Rectal-specific microbicide applicator: evaluation and comparison with a vaginal applicator used rectally

MTN-033: a Phase 1 Study Comparing Applicator versus "as Lubricant" Delivery of Rectal Dapivirine Gel

Data to inform behaviorally congruent delivery of rectal microbicides as lubricants are scant. Dapivirine (DPV) is a nonnucleoside reverse transcriptase inhibitor which has been demonstrated to be well-tolerated and efficacious in multiple clinical trials when used in a vaginal ring formulation. DPV gel administered rectally with an applicator was found to be well-tolerated in a phase 1 clinical trial. MTN-033, a single site, open label, sequence randomized, crossover study, enrolled HIV-negative men to receive 0.05% DPV gel intrarectally using an applicator (2.5 g) and self-administered on an artificial phallus as lubricant (up to 10 g). The study evaluated the pharmacokinetics (in plasma, rectal fluid, and mucosal rectal tissue), safety, acceptability, and pharmacodynamics of DPV gel when applied rectally. Statistical comparisons between methods of application were performed using mixed effects models or Wilcoxon's signed rank tests. Sixteen participants used DPV gel by applicator and 15/16 participants used gel as lubricant (mean, 1.8 g; SD, 0.8). DPV plasma AUC0-24h after use as lubricant was estimated to be 0.41 times the AUC0-24h (95% CI 0.24, 0.88) after use with applicator. While DPV was quantifiable in plasma and luminal fluid, it was not quantifiable in tissue for both applicator and as lubricant administration. No related adverse events (AE) were reported, and 15/15 participants felt the gel was easy to use. Evidence of local delivery and systemic absorption of DPV when dosed as an anal lubricant supports the feasibility and potential for development of lubricant-delivered rectal microbicides. There were no safety concerns associated with use of DPV gel and participants reported finding it easy to use. However, lower DPV exposure in plasma and lack of quantifiable DPV in rectal tissue indicate that higher potency, concentration, and longer half-life antiretrovirals with optimized formulations will be needed to achieve protective tissue concentrations.

Acceptability of PC-1005 Gel Administered Rectally to HIV-1 Seronegative Adults at Three Different Volume Levels (MTN-037)

Multipurpose prevention technologies (MPT) have been increasingly researched for their dual-purpose preventative properties against HIV and other STIs. The acceptability of PC-1005, a topical MPT candidate, was explored among men and women participating in the MTN-037 Phase I trial at two U.S. sites (Pittsburgh, PA, and Birmingham, AL). We triangulated quantitative and qualitative assessments of the acceptability of three volumes (4 mL, 16 mL, 32 mL) of PC-1005 administered rectally (N = 12; 6 males, 6 females). Participants rated overall gel acceptability on a scale of 1-10, with a median of 7.17 (SD = 2.04) and had positive feelings about all three dose volumes, citing them to be very comfortable or comfortable (dose 1 = 91.7%; dose 2 = 91.7%; dose 3 = 83.3%). High acceptability of and comfort with all three dose volumes shows promise for PC-1005 as an MPT to prevent HIV and STIs, warranting future clinical development.

Acceptability of a Dapivirine/Placebo Gel Administered Rectally to HIV-1 Seronegative Adults (MTN-026)

This study describes the acceptability of a rectal microbicide gel formulation using dapivirine (DPV) among men and women from two countries (United States and Thailand) participating in the Microbicide Trials Network-026 trial. We evaluated participants' acceptability of a rectal DPV/placebo gel as part of a Phase I trial (N = 26; 18 male, 8 female). Participants reported favorable acceptability of the study gel, with most participants reporting that they liked the gel the same (n = 14; 53.8%) or more (n = 11; 42.4%) than when they started the trial. Over half of participants noted that they would prefer the gel over condoms (n = 13; 50%) or that they liked condoms and the gel equally (n = 8; 30.8%). Side effects across products included leakage (n = 8; 30.8%), diarrhea (n = 4; 15.4%), or soiling (n = 1; 3.8%). The high acceptability of a rectal gel underscores its promise as a short-acting biomedical prevention, warranting future research for HIV prevention.Trial Registration: NCT03239483.

Acceptability of a Dapivirine Gel Administered Rectally to HIV-1 Seronegative Adults (MTN-033 Study)

We triangulated quantitative and qualitative assessments to evaluate participants' acceptability of 0.05% dapivirine rectal microbicide (RM) gel administered via two separate modalities (a rectal applicator and an artificial phallus for use as a coital simulation device) as part of a Phase I trial (N = 14) among men who have sex with men (MSM) randomized using a 1:1 ratio. Overall, participants reported favorable acceptability of the gel (n = 11; 78.6%), the same or more at the end of the study compared to when they started the study. Additionally, when discussing their preferred administration modality, they noted that both methods had positive qualities but also potential areas of improvement. Our findings underscore the need to create multiple delivery methods for a future microbicide gel (i.e., with and without the need for an applicator) and highlight the importance of offering MSM choices in how biomedical HIV prevention strategies are delivered.

Rectal Douching Practices Associated with Anal Intercourse: Implications for the Development of a Behaviorally Congruent HIV-Prevention Rectal Microbicide Douche

Tenofovir administration via rectal douching results in higher rectal-mucosa drug concentration than oral administration. Many who engage in receptive anal intercourse (RAI) use cleansing rectal douches. To inform development of a behaviorally-congruent tenofovir douche, 4751 individuals ≥ 18 years-old, born male, from all US states/territories, who engaged in anal intercourse responded to an online survey. Of those who reported RAI in the prior 3 months, 80% douched beforehand, 82% within 1 h, mean 2.9 consecutive applications; 27% douched afterwards, 83% within 1 h, mean 1.7 consecutive applications. Among multidose users, 78% applied doses within 2 min, and 76% retained liquid < 1 min. Most used tap water (89%) in an enema bottle (50%) or rubber bulb (43%), and douched for cleanliness (97%), to avoid smelling bad (65%), and to enhance pleasure (24%). 98% reported high likelihood of using an HIV-prevention douche. An ideal product will protect within a user's typical number of applications, within 1 h, and be dissolvable in tap water.

Effects of gel volume on pharmacokinetics for vaginal and rectal applications of combination DuoGel-IQB4012, a dual chamber-dual drug HIV microbicide gel, in pigtailed macaques

This study evaluated effects of differing gel volumes on pharmacokinetics (PK). IQB4012, a gel containing the non-nucleoside reverse transcriptase inhibitor IQP-0528 and tenofovir (TFV), was applied to the pigtailed macaque vagina and rectum. Vaginal gel volumes (1% loading of both drugs) were 0.5 or 1.5 ml; following wash-out, 1 or 4 ml of gel were then applied rectally. Blood, vaginal, and rectal fluids were collected at 0, 2, 4, and 24 h. Vaginal and rectal tissue biopsies were collected at 4 and 24 h. There were no statistically significant differences in concentrations for either drug between gel volumes within compartments at matched time points. After vaginal gel application, median IQP-0528 concentrations were ~ 10⁴-10⁵ ng/g, 10⁵-10⁶ ng/ml, and 10³-10⁵ ng/ml in vaginal tissues, vaginal fluids, and rectal fluids, respectively (over 24 h). Median vaginal TFV concentrations were 1-2 logs lower than IQP-0528 levels at matched time points. After rectal gel application, median IQP-0528 and TFV concentrations in rectal fluids were ~ 10³-10⁵ ng/ml and ~ 10²-10³ ng/ml, respectively. Concentrations of both drugs sampled in rectal tissues were low (~ 10¹-10³ ng/g). For 1 ml gel, half of sampled rectal tissues had undetectable concentrations of either drug, and over half of sampled rectal fluids had undetectable TFV concentrations. These results indicate differences in drug delivery between the vaginal and rectal compartments, and that smaller vaginal gel volumes may not significantly compromise microbicide PK and prophylactic potential. However, effects of rectal gel volume on PK for both drugs were less definitive.

On-demand microbicide products: design matters

Sexual intercourse (vaginal and anal) is the predominant mode of human immunodeficiency virus (HIV) transmission. Topical microbicides used in an on-demand format (i.e., immediately before or after sex) can be part of an effective tool kit utilized to prevent sexual transmission of HIV. The effectiveness of prevention products is positively correlated with adherence, which is likely to depend on user acceptability of the product. The development of an efficacious and acceptable product is therefore paramount for the success of an on-demand product. Acceptability of on-demand products (e.g., gels, films, and tablets) and their attributes is influenced by a multitude of user-specific factors that span behavioral, lifestyle, socio-economic, and cultural aspects. In addition, physicochemical properties of the drug, anatomical and physiological aspects of anorectal and vaginal compartments, issues relating to large-scale production, and cost can impact product development. These factors together with user preferences determine the design space of an effective, acceptable, and feasible on-demand product. In this review, we summarize the interacting factors that together determine product choice and its target product profile.

Factors Supporting and Hindering Adherence to Rectal Microbicide Gel Use with Receptive Anal Intercourse in a Phase 2 Trial

Adherence to product use in biomedical HIV prevention trials is essential to success. In MTN-017, a Phase 2 rectal microbicide gel trial, participants discussed applicator-inserted gel use in the context of receptive anal intercourse (RAI) with adherence counselors. We analyzed counseling session data to identify barriers to and facilitators of gel use for 26 participants in the United States who used gel with RAI as their first of three study regimens. The most common barriers were finding the gel application process cumbersome, physical discomfort after applying gel, difficulty with BAT-24 dosage regimen, and negative effects of gel on sex. The most common facilitators were incorporating gel use into routines, using gel in anticipation of sex, carrying gel when going out, reminders received via short message service, and ease of gel use. These findings can inform product development and future adherence counseling interventions for rectal gel trials to improve adherence outcomes.

Preference of Oral Tenofovir Disoproxil Fumarate/Emtricitabine Versus Rectal Tenofovir Reduced-Glycerin 1% Gel Regimens for HIV Prevention Among Cisgender Men and Transgender Women Who Engage in Receptive Anal Intercourse with Men

Oral pre-exposure prophylaxis (PrEP) can prevent HIV transmission. Yet, some may prefer not to take systemic daily medication. MTN-017 was a 3-period, phase 2 safety and acceptability study of microbicide gel applied rectally either daily or before and after receptive anal intercourse (RAI), compared to daily oral tablet. At baseline, cisgender men and transgender women who reported RAI (N = 187) rated the daily oral regimen higher in overall liking, ease of use, and likelihood of future use than the gel regimens. After trying all three, 28% liked daily oral the least. Gel did not affect sexual enjoyment (88%) or improved it (7-8%). Most partners had no reaction to gel use. Ease of gel use improved significantly between the first and the last few times of daily use. A rectal gel used before and after RAI may constitute an attractive alternative to daily tablet. Experience with product use may increase acceptability.

Lubricant Provides Poor Rectal Mucosal HIV Coverage

Given the rising HIV incidence in men who have sex with men (MSM) despite repeatedly proven effectiveness of oral HIV pre-exposure prophylaxis, behaviorally congruent periodic dosing strategies, such as dosing microbicides as lubricants, are now in demand. Rectal microbicide gel studies largely administer gels using vaginal applicators, which have not been well received and do not mimic lubricant use. We compared rectal gel manually dosed as lubricant with applicator dosing in five healthy, HIV-negative MSM who received 10 or 3.5 ml of ^99mTc-DTPA-radiolabeled hydroxyethyl cellulose universal placebo gel intrarectally. After washout, participants received 10 ml of radiolabeled Wet^® Original^® lubricant to apply to the anus with fingers and/or a phallus in a manner typical of sexual lubricant use with a partner, followed by simulated receptive anal intercourse. Single-photon emission computed tomography with transmission computed tomography was performed 4 h after each gel administration. Manual dosing was associated with more variable rectosigmoid distribution, 4.4-15.3 cm from the anorectal junction, compared with more uniform distribution, 5.9-7.4 and 5.3-7.6 cm after 10 and 3.5 ml applicator dosing, respectively. A significantly smaller fraction of the initial 10 ml dose was retained within the colon after manual dosing, 3.4%, compared with 94.9% and 88.4% after 10 and 3.5 ml applicator dosing, respectively (both p < .001). Manual dosing of a sexual lubricant delivered a small, variable fraction of the dose with variable rectosigmoid distribution compared with applicator dosing. These results raise concern that dosing a rectal microbicide gel as a sexual lubricant may not provide adequate or predictable mucosal coverage for HIV protection.

Lessons for Rectal Microbicide Development From an Acceptability Trial of a Placebo Gel Applied Prior to Receptive Anal Intercourse

Rectal microbicides, formulated as a gel to be applied before and/or after intercourse, are promising HIV prevention agents and are now in Phase II trials. However, both an optimal formulation and a practical delivery system are needed to ensure that the target population will use the product once efficacy is demonstrated. The precise dynamics of lubricant application by gay and bisexual men who practice anal sex and the qualities they seek in these products are underexplored. As part of a Phase I microbicide acceptability and adherence study conducted in one Puerto Rican and two continental U.S. cities, we recruited 124 young men who have sex with men (YMSM) with a history of unprotected receptive anal intercourse (RAI) and provided them with 40 rectal applicators containing a placebo gel to use prior to RAI during a 12-week period as a proxy for an eventual rectal microbicide. Ninety-five YMSM completed the trial. Their varied preferences as to product viscosity, durability, residue, and mode of application provide important lessons for the design of a product that will be satisfactory to users. Despite many reservations, the participants used the product frequently and found ways to overcome a range of obstacles. A successful rectal microbicide product may need to be presented in a range of viscosities to attract a broad client base.

Acceptability of Three Novel HIV Prevention Methods Among Young Male and Transgender Female Sex Workers in Puerto Rico

Sex workers need HIV-prevention methods they can control and incorporate easily in their work. We studied the acceptability of three methods: HIV self-test use with clients, oral pre-exposure prophylaxis (PrEP), and rectal microbicide gel. Four male and eight transgender female (TGF) sex workers in Puerto Rico completed a baseline survey with a quantitative measure of likelihood of use. From them, one male and four TGF also completed a 12-week study of rectal microbicide placebo gel use prior to receptive anal intercourse with male clients and evaluated via qualitative in-depth interviews and follow-up quantitative assessments how each method could be incorporated into their work. Most were interested in a rectal microbicide gel and able to use it covertly with clients. Challenges to using the HIV self-test with clients included the potential for both breach of confidentiality and confronting violent situations. Participants also expressed interest in oral PrEP, but raised concerns about side effects.

Influence of Partner Type on Acceptability and Likelihood of Use of a Rectal Microbicide Among Young Men Who Have Sex With Men in the United States and Puerto Rico

This study examined how acceptability of placebo gel with receptive anal intercourse (RAI) and likelihood of future rectal microbicide use varied across partner types. Because no rectal microbicide is available yet, use of placebo permitted the study of gel use behavior in real-life circumstances. A total of 87 men who have sex with men (MSM) aged 18 to 30 years inserted placebo gel rectally before RAI during 12 weeks. Using mixed-methods design, participants completed a behavioral questionnaire and in-depth interview. In all, 62 men (71.3%) reported gel use with a lover (i.e., spouse equivalent, boyfriend), 32 (36.8%) with a one-night stand (i.e., man with whom you had sex once), and 29 (33.3%) with an "other" male partner. While gel acceptability was high across partner types, use with lovers was facilitated by trust and familiarity; yet trust made participants believe protection was less necessary. Conversely, participants expressed high likelihood of using gel with one-night stands, whom they perceived as riskier; yet they felt less comfortable discussing gel with them, often resorting to covert use or forgoing gel. A successful microbicide will be positioned as a sexual pleasure enhancer so that men can present it to their lovers and other partners as a gel that improves sex and secondarily prevents human immunodeficiency virus (HIV).

Project Gel a Randomized Rectal Microbicide Safety and Acceptability Study in Young Men and Transgender Women

OBJECTIVES

The purpose of Project Gel was to determine the safety and acceptability of rectal microbicides in young men who have sex with men (MSM) and transgender women (TGW) at risk of HIV infection.

METHODS

MSM and TGW aged 18-30 years were enrolled at three sites; Pittsburgh, PA; Boston, MA; and San Juan, PR. Stage 1A was a cross-sectional assessment of sexual health and behavior in MSM and TGW. A subset of participants from Stage 1A were then enrolled in Stage 1B, a 12-week evaluation of the safety and acceptability of a placebo rectal gel. This was followed by the final phase of the study (Stage 2) in which a subset of participants from Stage 1B were enrolled into a Phase 1 rectal safety and acceptability evaluation of tenofovir (TFV) 1% gel.

RESULTS

248 participants were enrolled into Stage 1A. Participants' average age was 23.3 years. The most common sexually transmitted infection (STIs) at baseline were Herpes simplex (HSV)-2 (16.1% by serology) and rectal Chlamydia trachomatis (CT) (10.1% by NAAT). 134 participants were enrolled into Stage 1B. During the 12 week period of follow-up 2 HIV, 5 rectal CT, and 5 rectal Neisseria gonorrhea infections were detected. The majority of adverse events (AEs) were infections (N = 56) or gastrointestinal (N = 46) and were mild (69.6%) or moderate (28.0%). Of the participants who completed Stage 1B, 24 were enrolled into Stage 2 and randomized (1:1) to receive TFV or placebo gel. All participants completed Stage 2. The majority of AEs were gastrointestinal (N = 10) and of mild (87.2%) or moderate (10.3%) severity.

CONCLUSIONS

In this study we were able to enroll a sexually active population of young MSM and TGW who were willing to use rectal microbicides. TFV gel was safe and acceptable and should be further developed as an alternative HIV prevention intervention for this population.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01283360.

Perceptions among Dutch men who have sex with men and their willingness to use rectal microbicides and oral pre-exposure prophylaxis to reduce HIV risk--a preliminary study

Oral pre-exposure prophylaxis (PrEP) with antiretroviral (ARV) tablets and topical PrEP or microbicides containing ARV drugs could help to reduce HIV incidence. These methods hold promise for men who have sex with men (MSM) who are at higher risk of acquiring HIV. This mixed-methods study in the Netherlands explored perceptions of MSM and their willingness to use oral PrEP and rectal microbicides (RM) if made available. Recruited through social media (Facebook and Twitter), 108 MSM completed online questionnaires. Seven of them consented to discuss the survey results in semi-structured interviews. Survey participants preferred a RM that could be applied before and after anal intercourse (60.8%) to daily oral PrEP (20.3%). This preference was based on anticipated user friendliness, hypothetically fewer expected adverse events, and perceptions that RM would be less likely to be confused with ARVs for treatment. Those who preferred oral PrEP had stronger beliefs in the effectiveness of pills, perceived its use as easy, and viewed not requiring sexual partner awareness as advantages. No predictive factors were found for the choice of one prevention method over the other. Although Dutch MSM perceive both oral and topical PrEP positively, many barriers exist to the introduction of these products in the Netherlands. These include lack of regulatory approval of oral PrEP, no proven efficacy as yet for RM, and strong HIV stigma within the MSM population. In-depth qualitative research is needed to further explore the perceptions of MSM to inform implementation of programmes should these HIV prevention methods become available.

To Use a Rectal Microbicide, First Insert the Applicator: Gel and Applicator Satisfaction Among Young Men Who Have Sex With Men

We examined how experiences with a rectal placebo gel and applicator used with receptive anal intercourse (RAI) related to young men who have sex with men's (YMSM) likelihood of using a rectal microbicide gel and applicator in the future. An ethnically diverse sample of 95 YMSM (aged 18 to 30 years) were asked to insert hydroxyethylcellulose (HEC) placebo gel rectally before RAI during 12 weeks and report the product's acceptability (i.e., satisfaction with applicator and gel, respectively; perceived gel side effects; and sexual satisfaction when gel was used) and likelihood of future microbicide use. Main and interaction effects predicting future use intentions were tested using linear regression. We found a positive association between future use intentions and applicator satisfaction (b = .33, p < .001). In a subsequent interaction effects model, we found that greater gel satisfaction was associated with increased future use intentions; however, the strength of this relationship was magnified when YMSM reported greatest satisfaction with the rectal applicator. Applicator satisfaction may be a salient factor in YMSM's decision-making to use a rectal microbicide in the future. Although the importance of developing a satisfactory rectal microbicide gel for YMSM is undeniable for its future use, our results also emphasize the importance of developing strategies that increase YMSM's comfort and skill when using a rectal applicator. Future research examining how to optimize the design, properties, and characteristics of a rectal applicator as a strategy to promote greater satisfaction and use among YMSM is merited.

Awareness of Post-Exposure Prophylaxis (PEP) and Pre-Exposure Prophylaxis (PrEP) Is Low but Interest Is High Among Men Engaging in Condomless Anal Sex With Men in Boston, Pittsburgh, and San Juan

This study examines awareness of and experiences with post-exposure prophylaxis (PEP) and pre-exposure prophylaxis (PrEP) among 228 men recruited in Boston, Pittsburgh, and San Juan between 12/2010 and 6/2012. All of them reported having condomless anal sex with a man in the prior year. Overall, 41% had heard of PEP, ranging from 16% in San Juan to 64% in Boston. Only 21% had heard of PrEP, ranging from 8% in San Juan to 36% in Boston. Three had used PEP, and none had used PrEP. After the methods were described to participants, interest in both was high, with intentions to use PEP and PrEP respectively at 9.1 and 7.7 (10-point scale). Increased public education is needed to raise awareness of these HIV prevention methods, especially among MSM who acknowledge potential risk behavior. It also seems likely that many such men would use these methods once they become aware of them.

Formulation and delivery of anti-HIV rectal microbicides: advances and challenges

Men and women engaged in unprotected receptive anal intercourse (RAI) are at higher risk of acquiring HIV from infected partners. The implementation of preventive strategies is urgent and rectal microbicides may be a useful tool in reducing the sexual transmission of HIV. However, pre-clinical and first clinical trials have been able to identify limitations of candidate products, mostly related with safety issues, which can in turn enhance viral infection. Indeed, the development of suitable formulations for the rectal delivery of promising antiretroviral drugs is not an easy task, and has been mostly based on products specifically intended for vaginal delivery, but these have been shown to provide sub-optimal outcomes when administered rectally. Research and development in the rectal microbicide field are now charting their own path and important information is now available. In particular, specific formulation requirements of rectal microbicide products that need to be met have just recently been acknowledged despite additional work being still required. Desirable rectal microbicide product features regarding characteristics such as pH, osmolality, excipients, dosage forms, volume to be administered and the need for applicator use have been studied and defined in recent years, and specific guidance is now possible. This review provides a synopsis of the field of rectal microbicides, namely past and ongoing clinical studies, and details on formulation and drug delivery issues regarding the specific development of rectal microbicide products. Also, future work, as required for the advancement of the field, is discussed.