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

Eliciting Preferences for HIV Prevention Technologies: A Systematic Review

Background

Many human immunodeficiency virus (HIV) prevention technologies (pre-exposure prophylaxis, microbicides, vaccines) are available or in development. Preference elicitation methods provide insight into client preferences that may be used to optimize products and services. Given increased utilization of such methods in HIV prevention, this article identifies and reviews these methods and synthesizes their application to HIV prevention technologies.

Methods

In May 2020, we systematically searched peer-reviewed literature in PubMed, CINAHL, and Web of Science for studies employing quantitative preference elicitation methods to measure preferences for HIV prevention technologies among populations of any age, sex, or location. Quality assessment used an existing checklist (PREFS) and a novel adaptation of the Newcastle–Ottawa Scale (PROSPERO #CRD42018087027).

Results

We screened 5022 titles and abstracts, reviewed 318 full texts, and included 84 studies. Common methods employed were discrete-choice experiment (33%), conjoint analysis (25%), and willingness-to-participate/try/accept (21%). Studies were conducted in 25 countries and had a mean of 768 participants (range = 26–7176), two-thirds of them male. Common HIV prevention technologies included pre-exposure prophylaxis (23%), voluntary testing and counseling (19%), HIV self-testing (17%), vaccines (15%), and topical microbicides (9%). Most attributes focused on product design (side effects, frequency), service design (provider type, location), acceptability or willingness to accept/pay; results are summarized in these categories, by prevention type. Mean quality-adapted Newcastle–Ottawa Scale score was 4.5/8 (standard deviation = 2.1) and mean PREFS scores was 3.47/5 (standard deviation = 0.81).

Conclusions

This review synthesizes extant literature on quantitative measurement of preferences for HIV prevention technologies. This can enable practitioners to improve prevention products and interventions, and ultimately reduce HIV incidence.

Qualitative Analysis of Sexually Experienced Female Adolescents: Attitudes about Vaginal Health

STUDY OBJECTIVE

To explore adolescent's perceptions of vaginal health, practices, and vaginally-placed products.

DESIGN

Semistructured interviews were audio-recorded and transcribed until theoretical saturation was achieved.

SETTING

Adolescent medicine clinics in New York City.

PARTICIPANTS

Female adolescents (N = 22) who were sexually experienced, predominately Hispanic (73%, n = 16) with a mean age of 17.7 years (range, 15-20 years).

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Interviews were used to assess perspectives on vaginal health, specific vaginal hygiene practices, and attitudes about vaginally-placed products (contraceptive rings, intrauterine devices), and proposed multipurpose technologies administered as ring or gel). The interviews were transcribed and coded for relevant themes.

RESULTS

Overlapping themes included young women's view of their vagina as a space that needed to be healthy for sexual partners and future fertility. The vagina could not be presumed to be healthy and conversations about vaginal health were limited to include only specific individuals. All reported a variety of practices to maintain their vaginal health, including showering 1-5 times a day and using soaps specifically for the vagina. Attitudes about vaginally-placed products revealed concerns about the sensory experience of having a product in the vagina, safety concerns and interest in the product's objective (prevention of pregnancy or infection).

CONCLUSION

Adolescents have very specific views and practices about their vaginas. Clinicians should initiate conversations about vaginal health and hygiene with adolescents and focus on the normalcy of the vagina. Development of vaginally-placed products should focus on the sensory experience, safety, and purpose of the product.

Hypothetical Rectal Microbicide Acceptability and Factors Influencing It among Men Who Have Sex with Men in Tianjin, China

Objectives

To measure potential acceptability of rectal microbicides and to explore factors likely to affect their acceptability among men who have sex with men (MSM).

Methods

Cross-sectional and retrospective surveys were conducted in this study. A questionnaire and a scale were used to measure the acceptability score for physical and functional characteristics of hypothetical rectal microbicides. We also evaluated the involvement of other factors such as sexual behaviors, social context, etc.

Results

MSMs we interviewed showed a high acceptability to rectal microbicides, indicated by the mean acceptability score of 2.92 (SD, 0.54, scale of 1–4). The results also suggested that microbicides were preferred in a cream form that can moisten and lubricate the rectum, prevent HIV infection and go unnoticed by their partners. Multivariate analysis showed that the microbicides acceptability varied significantly by education level (β = 0.135; P = 0.028), having casual partners (β = 0.174; P = 0.007), frequency of lubricant use (β = 0.134; P = 0.031), history of HIV test (β = 0.129; P = 0.036), willingness to use lubricant (β = 0.126; P = 0.045), locus of control by partners regarding STI infection (β = 0.168; P = 0.009).

Conclusions

A positive response to rectal microbicides among MSMs was found in our study, suggesting that rectal microbicides might have a potential market in MSMs and they might play an important role in HIV/STIs prevention as a supplement. Further studies may be considered to combine the acceptability study with clinical research together to understand the true feelings of MSMs when they use the products.

Acceptability and preferences for vaginal dosage forms intended for prevention of HIV or HIV and pregnancy

This paper reviews key issues found to affect acceptability and preferences for vaginal products to prevent HIV infection or HIV and pregnancy. We focus on the interplay between the biological and physico-chemical aspects of formulation and the social and behavioral issues that may affect use. The need for an HIV prevention product that women can use is driven by women's increased biological and social vulnerability to HIV infection, and thus social and behavioral research on microbicide acceptability has been conducted alongside, as well as separate from, the earliest product development efforts. Some acceptability and preference issues are specific to a product's dosage form, use-requirements, and/or use indications, while others pertain to any vaginal product used for prevention of HIV or pregnancy. Although most of the work cited here was published since 2010, it draws on a much longer trajectory of research.

Relationships between perceptual attributes and rheology in over-the-counter vaginal products: a potential tool for microbicide development

Vaginal microbicides are believed to have substantial potential to empower women to protect themselves from HIV, although clinical trials to date have had mixed results at best. Issues with patient adherence in these trials suggest additional emphasis should be placed on optimizing acceptability. Acceptability is driven, in part, by the sensory properties of the microbicide, so better understanding of the relationships between sensory properties and the physical and rheological properties of microbicides should facilitate the simultaneous optimization of sensory properties in parallel with the biophysical properties required for drug deployment. Recently, we have applied standard methods to assess the potential acceptability of microbicide prototypes ex vivo and to quantify the sensory properties of microbicide surrogates. Here, we link quantitative perceptual data to the rheological properties of 6 over-the counter (OTC) vaginal products used as ex vivo microbicide surrogates. Shear-thinning behavior (n) and tan δ (10 rad/s) showed no relationship with any perceptual attributes while shear storage modulus, G’ (10 rad/s) was correlated with some attributes, but did not appear to be a strong predictor of sensory properties. Conversely, the storage loss modulus, G” (10 rad/s) and the consistency coefficient, K, were correlated with several sensory attributes: stickiness, rubberiness, and uniform thickness for G’’ and stickiness, rubberiness, and peaking for K. Although these relationships merit confirmation in later studies, this pilot study suggests rheological principles can be used to understand the sensory properties evoked by microbicide surrogates assessed ex vivo. Additional work is needed to determine if these findings would apply for microbicides in vivo.

User preferences in a carrageenan-based vaginal drug delivery system

Topical microbicides are a promising solution to address the global threat of HIV and other sexually transmitted infections. To be successful, a microbicide not only needs to be biologically functional but also highly acceptable to users. User acceptability of microbicides can be incorporated early in the product formulation and design process. Previous qualitative research revealed women had strong preferences regarding product shape, while preferences related to size and firmness were less clear. Here, we explored the effect of size and firmness on the acceptability of semisolid ovoid microbicide prototypes intended for vaginal use. Sexually active women (n = 74) were randomized to one of two conditions: with and without applicator. Nine different prototypes were evaluated; they were formulated to low, medium and high firmness using mixtures of kappa and iota carrageenan and potassium chloride. Three sizes were produced at each firmness level. Women manipulated all nine prototypes, rating them for perceived effectiveness, imagined ease-of-insertion and willingness-to-try on visual analog scales. The influence of size and firmness on these three outcome measures were assessed using ANOVA and response surface models. Results indicated size and firmness both influenced the outcome measures, but firmess was more influential than size. Also, the specific effects of size and firmness depended strongly on presence or absence of an applicator. Generally, women in the without applicator condition wanted a larger, firmer product. Collectively, these data suggest efforts to rationally design of microbicides for enhanced user acceptability must consider factors like size and firmness. Also, the decision to include or forego an applicator should be addressed early in the design process, as it strongly influences other design decisions.