Intermittent Pre-exposure Prophylaxis Research Articles

Impact of dosing strategies on plasma concentrations of tenofovir: Implications in HIV pre-exposure prophylaxis in China

BackgroundTenofovir disoproxil fumarate has been recommended for pre-exposure prophylaxis (PrEP) to prevent HIV infection. Several studies have shown short but potent intermittent PrEP could provide comparable protection to daily PrEP in men, suggesting such dosing strategy might be useful in Chinese as well. The objective of this study was to evaluate the impact of different dosing strategies on plasma concentrations of tenofovir. MethodsAn open label study in 40 Chinese healthy volunteers, randomized to receive the WHO-recommended dose of tenofovir (300mg) at four different dosing intervals: twice weekly for 4 weeks; once daily for 4 weeks with one missing dose in weeks 2–4; once daily for 4 weeks with two missing doses in weeks 2–4; and once every other day for 12 days. Plasma samples were collected at pre-dose, weekly trough and 24h post last dose and assayed using HPLC-UV. ResultsThe tenofovir trough concentrations were below the lower limit of quantification with the twice weekly regimen. The trough concentrations (24h dosing interval) at the steady state were 51.7±12.1ng/ml and 53.5±13.8ng/ml (mean±SD) in the once daily groups. Missing doses, once or twice weekly, had no significant impact on trough concentrations. Prolongation of dosing interval to 48h resulted with concentrations at 24h and 48h (trough) of ∼40 and 20ng/ml, respectively. ConclusionsIntermittent tenofovir regimens resulted with remarkably low plasma concentrations in Chinese participants. Missing doses did not affect trough concentrations significantly.

Cohort profile: l’Actuel Pre-Exposure Prophylaxis (PrEP) Cohort study in Montreal, Canada

PurposeThe l’Actuel PrEP Cohort was established to monitor the uptake, effectiveness, safety and changes in sexual risk behaviours among individuals receiving pre-exposure prophylaxis (PrEP) for the prevention of HIV. This...

In men who have sex with men, does intermittent pre-exposure prophylaxis demonstrate high efficacy in preventing HIV transmission?

Illinois Masonic Family Medicine Residency, Chicago, IL The authors declare no conflicts of interest.

Clinical exigencies, psychosocial realities: negotiating HIV pre-exposure prophylaxis beyond the cascade among gay, bisexual and other men who have sex with men in Canada.

IntroductionNotwithstanding the efficacy of oral pre‐exposure prophylaxis (PrEP) in clinical trials, a number of obstacles exist to achieving population‐level impact among gay, bisexual and other men who have sex with men (GBM). However, few studies have explored the subjective experiences of GBM PrEP users and non‐users in the community, outside of clinical trials. The objectives of this study were to explore GBM's experiences of considering, accessing and using (or not using) PrEP, and to understand emerging sexual health, social and community issues among GBM in the PrEP era.MethodsFrom October 2015 to March 2016, we purposively sampled PrEP‐naïve and PrEP‐experienced GBM from community organizations and health centres in Toronto, Canada. In‐depth, 45‐ to 90‐minute semi‐structured interviews explored PrEP perspectives and decision‐making, access, initiation, use over time, sexual practices and psychosocial considerations. Interviews were recorded, transcribed verbatim, uploaded into NVIVO, reviewed using thematic analysis and then contrasted with the PrEP cascade.ResultsParticipants included PrEP users (n = 15) and non‐users (n = 14) (mean age = 36.7 years; SD = 8.2), largely gay‐identified (86.2%), cisgender male (89.7%) and white (79.3%). Themes indicate not only correspondences, but also limitations of the PrEP cascade by complicating a user/non‐user binary and challenging the unilateral presupposition that HIV risk perception leads to PrEP acceptance. Findings further call into question assumptions of a linear stage progression and retention in care as a universal endpoint, instead revealing alternate trajectories of seasonal or intermittent PrEP use and, for some, an end goal of terminating PrEP. GBM's narratives also revealed potent psychological/affective experiences of untethering sex from HIV anxiety; multifaceted PrEP stigma; and challenges to sexual norms and practices that complicate existing behavioural prevention strategies and sexual and social relationships.ConclusionsAn expanded PrEP cascade should consider alternate trajectories of use based on dynamic relationships and behavioural risks that may call for seasonal or intermittent use; systemic barriers in access to and sustaining PrEP; and multiple end goals including PrEP maintenance and discontinuation. Incorporating GBM's lived experiences, evolving preferences, and psychosocial and community‐level challenges into PrEP implementation models, rather than a circumscribed biomedical approach, may more effectively support HIV prevention and GBM's broader sexual and psychological health.

Where next with preexposure prophylaxis?

Controlling the HIV epidemic remains a major public health challenge, and there is an urgent need for novel prevention strategies. Preexposure prophylaxis (PrEP) refers to the use of antiretrovirals in HIV-negative people at high risk to prevent infection and has the potential to be an important component in the global effort to end the HIV epidemic by 2030. We review the current evidence for the safety and efficacy of PrEP in its different forms and address emergent issues and concerns regarding its implementation. Two further randomized control trials report high efficacy of both daily and intermittent PrEP in MSM leading to renewed calls for wider availability of PrEP for this group. Oral tenofovir disoproxil/emtricitabine has been licensed for PrEP in many countries and is well tolerated, safe and effective. Oral PrEP is well tolerated and effective in reducing the incidence of HIV infection in individuals at high risk. Implementation in high-income countries is progressing slowly; demonstration projects and trials continue in low and middle-income countries.

Motives of Dutch men who have sex with men for daily and intermittent HIV pre-exposure prophylaxis usage and preferences for implementation: A qualitative study.

Although PrEP is not yet registered in Europe, including the Netherlands, its approval and implementation are expected in the near future. To inform future pre-exposure prophylaxis (PrEP) implementation, this study aimed to gain insight into motives and preferences for daily or intermittent PrEP use among Dutch HIV-negative men having sex with men (MSM).Between February and December 2013, semistructured interviews were conducted until data saturation was reached (N = 20). Interviews were analyzed using the Grounded Theory approach.Motives for (not) using daily PrEP were based on beliefs about PrEP efficacy and side effects, preferences for other prevention strategies, self-perceived HIV risk, self-perceived efficacy of PrEP adherence, beliefs about possible benefits (e.g., anxiety reduction, sex life improvement), and barriers of PrEP use (e.g., costs, monitoring procedures). The perceived benefits of intermittent versus daily PrEP use were the lower costs and side effects and the lower threshold to decision to start using intermittent PrEP. Barriers of intermittent PrEP versus daily PrEP use were the perceived need to plan their sex life and adhere to multiple prevention strategies. Although some perceived PrEP as a condom substitute, others were likely to combine PrEP and condoms for sexually transmitted infections (STI) prevention and increased HIV protection. Participants preferred PrEP service locations to have specialized knowledge of HIV, antiretroviral therapy, sexual behavior, STIs, patients’ medical background, be easily approachable, be able to perform PrEP follow-up monitoring, and provide support.To maximize the public health impact of PrEP, ensuring high uptake among MSM at highest risk is important. Therefore, targeted information about PrEP efficacy and side effects need to be developed, barriers for accessing PrEP services should be minimized, and perceived self-efficacy to use PrEP should be addressed and improved. To prevent increases in STIs, condom use should be monitored and PrEP should be integrated into routine STI screening and counseling.

Sexual Behavior Patterns and PrEP Dosing Preferences in a Large Sample of North American Men Who Have Sex With Men.

Pre-exposure prophylaxis (PrEP), taken as a single daily coformulated pill containing tenofovir -emtricitabine, is a promising intervention to reduce the likelihood of HIV acquisition in at-risk individuals, including men who have sex with men. Little is known about the acceptability of less than daily, intermittent PrEP regimens. We conducted an online survey of North American men who have sex with men to characterize their sexual frequency and planning behaviors and correlate these with PrEP dosing preferences. Of the 3217 respondents who completed the survey, 46% reported engaging in unplanned condomless anal intercourse (CAI) at least once in previous 3 months and 8% reported engaging in CAI more than once per week. In multivariable analysis, reporting unplanned CAI was associated with lower educational level, identifying as homosexual/gay as compared with bisexual, being in a monogamous relationship, having a higher self-perceived risk of HIV acquisition, reporting higher income, engaging in CAI more than five times in the last 3 months, and not having visited a health care provider in the previous year. Frequent CAI (>1 time per week) was associated with being younger, identifying as homosexual/gay as compared with bisexual, being in a monogamous relationship, and having a higher self-perceived risk of HIV. Having only planned sex over the last 3 months was associated with a preference for event-based PrEP, whereas having frequent or unplanned CAI was associated with a preference for daily or time-driven PrEP regimens, respectively. Our findings suggest that preferences for different PrEP regimens are associated with the sexual frequency and planning behaviors of potential users.

HIV pre-exposure prophylaxis (PrEP): a review of current knowledge of oral systemic HIV PrEP in humans.

Despite established HIV prevention strategies and broadly available diagnostic strategies in developed western countries, rates of HIV new infections remain high. Alternative strategies for HIV prevention, particularly among men who have sex with men (MSM), are crucial. HIV pre-exposure prophylaxis (PrEP) has been discussed as one additional option that this review seeks to explore. An online search identifying PrEP-relevant literature from 1st January 2010 to 1st August, 2015 was performed. The iPrEx study, first published in 2010, demonstrated a reduction in relative risk (RRR) of HIV seroconversion of 44 % for continuous PrEP with tenofovir disoproxil fumarate (TDF) and emtricitabine (FTC) in MSM. The efficacy of PrEP has been confirmed for continuous PrEP in the PROUD study and for intermittent PrEP in the IPERGAY study (RRR = 86 % in both studies). The PrEP was well tolerated in all studies, and the evolution of HIV resistance has been low. Compensatory increased sexual risk behavior was not observed in recent studies. In contrast to the high efficacy of risk reduction for HIV transmission in MSM, the results of TDF PrEP and TDF/FTC PrEP studies using microbicidal agents or pills among heterosexual women were different (RRR 6-75 %). Continuous and intermittent PrEP demonstrated high efficacy in preventing HIV seroconversion, notably among MSM. PrEP was well tolerated. Adherence was critical for high efficacy in all studies. Further studies to evaluate implementation strategies and cost-effectiveness in different risk populations are needed as well as drug approval in Europe.

Defining success with HIV pre-exposure prophylaxis: a prevention-effective adherence paradigm.

Clinical trial data have shown that oral pre-exposure prophylaxis (PrEP) is efficacious when taken as prescribed; however, PrEP adherence is complex and must be understood within the context of variable risk for HIV infection and use of other HIV prevention methods. Different levels of adherence may be needed in different populations to achieve HIV prevention, and the optimal methods for achieving the necessary adherence for both individual and public health benefits are unknown. Guidance for PrEP use must consider these questions to determine the success of PrEP-based HIV prevention programs. In this article, we propose a new paradigm for understanding and measuring PrEP adherence, termed prevention-effective adherence, which incorporates dynamic HIV acquisition risk behaviors and the use of HIV alternative prevention strategies. We discuss the need for daily PrEP use only during periods of risk for HIV exposure, describe key issues for measuring and understanding relevant behaviors, review lessons from another health prevention field (i.e., family planning), and provide guidance for prevention-effective PrEP use. Moreover, we challenge emerging calls for sustained, near perfect PrEP adherence regardless of risk exposure and offer a more practical and public health-focused vision for this prevention intervention.

Accuracy of highly sexually active gay and bisexual men's predictions of their daily likelihood of anal sex and its relevance for intermittent event-driven HIV pre-exposure prophylaxis.

We sought to examine highly sexually active gay and bisexual men's accuracy in predicting their sexual behavior for the purposes of informing future research on intermittent event-driven HIV Pre-Exposure Prophylaxis. For 30 days, 92 HIV-negative men completed a daily survey about their sexual behavior (n = 1688 days of data) and indicated their likelihood of having anal sex with a casual male partner next day. We used multilevel modeling to analyze the association between self-reported likelihood of and subsequent engagement in anal sex. We found a linear association between men's reported likelihood of anal sex with casual partners and the actual probability of engaging in sex, although men overestimated the likelihood of sex. Overall, we found that men were better at predicting when they would not have sex than when they would, particularly if any likelihood value greater than 0% was treated as indicative that sex might occur. We found no evidence that men's accuracy of prediction was affected by whether it was a weekend or whether they were using substances, although both did increase the probability of sex. These results suggested that, men taking event-driven intermittent Pre-Exposure Prophylaxis, 14% of doses could have been safely skipped with a minimal rate of false negatives using guidelines of taking a dose unless there was no chance (ie, 0% likelihood) of sex on next day. This would result in savings of over US $1300 per year in medication costs per participant.

HIV Drug Therapy in the Americas 16-18 April 2015, Mexico City, Mexico.

HIV Drug Therapy in the Americas 16-18 April 2015, Mexico City, Mexico.

A polyvalent Clade B virus-like particle HIV vaccine combined with partially protective oral preexposure prophylaxis prevents simian-human immunodeficiency virus Infection in macaques and primes for virus-amplified immunity.

Vaccination and preexposure prophylaxis (PrEP) with antiretrovirals have shown only partial protection from HIV-1 infection in human trials. Oral Truvada (emtricitabine/tenofovir disoproxil fumarate) is FDA approved as PrEP but partial adherence reduces efficacy. If combined as biomedical preventions (CBP), an HIV vaccine could protect when PrEP adherence is low and PrEP could prevent vaccine breakthroughs. The efficacy of combining oral PrEP with an HIV vaccine has not been evaluated in humans. We determined the efficacy of combining a DNA/virus-like particle (VLP) vaccine with partially effective intermittent PrEP in Indian rhesus macaques (RM). Eight RM received intramuscular inoculations of five DNA plasmids encoding four HIV-1 Clade B primary isolate Envs and SIVmac239 Gag (at weeks 0 and 4), followed by intramuscular and intranasal inoculations of homologous Gag VLPs and four Env VLPs (at weeks 12, 16, and 53). At week 61, we initiated weekly rectal exposures with heterologous SHIV162p3 (10 TCID50) along with oral Truvada (TDF, 22 mg/kg; FTC 20 mg/kg) dosing 2 h before and 22 h after each exposure. This PrEP regimen previously demonstrated 50% efficacy. Five controls (no vaccine, no PrEP) received weekly SHIV162p3. All controls were infected after a median of four exposures; the mean peak plasma viral load (VL) was 3.9×10(7) vRNA copies/ml. CBP protected seven of eight (87.5%) RM. The one infected CBP RM had a reduced peak VL of 8.8×10(5) copies/ml. SHIV exposures during PrEP amplified Gag and Env antibody titers in protected RM. These results suggest that combining oral PrEP with HIV vaccines could enhance protection against HIV-1 infection.

Preferences for daily or intermittent pre-exposure prophylaxis regimens and ability to anticipate sex among HIV uninfected members of Kenyan HIV serodiscordant couples.

Intermittent dosing for pre-exposure prophylaxis (PrEP) has been proposed as an alternative to daily PrEP to reduce cost and patient drug exposure and to improve adherence. One possible dosing regimen is pre-intercourse PrEP, which requires anticipating sex in advance. We examined preferences for daily versus pre-intercourse PrEP and ability to anticipate sex among 310 HIV uninfected members of HIV serodiscordant heterosexual couples in Thika, Kenya, with high HIV knowledge and experience with daily PrEP use in a clinical trial setting. Preferences were evenly split between daily PrEP (47.4%) and pre-intercourse PrEP (50.7%). Participants were more likely to prefer daily PrEP if they reported unprotected sex during the prior month (adjusted prevalence ratio [aPR] 1.48, 95% CI 1.20-1.81) or <80% adherence to study drug (aPR 1.50, 95% CI 1.25-1.79), and were less likely to prefer daily PrEP if sex was usually planned, versus spontaneous (aPR 0.76, 95% CI 0.61-0.96). A minority (24.2%) reported anticipating sex >3h in advance, with younger participants being less likely to do so (aPR 0.43, 95% CI 0.23-0.83 for ages 18-29 vs. ≥40). Findings suggest that intermittent PrEP could be a popular option in this population, but that optimal adherence and sufficient drug levels might be challenging with a pre-intercourse regimen.

Safety, Adherence and Acceptability of Intermittent Tenofovir/Emtricitabine as HIV Pre-Exposure Prophylaxis (PrEP) among HIV-Uninfected Ugandan Volunteers Living in HIV-Serodiscordant Relationships: A Randomized, Clinical Trial

BackgroundEfficacy of oral pre-exposure prophylaxis (PrEP) in prevention of HIV acquisition has been evaluated using a daily regimen. However, adherence to long term daily medication is rarely perfect. Intermittent regimen may be a feasible alternative. Preclinical studies have demonstrated effectiveness of intermittent PrEP in SHIV prevention among animals. However, little is known about intermittent PrEP regimens.DesignSeventy two HIV-uninfected volunteers in HIV serodiscordant couple relationships in Uganda were randomly assigned to receive daily oral Tenofovir/Emtricitabine (TDF/FTC-Truvada) or placebo, or intermittent (Monday, Friday and within 2 hours after sex, not to exceed one dose per day) oral TDF/FTC or placebo in a 2:1:2:1 ratio. Volunteers and study staff were blinded to drug assignment, but not to regimen assignment.MethodsVolunteers were followed for 4 months after randomization, with monthly clinical and laboratory safety assessments and comprehensive HIV risk reduction services. Adherence was monitored using medication event monitoring system (MEMS) and self-report. Sexual activity data were collected via daily short text message (SMS) and self-report. HIV-specific immune responses were assessed by IFN-γ ELISPOT.ResultsBoth daily and intermittent oral TDF/FTC regimens were well tolerated. Median MEMS adherence rates were 98% (IQR: 93-100) for daily PrEP regimen, 91% (IQR: 73-97) for fixed intermittent dosing and 45% (IQR: 20-63) for post-coital dosing. SMS response rate was 74%, but increased to 80% after excluding server outages; results may have been affected by the novelty of this measure. The majority of volunteers expressed willingness with no particular preference for either regimen.ConclusionsBoth daily and intermittent oral PrEP dosing regimens were safe. Adherence was high for daily and fixed intermittent dosing; post-coital dosing was associated with poor adherence. Fixed intermittent PrEP regimens may be feasible especially if a minimum effective drug concentration correlating with HIV prevention can be achieved with this dosing.Registration Clinicaltrials.gov number NCT00931346

Considerations regarding antiretroviral chemoprophylaxis in MSM

HIV infection among MSM remains a significant issue. Data relevant to MSM populations from animal models, pharmacokinetic studies and clinical trials are summarized and challenges and potential consequences of use of preexposure prophylaxis (PrEP) by MSM are discussed. Rectal simian-human immunodeficiency virus transmission in macaque models can be prevented by intermittent PrEP dosing. The Preexposure Prophylaxis Initiative (iPrEx) study found that daily oral emtricitabine-tenofovir disoproxyl fumarate (TDF/FTC) decreased HIV infection by 44% among 2499 high-risk MSM. Men with detectable levels of TDF or FTC in plasma and peripheral blood mononuclear cells experienced more than 90% protective effect, emphasizing the importance of adherence. In iPrEX and other studies, PrEP was generally safe and well tolerated. However, it appears that TDF use is associated with a small but significant decrease in mean bone mineral density. No risk compensation has been demonstrated, but this remains an area of potential concern when PrEP is used outside the setting of a placebo-controlled trial. Numerous PrEP trials in MSM are currently underway. Oral FTC/TDF is effective in preventing HIV infection among MSM. Optimal PrEP agents and dosing regimens now need to be identified. Understanding the patterns of and impediments to PrEP use among MSM is vital and these should be monitored in ongoing demonstration projects and open-label studies.

High Acceptability of HIV Pre-exposure Prophylaxis but Challenges in Adherence and Use: Qualitative Insights from a Phase I Trial of Intermittent and Daily PrEP in At-Risk Populations in Kenya

This paper used qualitative methods to explore experiences of men who have sex with men and female sex workers in Nairobi and Mtwapa, Kenya, who used oral pre-exposure prophylaxis (PrEP) for HIV prevention as part of a four-month trial of safety, acceptability and adherence. Fifty-one of 72 volunteers who took part in a randomized, placebo-controlled, blinded trial that compared daily and intermittent dosage of PrEP underwent qualitative assessments after completing the trial. Analyses identified three themes: (i) acceptability of PrEP was high, i.e. side effects were experienced early in the study but diminished over time, however characteristics of pills could improve comfort and use; (ii) social impacts such as stigma, rumors, and relationship difficulties due to being perceived as HIV positive were prevalent; (iii) adherence was challenged by complexities of daily life, in particular post-coital dosing adherence suffered from alcohol use around time of sex, mobile populations, and transactional sex work. These themes resonated across dosing regimens and gender, and while most participants favored the intermittent dosing schedule, those in the intermittent group noted particular challenges in adhering to the post-coital dose. Culturally appropriate and consistent counseling addressing these issues may be critical for PrEP effectiveness.

Safety and Adherence to Intermittent Pre-Exposure Prophylaxis (PrEP) for HIV-1 in African Men Who Have Sex with Men and Female Sex Workers

BackgroundLittle is known about safety of and adherence to intermittent HIV PrEP regimens, which may be more feasible than daily dosing in some settings. We present safety and adherence data from the first trial of an intermittent PrEP regimen among Kenyan men who have sex with men (MSM) and female sex workers (FSW).Methods/Principal FindingsMSM and FSW were randomized to daily oral FTC/TDF or placebo, or intermittent (Monday, Friday and within 2 hours after sex, not to exceed one dose per day) oral FTC/TDF or placebo in a 2∶1∶2∶1 ratio; volunteers were followed monthly for 4 months. Adherence was assessed with the medication event monitoring system (MEMS). Sexual activity data were collected via daily text message (SMS) queries and timeline followback interviews with a one-month recall period. Sixty-seven men and 5 women were randomized into the study. Safety was similar among all groups. Median MEMS adherence rates were 83% [IQR: 63–92] for daily dosing and 55% [IQR:28–78] for fixed intermittent dosing (p = 0.003), while adherence to any post-coital doses was 26% [IQR:14–50]. SMS response rates were low, which may have impaired measurement of post-coital dosing adherence. Acceptability of PrEP was high, regardless of dosing regimen.Conclusions/SignificanceAdherence to intermittent dosing regimens, fixed doses, and in particular coitally-dependent doses, may be more difficult than adherence to daily dosing. However, intermittent dosing may still be appropriate for PrEP if intracellular drug levels, which correlate with prevention of HIV acquisition, can be attained with less than daily dosing and if barriers to adherence can be addressed. Additional drug level data, qualitative data on adherence barriers, and better methods to measure sexual activity are necessary to determine whether adherence to post-coital PrEP could be comparable to more standard regimens.Trial RegistrationClinicalTrials.gov NCT00971230

Sexual frequency and planning among at-risk MSM in the US: Implications for daily vs. intermittent pre-exposure prophylaxis (PrEP)

Sexual frequency and planning among at-risk MSM in the US: Implications for daily vs. intermittent pre-exposure prophylaxis (PrEP)

Delayed Maturation of Antibody Avidity but Not Seroconversion in Rhesus Macaques Infected With Simian HIV During Oral Pre-Exposure Prophylaxis

Pre-exposure prophylaxis (PrEP) is a novel intervention strategy for the prevention HIV transmission. Because several clinical trials are at various stages of completion, it is important to understand the impact of PrEP treatment on the development of the immune response to HIV, particularly in individuals who exhibit breakthrough infections despite PrEP. A model of HIV infection, using rhesus macaques and the simian/human immunodeficiency virus (SHIV), was used to evaluate the effects of PrEP on the evolution of the humoral immune response. Time to seroconversion, neutralizing and binding antibody levels, and antibody avidity were measured in 12 rhesus macaques infected during daily or intermittent PrEP with FTC (emtricitabine) or Truvada (FTC/tenofovir combination) and compared with 11 untreated, simian HIV-infected controls. Macaques that became infected while receiving PrEP exhibited significantly lower peak virus loads during acute infection as compared with untreated animals. Although the timing of seroconversion and SHIV binding and neutralizing antibody levels were not impacted by treatment, lower maturation rates of antibody avidity for anti-p27, gp120, gp160, and gp41 were observed. This study suggests that reduced virus loads associated with PrEP treatment have little impact on timing of seroconversion and neutralizing/binding antibody levels; however, maturation of antibody avidity was suppressed.

Pre-exposure prophylaxis of HIV

Pre-exposure prophylaxis (PrEP) is an experimental approach to HIV prevention and consists of antiretroviral drugs to be taken before potential HIV exposure in order to reduce the risk of HIV infection and continued during periods of risk. An effective PrEP could provide an additional safety net to sexually active persons at risk, when combined with other prevention strategies. Women represent nearly 60% of adults infected with HIV and PrEP can be a female-controlled prevention method for women who are unable to negotiate condom use. Two antiretroviral nucleoside analog HIV-1 reverse transcriptase inhibitor drugs are currently under trial as PrEP drugs, namely tenofovirdisoproxilfumarate (TDF) alone and TDF in combination with emricitabine (FTC), to be taken as daily single dose oral drugs. There are 11 ongoing trials of ARV-based prevention in different at risk populations across the world. The iPrex trial showed that daily use of oral TDF/FTC by MSM resulted in 44% reduction in the incidence of HIV. This led to publication of interim guidance by CDC to use of PrEP by health providers for MSM. Few other trials are Bangkok Tenofovir Study, Partners PrEP Study, FEM-PrEP study, and VOICE (MTN-003) study. Future trials are being formulated for intermittent PrEP (iPrEP) where drugs are taken before and after sex, "stand-in dose" iPrEP, vaginal or rectal PrEP, etc. There are various issues/concerns with PrEP such as ADRs and resistance to TDF/FTC, adherence to drugs, acceptability, sexual disinhibition, use of PrEP as first line of defense for HIV without other prevention strategies, and cost. The PrEP has a potential to address unmet need in public health if delivered as a part of comprehensive toolkit of prevention services, including risk-reduction, correct and consistent use of condoms, and diagnosis and treatment of sexually transmitted infections.