Willingness to use microbicides is affected by the importance of product characteristics, use parameters, and protective properties

Who prefers what? Correlates of preferences for next-generation HIV prevention products among a national U.S. sample of young men who have sex with men

INTRODUCTION

Pre-exposure prophylaxis (PrEP) has been available for young people for over a decade, yet only ∼15% of young people in the United States with indications for PrEP have a prescription for it. Next-generation PrEP modalities may address some of the challenges of daily oral PrEP. However, preferences for these products are unknown.

METHODS

From October 2020 to June 2021, we conducted an online survey of 737 cisgender, young men who have sex with men (age 15-24 years) without HIV across the United States who reported same-sex attraction or consensual sex with another man in the past 6 months. Participants completed a conjoint experiment comparing daily oral pills, event-driven oral pills, event-driven rectal douches, intramuscular injections, intravenous broadly neutralizing antibody (bnAb) infusions and subcutaneous implants. Participants ranked the products from most to least preferred. Exploded logit models examined the association between ranked preferences of PrEP modalities and socio-demographic and behavioural characteristics.

RESULTS

Participants' mean age was 21 years (SD = 2.3), and 56% identified as White. Nineteen percent were currently taking daily oral PrEP, and another 9% had previously taken it. Participants prioritized efficacy, absence of side effects and costs in the conjoint analyses. Daily oral PrEP had the highest preference ranking, followed by event-driven oral (OR = 0.89, p = 0.058), injectable (OR = 0.83, p = 0.005), implant (OR = 0.48, p < 0.0001), bnAb infusions (OR = 0.38, p < 0.0001) and rectal douches (OR = 0.24, p < 0.0001). There were differences in PrEP preferences across age, insurance status, sexual behaviour, PrEP use history, HIV and sexually transmitted infection (STI) testing history, and STI diagnoses (omnibus tests: p < 0.05). Participants also provided reasons for selecting their top product choice: ease of use for those who chose daily oral (99%) and daily event-driven (98.5%); feel more protected against HIV for those who chose injectable (95.4%) and implants (100%); not worrying about forgetting to take it for those who chose bnAbs (93.8%); and being able to stop taking it when they want for those who chose rectal douche (90.9%).

CONCLUSIONS

Next-generation modalities were less likely to be preferred over daily oral PrEP, with differences in the magnitude by socio-demographic and behavioural characteristics. Given the low uptake of daily oral PrEP, end-users' preferences for and concerns about PrEP products must be understood to ensure high acceptability and penetration.

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.

Users' Preferred Characteristics of Vaginal Rings for HIV Prevention: A Qualitative Analysis of Two Phase I Trials

Vaginal rings address a critical need for an independently initiated, long-acting HIV prevention method, but their design must be acceptable to promote uptake and adherence. Human-centered design (HCD) may help address design preference questions. In two Phase I studies of vaginal rings for HIV prevention conducted in the United States, we used qualitative interviews to assess participants' perceptions and opinions of the physical characteristics of the ring they used and of a ring's physical characteristics after comparing four ring designs presented via a visual tool. Users were found to prefer ring designs that appear easy to use, are physically comfortable, that function well, and are aesthetically pleasing. The parameters for these features varied widely. Product developers and marketers should consider marketing messages in which the target users feel this product is made to meet their needs and desires. Product developers are encouraged to design using HCD early in ring development (Clinical Trial Registration number: NCT03234400 and NCT03670355).

Development of multipurpose technologies products for pregnancy and STI prevention: update on polyphenylene carboxymethylene MPT gel development†

Current modern contraceptives rely heavily on the use of hormones. These birth control drug products, including pills, patches, injections, and IUDS, have been extremely beneficial to millions of women and their families over the past 50 years. But a surprisingly high number of women abandon such modern methods, many because they cannot tolerate the side effects and others because they have medical issues for which hormonal methods are contraindicated. In addition, modern hormonal methods are simply not available to many women. The extent of this problem is steadily becoming more apparent. We present the case for developing simple nonhormonal vaginal products that women can use when needed, ideal products that are multipurpose and offer both contraception and sexually transmitted disease protection. Gel-based vaginal products are particularly well suited for this purpose. Gels are easy to use, highly acceptable to many women, and can be safely formulated to enhance natural vaginal defenses against infection. However, the development of a new chemical entity for this application faces significant technical and regulatory hurdles. These challenges and our solutions are described for polyphenylene carboxymethylene (PPCM), a novel topical drug in a vaginal gel nearing human clinical trials. We have advanced PPCM from benchtop to IND-enabling studies and provide a brief description of the complex development process. We also describe a simple lab assay which can be used as a biomarker for contraceptive activity to enable pharmacodynamic studies in vaginal contraceptive development, both preclinically and in early human clinical trials.

Qualitative exploration of intrinsic and extrinsic factors that influence acceptability of semisoft vaginal suppositories

BACKGROUND

Vaginal microbicides are a promising means to prevent the transmission of HIV and other sexually transmitted infections, by empowering women to initiate use prophylactically when they perceive themselves to be at risk. However, in clinical trials, microbicides have shown mixed results, with the consistent finding that effectiveness varies substantially as a function of user adherence.

METHODS

Based on the assumption that adherence is driven, at least in part, by product properties that influence acceptability, we used softgel technology to develop vaginal drug delivery systems in the intermediate texture space between solids and liquids to overcome potential shortcomings of current dosage forms. Here, we used focus groups and surveys to determine women's initial reactions (i.e., acceptance and willingness-to-try) for semisoft vaginal suppositories intended for HIV and STI prevention, with a specific focus on how perception of and preferences for vaginal suppositories may be influenced by product characteristics such as size, shape, and firmness.

RESULTS

Via focus groups, we identified intrinsic and extrinsic factors relevant to acceptability of semisoft suppository prototypes. Willingness-to-try depended on factors like intended functionality, anticipated leakage, type of sex, recommended frequency of use, type of sexual partner, and perceived risk. When handled ex vivo, shape, size, and firmness of suppositories communicated information about ease of imagined insertion and handling, perceived effectiveness, anticipated awareness and comfort of the product in the body. These impressions were partly based on prior experience with vaginal products.

CONCLUSIONS

Sensory attributes appear to play a substantial role in women's preferences and willingness to try the semisoft suppositories. Using these methods during preclinical development should help efficiently optimize a final product that is both biologically efficacious and preferred by women, toward a goal of enhancing adherence and effectiveness.

Measuring self-efficacy to use vaginal microbicides: the Microbicide Use Self-Efficacy instrument

Objectives To evaluate the psychometric properties of the Microbicide Use Self-Efficacy (MUSE) instrument and to examine correlates of self-efficacy to use vaginal microbicides among a sample of racially and ethnically diverse women living in the north-eastern United States.

METHODS

Exploratory and confirmatory factor analytic methods were used to explore and determine the dimensionality and psychometric properties of the MUSE instrument. Construct validity was assessed by examining the relationships of the MUSE instrument to key sexual behaviour, partner communication, relationship and psychosocial variables.

RESULTS

Two dimensions of self-efficacy to use microbicides were psychometrically validated and identified as 'Adherence and Access' and 'Situational Challenges.' The two four-item subscales measuring Adherence and Access and Situational Challenges had reliability coefficients of 0.78 and 0.85, respectively. Correlates of the two measures were tested at a Bonferroni-adjusted α level of P=0.001, and 19 of 43 variables analysed were found to significantly relate to Adherence and Access, whereas 16 of 43 variables were significantly related to Situational Challenges. Of the 35 significant relationships, 32 were in the domains of partner communication, partner relationships, and behavioural and psychosocial variables.

CONCLUSIONS

The MUSE instrument demonstrated strong internal validity, reliability and initial construct validity. The MUSE instrument can be a useful tool in capturing the multidimensional nature of self-efficacy to use microbicides among diverse populations of women.

Psychometric Properties and Validity of a Multi-dimensional Risk Perception Scale Developed in the Context of a Microbicide Acceptability Study

Currently available risk perception scales tend to focus on risk behaviors and overall risk (vs partner-specific risk). While these types of assessments may be useful in clinical contexts, they may be inadequate for understanding the relationship between sexual risk and motivations to engage in safer sex or one's willingness to use prevention products during a specific sexual encounter. We present the psychometric evaluation and validation of a scale that includes both general and specific dimensions of sexual risk perception. A one-time, audio computer-assisted self-interview was administered to 531 women aged 18-55 years. Items assessing sexual risk perceptions, both in general and in regards to a specific partner, were examined in the context of a larger study of willingness to use HIV/STD prevention products and preferences for specific product characteristics. Exploratory and confirmatory factor analyses yielded two subscales: general perceived risk and partner-specific perceived risk. Validity analyses demonstrated that the two subscales were related to many sociodemographic and relationship factors. We suggest that this risk perception scale may be useful in research settings where the outcomes of interest are related to motivations to use HIV and STD prevention products and/or product acceptability. Further, we provide specific guidance on how this risk perception scale might be utilized to understand such motivations with one or more specific partners.

Use of partial least squares path modelling to assess the willingness of Chinese female sex workers to participate in a microbicide trial

OBJECTIVES

To investigate the willingness of Chinese female sex workers (FSWs) to participate (WTP) in a clinical trial of microbicides; to explore the potential hindrances and facilitating factors; and to provide support for future microbicide clinical trials by tailoring their design to better meet the specific needs of FSWs.

STUDY DESIGN

Cross-sectional study.

METHODS

In total, 404 FSWs were investigated using structured questionnaires. Exploratory factor analysis and partial least squares path modelling were used to explore the correlations between several influencing factors and WTP.

RESULTS

The WTP of FSWs enrolled in this study was high (53.47%, 216/404). Possible benefits from enrolment in the trial were positively associated with WTP, while concern about a hypothetical microbicide, potential physical harm, economic loss from participation, and fear of family or social isolation were negatively associated with WTP.

CONCLUSION

FSWs are appropriate participants in microbicide clinical trials, and are likely to benefit from effective microbicides. In a microbicide clinical trial, it is imperative to ensure protection of the rights, dignity, safety, confidentiality and welfare of FSW participants.

Interest in multipurpose prevention of HIV and pregnancy: perspectives of women, men, health professionals and community stakeholders in two vaginal gel studies in southern Africa

OBJECTIVE

The pipeline of vaginal microbicides for HIV prevention has expanded to include products for multipurpose prevention, but the interests of potential users and those advising on use have not been sufficiently investigated. Rather, assumptions about interest in multipurpose prevention technologies (MPTs) are inferred from what is known about acceptability and use of microbicides or contraceptives.

DESIGN AND SETTING

This paper presents data on concerns and preferences for multipurpose prevention of HIV and pregnancy. Data were collected in two microbicide gel studies in Malawi and Zimbabwe. Participants were women using candidate vaginal products, their male partners, health professionals and community stakeholders.

METHODS

An individual interview was conducted with participants. Interviews were audio-recorded, transcribed, coded for content and analysed for key themes.

RESULTS

Participants indicated strong interest in a vaginal HIV prevention product that could also prevent pregnancy. Reasons for this interest were convenience, problems with adverse effects with current contraceptive methods, concerns about long-term effects of contraceptives, and concerns about the health burdens of HIV infection during pregnancy. The main disadvantage of an MPT was recognition that while interest in preventing HIV is constant, contraceptive needs change over time.

CONCLUSION

The study population indicated support for an MPT to prevent HIV and pregnancy. This support may be further strengthened if the product is also available for prevention of only HIV. Women and men will be more willing to use an MPT if they can be reassured that its use will have no long-term effect on fertility.

Aligning product development and user perspectives: social-behavioural dimensions of multipurpose prevention technologies

Multipurpose prevention technologies provide a compelling response to the multiple and reinforcing sexual and reproductive health risks faced by women globally. To ensure that this potential is realised, product-specific characteristics and their social-behavioural correlates must be considered early in the product development process. This paper provides an overview of the key user-related social and behavioural dimensions of three broad categories of multipurpose prevention technologies: 1) sustained release vaginal rings, 2) pericoital vaginal products, and 3) co-formulated or co-administered injectables. The authors build upon the broad parameters of Target Product Profiles for such products, aligning them with user perspective considerations.

User-identified gel characteristics: a qualitative exploration of perceived product efficacy of topical vaginal microbicides

Research has demonstrated that certain vaginal gel products--microbicides containing antiretroviral drugs--may reduce HIV infection risk among women. But for vaginal gels to avert HIV and other sexually transmitted infections (STIs), at-risk women must be willing to use them as directed. These products must therefore be "acceptable" to women and an important component of acceptability is users' perception that the product will work to prevent infection. We sought to understand how women's perceptions of vaginal gel properties may shape their understanding of product efficacy for HIV and STI prevention. Sixteen women completed two in-depth qualitative interviews (k = 32) to identify the range and types of sensory perceptions they experienced when using two vaginal gels. We identified emergent themes and linkages between users' sensory perceptions and their beliefs about product efficacy. Users' predictions about product efficacy for preventing infection corresponded to measurable physical properties, including gel volume, location in the vagina, coating behavior, sensation of the gel in the vagina, leakage, and gel changes during coital acts. Although the women described similar sensory experiences (e.g., gel leaked from the vagina), they interpreted these experiences to have varying implications for product efficacy (e.g., leakage was predicted to increase or decrease efficacy). To improve microbicide acceptability, gel developers should investigate and deliberately incorporate properties that influence users' perceptions of efficacy. When a microbicide is approved for use, providers should educate users to anticipate and understand their sensory experiences; improving users' experience can maximize adherence and product effectiveness.

Designing preclinical perceptibility measures to evaluate topical vaginal gel formulations: relating user sensory perceptions and experiences to formulation properties

Abstract The effectiveness of any biomedical prevention technology relies on both biological efficacy and behavioral adherence. Microbicide trials have been hampered by low adherence, limiting the ability to draw meaningful conclusions about product effectiveness. Central to this problem may be an inadequate conceptualization of how product properties themselves impact user experience and adherence. Our goal is to expand the current microbicide development framework to include product "perceptibility," the objective measurement of user sensory perceptions (i.e., sensations) and experiences of formulation performance during use. For vaginal gels, a set of biophysical properties, including rheological properties and measures of spreading and retention, may critically impact user experiences. Project LINK sought to characterize the user experience in this regard, and to validate measures of user sensory perceptions and experiences (USPEs) using four prototype topical vaginal gel formulations designed for pericoital use. Perceptibility scales captured a range of USPEs during the product application process (five scales), ambulation after product insertion (six scales), and during sexual activity (eight scales). Comparative statistical analyses provided empirical support for hypothesized relationships between gel properties, spreading performance, and the user experience. Project LINK provides preliminary evidence for the utility of evaluating USPEs, introducing a paradigm shift in the field of microbicide formulation design. We propose that these user sensory perceptions and experiences initiate cognitive processes in users resulting in product choice and willingness-to-use. By understanding the impact of USPEs on that process, formulation development can optimize both drug delivery and adherence.

Designing a multipurpose technology for acceptability and adherence

Multipurpose Prevention Technologies (MPTs) are new tools aimed at reducing or preventing multiple and overlapping sexual and reproductive health risks faced by women and couples around the globe. While MPTs could prove more acceptable and easier to adhere to than single-purpose prevention products, continuing high rates of HIV and unintended pregnancy remind us that these new products will need to be efficacious, acceptable and effectively used to achieve a public health impact. In this paper, we describe how a range of research methods can be applied during the pre-clinical phase of product development to inform decisions related to formulation and vehicle or product delivery mechanisms, and consider how choices in product-related characteristics may influence future demand for, delivery and use of future products. We draw on examples from the development of new single-purpose HIV and contraceptive products and then extend our discussion to the development of MPTs, including vaginal rings and injections. This article is based on a presentation at the "Product Development Workshop 2013: HIV and Multipurpose Prevention Technologies," held in Arlington, Virginia on February 21-22, 2013. It forms part of a special supplement to Antiviral Research.

Microbicide clinical trial adherence: insights for introduction

After two decades of microbicide clinical trials it remains uncertain if vaginally- delivered products will be clearly shown to reduce the risk of HIV infection in women and girls. Furthermore, a microbicide product with demonstrated clinical efficacy must be used correctly and consistently if it is to prevent infection. Information on adherence that can be gleaned from microbicide trials is relevant for future microbicide safety and efficacy trials, pre-licensure implementation trials, Phase IV post-marketing research, and microbicide introduction and delivery. Drawing primarily from data and experience that has emerged from the large-scale microbicide efficacy trials completed to-date, the paper identifies six broad areas of adherence lessons learned: (1) Adherence measurement in clinical trials, (2) Comprehension of use instructions/Instructions for use, (3) Unknown efficacy and its effect on adherence/Messages regarding effectiveness, (4) Partner influence on use, (5) Retention and continuation and (6) Generalizability of trial participants' adherence behavior. Each is discussed, with examples provided from microbicide trials. For each of these adherence topics, recommendations are provided for using trial findings to prepare for future microbicide safety and efficacy trials, Phase IV post-marketing research, and microbicide introduction and delivery programs.

User experiences and acceptability attributes of the diaphragm and lubricant gel in an HIV prevention trial in southern Africa

Methods for Improving Reproductive Health in Africa (MIRA), a phase III HIV prevention trial, was conducted among 5039 Zimbabwean and South African women to test the Ortho All-Flex diaphragm and Replens(®) lubricant gel. Among the 2418 intervention group participants, 105 women who had completed the trial and 41 male partners participated in focus group discussions and in-depth interviews about the acceptability of the diaphragm and gel and their experiences using the study products. Women who participated in the qualitative study had exited the trial in the prior nine months, were HIV negative, and used the diaphragm and gel for 12-24 months. The comprehensive and flexible conceptual framework was applied to investigate the salient attributes for acceptability of the products as potential HIV prevention methods, and emerging themes for acceptability were framed within three categories of attributes (product, relationship, and sexual intercourse attributes). Both diaphragm and gel were found to be highly acceptable in the study group, and the gel was popular due to its effect of enhancing sexual pleasure. Some of the important product attributes influencing acceptability as reported by users were convenience, ease of use, dual use potential for contraception and disease prevention, and being female-initiated. It was also noted that some elements (such as sexual pleasure, couple communication, and the necessity of diaphragm negotiation) could be more important than others in terms of influencing product acceptability and use. Acceptability attributes reflective of the broader contextual environment (beliefs generated in the trial community suggesting preventive efficacy - preventive method optimism - and gendered norms favoring male superiority in sexual decision making) also emerged as important themes. The high level of acceptability of the diaphragm and gel among MIRA trial participants and their male partners is an indicator of the continued need for an effective female-initiated product.

Antiretroviral-based microbicides and oral pre-exposure prophylaxis for HIV prevention

Numerous HIV prevention options have been tested, with limited success. Microbicides have been the focus of research specifically targeted to prevent new infections among women. After decades of research using non-HIV-specific microbicides, we now have proof of concept for antiretroviral-based microbicides. Issues of drug resistance, frequency of HIV testing and adherence to treatment remain to be explored. Drugs used for HIV treatment and with good safety profiles have been shown to provide protection to men who have sex with men. Ethical issues surrounding cost, access, future design of HIV prevention trials and composition of the prevention package offered to trial participants remain. The role of advocacy and market research will be crucial to ensure effective interventions are accessed and supported. There is renewed hope in the HIV prevention field with collective efforts needed to ensure we get the new prevention tools and options into the hands of men and women at risk of HIV infection. The purpose of this paper is to provide a review of existing research and identify issues for future enquiry.

Using integrated mixed methods to develop behavioral measures of factors associated with microbicide acceptability

Our current understanding of factors associated with microbicide acceptability and consistent use typically has been derived from separate and distinct qualitative or quantitative studies. Specifically, rarely have investigators used mixed methods to both develop and validate behavioral measures. We utilized an integrated mixed methods design, including qualitative metasyntheses, cognitive interviews and expert reviews, psychometric evaluation, and confirmatory qualitative analyses of the correspondence between quantitative items and original qualitative data to develop and validate measures of factors associated with microbicide acceptability and use. We describe this methodology and use the development of the Relationship Context Scale to illustrate it. As a result of independent confirmatory analyses of qualitative passages corresponding to survey items, we demonstrated that items from the same subscales are frequently double coded within a particular textual passage, and thematically related, suggesting associations that resulted in a unique factor structure within the subscale. This integrated mixed method design was critical to the development of this psychometrically validated behavioral measure, and could serve as a model for future measure development.

Clinical evaluation of microbicide formulations

The clinical evaluation of microbicide formulations presents variable and interacting challenges. Specific domains of acceptability, pharmacokinetics, and toxicity interact with each other to potentially inhibit or enhance a microbicide's efficacy. Each of these is further influenced by application and use parameters in the relative presence (or absence) of vaginal and/or seminal fluids, ultimately impacting effectiveness. Historically, acceptability of formulation and use parameters, and their concomitant behavioral influences, have been considered separately from pharmacokinetics and toxicity. While independent evaluation of these elements is necessary in some respects, we must acknowledge that this approach is not sufficient for the successful development of microbicides. Each needs to be considered in an integrated clinical evaluation strategy. This article presents the rationale for such an approach. This article forms part of a special supplement covering two presentations on clinical evaluation of microbicides from the symposium on "Recent Trends in Microbicide Formulations" held on 25 and 26 January 2010, Arlington, VA.

Increasing the effectiveness of vaginal microbicides: a biophysical framework to rethink behavioral acceptability

BACKGROUND

Microbicide candidates delivered via gel vehicles are intended to coat the vaginal epithelium after application. The coating process depends on intrinsic biophysical properties of the gel texture, which restricts the potential choices for an effective product: the gel first must be physically synthesizable, then acceptable to the user, and finally applied in a manner promoting timely adequate coating, so that the user adherence is optimized. We present a conceptual framework anchoring microbicide behavioral acceptability within the fulfillment of the product biophysical requirements.

METHODS

We conducted a semi-qualitative/quantitative study targeting women aged 18-55 in Northern California to assess user preferences for microbicide gel attributes. Attributes included: (i) the wait time between application and intercourse, (ii) the gel texture and (iii) the trade-off between wait time and gel texture. Wait times were assessed using a mathematical model determining coating rates depending upon the gel's physical attributes.

RESULTS

71 women participated. Results suggest that women would independently prefer a gel spreading rapidly, in 2 to 15 minutes (P<0.0001), as well as one that is thick or slippery (P<0.02). Clearly, thick gels do not spread rapidly; hence the motivation to study the trade-off. When asked the same question 'constrained' by the biophysical reality, women indicated no significant preference for a particular gel thickness (and therefore waiting time) (P>0.10) for use with a steady partner, a preference for a watery gel spreading rapidly rather than one having intermediate properties for use with a casual partner (P = 0.024).

CONCLUSIONS

Biophysical constraints alter women's preferences regarding acceptable microbicide attributes. Product developers should offer a range of formulations in order to address all preferences. We designed a conceptual framework to rethink behavioral acceptability in terms of biophysical requirements that can help improve adherence in microbicide use ultimately enhancing microbicide effectiveness.

Microbicides and HIV prevention: lessons from the past, looking to the future

PURPOSE OF REVIEW

This review provides an update on developments in HIV microbicide research in the light of recent phase 3 efficacy studies and discusses how lessons learnt from early generation microbicide candidates can assist the development of future agents.

RECENT FINDINGS

Results of an interim analysis of a phase 3 trial suggested that cellulose sulfate increased the risk of HIV acquisition compared with placebo. Carraguard, SAVVY and Buffergel also failed to show any HIV protection in human efficacy trials. Recent research has focused on elucidating the reasons behind these failures as well as improving the assessment of safety and efficacy for the next generation of microbicide candidates. PRO 2000 0.5% gel is the only HIV microbicide candidate for which there are preliminary data suggesting efficacy in women. Antiretroviral agents and entry inhibitors may provide the key in the future to developing an effective HIV microbicide both for vaginal and rectal use.

SUMMARY

Development of a protective 'barrier' which can be controlled by the receptive partner independent of time of coitus remains a key goal in HIV prevention. A gel or ring-delivered combination of active anti-HIV agents may prove more efficacious than a single agent alone. Challenges in evaluating and manufacturing new candidates must be overcome before a well tolerated, effective, acceptable and affordable microbicide can be produced.

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.

Microbicide acceptability among female sex workers in Beijing, China: results from a pilot study

OBJECTIVES

To explore attitudes toward hypothetical vaginal microbicides and willingness to use them among female sex workers (FSWs) in a district of Beijing, China, and to identify factors likely to affect acceptability and use of microbicides for HIV prevention among this population.

METHODS

An exploratory cross-sectional study using convenience sampling was conducted. A total of 54 FSWs were recruited from Shijingshan District in Beijing for a face-to-face interview. Main outcome variables were measured by a microbicide acceptability score, perception of HIV/STI risk and self-reported high-risk sexual behaviors, condom use, HIV/STI history, and self-reported experience of vaginal product use.

RESULTS

Mean score of microbicide acceptability in FSWs was 2.73, with a standard deviation (SD) of 0.46 (ranging from 1 to 4). Acceptability score varied by partner types (p = 0.025), history of HIV testing (p = 0.037), and concern about contracting an STI (p = 0.042). Covert use of microbicides in FSWs with various sexual partners was statistically different (p = 0.001). FSWs preferred to pay for microbicides and to use them covertly.

CONCLUSIONS

In general, FSWs in Shijinghsan District might have a positive response to microbicides across all hypothetical characteristics. Further study is needed for comprehensive understanding of the contextual factors of microbicide use.

Effect of acculturation on the acceptability of potential microbicides and sexual risk-taking

BACKGROUND

The objective was to determine the acceptability and use patterns of potential microbicides among African American (AA), acculturated Hispanic (AH), and less acculturated Hispanic (LAH) women. We measured baseline sexual risk-taking and the likelihood of behavioral change, given effective microbicides.

METHODS

Interview of 506 Mexican-American and AA women, all of whom have a sexually transmitted infection enrolled in Project Sexual Awareness for Everyone.

RESULTS

The 3 groups reported similarly high acceptance of potential microbicides (76%-83% P = 0.24). LAHs were most likely to report they would use microbicides covertly (P = 0.03). Given the possibility of effective microbicides, AHs were consistently more likely to report risk disinhibition. AHs, as compared to LAHs and AAs, respectively, were most likely to report that they would not use condoms, (53% vs. 33% vs. 30% P <0.001), would have a 1-night stand (18% vs. 8% vs. 6% P = 0.02), or would have sex with humans before they got to know them (18% vs. 8% vs. 6% P = 0.01). AHs were also most likely to say they would or probably would change from baseline safe sexual practices to unsafe sexual behaviors if potential microbicides were available. Age was controlled for in the analysis as AHs were younger than AAs and LAHs.

CONCLUSIONS

Future microbicides were acceptable among this at risk cohort. Acculturation was a predictor of risk disinhibition and should be considered when tailoring sexually transmitted infection prevention messages, given the advent of effective microbicides.

Microbicide acceptability research: recent findings and evolution across phases of product development

PURPOSE OF REVIEW

Research on the acceptability of microbicides has the potential to inform the microbicide development process by shedding light on desirable product characteristics, issues around product use and potential barriers. The purpose of this review is both to synthesize recent findings that are related to microbicide acceptability, highlight areas of deficiencies, and to point to the new directions in which research is needed.

RECENT FINDINGS

Recent studies have assessed acceptability using candidate microbicides in clinical trials, surrogate products, and descriptions of hypothetical products. While most studies have focused on physical characteristics of products, some small studies have investigated participants' short-term experiences with products during sexual intercourse. Overall, as currently measured and in their present formulations, vaginal microbicides have been found to be acceptable to adolescent girls, women, heterosexual men, whereas rectal microbicides were acceptable to men who have sex with men. Few studies have examined acceptability among high-risk HIV-uninfected women. The relationship between acceptability and adherence in trials, and ultimately in real-world settings, remains unknown.

SUMMARY

Data are needed on acceptability of microbicides from larger populations, high-risk HIV-uninfected women, as well as long-term acceptability and contextual factors surrounding acceptability. The association between acceptability and long-term adherence in clinical trials or ultimately in the open market has yet to be demonstrated.