Safety and Pharmacokinetics of Quick-Dissolving Polymeric Vaginal Films Delivering the Antiretroviral IQP-0528 for Preexposure Prophylaxis

Next-generation 3D printed multipurpose prevention intravaginal ring for prevention of HIV, HSV-2, and unintended pregnancy

Globally, nearly half of all pregnancies are unintended, ∼1.3 million new human immunodeficiency virus (HIV) infections are reported every year, and more than 500 million people are estimated to have a genital herpes simplex virus (HSV-2) infection. Here we report the first 3D printed multipurpose prevention technology (MPT) intravaginal ring (IVR) for prevention of HIV, HSV-2, and unintended pregnancy. The IVRs were fabricated using state-of-the-art Continuous Liquid Interface Production (CLIP™) 3D printing technology using a biocompatible silicone-urethane based resin. Anti-HIV drug (Dapivirine, DPV), anti-herpes drug (Pritelivir, PTV) and a contraceptive drug (Levonorgestrel, LNG) were loaded in a macaque size IVR (25 mm outer diameter, OD; 6.0 mm cross-section, CS) allometrically scaled from the human size (54 mm OD; 7.6 mm CS) IVR analogue. All three active pharmaceutical ingredients (APIs) were loaded in the IVR using a single-step drug loading process driven by absorption. DPV, PTV, and LNG elicited zero-order release kinetics in vitro in simulated vaginal fluid (SVF) at pH 4 and pH 8 relevant to human and macaque vaginal pH respectively. CLIP 3D printed MPT IVRs remained stable after 6 months of storage at 4 °C with no change in physical, dimensional, or mechanical properties and no change in drug concentration and absence of drug degradation byproducts. The MPT IVRs elicited sustained release of all three APIs in macaques for 28 days with median plasma concentrations of 138 pg/mL (DPV), 18,700 pg/mL (PTV), and 335 pg/mL (LNG). Safety studies demonstrated that the MPT IVRs were safe and well tolerated in the macaques with no observed change or abnormalities in vaginal pH and no significant changes in any of the 22 mucosal cytokines and chemokines tested including pro-inflammatory (IL-1β, IL-6, IL-8, IFN-γ, TNF-α, IL-17, IL-18) and anti-inflammatory (IL-10, IL-12) cytokines while the MPT IVR was in place or after its removal. Additionally, MPT IVRs elicited no observed alterations in systemic CD4+ and CD8+ T cells during the entire study. Collectively, the proposed MPT IVR has potential to expand preventative choices for young women and girls against unintended pregnancy and two highly prevalent sexually transmitted infections (STIs).

Pilot PET study of vaginally administered bioadhesive nanoparticles in cynomolgus monkeys: Kinetics and safety evaluation

Long-lasting vaginal dosage forms could improve the therapeutic efficacy of vaginal microbicides, but achieving long-term delivery to the vaginal canal has been a significant challenge. To advance understanding of vaginal dosage retention and biodistribution, we describe a method of noninvasive imaging with 89Zr-labeled bioadhesive nanoparticles (BNPs) in non-human primates. We additionally examined the safety of repeated BNP application. BNPs administered vaginally to cynomolgus monkeys were still detected after 24 h (1.7% retention) and 120 h (0.1% retention). BNPs did not translocate to the uterus or into systemic circulation. Analysis of inflammatory biomarkers in the vaginal fluid and plasma suggest that BNPs are safe and biocompatible, even after multiple doses. BNPs are a promising delivery vehicle for vaginally administered therapeutics. Further studies using the non-human primate imaging materials and methods developed here could help advance clinical translation of BNPs and other long-lasting vaginal dosage forms.

CDC Prioritizes HIV Prevention and Treatment to Reduce HIV Disparities Among Cis-Gender Black Women

To succeed in ending the HIV epidemic in the United States, the Centers for Disease Control and Prevention (CDC) focuses on delivering combinations of scientifically proven, cost-effective, and scalable interventions to priority populations. Systemic factors continue to contribute to persistent health disparities and disproportionately higher rates of HIV diagnosis in some communities. The National HIV/AIDS Strategy has designated cis-gender Black women (CgBW) as a priority population to address the racial and ethnic inequities in HIV. This report presents the portfolio of projects, programs, and initiatives funded by the CDC's Division of HIV Prevention (DHP) to address disparities in HIV and improve health and QOL among CgBW. These funded activities include the development, planning, and implementation of HIV prevention programs, mass media campaigns, and behavioral interventions focused on CgBW. This report also summarizes DHP's community engagement, capacity building, and partnership efforts, and highlights research and surveillance activities focusing on CgBW. Finally, this report outlines future directions for CDC's efforts to improve access to HIV testing, treatment, and prevention for CgBW in the United States.

Current insights and molecular docking studies of HIV-1 reverse transcriptase inhibitors

Human immunodeficiency virus (HIV) causes acquired immunodeficiency syndrome (AIDS), a lethal disease that is prevalent worldwide. According to the Joint United Nations Programme on HIV/AIDS (UNAIDS) data, 38.4 million people worldwide were living with HIV in 2021. Viral reverse transcriptase (RT) is an excellent target for drug intervention. Nucleoside reverse transcriptase inhibitors (NRTIs) were the first class of approved antiretroviral drugs. Later, a new type of non-nucleoside reverse transcriptase inhibitors (NNRTIs) were approved as anti-HIV drugs. Zidovudine, didanosine, and stavudine are FDA-approved NRTIs, while nevirapine, efavirenz, and delavirdine are FDA-approved NNRTIs. Several agents are in clinical trials, including apricitabine, racivir, elvucitabine, doravirine, dapivirine, and elsulfavirine. This review addresses HIV-1 structure, replication cycle, reverse transcription, and HIV drug targets. This study focuses on NRTIs and NNRTIs, their binding sites, mechanisms of action, FDA-approved drugs and drugs in clinical trials, their resistance and adverse effects, their molecular docking studies, and highly active antiretroviral therapy (HAART).

Next generation 3D-printed intravaginal ring for prevention of HIV and unintended pregnancy

Globally, there are 20 million adolescent girls and young women living with HIV who have limited access to long-acting, effective, women-controlled preventative methods. Additionally, although there are many contraceptive methods available, globally, half of all pregnancies remain unintended. Here we report the first 3D-printed multipurpose prevention technology (MPT) intravaginal ring (IVR) for HIV prevention and contraception. We utilized continuous liquid interface production (CLIP™) to fabricate MPT IVRs in a biocompatible silicone-based resin. Etonogestrel (ENG), ethinyl estradiol (EE), and islatravir (ISL) were loaded into the silicone poly(urethane) IVR in a controlled single step drug loading process driven by absorption. ENG/EE/ISL IVR promoted sustained release of drugs for 150 days in vitro and 14 days in sheep. There were no adverse MPT IVR-related findings of cervicovaginal toxicity or changes in vaginal biopsies or microbiome community profiles evaluated in sheep. Furthermore, ISL IVR in macaques promoted sustained release for 28 days with ISL-triphosphate levels above the established pharmacokinetic benchmark of 50-100 fmol/106 PBMCs. The ISL IVR was found to be safe and well tolerated in the macaques with no observed mucosal cytokine changes or alterations in peripheral CD4 T-cell populations. Collectively, the proposed MPT IVR has potential to expand preventative choices for young women and girls.

Women-specific routes of administration for drugs: A critical overview

The woman's body presents a number of unique anatomical features that can constitute valuable routes for the administration of drugs, either for local or systemic action. These are associated with genitalia (vaginal, endocervical, intrauterine, intrafallopian and intraovarian routes), changes occurring during pregnancy (extra-amniotic, intra-amniotic and intraplacental routes) and the female breast (breast intraductal route). While the vaginal administration of drug products is common, other routes have limited clinical application and are fairly unknown even for scientists involved in drug delivery science. Understanding the possibilities and limitations of women-specific routes is of key importance for the development of new preventative, diagnostic and therapeutic strategies that will ultimately contribute to the advancement of women's health. This article provides an overview on women-specific routes for the administration of drugs, focusing on aspects such as biological features pertaining to drug delivery, relevance in current clinical practice, available drug dosage forms/delivery systems and administration techniques, as well as recent trends in the field.

Development and optimization of a new tioconazole vaginal mucoadhesive film using an experimental design strategy. Physicochemical and biological characterization

A new tioconazole (TCZ) mucoadhesive film, based on a biodegradable chitosan/ hydroxypropyl methylcellulose (CH/HPMC) blend, was developed for treatment of vaginal candidiasis. The formulation was optimized through an I-optimal design (minimizing the integral of the prediction variance across the factor space), where the impact of the proportion of the ingredients and processing variables on the quality of the final product was evaluated. Both, the thickness of the film and the swelling index, which affect patients' comfort and compliance, were considered. Mechanical testing, such as load at break, elongation at break, and mucoadhesive strength were also included as dependent variables. The optimal mucoadhesive film formulation, which should be obtained at a drying temperature of 30 °C, was found to include the combination of CH and HPMC (forming polymers) at 0.25:0.75 ratio, a mixture of polyethylene glycol 400 and propylene glycol as plasticizers (0.07:0.93, 5% w/w), and TCZ loaded at 15 % w/w. The optimal preparation was subjected to exhaustive characterization studies, which revealed that the drug was entrapped in the polymeric matrix in an amorphous state and that the film exhibited a smooth and uniform surface, demonstrating excellent component compatibility. In vitro tests showed that the formulation has an excellent time to kill value (3 min) and lacks cytotoxicity, suggesting that it should be highly effective and safe.

Recent Advances in Polymer-Based Vaginal Drug Delivery Systems

The vagina has been considered a potential drug administration route for centuries. Most of the currently marketed and investigated vaginal formulations are composed with the use of natural or synthetic polymers having different functions in the product. The vaginal route is usually investigated as an administration site for topically acting active ingredients; however, the anatomical and physiological features of the vagina make it suitable also for drug systemic absorption. In this review, the most important natural and synthetic polymers used in vaginal products are summarized and described, with special attention paid to the properties important in terms of vaginal application. Moreover, the current knowledge on the commonly applied and innovative dosage forms designed for vaginal administration was presented. The aim of this work was to highlight the most recent research directions and indicate challenges related to vaginal drug administrations. As revealed in the literature overview, intravaginal products still gain enormous scientific attention, and novel polymers and formulations are still explored. However, there are research areas that require more extensive studies in order to provide the safety of novel vaginal products.

Engineering monoclonal antibody-based contraception and multipurpose prevention technologies†

Sexually transmitted infections are highly prevalent, and over 40% of pregnancies are unplanned. We are producing new antibody-based multipurpose prevention technology products to address these problems and fill an unmet need in female reproductive health. We used a Nicotiana platform to manufacture monoclonal antibodies against two prevalent sexually transmitted pathogens, HIV-1 and HSV-2, and incorporated them into a vaginal film (MB66) for preclinical and Phase 1 clinical testing. These tests are now complete and indicate that MB66 is effective and safe in women. We are now developing an antisperm monoclonal antibody to add contraceptive efficacy to this product. The antisperm antibody, H6-3C4, originally isolated by Shinzo Isojima from the blood of an infertile woman, recognizes a carbohydrate epitope on CD52g, a glycosylphosphatidylinositol-anchored glycoprotein found in abundance on the surface of human sperm. We engineered the antibody for production in Nicotiana; the new antibody which we call "human contraception antibody," effectively agglutinates sperm at concentrations >10 μg/ml and maintains activity under a variety of physiological conditions. We are currently seeking regulatory approval for a Phase 1 clinical trial, which will include safety and "proof of principle" efficacy endpoints. Concurrently, we are working with new antibody production platforms to bring the costs down, innovative antibody designs that may produce more effective second-generation antibodies, and delivery systems to provide extended protection.

20S Proteasome as a Drug Target in Trichomonas vaginalis

Trichomoniasis is a sexually transmitted disease with hundreds of millions of annual cases worldwide. Approved treatment options are limited to two related nitro-heterocyclic compounds, yet resistance to these drugs is an increasing concern. New antimicrobials against the causative agent, Trichomonas vaginalis, are urgently needed. We show here that clinically approved anticancer drugs that inhibit the proteasome, a large protease complex with a critical role in degrading intracellular proteins in eukaryotes, have submicromolar activity against the parasite in vitro and on-target activity against the enriched T. vaginalis proteasome in cell-free assays. Proteomic analysis confirmed that the parasite has all seven α and seven β subunits of the eukaryotic proteasome although they have only modest sequence identities, ranging from 28 to 52%, relative to the respective human proteasome subunits. A screen of proteasome inhibitors derived from a marine natural product, carmaphycin, revealed one derivative, carmaphycin-17, with greater activity against T. vaginalis than the reference drug metronidazole, the ability to overcome metronidazole resistance, and reduced human cytotoxicity compared to that of the anticancer proteasome inhibitors. The increased selectivity of carmaphycin-17 for T. vaginalis was related to its >5-fold greater potency against the β1 and β5 catalytic subunits of the T. vaginalis proteasome than against the human proteasome subunits. In a murine model of vaginal trichomonad infection, proteasome inhibitors eliminated or significantly reduced parasite burden upon topical treatment without any apparent adverse effects. Together, these findings validate the proteasome of T. vaginalis as a therapeutic target for development of a novel class of trichomonacidal agents.

Development of mucoadhesive vaginal films based on HPMC and zein as novel formulations to prevent sexual transmission of HIV

Although vaginal films were initially developed for a fast release of the drug, with the adequate formulation they can also be useful for sustained release. The latest strategies for the prevention of the sexual transmission of HIV have moved towards sustained-release dosage forms, so films may be an effective strategy that could also improve the patient's comfort. A hydrophilic polymer (hydroxypropylmethyl cellulose) and an amphiphilic polymer (zein) have been evaluated for the development of Tenofovir sustained-release vaginal films. The modification of the film's properties by the inclusion of polar (glycerol and polyethylene glycol 400 (PEG)) and amphiphilic (tributyl citrate and oleic acid) plasticisers was also evaluated. The films' physicochemical and mechanical properties were determined. The in vitro release of Tenofovir from the films and their bioadhesive capacity and behaviour in simulated vaginal fluid were also assessed. The combination of hydroxypropylmethyl cellulose and zein in films (ratio 1:5), with the inclusion of PEG (40% w/w) proved not only to have excellent mechanical properties, but was also able to release TFV in a sustained manner for 120 h and remain attached to biological tissues throughout this time. This film could be an interesting option for the prevention of sexual transmission of HIV.

Pharmaceutical Vehicles for Vaginal and Rectal Administration of Anti-HIV Microbicide Nanosystems

Prevention strategies play a key role in the fight against HIV/AIDS. Vaginal and rectal microbicides hold great promise in tackling sexual transmission of HIV-1, but effective and safe products are yet to be approved and made available to those in need. While most efforts have been placed in finding and testing suitable active drug candidates to be used in microbicide development, the last decade also saw considerable advances in the design of adequate carrier systems and formulations that could lead to products presenting enhanced performance in protecting from infection. One strategy demonstrating great potential encompasses the use of nanosystems, either with intrinsic antiviral activity or acting as carriers for promising microbicide drug candidates. Polymeric nanoparticles, in particular, have been shown to be able to enhance mucosal distribution and retention of promising antiretroviral compounds. One important aspect in the development of nanotechnology-based microbicides relates to the design of pharmaceutical vehicles that allow not only convenient vaginal and/or rectal administration, but also preserve or even enhance the performance of nanosystems. In this manuscript, we revise relevant work concerning the selection of vaginal/rectal dosage forms and vehicle formulation development for the administration of microbicide nanosystems. We also pinpoint major gaps in the field and provide pertinent hints for future work.

Evaluation of the reproductive toxicity of antiretroviral drug loaded lactoferrin nanoparticles

Multiple prevention therapy has gained importance for the prevention and treatment of sexually transmitted diseases, especially HIV/AIDS. Antiretroviral drugs encapsulated in nanoparticles have been developed for efficient delivery of the drugs to the vaginal surface. Lactoferrin nanoparticles (LFNPs) encapsulating anticancer or antiretroviral drugs are found to be promising agents to specifically deliver drugs at the target sites. Recent studies indicate that the bioavailability is higher for antiretroviral drugs delivered by LFNPs than when the drugs are administered alone. Although LFNP-mediated drug delivery via the oral or vaginal route for the treatment of HIV/AIDS is promising, the effect of such administrations is not well studied. Drug-loaded LFNPs when administered to rats by the vaginal route did not show any effect on the reproductive performance, fertility, and postnatal development. Oral administration of drug-loaded LFNPs caused a significant decrease in litter size, whereas the reproductive performance and postnatal development remained normal. In our model system, the results indicate that vaginal administration of drug-loaded LFNPs appears safer and can be projected for the delivery of antiretroviral agents via the vaginal route. Abbreviations: LFNPs: lactoferrin nanoparticles; STIs: sexually transmitted diseases infections; NPs: nanoparticles; LF: lactoferrin; DL-LFNPs: drug loaded lactoferrin nanoparticles; MPT: multiple prevention techniques.

Clinically advancing and promising polymer-based therapeutics

In this review article, we will examine the history of polymers and their evolution from provisional World War II materials to medical therapeutics. To provide a comprehensive look at the current state of polymer-based therapeutics, we will classify technologies according to targeted areas of interest, including central nervous system-based and intraocular-, gastrointestinal-, cardiovascular-, dermal-, reproductive-, skeletal-, and neoplastic-based systems. Within each of these areas, we will consider several examples of novel, clinically available polymer-based therapeutics; in addition, this review will also include a discussion of developing therapies, ranging from the in vivo to clinical trial stage, for each targeted area of treatment. Finally, we will emphasize areas of patient care in need of more effective, accessible, and targeted treatment approaches where polymer-based therapeutics may offer potential solutions.

Nanotechnologies for early diagnosis, in situ disease monitoring, and prevention

Nanotechnology is an enabling technology with great potential for applications in stem cell research and regenerative medicine. Fluorescent nanodiamond (FND), an inherently biocompatible and nontoxic nanoparticle, is well suited for such applications. We had developed a prospective isolation method using CD157, CD45, and CD54 to obtain lung stem cells. Labeling of CD45⁻CD54⁺CD157⁺ cells with FNDs did not eliminate their abilities for self-renewal and differentiation. The FND labeling in combination with cell sorting, fluorescence lifetime imaging microscopy, and immunostaining identified transplanted stem cells allowed tracking of their engraftment and regenerative capabilities with single-cell resolution. Time-gated fluorescence (TGF) imaging in mouse tissue sections indicated that they reside preferentially at the bronchoalveolar junctions of lungs, especially in naphthalene-injured mice. Our results presented in Subchapter 1.1 demonstrate not only the remarkable homing capacity and regenerative potential of the isolated stem cells, but also the ability of finding rare lung stem cells in vivo using FNDs.

The topical use of antiretroviral-based microbicides, namely of a dapivirine ring, has been recently shown to partially prevent transmission of HIV through the vaginal route. Among different formulation approaches, nanotechnology tools and principles have been used for the development of tentative vaginal and rectal microbicide products. Subchapter 1.2 provides an overview of antiretroviral drug nanocarriers as novel microbicide candidates and discusses recent and relevant research on the topic. Furthermore, advances in developing vaginal delivery platforms for the administration of promising antiretroviral drug nanocarriers are reviewed. Although mostly dedicated to the discussion of nanosystems for vaginal use, the development of rectal nanomicrobicides is also addressed.

Infectious diseases are currently responsible for over 8 million deaths per year. Efficient treatments require accurate recognition of pathogens at low concentrations, which in the case of blood infection (septicemia) can go as low as 1 mL^–1. Detecting and quantifying bacteria at such low concentrations is challenging and typically demands cultures of large samples of blood (∼1 mL) extending over 24–72 h. This delay seriously compromises the health of patients and is largely responsible for the death toll of bacterial infections. Recent advances in nanoscience, spectroscopy, plasmonics, and microfluidics allow for the development of optical devices capable of monitoring minute amounts of analytes in liquid samples. In Subchapter 1.3 we critically discuss these recent developments that will, in the future, enable the multiplex identification and quantification of microorganisms directly on their biological matrix with unprecedented speed, low cost, and sensitivity.

Radiolabeled nanoparticles (NPs) are finding an increasing interest in a broad range of biomedical applications. They may be used to detect and characterize diseases, to deliver relevant therapeutics, and to study the pharmacokinetic/pharmacodynamic parameters of nanomaterials. The use of radiotracer techniques in the research of novel NPs offers many advantages, but there are still some limitations. The binding of radionuclides to NPs has to be irreversible to prevent their escape to other tissues or organs. Due to the short half-lives of radionuclides, the manufacturing process is time limited and difficult, and there is also a risk of contamination. Subchapter 1.4 presents the main selection criteria for radionuclides and applicable radiolabeling procedures used for the radiolabeling of various NPs. Also, an overview of different types of NPs that have so far been labeled with radionuclides is presented.

Nanoparticle Encapsulation for Antiretroviral Pre-Exposure Prophylaxis

HIV continues to be one of the greatest challenges facing the global health community. More than 36 million people currently live with HIV and, in 2015 2.1 million new infections were reported globally. Pre-Exposure Prophylaxis (PrEP) prevents HIV infection by inhibiting viral entry, replication, or integration at the primary site of pathogenic contraction. Failures of large antiretroviral drug (ARV) PrEP clinical trials indicate the current insufficiencies of PrEP for women in high-risk areas, such as sub-Saharan Africa. A combination of social, adherence, and drug barriers create these insufficiencies and limit the efficacy of ARV. Nanotechnology offers the promise of extended drug release and enhances bioavailability of ARVs when encapsulated in polymeric nano-particles. Nanoparticle encapsulation has been evaluated in vitro in comparative studies to drug solutions and exhibit higher efficacy and lower cytotoxicity profiles. Delivery systems for nanoparticle PrEP facilitate administration of nano-encapsulated ARVs to high-risk tissues. In this mini-review, we summarize the comparative nanoparticle and drug solution studies and the potential of two delivery methods: thermosensitive gels and polymeric nanoparticle films for direct prophylactic applications.

A Dose Ranging Pharmacokinetic Evaluation of IQP-0528 Released from Intravaginal Rings in Non-Human Primates

PURPOSE

Design of intravaginal rings (IVRs) for delivery of antiretrovirals is often guided by in vitro release under sink conditions, based on the assumption that in vivo release will follow a similar release profile.

METHODS

We conducted a dose-ranging study in the female reproductive tract of pigtail macaques using matrix IVRs containing IQP-0528, a poorly soluble but highly potent antiretroviral drug with an IC₉₀ of 146 ng/mL. These IVRs consisted of drug-loaded segments, 15.6% IQP-0528 in Tecoflex 85A, comprising either all, half, or a quarter of the entire ring.

RESULTS

In vitro release under sink conditions demonstrates loading-proportional release, with a cumulative 30-day release of 48.5 ± 2.2 mg for our 100% loaded ring, 24.8 ± .36 mg from our 50% loaded ring, and 13.99 ± 1.58 mg from our 25% loaded ring. In vivo, while drug concentration in vaginal fluid is well in excess of IQP-0528's EC₉₀, we find no statistical difference between the different ring loadings in either swab drug levels or drug released from our rings.

CONCLUSIONS

We show that in vitro release may not accurately reflect in vivo release, particularly for poorly soluble drugs. All tested loadings of our IVRs are capable of delivering IQP-0528 well in excess of the IC₉₀.

Repeated administration of high-dose depot medroxyprogesterone acetate does not alter SHIVSF162p3 viral kinetics and tenofovir pharmacokinetics when delivered via intravaginal rings

BACKGROUND

Intravaginal rings (IVR) for HIV prevention will likely be used by women on depot medroxyprogesterone acetate (DMPA) hormonal contraception. We used pigtailed macaques to evaluate the effects of DMPA on tenofovir disoproxil fumarate (TDF) IVR pharmacokinetics and viral shedding.

METHODS

Mucosal tenofovir (TFV) levels were compared in SHIVSF162p3 -negative DMPA-treated (n=4) and normally cycling (n=6) macaques receiving TDF IVRs. Plasma viremia and vaginal shedding were determined in groups of SHIVSF162p3 -positive DMPA-treated (n=6) and normally cycling (n=5) macaques.

RESULTS

Similar median vaginal fluid TFV concentrations were observed in the DMPA-treated and cycling macaques over 4 weeks (1.2×105 and 1.1.×105  ng/mL, respectively). Median plasma viremia and vaginal shedding AUC of the DMPA-treated (2.73×107 and 8.15×104 copies/mL, respectively) and cycling macaques (3.98×107 and 1.47×103 copies/mL, respectively) were statistically similar.

CONCLUSIONS

DMPA does not affect TDF IVR pharmacokinetics or SHIV shedding.

Historical development of vaginal microbicides to prevent sexual transmission of HIV in women: from past failures to future hopes

Infection with human immunodeficiency virus (HIV) remains a global public health concern and is particularly serious in low- and middle-income countries. Widespread sexual violence and poverty, among other factors, increase the risk of infection in women, while currently available prevention methods are outside the control of most. This has driven the study of vaginal microbicides to prevent sexual transmission of HIV from men to women in recent decades. The first microbicides evaluated were formulated as gels for daily use and contained different substances such as surfactants, acidifiers and monoclonal antibodies, which failed to demonstrate efficacy in clinical trials. A gel containing the reverse transcriptase inhibitor tenofovir showed protective efficacy in women. However, the lack of adherence by patients led to the search for dosage forms capable of releasing the active principle for longer periods, and hence to the emergence of the vaginal ring loaded with dapivirine, which requires a monthly application and is able to reduce the sexual transmission of HIV. The future of vaginal microbicides will feature the use of alternative dosage forms, nanosystems for drug release and probiotics, which have emerged as potential microbicides but are still in the early stages of development. Protecting women with vaginal microbicide formulations would, therefore, be a valuable tool for avoiding sexual transmission of HIV.

The future of pre-exposure prophylaxis (PrEP) for human immunodeficiency virus (HIV) infection

INTRODUCTION

People at high risk for HIV acquisition should be offered pre-exposure prophylaxis (PrEP). Tenofovir disoproxil fumarate (TDF)/emtricitabine (FTC) is currently the only medication recommended for pre-exposure prophylaxis (PrEP) by the Centers for Disease Control and Prevention (CDC) in people at high risk for HIV acquisition. This article will review medications currently under investigation and the future landscape of PrEP therapy. Areas covered: This article will review clinical trials that have investigated nontraditional regimens of TDF/FTC, antiretroviral agents from different drug classes such as integrase strand transfer inhibitors (INSTI), nucleoside reverse transcriptase inhibitors (NRTI), and non-nucleoside reverse transcriptase inhibitors (NNRTI) as potential PrEP therapies. Expert commentary: Currently, there are several investigational drugs in the pipeline for PrEP against HIV infection. Increased utilization of PrEP therapy depends on provider identification of people at high risk for HIV transmission. Advances in PrEP development will expand options and access for people and reduce the risk of HIV acquisition.

Nanoparticles-in-film for the combined vaginal delivery of anti-HIV microbicide drugs

Combining two or more antiretroviral drugs in one medical product is an interesting but challenging strategy for developing topical anti-HIV microbicides. We developed a new vaginal delivery system comprising the incorporation of nanoparticles (NPs) into a polymeric film base - NPs-in-film - and tested its ability to deliver tenofovir (TFV) and efavirenz (EFV). EFV-loaded poly(lactic-co-glycolic acid) NPs were incorporated alongside free TFV into fast dissolving films during film manufacturing. The delivery system was characterized for physicochemical properties, as well as genital distribution, local and systemic 24h pharmacokinetics (PK), and safety upon intravaginal administration to mice. NPs-in-film presented suitable technological, mechanical and cytotoxicity features for vaginal use. Retention of NPs in vivo was enhanced both in vaginal lavages and tissue when associated to film. PK data evidenced that vaginal drug levels rapidly decreased after administration but NPs-in-film were still able to enhance drug concentrations of EFV. Obtained values for area-under-the-curve for EFV were around one log10 higher than those for the free drugs in aqueous vehicle (phosphate buffered saline). Film alone also contributed to higher and more prolonged local drug levels as compared to the administration of TFV and EFV in aqueous vehicle. Systemic exposure to both drugs was low. NPs-in-film was found to be safe upon once daily vaginal administration to mice, with no significant genital histological changes or major alterations in cytokine/chemokine profiles being observed. Overall, the proposed NPs-in-film system seems to be an interesting delivery platform for developing combination vaginal anti-HIV microbicides.