Formulation of tenofovir-loaded functionalized solid lipid nanoparticles intended for HIV prevention

A review of nanotechnological approaches for the prophylaxis of HIV/AIDS

Successful treatment and control of HIV/AIDS is one of the biggest challenges of 21st century. More than 33 million individuals are infected with HIV worldwide and more than 2 million new cases of HIV infection have been reported. The situation demands development of effective prevention strategies to control the pandemic of AIDS. Due to lack of availability of an effective HIV vaccine, antiretroviral drugs and nucleic acid therapeutics like siRNA have been explored for HIV prophylaxis. Clinical trials shave shown that antiretroviral drugs, tenofovir and emtricitabine can offer some degree of HIV prevention. However, complete prevention of HIV infection has not been achieved yet. Nanotechnology has brought a paradigm shift in the diagnosis, treatment and prevention of many diseases. The current review discusses potential of various nanocarriers such as dendrimers, polymeric nanoparticles, liposomes, lipid nanocarriers, drug nanocrystals, inorganic nanocarriers and nanofibers in improving efficacy of various modalities available for HIV prophylaxis.

The importance of the vaginal delivery route for antiretrovirals in HIV prevention

The HIV/AIDS pandemic continues to be a global health priority, with high rates of new HIV-I infections persisting in young women. One HIV prevention strategy is topical pre-exposure prophylactics or microbicides, which are applied vaginally or rectally to protect the user from HIV and possibly other sexually transmitted infections. Vaginal microbicide delivery will be the focus of this review. Multiple nonspecific and specific antiretroviral microbicide products have been clinically evaluated, and many are in preclinical development, The events of HIV mucosal transmission and dynamics of the cervicovaginal environment should be considered for successful vaginal microbicide delivery. Beyond conventional vaginal formulations, intravaginal rings, tablets and films are employed as platforms in the hope to increase the likelihood of microbicide use. Furthermore, combining multiple antiretrovirals within a given formulation, combining a microbicide product with a vaginal device and integrating novel drug-delivery strategies within a microbicide product are approaches to successful vaginal-microbicide delivery.

Potential role of tenofovir vaginal gel for reduction of risk of herpes simplex virus in females

A surprising result of the groundbreaking CAPRISA-004 trial, which demonstrated the efficacy of vaginal tenofovir 1% gel in reducing the risk of human immunodeficiency virus (HIV)-1 infection by 39% in heterosexual women, was the added benefit of this microbicide in reducing acquisition of herpes simplex virus type 2 (HSV-2) by 51%. HSV-2 is the most common cause of genital ulcer disease worldwide, and is responsible for considerable morbidity among women and neonates. The virus is further implicated in increasing the risk of both HIV acquisition and transmission, and may have additional adverse consequences in HIV-coinfected persons, making HSV-2 prevention an important clinical and public health objective. While tenofovir had not previously been widely considered to be an anti-herpes drug, in vitro activity against HSV is well documented, raising interest in potential future applications of tenofovir and its prodrugs in HSV-2 control. This article reviews the currently available data for tenofovir as an anti-herpes agent, as well as unanswered questions about delivery systems, drug formulation, rectal administration, drug resistance, and clinical applications.

Drug delivery in multiple indication (multipurpose) prevention technologies: systems to prevent HIV-1 transmission and unintended pregnancies or HSV-2 transmission

INTRODUCTION

The development of multiple indication (multipurpose) prevention technologies (MIPTs) is driven by overlapping relationships in the area of female reproductive health.

AREAS COVERED

In this review, the basis for MIPTs is detailed. The current state of the field for the use of drug delivery in novel MIPTs is covered. Of particular interest is the application of intravaginal rings (IVRs) for the delivery of two drugs simultaneously, to prevent one STI and pregnancy, or two STIs. IVRs are currently available commercially for contraception and have been developed for release of microbicides to prevent sexual transmission of HIV-1. Novel IVRs capable of releasing relatively large amounts of drugs such as tenofovir are discussed, along with those that contain independent delivery elements, such as pods, that can be used to release drugs at independent rates. The vaginal administration of macromolecules (antibodies and vaccines) is also reviewed in the context of MIPTs.

EXPERT OPINION

The field of MIPTs remains one of potential. There is yet to be a proven microbicide effective at preventing sexual transmission of HIV-1. Development of MIPTs in the near term will proceed under the assumption that one or more antiretroviral (ARV) drugs will eventually be proven successful. IVRs have already demonstrated success in the area of contraception. Prevention of sexual transmission of HIV-1 and herpes simplex virus-2 (HSV-2) (or suppression of recurrence) remains an attractive MIPT target. In the long term, development of MIPTs will require validation of surrogate end points, particularly for prevention of HIV-1 transmission.

Sensitive and rapid HPLC quantification of tenofovir from hyaluronic acid-based nanomedicine

The purpose of this study was to develop and validate a rapid, sensitive, and specific reversed-phase high-performance liquid chromatography method for the quantitative determination of native tenofovir (TNF) for various applications. Different analytical performance parameters such as linearity, precision, accuracy, limit of quantification (LOQ), limit of detection (LOD), and robustness were determined according to International Conference on Harmonization (ICH) guidelines. A Bridge™ C18 column (150 × 4.6 mm, 5 μm) was used as stationary phase. The retention time of TNF was 1.54 ± 0.03 min (n = 6). The assay was linear over the concentration range of 0.1-10 μg/mL. The proposed method was sensitive with LOD and LOQ values equal to 50 and 100 ng/mL, respectively. The method was accurate with percent mean recovery from 95.41% to 102.90% and precise as percent RSD (relative standard deviation) values for intra-day, and inter-day precision were less than 2%. This method was utilized for the estimation of molar absorptivity of TNF at 259 nm (ε(259) = 12,518 L/mol/cm), calculated from linear regression analysis. The method was applied for determination of percentage of encapsulation efficiency (22.93 ± 0.04%), drug loading (12.25 ± 1.03%), in vitro drug release profile in the presence of enzyme (43% release in the first 3 h) and purification analysis of hyaluronic acid-based nanomedicine.

Encapsulation of docetaxel in oily core polyester nanocapsules intended for breast cancer therapy

This study is designed to test the hypothesis that docetaxel [Doc] containing oily core nanocapsules [NCs] could be successfully prepared with a high percentage encapsulation efficiency [EE%] and high drug loading. The oily core NCs were generated according to the emulsion solvent diffusion method using neutral Labrafac CC and poly(d, l-lactide) [PLA] as oily core and shell, respectively. The engineered NCs were characterized for particle mean diameter, zeta potential, EE%, drug release kinetics, morphology, crystallinity, and cytotoxicity on the SUM 225 breast cancer cell line by dynamic light scattering, high performance liquid chromatography, electron microscopies, powder X-ray diffraction, and lactate dehydrogenase bioassay. Typically, the formation of Doc-loaded, oily core, polyester-based NCs was evidenced by spherical nanometric particles (115 to 582 nm) with a low polydispersity index (< 0.05), high EE% (65% to 93%), high drug loading (up to 68.3%), and a smooth surface. Powder X-ray diffraction analysis revealed that Doc was not present in a crystalline state because it was dissolved within the NCs' oily core and the PLA shell. The drug/polymer interaction has been indeed thermodynamically explained using the Flory-Huggins interaction parameters. Doc release kinetic data over 144 h fitted very well with the Higuchi model (R2 > 0.93), indicating that drug release occurred mainly by controlled diffusion. At the highest drug concentration (5 μM), the Doc-loaded oily core NCs (as a reservoir nanosystem) enhanced the native drug cytotoxicity. These data suggest that the oily core NCs are promising templates for controlled delivery of poorly water soluble chemotherapeutic agents, such as Doc.

A novel VSV/HIV pseudotype approach for the study of HIV microbicides without requirement for level 3 biocontainment

Studies of potential HIV mucosal microbicides are difficult to undertake due to the requirement for a suitable animal model and the use of biosafety level 3 containment, which are not always available to researchers. Here we show the use of a mouse model of vaginal and rectal transmission of an HIV chimeric virus that does not require level 3 biosafety containment, to test the ex vivo efficacy of soluble Gb3 analogs for the prevention of mucosal HIV infection. The model uses a pseudoenvelope-typed vesicular stomatitis virus (VSV)/HIV recombinant virus that can infect all murine cell types. We demonstrate that the envelope glycoproteins VSV-G of VSV and gp-120 of HIV both bind Gb3. We show that soluble Gb3 analogs inhibit in vitro infection of cervical and vaginal-derived cell lines by both intact HIV and the VSV/HIV recombinant virus. Soluble Gb3 analogs incorporated into gel or used alone and applied directly to the vaginal and rectal mucosal tissue of mice were able to resist viral infection as monitored by PCR and quantitative real-time PCR copy number of HIV cDNA extracted from mouse tissue. Only a trend towards significant efficacy for prevention of mucosal transmission through lower copy number in the treatment groups was evident from these studies; however, this finding warrants further evaluation. In addition, we illustrate a methodology to evaluate inflammatory responses in either vagina or rectum after administration of soluble microbicidal compounds. These studies provide a potential new ex vivo methodology suitable for animal facilities in general, to screen microbicide drug candidates, including drug candidates that target viral proteins, for efficacy and safety, in order to accelerate development and discovery of prophylactic and therapeutic agents for HIV/AIDS.

Nanoparticles containing siRNA to silence CD4 and CCR5 reduce expression of these receptors and inhibit HIV-1 infection in human female reproductive tract tissue explants

Human Immunodeficiency Virus-type 1 (HIV-1) binds to CD4 and CCR5 receptors on target cells in the human female reproductive tract. We sought to determine whether reducing levels of messenger RNA (mRNA) transcripts that encode these receptors in female reproductive tract cells could protect mucosal tissue explants from HIV-1 infection. Explants prepared from the endometrium, endocervix, and ectocervix of hysterectomy tissues from HIV-1 sero-negative women were exposed to nanoparticles containing CD4- and CCR5-specific short-interfering RNA (siRNA) sequences. Explants were then exposed two days later to HIV-1, and HIV-1 reverse transcripts were measured five days post-infection. Explants treated with nanoparticles containing CD4- and CCR5-specific siRNA showed reduced levels of CD4 and CCR5 transcripts, and significantly lower levels of HIV-1 reverse transcripts compared to those treated with an irrelevant siRNA. In female reproductive tract explants and in peripheral blood cell cultures, siRNA transfection induced the secretion of IFN-alpha (IFN-α), a potent antiviral cytokine. In female mice, murine-specific Cd4-siRNA nanoparticles instilled within the uterus significantly reduced murine Cd4 transcripts by day 3. Our findings demonstrate that siRNA nanoparticles reduce expression of HIV-1 infectivity receptors in human female reproductive tract tissues and also inhibit HIV-1 infection. Murine studies demonstrate that nanoparticles can penetrate the reproductive tract tissues in vivo and silence gene expression. The induction of IFN-α after siRNA transfection can potentially contribute to the antiviral effect. These findings support the therapeutic development of nanoparticles to deliver siRNA molecules to silence host cell receptors in the female reproductive tract as a novel microbicide to inhibit mucosal HIV-1 transmission.

Functionalized lipid nanoparticles-cellophane hybrid films for molecular delivery: preparation, physicochemical characterization, and stability

Lipid nanoparticles functionalized with the sunscreen 2,4-dihydroxybenzophenone (FLNPs) have been prepared by the ultrasound method and embedded in highly hydrophilic cellophane supports (regenerated cellulose, RC), creating biocompatible hybrid films (RC-FLNPs samples). The morphology of the FLNPs was studied with transmission microscopy, whereas the surface and interior chemical composition was analyzed by micro-Raman spectroscopy. RC-FLNPs hybrid films were prepared from the immersion of two cellophane supports with different thicknesses and water uptake properties (RC-3 and RC-6) in an aqueous dispersion of FLNPs. The structure of this hybrid material was visualized with bright-field microscopy, which clearly showed the inclusion of the FLNPs in the cellophane matrix. The stability of the RC-FLNPs films with respect to both aqueous environments and time was demonstrated by NaCl diffusion measurements. The reduction in the diffusion coefficient through the nanoparticle-modified films compared with the original supports confirms the presence of nanoparticles for concentration gradients of up to 0.4 M (osmotic pressure around 10 bar), indicating the stability of the hybrid hydrophilic material, even in aqueous environments and under matter flow conditions for a period of 21 days.

Engineering tenofovir loaded chitosan nanoparticles to maximize microbicide mucoadhesion

The objective of this study was to engineer a model anti-HIV microbicide (tenofovir) loaded chitosan based nanoparticles (NPs). Box-Behnken design allowed to assess the influence of formulation variables on the size of NPs and drug encapsulation efficiency (EE%) that were analyzed by dynamic light scattering and UV spectroscopy, respectively. The effect of the NPs on vaginal epithelial cells and Lactobacillus crispatus viability and their mucoadhesion to porcine vaginal tissue were assessed by cytotoxicity assays and fluorimetry, respectively. In the optimal aqueous conditions, the EE% and NPs size were 5.83% and 207.97nm, respectively. With 50% (v/v) ethanol/water as alternative solvent, these two responses increased to 20% and 602 nm, respectively. Unlike small size (182nm) exhibiting burst release, drug release from medium (281 nm) and large (602 nm)-sized NPs fitted the Higuchi (r(2)=0.991) and first-order release (r(2)=0.999) models, respectively. These NPs were not cytotoxic to both the vaginal epithelial cell line and L. crispatus for 48h. When the diameter of the NPs decreased from 900 to 188 nm, the mucoadhesion increased from 6% to 12%. However, the combinatorial effect of EE% and percent mucoadhesion for larger size NPs was the highest. Overall, large-size, microbicide loaded chitosan NPs appeared to be promising nanomedicines for the prevention of HIV transmission.