Why rectal douches may be acceptable rectal-microbicide delivery vehicles for men who have sex with men

Tenofovir Douche as HIV Preexposure Prophylaxis for Receptive Anal Intercourse: Safety, Acceptability, Pharmacokinetics, and Pharmacodynamics (DREAM 01)

BACKGROUND

Despite highly effective HIV preexposure prophylaxis (PrEP) options, no options provide on-demand, nonsystemic, behaviorally congruent PrEP that many desire. A tenofovir-medicated rectal douche before receptive anal intercourse may provide this option.

METHODS

Three tenofovir rectal douches-220 mg iso-osmolar product A, 660 mg iso-osmolar product B, and 660 mg hypo-osmolar product C-were studied in 21 HIV-negative men who have sex with men. We sampled blood and colorectal tissue to assess safety, acceptability, pharmacokinetics, and pharmacodynamics.

RESULTS

The douches had high acceptability without toxicity. Median plasma tenofovir peak concentrations for all products were several-fold below trough concentrations associated with oral tenofovir disoproxil fumarate (TDF). Median colon tissue mucosal mononuclear cell (MMC) tenofovir-diphosphate concentrations exceeded target concentrations from 1 hour through 3 to 7 days after dosing. For 6-7 days after a single product C dose, MMC tenofovir-diphosphate exceeded concentrations expected with steady-state oral TDF 300 mg on-demand 2-1-1 dosing. Compared to predrug baseline, HIV replication after ex vivo colon tissue HIV challenge demonstrated a concentration-response relationship with 1.9 log10 maximal effect.

CONCLUSIONS

All 3 tenofovir douches achieved tissue tenofovir-diphosphate concentrations and colorectal antiviral effect exceeding oral TDF and with lower systemic tenofovir. Tenofovir douches may provide a single-dose, on-demand, behaviorally congruent PrEP option, and warrant continued development. Clinical Trials Registration . NCT02750540.

A conjoint experiment of three placebo rectal products used with receptive anal sex: results from MTN-035

INTRODUCTION

End-user perspectives are vital to the design of new biomedical HIV prevention products. Conjoint analysis can support the integration of end-user perspectives by examining their preferences of potential pre-exposure prophylaxis (PrEP) products. The Microbicides Trial Network (MTN) 035 protocol examined three placebo rectal dosage forms (insert, enema and suppository) that could deliver PrEP prior to receptive anal sex (RAS).

METHODS

Between April 2019 and July 2020, we enrolled 217 HIV-negative, cisgender men who have sex with men (MSM; n = 172; 79.3%) and transgender people (n = 47; 20.7%) ages 18-35 into a randomized cross-over trial across Malawi, Peru, South Africa, Thailand and the United States. Participants used each product prior to RAS over 4-week periods. Participants completed a conjoint experiment where they selected between random profiles using seven features (dosage form, timing of use before sex, side effects, duration of protection, effectiveness, frequency of use and need for a prescription).

RESULTS

Effectiveness was the strongest determinant of choice (30.4%), followed by modality (18.0%), potential side effects (17.2%), frequency of use (10.8%), duration of protection (10.4%), timing of use before sex (7.4%) and need for a prescription (5.9%). Relative utility scores indicated that the most desirable combination of attributes was a product with 95% efficacy, used 30 minutes before sex, offering a 3- to 5-day protection window, used weekly, having no side effects, in the form of an enema and available over-the-counter.

CONCLUSIONS

Choice in next-generation PrEP products is highly desired by MSM and transgender people, as no one-size-fits-all approach satisfies all the preferences. MTN-035 participants weighed product features differently, recognizing the need for diverse, behaviourally congruent biomedical options that fit the needs of intended end-users.

A randomized trial of safety, acceptability and adherence of three rectal microbicide placebo formulations among young sexual and gender minorities who engage in receptive anal intercourse (MTN-035)

Efforts to develop a range of HIV prevention products that can serve as behaviorally congruent viable alternatives to consistent condom use and oral pre-exposure prophylaxis (PrEP) remain crucial. MTN-035 was a randomized crossover trial seeking to evaluate the safety, acceptability, and adherence to three placebo modalities (insert, suppository, enema) prior to receptive anal intercourse (RAI). If participants had no RAI in a week, they were asked to use their assigned product without sex. We hypothesized that the modalities would be acceptable and safe for use prior to RAI, and that participants would report high adherence given their behavioral congruence with cleansing practices (e.g., douches and/or enemas) and their existing use to deliver medications (e.g., suppositories; fast-dissolving inserts) via the rectum. Participants (N = 217) were sexual and gender minorities enrolled in five different countries (Malawi, Peru, South Africa, Thailand, and the United States of America). Mean age was 24.9 years (range 18-35 years). 204 adverse events were reported by 98 participants (45.2%); 37 (18.1%) were deemed related to the study products. The proportion of participants reporting "high acceptability" was 72% (95%CI: 65% - 78%) for inserts, 66% (95%CI: 59% - 73%) for suppositories, and 73% (95%CI: 66% - 79%) for enemas. The proportion of participants reporting fully adherent per protocol (i.e., at least one use per week) was 75% (95%CI: 69% - 81%) for inserts, 74% (95%CI: 68% - 80%) for suppositories, and 83% (95%CI: 77% - 88%) for enemas. Participants fully adherent per RAI-act was similar among the three products: insert (n = 99; 58.9%), suppository (n = 101; 58.0%) and enema (n = 107; 58.8%). The efficacy and effectiveness of emerging HIV prevention drug depends on safe and acceptable delivery modalities that are easy to use consistently. Our findings demonstrate the safety and acceptability of, and adherence to, enemas, inserts, and suppositories as potential modalities through which to deliver a rectal microbicide.

Estimating HIV Incident Diagnoses Among Men Who Have Sex With Men Eligible for Pre-exposure Prophylaxis but Not Taking It: Protocol and Feasibility Assessment of Data Sources and Methods

BACKGROUND

HIV incidence estimates are published each year for all Ending the HIV Epidemic (EHE) counties, but they are not stratified by the demographic variables highly associated with risk of infection. Regularly updated estimates of HIV incident diagnoses available at local levels are required to monitor the epidemic in the United States over time and could contribute to background incidence rate estimates for alternative clinical trial designs for new HIV prevention products.

OBJECTIVE

We describe methods using existing, robust data sources within areas in the United States to reliably estimate longitudinal HIV incident diagnoses stratified by race and age categories among men who have sex with other men (MSM) eligible for pre-exposure prophylaxis (PrEP) but not taking it.

METHODS

This is a secondary analysis of existing data sources to develop new estimates of incident HIV diagnoses in MSM. We reviewed past methods used to estimate incident diagnoses and explored opportunities to improve these estimates. We will use existing surveillance data sources and population sizes of HIV PrEP-eligible MSM estimated from population-based data sources (eg, US Census data and pharmaceutical prescription databases) to develop metropolitan statistical area-level estimates of new HIV diagnoses among PrEP-eligible MSM. Required parameters are number of new diagnoses among MSM, estimates of MSM with an indication for PrEP, and prevalent PrEP use including median duration of use; these parameters will be stratified by jurisdiction and age group or race or ethnicity. Preliminary outputs will be available in 2023, and updated estimates will be produced annually thereafter.

RESULTS

Data to parameterize new HIV diagnoses among PrEP-eligible MSM are available with varying levels of public availability and timeliness. In early 2023, the most recent available data on new HIV diagnoses were from the 2020 HIV surveillance report, which reports 30,689 new HIV infections in 2020, and 24,724 of them occurred in an MSA with a population of ≥500,000. Updated estimates for PrEP coverage based on commercial pharmacy claims data through February 2023 will be generated. The rate of new HIV diagnoses among MSM can be estimated from new diagnoses within each demographic group (numerator) and the total person-time at risk of diagnosis for each group (denominator) by metropolitan statistical area and year. To estimate time at risk, the person-time of individuals on PrEP or person-time after incident HIV infection but before diagnosis should be removed from stratified population size estimates of the total number of person-years with indications for PrEP.

CONCLUSIONS

Reliable, serial, cross-sectional estimates for rates of new HIV diagnoses for MSM with PrEP indications can serve as benchmark community estimates of failures of HIV prevention and opportunities to improve services and will support public health epidemic monitoring and alternative clinical trial designs.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/42267.

Hypo-osmolar rectal douche tenofovir formulation prevents simian/human immunodeficiency virus acquisition in macaques

In spite of the rollout of oral pre-exposure prophylaxis (PrEP), the rate of new HIV infections remains a major health crisis. In the United States, new infections occur predominantly in men having sex with men (MSM) in rural settings where access to PrEP can be limited. As an alternative congruent with MSM sexual behavior, we have optimized and tested tenofovir (TFV) and analog-based iso-osmolar and hypo-osmolar (HOsm) rectal douches for efficacy against rectal simian/human immunodeficiency virus (SHIV) infection of macaques. Single TFV HOsm high-dose douches achieved peak plasma TFV levels similar to daily oral PrEP, while other formulations yielded lower concentrations. Rectal tissue TFV-diphosphate (TFV-DP) concentrations at the portal of virus entry, however, were markedly higher after HOsm douching than daily oral PrEP. Repeated douches led to significantly higher plasma TFV and higher TFV-DP concentrations in rectal tissue at 24 hours compared with single douches, without detectable mucosal or systemic toxicity. Using stringent repeated intrarectal SHIV exposures, single HOsm high-dose douches delivered greater protection from virus acquisition for more than 24 hours compared with oral PrEP. Our results demonstrate a rapid delivery of protective TFV doses to the rectal portal of virus entry as a potential low-cost and safe PrEP alternative.

More than just oral PrEP: exploring interest in rectal douche, dissolvable implant, removable implant and injection HIV prevention approaches among racially diverse men who have sex with men in the Northeast Corridor

OBJECTIVES

HIV scholars and practitioners have worked to expand strategies for prevention among marginalised populations who are disproportionately impacted by the epidemic, such as racial minority men who have sex with men (MSM). Given this urgency, the objective of this study was to assess interest in biomedical prevention strategies.

METHODS

This exploratory and cross-sectional study investigated interest in four biomedical prevention tools-rectal douche, dissolvable implant, removable implant and injection-among a racially diverse sample of MSM from the Northeast Corridor region between Philadelphia and Trenton. Data were collected as part of screening for Connecting Latinos en Pareja, a couples-based HIV prevention intervention for Latino MSM and their partners.

RESULTS

A total of 381 individuals participated in the screener and provided information about their interest in bio tools. Approximately 26% of participants identified as black, 28% as white and 42% as 'other' or multiracial; 49% identified as Latino. Majority (54%) reported some form of child sexual abuse. Of the participants who reported being in a primary relationship (n=217), two-thirds reported unprotected anal sex within that relationship over the past 90 days (n=138, 64%) and approximately half (n=117, 54%) reported unprotected anal sex outside of the relationship in this period. Majority of participants reported interest in all bio tools assessed, including dissolvable implants (60%), removable implants (64%), rectal douching (79%) and injection (79%). Although interest in bio tools was broadly unassociated with demographics and sexual risk behaviours, analyses revealed significant associations between reports of child sexual abuse and interest in implant and injection methods.

CONCLUSIONS

The authors recommend investing in these prevention methods, particularly rectal douching and injection, as a means of preventing HIV among racial minority MSM. Given the interest in biomedical prevention tools, future studies should explore potential strategies for adherence.

Getting Clear About Rectal Douching Among Men Who Have Sex With Men

Receptive anal sex is the primary means through which HIV is transmitted among men who have sex with men (MSM). Recently, researchers have begun investigating the role that rectal douching may play in amplifying risk for transmission. Yet, there is limited research on the frequency with which MSM douche, the products they use, and how this may vary across sociodemographic characteristics. A U.S. national sample of 4745 MSM completed an online survey that assessed their douching behavior, demographic characteristics, sexual behavior, and their anal sexual positioning (i.e., top, bottom, versatile). Nearly two-thirds (65.8%) had engaged in rectal douching in the last three months. Among those who douched, water was commonly reported (84.2%) and 20.1% reported using commercial enemas (e.g., Fleet), as well as water and soap (15.0%)-numbers exceed 100% as some participants reported more than one. Men who douched reported significantly more receptive and insertive condomless anal sex acts in the prior 3 months. One-in-ten men reported rectal bleeding after douching. Compared to HIV-negative participants who had not taken PrEP, participants had higher odds of reporting douching in the past 3 months if they were HIV-negative and currently on PrEP (AOR = 1.82), HIV-negative and previously used PrEP (AOR = 1.58), and HIV-positive (AOR = 1.83). Douching was common in this sample. Given that douching could amplify risk for HIV transmission, healthcare providers should discuss douching safety with their patients, with a focus on harm reduction (e.g., reduce risk of bleeding, as opposed to abstinence from douching).

Rectal douching in a community sample of men and women

Rectal douching (RD) may be a vector for sexually transmitted infection (STI) acquisition. The aim of this study was to describe the relationship between RD, and the prevalence of various STIs and sexual behaviors in a sample of women and men in Long Beach, California. Five hundred and forty-seven men (mean age 42.8 years) and 530 women (mean age 37 years) recruited from a community-based setting between April 2010 and August 2014 completed the Risk Behavior Assessment and a questionnaire eliciting information on use of lubricants and enemas for vaginal intercourse (VI) and anal intercourse (AI). Participants were screened for high-risk behaviors for human immunodeficiency virus infection including injection drug use. Bivariate analyses were conducted separately for women and men. Based on the empirical results, separate logistic regression models for women and men were constructed. Sensitivity analysis was conducted to assess model fit for reduced samples of only those men and women who reported AI. For men, RD was associated with a lower odds of being hepatitis C antibody positive, greater odds of being positive for hepatitis B virus surface antigen, syphilis, and using lubricants for receptive anal intercourse (RAI). RD in women was associated with higher odds of a positive test for syphilis, ever vaginally douching for VI, and using lubricants for RAI. Men and women who practice RD report positive syphilis test results and use of lubricants for RAI. RD should not be perceived as preventing STIs.

Rectal Douching and Microbicide Acceptability among Young Men who Have Sex with Men

Men who have sex with men (MSM) commonly report engaging in rectal douching (RD) practices prior to receptive anal intercourse. Researchers are interested in the possibility of designing a RD with a microbicide component. In our analyses, we examined whether YMSM who engaged in RD behaviors differ in HIV prevention behaviors from their non-RD peers. We then examined whether RD frequency was associated with rectal microbicide acceptability. Half the participants (47.8%) reported having ever douched. Participants were more likely to douche if they were racial/ethnic minorities (AOR = 2.24, p = 0.02) and had recently tested for HIV (AOR = 1.96, p = 0.04). Greater douching frequency was associated with racial/ethnic minorities (β = 0.20, p = 0.009) and recent HIV testing (β = 0.19, p < 0.01). Participants who reported frequently douching indicated greater microbicide acceptability (β = 0.32, p < 0.001). Designing behaviorally congruent products remains a priority in next generation Pre-Exposure Prophylaxis (PrEP) and a rectal douche might be an additional tool if found to be efficacious.

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.

Not All Orgasms Were Created Equal: Differences in Frequency and Satisfaction of Orgasm Experiences by Sexual Activity in Same-Sex Versus Mixed-Sex Relationships

Which sexual activities result in the most frequent and most satisfying orgasms for men and women in same- and mixed-sex relationships? The current study utilized a convenience sample of 806 participants who completed an online survey concerning the types of sexual activities through which they experience orgasms. Participants indicated how frequently they reached orgasm, how satisfied they were from orgasms resulting from 14 sexual activities, and whether they desired a frequency change for each sexual activity. We present the overall levels of satisfaction, frequency, and desired frequency change for the whole sample and also compare responses across four groups of participants: men and women in same-sex relationships and men and women in mixed-sex relationships. While all participants reported engaging in a wide variety of activities that either could, or often did, lead to the experience of orgasm, there were differences in the levels of satisfaction derived from different types of orgasms for different types of participants, who also engaged in such activities with varying degrees of frequency. We discuss group differences within the context of sexual scripts for same- and mixed-sex couples and question the potential explanations for gender differences in the ability to experience orgasm during partnered sexual activity.

Effect of rectal douching/enema on rectal gonorrhoea and chlamydia among a cohort of men who have sex with men on HIV pre-exposure prophylaxis

OBJECTIVES

Rectal douching/enema (RD) is a common practice among men who have sex with men (MSM) in preparation for sex. RD can break down the rectal mucosal barrier and potentially affect the rectal microbiome. The objective of this study was to understand if RD is associated with acquiring rectal infections (RI) with rectal gonorrhoea (NG) and/or chlamydia (CT).

METHODS

From 2013 to 2015, 395 adult HIV-uninfected MSM were enrolled in a randomised controlled study for pre-exposure prophylaxis (PrEP) adherence with routine sexual risk survey and testing. Using data from this cohort, baseline differences by RI were assessed using Pearson's χ² and Wilcoxon-Mann-Whitney test. Association between RD and RI was modelled using multivariable logistic regression adjusted for potential confounders (sexual behaviour, substance use and age) selected a priori. Effect modification by number of male partners and sensitivity analysis to rule out reverse causality were also conducted.

RESULTS

Of 395 participants, 261 (66%) performed RD and 133 (33%) had at least one NG/CT RI over 48 weeks. Number of condomless anal receptive sex (med: 4, p<0.001), male partners (med:6, p<0.001) and substance use (any of methamphetamine/hallucinogens/dissociative/poppers) (p<0.001) were associated with increased odds of RI. Controlling for potential confounders, odds of prevalent RI were 3.59 (p<0.001, 95% CI 1.90 to 6.78) and incident RI 3.87 (p=0.001, 95% CI 1.78 to 8.39) when douching weekly or more compared with not douching. MSM with more than six male partners had 5.34 (p=0.002, 95% CI 1.87 to 15.31) increased odds of RI when douching weekly or more compared with not douching.

CONCLUSION

Rectal hygiene with RD is a common practice (66%) among HIV-uninfected MSM on PrEP in this study, which increases the odds of acquiring rectal NG and/or CT independent of sexual risk behaviour, substance use and other factors. This suggests interventional approaches targeting rectal hygiene products and practices could reduce sexually transmitted infections.

Development of rectal enema as microbicide (DREAM): Preclinical progressive selection of a tenofovir prodrug enema

HIV pre-exposure prophylaxis (PrEP) strategies have the potential to prevent millions of incident HIV infections each year. However, the efficacy of PrEP strategies has been plagued by issues of non-adherence, likely because of the difficulty in motivating otherwise healthy people to adhere to treatment regimens that require significant behavioral changes and daily discipline. An alternative approach to PrEP is to focus on strategies that fit in to normal, and even desirable, sexual behaviors, such as the use of cleansing enemas by men who have sex with men (MSM) prior to receptive anal intercourse (RAI). Here, we describe preclinical efforts toward optimizing a tenofovir (TFV)-based enema formulation for rectal PrEP. Using a murine model, we compared the plasma and tissue pharmacokinetics of TFV and various TFV prodrugs, including tenofovir disoproxil fumarate (TDF), tenofovir alafenamide (TAF), and hexadecyloxypropyl tenofovir (CMX157), after dosing as enema formulations with varying osmolality and ion content. We observed that the enema vehicle composition played a more important role than the TFV prodrug properties in achieving rapid and therapeutically relevant tenofovir diphosphate (TFV-DP) concentrations in mouse colorectal tissue. Our results support the next steps, which are further preclinical (non-human primate) and clinical development of a hypo-osmolar TFV enema product for rectal PrEP.

Rectal Douching Associated with Receptive Anal Intercourse: A Literature Review

To inform the development of HIV-prevention rectal douches, we reviewed the scientific literature and online instructional videos on rectal douching associated with receptive anal intercourse (RAI). Up to 88% of men who practice RAI ever have douched, while 43-64% have douched recently. Of them, 87-97% douche before RAI and 13-48% afterwards. Water, occasionally mixed with soap or salt, is used most often, although up to 31% of men use commercial products. Douching is more common among individuals reporting substance use, sexually transmitted infections, or being HIV-infected. Scant literature is available on women's rectal douching practices, but it is apparently less frequent than among men (32 vs. 70%). Videos advise using 2-3 doses of liquid and retaining it for 10-30 s before expelling. These findings can inform the development of a safe and acceptable rectal douche for HIV prevention.

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.

Prevalence and types of rectal douches used for anal intercourse among men who have sex with men in Brazil

INTRODUCTION

Rectal douching (RD) is practised among men who have sex with men (MSM), and various products and materials are used. There have been no studies in Brazil on this practice and its risks in the transmission of sexually transmitted infections and HIV.

METHOD

Between June and August 2015, 401 MSM over the age of 18 were interviewed about their sexual practices associated with RD over the last 3 months. RD was associated with the reported sexual behaviour, and descriptive statistical analyses were conducted on the same.

RESULTS

Among the respondents, 85.6% identified themselves as men and 14.4% as transgender; 255 declared themselves to be white (63.6%) and 104 to be mixed (25.9%). From among those who had performed anal sex within the last 3 months (n=369), 197 reported having used RD (53.4%). The most commonly used material was a shower hose (84.5%) and the main product used was water (93%). Of those interviewed, 94.5% never received guidelines from health professionals on this practice and its potential risks. Receptive anal intercourse and RD were found to be associated (p<0.001).

CONCLUSIONS

RD is a common practice among the MSM population. Health professionals must deepen their knowledge of this. We propose studies in Brazil on the practice of RD that-from that knowledge strategies for prevention and harm reduction-can be incorporated to the vulnerable populations.

Rectal Douching Prevalence and Practices Among Peruvian Men Who have Sex with Men and Transwomen: Implications for Rectal Microbicides

Peruvian men who have sex with men (MSM) and transwomen (TW) could benefit from a rectal microbicide (RM) formulated as a rectal douche to prevent HIV infection. However, little is known about rectal douching practices among Peruvian MSM and TW, information necessary to inform RM douche development and future uptake. Using a self-administered interview, we examined the prevalence of and factors associated with rectal douching among a convenience sample of 415 Peruvian MSM and 68 TW. In the previous 6 months, 18 % of participants reported rectal douching using pre-filled commercial kits or plastic bottles or enema bags filled with water, water/soap or saltwater. Multivariate logistic analysis found that "equally insertive and receptive" or "exclusively/mainly receptive" sex roles were associated with douche use. Rectal douching among Peruvian MSM and TW is similar to reports from other studies and supports the potential uptake of a douche-formulated RM in these populations.

Anal Douche Practices and Willingness to Use a Rectal Microbicide Enema for HIV Prevention and Associated Factors Among an Internet Sample of HIV-Negative and HIV-Discordant Male Couples in the US

A significant proportion of MSM acquire HIV from their primary relationship partners. Rectal microbicides are currently being studied to determine their efficacy for HIV prevention, yet willingness to use rectal microbicides among male couples is largely unknown. Dyadic data from 333 HIV-negative and HIV-discordant male couples, representing 631 HIV-negative men, were used to assess anal douching practices and willingness to use a rectal microbicide for HIV prevention. 17 % of men douched 100 % of the time before having anal sex within their primary partner. Among those who had sex outside of their relationship, 36 % had douched 100 % of the time before having anal sex with a casual MSM partner. Most men (63 %) indicated a willingness to use a theoretically effective rectal microbicide prior to anal sex for HIV prevention. If found effective, rectal microbicides delivered as an anal douche may be an acceptable format for HIV prevention to some MSM who already engage in anal douching. Understanding current douching practices will be important in successfully promoting the uptake of rectal microbicides.

Enema ion compositions for enhancing colorectal drug delivery

Delivering drugs to the colorectum by enema has advantages for treating or preventing both local and systemic diseases. However, the properties of the enema itself are not typically exploited for improving drug delivery. Sodium ions are actively pumped out of the lumen of the colon, which is followed by osmotically-driven water absorption, so we hypothesized that this natural mechanism could be exploited to drive nanoparticles and drugs to the colorectal tissue surface. Here, we report that sodium-based, absorption-inducing (hypotonic) enemas rapidly transport hydrophilic drugs and non-mucoadhesive, mucus penetrating nanoparticles (MPP), deep into the colorectal folds to reach virtually the entire colorectal epithelial surface. In contrast, isotonic and secretion-inducing (hypertonic) vehicles led to non-uniform, poor surface coverage. Sodium-based enemas induced rapid fluid absorption even when moderately hyper-osmolal (~350 mOsm) compared to blood (~300 mOsm), which suggests that active sodium absorption plays a key role in osmosis-driven fluid uptake. We then used tenofovir, an antiretroviral drug in clinical trials for preventing HIV, to test the effects of enema composition on local and systemic drug delivery. We found that strongly hypotonic and hypertonic enemas caused rapid systemic drug uptake, whereas moderately hypotonic enemas with ion compositions similar to feces resulted in high local tissue levels with minimal systemic drug exposure. Similarly, moderately hypotonic enemas provided improved local drug retention in colorectal tissue, whereas hypertonic and isotonic enemas provided markedly reduced drug retention in colorectal tissue. Lastly, we found that moderately hypotonic enema formulations caused little to no detectable epithelial damage, while hypertonic solutions caused significant damage, including epithelial sloughing; the epithelial damage caused increased systemic drug absorption and penetration of MPP into colorectal tissue, a potential advantage in certain drug delivery applications. In summary, we illustrate that enema composition can be adjusted to maximize local versus systemic drug delivery, and that mildly hypotonic, sodium-based vehicles can provide uniform drug and MPP delivery in the colon that maximizes local drug concentrations.

Effect of surface chemistry on nanoparticle interaction with gastrointestinal mucus and distribution in the gastrointestinal tract following oral and rectal administration in the mouse

It is believed that mucoadhesive surface properties on particles delivered to the gastrointestinal (GI) tract improve oral absorption or local targeting of various difficult-to-deliver drug classes. To test the effect of nanoparticle mucoadhesion on distribution of nanoparticles in the GI tract, we orally and rectally administered nano- and microparticles that we confirmed possessed surfaces that were either strongly mucoadhesive or non-mucoadhesive. We found that mucoadhesive particles (MAP) aggregated in mucus in the center of the GI lumen, far away from the absorptive epithelium, both in healthy mice and in a mouse model of ulcerative colitis (UC). In striking contrast, water absorption by the GI tract rapidly and uniformly transported non-mucoadhesive mucus-penetrating particles (MPP) to epithelial surfaces, including reaching the surfaces between villi in the small intestine. When using high gavage fluid volumes or injection into ligated intestinal loops, common methods for assessing oral drug and nanoparticle absorption, we found that both MAP and MPP became well-distributed throughout the intestine, indicating that the barrier properties of GI mucus were compromised. In the mouse colorectum, MPP penetrated into mucus in the deeply in-folded surfaces to evenly coat the entire epithelial surface. Moreover, in a mouse model of UC, MPP were transported preferentially into the disrupted, ulcerated tissue. Our results suggest that delivering drugs in non-mucoadhesive MPP is likely to provide enhanced particle distribution, and thus drug delivery, in the GI tract, including to ulcerated tissues.

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.

Enema use among men who have sex with men: a behavioral epidemiologic study with implications for HIV/STI prevention

Enema use or douching is a risk factor for HIV/STI in men who have sex with men (MSM). However, few studies have explored enema use practices. We examined the frequency of enema use, type of products used, and reasons to use and not to use before and after receptive anal sex in a large sample of MSM (N = 4,992) recruited from 16 U.S. cities. Through online surveys, we examined personal, behavioral, and environmental factors associated with enema use. Most (52 %) participants reported having douched at least once and 35 % reported douching within the last 3 months. While most (88 %) reported enema use before receptive anal sex, 28 % douched after receptive anal sex. Most participants (65 %) used water to douche, 24 % added salt, soap, and/or antibacterial products to water, and 30 % reported using commercially available products. Being a man of color, HIV-positive, diagnosed with an STI, identifying as "versatile" in sex, and having more than two unprotected sex partners were significantly associated with recent enema use. Douching behavior appears closely associated with HIV/STI risk. Douching with water may be a concern since it may increase HIV/STI infection by damaging the epithelium. Development and promotion of a non-damaging, non-water based enema specifically for use in anal sex are recommended. In addition, the seemingly contradictory recommendations that water-based lubricant is recommended for anal sex but water-based enemas are dangerous need to be reconciled into a single consistent message.

Preparing for rectal microbicides: sociocultural factors affecting product uptake among potential South American users

OBJECTIVES

We examined views on rectal microbicides (RMs), a potential HIV prevention option, among men who have sex with men and transgender women in 3 South American cities.

METHODS

During September 2009 to September 2010, we conducted 10 focus groups and 36 in-depth interviews (n = 140) in Lima and Iquitos, Peru, and Guayaquil, Ecuador, to examine 5 RM domains: knowledge, thoughts and opinions about RM as an HIV prevention tool, use, condoms, and social concerns. We coded emergent themes in recorded and transcribed data sets and extracted representative quotes. We collected sociodemographic information with a self-administered questionnaire.

RESULTS

RM issues identified included limited knowledge; concerns regarding plausibility, side effects, and efficacy; impact on condom use; target users (insertive vs receptive partners); and access concerns.

CONCLUSIONS

Understanding the sociocultural issues affecting RMs is critical to their uptake and should be addressed prior to product launch.

Prevalence and types of rectal douches used for anal intercourse: results from an international survey

BACKGROUND

Rectal products used with anal intercourse (AI) may facilitate transmission of STIs/HIV. However, there is limited data on rectal douching behavior in populations practicing AI. We examined the content, types of products, rectal douching practices and risk behaviors among those reporting AI.

METHODS

From August 2011 to May 2012, 1,725 women and men reporting receptive AI in the past 3 months completed an internet-based survey on rectal douching practices. The survey was available in English, French, German, Mandarin, Portuguese, Russian, Spanish, and Thai and included questions on sexual behaviors associated with AI including rectal douching. Differences by rectal douching practices were evaluated using chi-square methods and associations between reported douching practices and other factors including age and reported STI history were evaluated using logistic regression analysis.

RESULTS

Respondents represented 112 countries, were mostly male (88%), and from North America (55%) or Europe (22%). Among the 1,339 respondents (66%) who reported rectal douching, most (83%) reported always/almost always douching before receptive AI. The majority of rectal douchers reported using non-commercial/homemade products (93%), with water being the most commonly used product (82%). Commercial products were used by 31%, with the most common product being saline-based (56%). Rectal douching varied by demographic and risk behaviors. The prevalence of rectal douching was higher among men (70% vs. 32%; p-value < .01), those reporting substance-use with sex (74% vs. 46%; p-value < .01), and those reporting an STI in the past year (69% vs. 57% p-value < .01) or ever testing HIV-positive (72% vs. 53%; p-value < .01). In multivariable analysis, adjusting for age, gender, region, condom and lubricant use, substance use, and HIV-status, douchers had a 74% increased odds of reporting STI in the past year as compared to non-douchers [adjusted odds ratio (AOR) = 1.74; 95% CI 1.01-3.00].

CONCLUSION

Given that rectal douching before receptive AI is common and because rectal douching was associated with other sexual risk behaviors the contribution of this practice to the transmission and acquisition of STIs including HIV may be important.

Isoosmolar enemas demonstrate preferential gastrointestinal distribution, safety, and acceptability compared with hyperosmolar and hypoosmolar enemas as a potential delivery vehicle for rectal microbicides

Rectally applied antiretroviral microbicides for preexposure prophylaxis (PrEP) of HIV infection are currently in development. Since enemas (rectal douches) are commonly used by men who have sex with men prior to receptive anal intercourse, a microbicide enema could enhance PrEP adherence by fitting seamlessly within the usual sexual practices. We assessed the distribution, safety, and acceptability of three enema types-hyperosmolar (Fleet), hypoosmolar (distilled water), and isoosmolar (Normosol-R)-in a crossover design. Nine men received each enema type in random order. Enemas were radiolabeled [(99m)Tc-diethylene triamine pentaacetic acid (DTPA)] to assess enema distribution in the colon using single photon emission computed tomography/computed tomography (SPECT/CT) imaging. Plasma (99m)Tc-DTPA indicated mucosal permeability. Sigmoidoscopic colon tissue biopsies were taken to assess injury as well as tissue penetration of the (99m)Tc-DTPA. Acceptability was assessed after each product use and at the end of the study. SPECT/CT imaging showed that the isoosmolar enema had greater proximal colonic distribution (up to the splenic flexure) and greater luminal and colon tissue concentrations of (99m)Tc-DTPA when compared to the other enemas (p<0.01). Colon biopsies also showed that only the hyperosmolar enema caused sloughing of the colonic epithelium (p<0.05). In permeability testing, the hypoosmolar enema had higher plasma (99m)Tc-DTPA 24-h area under the concentration-time curve and peak concentration compared to the hyperosmolar and isoosmolar enemas, respectively. Acceptability was generally good with no clear preferences among the three enema types. The isoosmolar enema was superior or similar to the other enemas in all categories and is a good candidate for further development as a rectal microbicide vehicle.

Rectal douching and implications for rectal microbicides among populations vulnerable to HIV in South America: a qualitative study

OBJECTIVE

While gel-formulated rectal microbicides (RM) are the first to enter clinical trials, rectal douching in preparation for anal intercourse is a common practice; thus RMs formulated as douches may be a convenient alternative to gels. Nonetheless, little is known about potential users' thoughts regarding douche-formulated RMs or rectal douching practices, data that is needed to inform the advancement of douche-based RMs. This qualitative study examined thoughts regarding douches, their use as an RM and current douching practices among men who have sex with men and transgender women.

METHODS

12 focus groups and 36 in-depth interviews were conducted (N=140) to examine the overall acceptability of RM, of which one component focused on rectal douching. Focus groups and interviews were recorded, transcribed verbatim and coded; text relating to rectal douching was extracted and analysed. Sociodemographic information was collected using a self-administered questionnaire.

RESULTS

Support for a douche-formulated RM centred on the possibility of combined precoital hygiene and HIV protection, and it was believed that a deeply penetrating liquid douche would confer greater HIV protection than a gel. Drawbacks included rectal dryness, impracticality and portability issues, and potential side effects. Non-commercial douching apparatus use was common and liquids used included detergents, vinegar, bleach, lemon juice and alcohol.

CONCLUSIONS

A douche-formulated RM, while desirable and perceived as more effective than a gel-formulated RM, also generated questions regarding practicality and side effects. Of immediate concern were the non-commercial liquids already being used that likely damage rectal epithelia, potentially increasing HIV infection risk. Precoital rectal douching is common and an RM formulated as such is desirable, but education on rectal douching practices is needed now.

Acceptability of potential rectal microbicide delivery systems for HIV prevention: a randomized crossover trial

We assessed the acceptability of three of over-the-counter products representative of potential rectal microbicide (RM) delivery systems. From 2009 to 2010, 117 HIV-uninfected males (79 %) and females (21 %) who engage in receptive anal intercourse participated in a 6-week randomized crossover acceptability trial. Participants received each of three products (enema, lubricant-filled applicator, suppository) every 2 weeks in a randomized sequence. CASI and T-ACASI scales assessed product acceptability via Likert responses. Factor analysis was used to identify underlying factors measured by each scale. Random effects models were fit to examine age and gender effects on product acceptability. Three underlying factors were identified: Satisfaction with Product Use, Sexual Pleasure, and Ease of Product Use. For acceptability, the applicator ranked highest; however, differences between product acceptability scores were greatest among females and younger participants. These findings indicate that RM delivery systems impact their acceptability and should be considered early in RM development to enhance potential use.

An event-level comparison of risk-related sexual practices between black and other-race men who have sex with men: condoms, semen, lubricant, and rectal douching

Black men who have sex with men (MSM) living in the U.S. are disproportionately affected by HIV/AIDS. An online survey of sexual behavior was completed by Black, White, Hispanic/Latino, Asian/Pacific Islander, and other-race MSM (n=11,766) ages 18-87 years. Complete condom use, semen exposure, pre-coital rectal douching (enema use), and lubricant use at last male-partnered sexual event were compared by race, controlling for relevant sociodemographic variables and stratifying by sexual position (receptive, insertive, or both). Across sexual positions, 55-62% of Black MSM reported condom use, 5-8% reported semen exposure, 18-53% reported douching, and 33-43% reported lubricant use. Reported behavioral profiles were not significantly different from other races, except that Black MSM reported greater condom use than White MSM in the insertive position. Although findings argue against disproportionate rates of risk behavior accounting for racial disparities in HIV prevalence, they nonetheless highlight a need for continued behavioral intervention.

Using conjoint analysis to measure the acceptability of rectal microbicides among men who have sex with men in four South American cities

Conjoint Analysis (CJA), a statistical market-based technique that assesses the value consumers place on product characteristics, may be used to predict acceptability of hypothetical products. Rectal Microbicides (RM)-substances that would prevent HIV infection during receptive anal intercourse-will require acceptability data from potential users in multiple settings to inform the development process by providing valuable information on desirable product characteristics and issues surrounding potential barriers to product use. This study applied CJA to explore the acceptability of eight different hypothetical RM among 128 MSM in Lima and Iquitos, Peru; Guayaquil, Ecuador; and Rio de Janeiro, Brazil. Overall RM acceptability was highest in Guayaquil and lowest in Rio. Product effectiveness had the greatest impact on acceptability in all four cities, but the impact of other product characteristics varied by city. This study demonstrates that MSM from the same region but from different cities place different values on RM characteristics that could impact uptake of an actual RM. Understanding specific consumer preferences is crucial during RM product development, clinical trials and eventual product dissemination.