcopy showed no genital ulceration nor epithelial lesions. No major changes in vaginal flora or vaginal pH were detected. None of the women had to stop product application because of AEs. The majority of AEs were mild. Common AEs were itching, dryness, burning sensation, erythema and discharge. Satisfaction questionnaire showed that the gel and applicator were acceptable.

CONCLUSION

The Invisible Condom and applicator were safe, well tolerated and acceptable when applied intravaginally for 14 days. Thus, expanded safety and effectiveness evaluation is warranted.