Evaluation of atazanavir and darunavir interactions with lipids for developing pH-responsive anti-HIV drug combination nanoparticles

Prolonged release and antiviral efficacy of HIV fusion inhibitor LP-98-loaded microspheres in rhesus macaques

Non-adherence to antiretroviral treatment is a critical obstacle to effectively managing the progression of AIDS and reducing transmission and mortality rates. A promising strategy to address the clinical disadvantages of user-dependent dosing and decrease medication frequency is the development of long-acting antiretrovirals. In this study, we fabricated PLGA microspheres (MS) incorporating the lipopeptide LP-98 (LP-98-MS), which has previously exhibited potent anti-HIV efficacy. Our findings demonstrate that a single-dose injection of LP-98-MS in SHIV-infected rhesus macaques resulted in sustained and gradual release, maintaining antiviral effects at least 28 days. Notably, a single administration of LP-98-MS provided more than 28 days of sustained release, resulting in high-level pre-exposure prophylaxis (PrEP) for rhesus macaques, even providing complete protection when exposed to repeated intravaginal and intrarectal SHIV challenges. Overall, LP-98-MS holds significant potential in reducing medication frequency and shows promising prospects for further development.

Next-generation bNAbs for HIV-1 cure strategies

Despite the ability to suppress viral replication using anti-retroviral therapy (ART), HIV-1 remains a global public health problem. Curative strategies for HIV-1 have to target and eradicate latently infected cells across the body, i.e. the viral reservoir. Broadly neutralizing antibodies (bNAbs) targeting the HIV-1 envelope glycoprotein (Env) have the capacity to neutralize virions and bind to infected cells to initiate elimination of these cells. To improve the efficacy of bNAbs in terms of viral suppression and viral reservoir eradication, next generation antibodies (Abs) are being developed that address the current limitations of Ab treatment efficacy; (1) low antigen (Env) density on (reactivated) HIV-1 infected cells, (2) high viral genetic diversity, (3) exhaustion of immune cells and (4) short half-life of Abs. In this review we summarize and discuss preclinical and clinical studies in which anti-HIV-1 Abs demonstrated potent viral control, and describe the development of engineered Abs that could address the limitations described above. Next generation Abs with optimized effector function, avidity, effector cell recruitment and immune cell activation have the potential to contribute to an HIV-1 cure or durable control.

Molecular Factors and Pathways of Hepatotoxicity Associated with HIV/SARS-CoV-2 Protease Inhibitors

Antiviral protease inhibitors are peptidomimetic molecules that block the active catalytic center of viral proteases and, thereby, prevent the cleavage of viral polyprotein precursors into maturation. They continue to be a key class of antiviral drugs that can be used either as boosters for other classes of antivirals or as major components of current regimens in therapies for the treatment of infections with human immunodeficiency virus (HIV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, sustained/lifelong treatment with the drugs or drugs combined with other substance(s) often leads to severe hepatic side effects such as lipid abnormalities, insulin resistance, and hepatotoxicity. The underlying pathogenic mechanisms are not fully known and are under continuous investigation. This review focuses on the general as well as specific molecular mechanisms of the protease inhibitor-induced hepatotoxicity involving transporter proteins, apolipoprotein B, cytochrome P450 isozymes, insulin-receptor substrate 1, Akt/PKB signaling, lipogenic factors, UDP-glucuronosyltransferase, pregnane X receptor, hepatocyte nuclear factor 4α, reactive oxygen species, inflammatory cytokines, off-target proteases, and small GTPase Rab proteins related to ER-Golgi trafficking, organelle stress, and liver injury. Potential pharmaceutical/therapeutic solutions to antiviral drug-induced hepatic side effects are also discussed.

Monoclonal CCR5 Antibody: A Promising Therapy for HIV

HIV is one of the world's most devastating viral infections and has claimed tens of millions of lives worldwide since it was first identified in the 1980s. There is no cure for HIV infection. However, with tremendous progress in HIV diagnosis, prevention, and treatment, HIV has become a manageable chronic health disease. CCR5 is an important coreceptor used by HIV to infect target cells, and genetic deficiency of the chemokine receptor CCR5 confers a significant degree of protection against HIV infection. In addition, since CCR5 deficiency does not appear to cause any adverse health effects, targeting this coreceptor is a promising strategy for the treatment and prevention of HIV. Monoclonal antibodies are frequently used as therapeutics for many diseases and therefore are being used as a potential therapy for HIV-1 infection. This review reports on CCR5 antibody research in detail and describes the role and advantages of CCR5 antibodies in HIV prevention or treatment, introduces several main CCR5 antibodies, and discusses the future strategy of antibody-conjugated nanoparticles including the potential challenges. CCR5 antibodies may be a novel therapy for treating HIV infection effectively and could overcome the limitations of the currently available options.

Antiviral role of nanomaterials: a material scientist's perspective

The present world continues to face unprecedented challenges caused by the COVID-19 pandemic. Collaboration between researchers of multiple disciplines is the need of the hour. There is a need to develop antiviral agents capable of inhibiting viruses and tailoring existing antiviral drugs for efficient delivery to prevent a surge in deaths caused by viruses globally. Biocompatible systems have been designed using nanotechnological principles which showed appreciable results against a wide range of viruses. Many nanoparticles can act as antiviral therapeutic agents if synthesized by the correct approach. Moreover, nanoparticles can act as carriers of antiviral drugs while overcoming their inherent drawbacks such as low solubility, poor bioavailability, uncontrolled release, and side effects. This review highlights the potential of nanomaterials in antiviral applications by discussing various studies and their results regarding antiviral potential of nanoparticles while also suggesting future directions to researchers.

Thermodynamic Correlation between Liquid-Liquid Phase Separation and Crystalline Solubility of Drug-Like Molecules

The purpose of the present study was to experimentally confirm the thermodynamic correlation between the intrinsic liquid−liquid phase separation (LLPS) concentration (S0LLPS) and crystalline solubility (S0c) of drug-like molecules. Based on the thermodynamic principles, the crystalline solubility LLPS concentration melting point (Tm) equation (CLME) was derived (log10S0C=log10S0LLPS−0.0095Tm−310 for 310 K). The S0LLPS values of 31 drugs were newly measured by simple bulk phase pH-shift or solvent-shift precipitation tests coupled with laser-assisted visual turbidity detection. To ensure the precipitant was not made crystalline at <10 s, the precipitation tests were also performed under the polarized light microscope. The calculated and observed log10S0C values showed a good correlation (root mean squared error: 0.40 log unit, absolute average error: 0.32 log unit).

State-of-the-Art of Nanodiagnostics and Nanotherapeutics against SARS-CoV-2

The pandemic outbreak of SARS-CoV-2, with millions of infected patients worldwide, has severely challenged all aspects of public health. In this regard, early and rapid detection of infected cases and providing effective therapeutics against the virus are in urgent demand. Along with conventional clinical protocols, nanomaterial-based diagnostics and therapeutics hold a great potential against coronavirus disease 2019 (COVID-19). Indeed, nanoparticles with their outstanding characteristics would render additional advantages to the current approaches for rapid and accurate diagnosis and also developing prophylactic vaccines or antiviral therapeutics. In this review, besides presenting an overview of the coronaviruses and SARS-CoV-2, we discuss the introduced nanomaterial-based detection assays and devices and also antiviral formulations and vaccines for coronaviruses.

Nanotechnology advances in pathogen- and host-targeted antiviral delivery: multipronged therapeutic intervention for pandemic control

The COVID-19 pandemic's high mortality rate and severe socioeconomic impact serve as a reminder of the urgent need for effective countermeasures against viral pandemic threats. In particular, effective antiviral therapeutics capable of stopping infections in its tracks is critical to reducing infection fatality rate and healthcare burden. With the field of drug delivery witnessing tremendous advancement in the last two decades owing to a panoply of nanotechnology advances, the present review summarizes and expounds on the research and development of therapeutic nanoformulations against various infectious viral pathogens, including HIV, influenza, and coronaviruses. Specifically, nanotechnology advances towards improving pathogen- and host-targeted antiviral drug delivery are reviewed, and the prospect of achieving effective viral eradication, broad-spectrum antiviral effect, and resisting viral mutations are discussed. As several COVID-19 antiviral clinical trials are met with lackluster treatment efficacy, nanocarrier strategies aimed at improving drug pharmacokinetics, biodistributions, and synergism are expected to not only contribute to the current disease treatment efforts but also expand the antiviral arsenal against other emerging viral diseases.

An in-depth analysis of novel combinatorial drug therapy via nanocarriers against HIV/AIDS infection and their clinical perspectives: a systematic review

Introduction: Conventional antiretroviral therapy against HIV infections is threatening to become outdated due to the low chemical, physical, biological, and pharmacokinetic characteristics of therapeutic molecules, followed by the high chance of emergence of drug resistance. Considering the co-encapsulation of multi-infection agents in a single nanocarrier is emerging to offer various benefits such as synergistic action, improved therapeutic efficacy, reduced drug resistance development, patient compliance, and economical therapy.Areas covered: A systematic review of nano-based combinatorial drug therapy was performed using various databases including Scopus, PubMed, Google Scholar, and Science Direct between 2000 and 2020. The search set was screened as per the inclusion and exclusion criteria, followed by 46 scientific articles and seven clinical studies selected for in-depth analysis.Expert opinion: There has been an immense effort to analyze the mechanism of HIV infection to develop a promising therapeutic approach, although the aim of complete prevention has not been succeeded yet. The key finding is to overcome the challenges associated with conventional therapy by the combinatorial drug in a single nanoformulation, which holds great potential for impact in the management of HIV infection.

Controlled Solvent Removal from Antiviral Drugs and Excipients in Solution Enables the Formation of Novel Combination Multi-Drug-Motifs in Pharmaceutical Powders Composed of Lopinavir, Ritonavir and Tenofovir

Diverging physicochemical properties of HIV drug combinations are challenging to formulate as a single dosage form. We have found that 2-to-4 hydrophilic and hydrophobic HIV drugs in combination can be stabilized with lipid excipients under a controlled solvent removal process to form a novel pharmaceutical powder distinct from typical amorphous material. This discovery has enabled production of a drug combination nanoparticle (DcNP) powder composed of 3 HIV drugs-water-insoluble lopinavir (LogP = 4.7) and ritonavir (LogP = 5.6) and water-soluble tenofovir (LogP = -1.6). DcNP powder, exhibiting repeating units of multi-drug-motifs (referred to as MDM), is made by dissolving all constituents in ethanolic solution, followed by controlled solvent removal. The DcNP powder intersperses chemically diverse drug molecules with lipid excipients to form repeating MDM units. The proposed MDM structure is consistent with data collected with X-ray diffraction, differential calorimetry, and time-of-flight secondary ion mass spectrometry. The successful assembly of chemically diverse drugs in MDM structure is likely due to a novel process of making drug combination powders. The method described here has successfully extended to formulating other clinically prescribed antiviral drug combinations, and thus may serve as a platform technology for developing drug combination nanoparticles for treating a wide range of chronic diseases.

Nanomaterials and Nanotechnology-Associated Innovations against Viral Infections with a Focus on Coronaviruses

Viral infections have recently emerged not only as a health threat to people but rapidly became the cause of universal fatality on a large scale. Nanomaterials comprising functionalized nanoparticles (NPs) and quantum dots and nanotechnology-associated innovative detection methods, vaccine design, and nanodrug production have shown immense promise for interfacing with pathogenic viruses and restricting their entrance into cells. These viruses have been scrutinized using rapid diagnostic detection and therapeutic interventional options against the caused infections including vaccine development for prevention and control. Coronaviruses, namely SARS-CoV, MERS-CoV, and SARS-CoV-2, have endangered human life, and the COVID-19 (caused by SARS-CoV-2) outbreak has become a perilous challenge to public health globally with huge accompanying morbidity rates. Thus, it is imperative to expedite the drug and vaccine development efforts that would help mitigate this pandemic. In this regard, smart and innovative nano-based technologies and approaches encompassing applications of green nanomedicine, bio-inspired methods, multifunctional bioengineered nanomaterials, and biomimetic drug delivery systems/carriers can help resolve the critical issues regarding detection, prevention, and treatment of viral infections. This perspective review expounds recent nanoscience advancements for the detection and treatment of viral infections with focus on coronaviruses and encompasses nano-based formulations and delivery platforms, nanovaccines, and promising methods for clinical diagnosis, especially regarding SARS-CoV-2.

Recent advances in long-acting nanoformulations for delivery of antiretroviral drugs

In spite of introduction of combination antiretroviral therapy (cART) against human immunodeficiency virus (HIV) infection; inaccessibility and poor adherence to oral cART costs 10 in 100,000 death worldwide. Failure in adherence leads to viral rebound, emergence of drug resistance and anticipated HIV infection in high risk individuals. Various Long-acting antiretroviral (LA ARV) nanoformulations including nano-prodrug, solid drug nanoparticles (SDN), nanocrystals, aspherical nanoparticles, polymeric and lipidic nanoparticles have shown plasma/tissue drug concentration in the therapeutic range for several weeks during pre-clinical evaluation. LA ARV nanoformulations therefore have replaced cART as better alternative for the treatment of HIV infection. Cabenuva™ is recently approved by Health Canada containing LA cabotegravir+LA rilpivirine nanocrystals (ViiV healthcare) for once monthly administration by intramuscular route. The LA nanoformulation due to its nanosize insist on better stability, delivery to lymphatic, slow release into systemic circulation via lymphatic-circulatory system conjoint and secondary drug depot within infiltered immune cells at site of administration and systemic circulation in contrast to conventional drugs. However, the pharmacokinetic, biodistribution and efficacy of LA nanoformulations hinge onto physicochemical properties of the drugs and route of administration. Therefore, current review emphasizes on these contradistinctive factors that affects the reproducibility, safety, efficacy and toxicity of LA anti-HIV nanoformulations. Moreover, it expatiates on application of profuse nanoformulations for long-acting effect with promising preclinical discoveries and two clinical leads. To add on, utilization of physiology-based and mechanism-based pharmacokinetic modelling and in vivo animal models which could lead to enhanced safety and efficacy of LA ARV nanoformulations in humans have been included.

Nanomaterials Designed for Antiviral Drug Delivery Transport across Biological Barriers

Viral infections are a major global health problem, representing a significant cause of mortality with an unfavorable continuously amplified socio-economic impact. The increased drug resistance and constant viral replication have been the trigger for important studies regarding the use of nanotechnology in antiviral therapies. Nanomaterials offer unique physico-chemical properties that have linked benefits for drug delivery as ideal tools for viral treatment. Currently, different types of nanomaterials namely nanoparticles, liposomes, nanospheres, nanogels, nanosuspensions and nanoemulsions were studied either in vitro or in vivo for drug delivery of antiviral agents with prospects to be translated in clinical practice. This review highlights the drug delivery nanosystems incorporating the major antiviral classes and their transport across specific barriers at cellular and intracellular level. Important reflections on nanomedicines currently approved or undergoing investigations for the treatment of viral infections are also discussed. Finally, the authors present an overview on the requirements for the design of antiviral nanotherapeutics.

A review of CCR5 antibodies against HIV: current and future aspects

HIV is one of the most devastating viral infections the world has ever encountered. Ever since HIV was first identified in the 1980s, it has claimed millions of lives worldwide. There has been tremendous research and development in the diagnosis, prevention and treatment of HIV. Small molecules have been shown to reduce the virus to nondetectable level in human plasma, however, there are reservoirs of latent virus that reemerge if antiretroviral therapy is stopped. There is no vaccine to prevent or cure HIV. A significant amount of research has been reported in the literature regarding antibodies for CCR5, a HIV entry host receptor. This report describes the role of CCR5 antibody in HIV prevention/treatment and how antibody-conjugated nanoparticles could be a future strategy with the potential to effectively eradicate the virus from the human system.

Synthesis and Characterization of Long-Acting Darunavir Prodrugs

Antiretroviral therapy (ART) has improved the quality of life in patients infected with HIV-1. However, complete viral suppression within anatomical compartments remains unattainable. This is complicated by adverse side effects and poor adherence to lifelong therapy leading to the emergence of viral drug resistance. Thus, there is an immediate need for cellular and tissue-targeted long-acting (LA) ART formulations. Herein, we describe two LA prodrug formulations of darunavir (DRV), a potent antiretroviral protease inhibitor. Two classes of DRV prodrugs, M1DRV and M2DRV, were synthesized as lipophilic and hydrophobic prodrugs and stabilized into aqueous suspensions designated NM1DRV and NM2DRV. The formulations demonstrated enhanced intracellular prodrug levels with sustained drug retention and antiretroviral activities for 15 and 30 days compared to native DRV formulation in human monocyte-derived macrophages. Pharmacokinetics tests of NM1DRV and NM2DRV administered to mice demonstrated sustained drug levels in blood and tissues for 30 days. These data, taken together, support the idea that LA DRV with sustained antiretroviral responses through prodrug nanoformulations is achievable.

Reverse Transcriptase Inhibitors Nanosystems Designed for Drug Stability and Controlled Delivery

An in-depth analysis of nanotechnology applications for the improvement of solubility, distribution, bioavailability and stability of reverse transcriptase inhibitors is reported. Current clinically used nucleoside and non-nucleoside agents, included in combination therapies, were examined in the present survey, as drugs belonging to these classes are the major component of highly active antiretroviral treatments. The inclusion of such agents into supramolecular vesicular systems, such as liposomes, niosomes and lipid solid NPs, overcomes several drawbacks related to the action of these drugs, including drug instability and unfavorable pharmacokinetics. Overall results reported in the literature show that the performances of these drugs could be significantly improved by inclusion into nanosystems.

Three HIV Drugs, Atazanavir, Ritonavir, and Tenofovir, Coformulated in Drug-Combination Nanoparticles Exhibit Long-Acting and Lymphocyte-Targeting Properties in Nonhuman Primates

Drug-combination nanoparticles (DcNPs) administered subcutaneously represent a potential long-acting lymphatic-targeting treatment for HIV infection. The DcNP containing lopinavir (LPV)-ritonavir (RTV)-tenofovir (TFV), Targeted-Long-Acting-Antiretroviral-Therapy product candidate 101 (TLC-ART 101), has shown to provide long-acting lymphocyte-targeting performance in nonhuman primates. To extend the TLC-ART platform, we replaced TLC-ART 101 LPV with second-generation protease inhibitor, atazanavir (ATV). Pharmacokinetics of the ATV-RTV-TFV DcNP was assessed in macaques, in comparison to the equivalent free drug formulation and to the TLC-ART 101. After single subcutaneous administration of the DcNP formulation, ATV, RTV, and TFV concentrations were sustained in plasma for up to 14 days, and in peripheral blood mononuclear cells for 8 to 14 days, compared with 1 to 2 days in those macaques treated with free drug combination. By 1 week, lymph node mononuclear cells showed significant levels for all 3 drugs from DcNPs, whereas the free controls were undetectable. Compared with TLC-ART 101, the ATV-RTV-TFV DcNP exhibited similar lymphocyte-targeted long-acting features for all 3 drugs and similar pharmacokinetics for RTV and TFV, whereas some pharmacokinetic differences were observed for ATV versus LPV. The present study demonstrated the flexibility of the TLC-ART's DcNP platform to include different antiretroviral combinations that produce targeted long-acting effects on both plasma and cells.

Recent developments of nanotherapeutics for targeted and long-acting, combination HIV chemotherapy

Combination antiretroviral therapy (cART) given orally has transformed HIV from a terminal illness to a manageable chronic disease. Yet despite the recent development of newer and more potent drugs for cART and suppression of virus in blood to undetectable levels, residual virus remains in tissues. Upon stopping cART, virus rebounds and progresses to AIDS. Current oral cART regimens have several drawbacks including (1) challenges in patient adherence due to pill fatigue or side-effects, (2) the requirement of life-long daily drug intake, and (3) limited penetration and retention in cells within lymph nodes. Appropriately designed injectable nano-drug combinations that are long-acting and retained in HIV susceptible cells within lymph nodes may address these challenges. While a number of nanomaterials have been investigated for delivery of HIV drugs and drug combinations, key challenges involve developing and scaling delivery systems that provide a drug combination targeted to HIV host cells and tissues where residual virus persists. With validation of the drug-insufficiency hypothesis in lymph nodes, progress has been made in the development of drug combination nanoparticles that are long-acting and targeted to lymph nodes and cells. Unique drug combination nanoparticles (DcNPs) composed of three HIV drugs-lopinavir, ritonavir, and tenofovir-have been shown to provide enhanced drug levels in lymph nodes; and elevated drug-combination levels in HIV-host cells in the blood and plasma for two weeks. This review summarizes the progress in the development of nanoparticle-based drug delivery systems for HIV therapy. It discusses how injectable nanocarriers may be designed to enable delivery of drug combinations that are long-lasting and target-selective in physiological contexts (in vivo) to provide safe and effective use. Consistent drug combination exposure in the sites of residual HIV in tissues and cells may overcome drug insufficiency observed in patients on oral cART.

Long-Acting Profile of 4 Drugs in 1 Anti-HIV Nanosuspension in Nonhuman Primates for 5 Weeks After a Single Subcutaneous Injection

Daily oral antiretroviral therapy regimens produce limited drug exposure in tissues where residual HIV persists and suffer from poor patient adherence and disparate drug kinetics, which all negatively impact outcomes. To address this, we developed a tissue- and cell-targeted long-acting 4-in-1 nanosuspension composed of lopinavir (LPV), ritonavir, tenofovir (TFV), and lamivudine (3TC). In 4 macaques dosed subcutaneously, drug levels over 5 weeks in plasma, lymph node mononuclear cells (LNMCs), and peripheral blood mononuclear cells (PBMCs) were analyzed by liquid chromatography-tandem mass spectrometry. Plasma and PBMC levels of the active drugs (LPV, TFV, and 3TC) were sustained for 5 weeks; PBMC exposures to LPV, ritonavir, and 3TC were 12-, 16-, 42-fold higher than those in plasma. Apparent T_1/2z of LPV, TFV, and 3TC were 219.1, 63.1, and 136.3 h in plasma; 1045.7, 105.9, and 127.7 h in PBMCs. At day 8, LPV, TFV, and 3TC levels in LNMCs were 4.1-, 5.0-, and 1.9-fold higher than in those in PBMCs and much higher than in plasma. Therefore, 1 dose of a 4-drug nanosuspension exhibited persistent drug levels in LNMCs, PBMCs, and plasma for 5 weeks. With interspecies scaling and dose adjustment, this 4-in-1 HIV drug-combination could be a long-acting treatment with the potential to target residual virus in tissues and improve patient adherence.

Sulpiride, Amisulpride, Thioridazine, and Olanzapine: Interaction with Model Membranes. Thermodynamic and Structural Aspects

Neuroleptic drugs are widely applied in effective treatment of schizophrenia and related disorders. The lipophilic character of neuroleptics means that they tend to accumulate in the lipid membranes, impacting their functioning and processing. In this paper, the effect of four drugs, namely, thioridazine, olanzapine, sulpiride, and amisulpride, on neutral and negatively charged lipid bilayers was examined. The interaction of neuroleptics with lipids and the subsequent changes in the membrane physical properties was assessed using several complementary biophysical approaches (isothermal titration calorimetry, electron paramagnetic resonance spectroscopy, dynamic light scattering, and ζ potential measurements). We have determined the thermodynamic parameters, that is, the enthalpy of interaction and the binding constant, to describe the interactions of the investigated drugs with model membranes. Unlike thioridazine and olanzapine, which bind to both neutral and negatively charged membranes, amisulpride interacts with only the negatively charged one, while sulpiride does not bind to any of them. The mechanism of olanzapine and thioridazine insertion into the bilayer membrane cannot be described merely by a simple molecule partition between two different phases (the aqueous and the lipid phase). We have estimated the number of protons transferred in the course of drug binding to determine which of its forms, ionized or neutral, binds more strongly to the membrane. Finally, electron paramagnetic resonance results indicated that the drugs are localized near the water-membrane interface of the bilayer and presence of a negative charge promotes their burying deeper into the membrane.

An Enhanced Emtricitabine-Loaded Long-Acting Nanoformulation for Prevention or Treatment of HIV Infection

Among various FDA-approved combination antiretroviral drugs (cARVs), emtricitabine (FTC) has been a very effective nucleoside reverse transcriptase inhibitor. Thus far, FTC is the only deoxycytidine nucleoside analog. However, a major drawback of FTC is its large volume distribution (averaging 1.4 liters/kg) and short plasma half-life (8 to 10 h), necessitating a high daily dosage. Thus, we propose an innovative fabrication method of loading FTC in poly(lactic-co-glycolic acid) polymeric nanoparticles (FTC-NPs), potentially overcoming these drawbacks. Our nanoformulation demonstrated enhanced FTC loading (size of <200 nm and surface charge of -23 mV) and no to low cytotoxicity with improved biocompatibility compared to those with FTC solution. An ex vivo endosomal release assay illustrated that NP entrapment prolongs FTC release over a month. Intracellular retention studies demonstrate sustained FTC retention over time, with approximately 8% (24 h) to 68% (96 h) release with a mean retention of ∼0.74 μg of FTC/10⁵ cells after 4 days. An in vitro HIV-1 inhibition study demonstrated that FTC-NP treatment results in a 50% inhibitory concentration (IC₅₀) ∼43 times lower in TZM-bl cells (0.00043 μg/ml) and ∼3.7 times lower (0.009 μg/ml) in peripheral blood mononuclear cells (PBMCs) than with FTC solution (TZM-bl cells, 0.01861, and PBMCs, 0.033 μg/ml). Further, on primary PBMCs, FTC-NPs also illustrate an HIV-1 infection blocking efficacy comparable to that of FTC solution. All the above-described studies substantiate that FTC nanoformulation prolongs intracellular FTC concentration and inhibition of HIV infection. Therefore, FTC-NPs potentially could be a long-acting, stable formulation to ensure once-biweekly dosing to prevent or treat HIV infection.

Nanoformulation strategies for the enhanced oral bioavailability of antiretroviral therapeutics

The oral delivery of drugs with poor aqueous solubility is challenging and often results in poor bioavailability. Various nanoformulation platforms have demonstrated improved oral bioavailability of a range of drugs for different indications. The focus of this review is to provide an overview of the application of nanomedicine to oral antiretroviral therapy and outline how the current short-falls of this life-long therapy may be resolved using nanotechnology. As well as highlighting the rationale for a nanomedicine-based approach, the review focuses on the various strategies used to enhance oral bioavailability and describes the mechanisms of particle absorption across the GI tract. The recent advances in the development of long-acting formulations for both HIV treatment and pre-exposure prophylaxis are also discussed.

Clinical challenges in HIV/AIDS: Hints for advancing prevention and patient management strategies

Acquired immune deficiency syndrome has been one of the most devastating epidemics of the last century. The current estimate for people living with the HIV is 36.9 million. Today, despite availability of potent and safe drugs for effective treatment, lifelong therapy is required for preventing HIV re-emergence from a pool of latently infected cells. However, recent evidence show the importance to expand HIV testing, to offer antiretroviral treatment to all infected individuals, and to ensure retention through all the cascade of care. In addition, circumcision, pre-exposure prophylaxis, and other biomedical tools are now available for included in a comprehensive preventive package. Use of all the available tools might allow cutting the HIV transmission in 2030. In this article, we review the status of the epidemic, the latest advances in prevention and treatment, the concept of treatment as prevention and the challenges and opportunities for the HIV cure agenda.

Drug delivery strategies and systems for HIV/AIDS pre-exposure prophylaxis and treatment

The year 2016 will mark an important milestone - the 35th anniversary of the first reported cases of HIV/AIDS. Antiretroviral Therapy (ART) including Highly Active Antiretroviral Therapy (HAART) drug regimens is widely considered to be one of the greatest achievements in therapeutic drug research having transformed HIV infection into a chronically managed disease. Unfortunately, the lack of widespread preventive measures and the inability to eradicate HIV from infected cells highlight the significant challenges remaining today. Moving forward there are at least three high priority goals for anti-HIV drug delivery (DD) research: (1) to prevent new HIV infections from occurring, (2) to facilitate a functional cure, i.e., when HIV is present but the body controls it without drugs and (3) to eradicate established infection. Pre-exposure Prophylaxis (PrEP) represents a significant step forward in preventing the establishment of chronic HIV infection. However, the ultimate success of PrEP will depend on achieving sustained antiretroviral (ARV) tissue concentrations and will require strict patient adherence to the regimen. While first generation long acting/extended release (LA/ER) DD Systems (DDS) currently in development show considerable promise, significant DD treatment and prevention challenges persist. First, there is a critical need to improve cell specificity through targeting in order to selectively achieve efficacious drug concentrations in HIV reservoir sites to control/eradicate HIV as well as mitigate systemic side effects. In addition, approaches for reducing cellular efflux and metabolism of ARV drugs to prolong effective concentrations in target cells need to be developed. Finally, given the current understanding of HIV pathogenesis, next generation anti-HIV DDS need to address selective DD to the gut mucosa and lymph nodes. The current review focuses on the DDS technologies, critical challenges, opportunities, strategies, and approaches by which novel delivery systems will help iterate towards prevention, functional cure and eventually the eradication of HIV infection.