Microbicide dosage forms

Baseline and time-updated factors in preclinical development of anionic dendrimers as successful anti-HIV-1 vaginal microbicides

Although a wide variety of topical microbicides provide promising in vitro and in vivo efficacy, most of them failed to prevent sexual transmission of human immunodeficiency virus type 1 (HIV-1) in human clinical trials. In vitro, ex vivo, and in vivo models must be optimized, considering the knowledge acquired from unsuccessful and successful clinical trials to improve the current gaps and the preclinical development protocols. To date, dendrimers are the only nanotool that has advanced to human clinical trials as topical microbicides to prevent HIV-1 transmission. This fact demonstrates the importance and the potential of these molecules as microbicides. Polyanionic dendrimers are highly branched nanocompounds with potent activity against HIV-1 that disturb HIV-1 entry. Herein, the most significant advancements in topical microbicide development, trying to mimic the real-life conditions as closely as possible, are discussed. This review also provides the preclinical assays that anionic dendrimers have passed as microbicides because they can improve current antiviral treatments' efficacy. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease Toxicology and Regulatory Issues in Nanomedicine > Regulatory and Policy Issues in Nanomedicine.

Safety Assessment of Microbicide 2P23 on the Rectal and Vaginal Microbiota and Its Antiviral Activity on HIV Infection

Containment of the AIDS pandemic requires reducing HIV transmission. HIV infection is initiated by the fusion of the membrane between the virus and the cell membrane of the host. 2P23 is an effective HIV membrane fusion inhibitor that may be a good entry inhibitor microbicide candidate. This study evaluated the potential of using gel-formulated 2P23 as a topical microbicide to prevent sexual transmission of HIV in the rectum and vagina. Our data revealed that 2P23 formulated in gel is effective against HIV. There was no change in antiviral activity at 25°C for 4 months or 60°C for 1 week. In addition, we demonstrated that the 2P23 gel was stable and fully functional at pH 4.0-8.0 and under different concentrations of H2O2. Finally, the 2P23 gel exhibited no cytotoxicity or antimicrobial activity and did not induce inflammatory changes in the rectal or vaginal mucosal epithelium in New Zealand rabbits after 20 mg/day daily rectovaginal application for 14 consecutive days. Despite repeated tissue sampling and 2P23 gel treatment, the inflammatory cytokines and microbiota of the rectum and vagina remained stable. These results add to general knowledge on the in vivo evaluation of anti-HIV microbicide application concerning inflammatory cytokines and microbiota changes in the rectum and vagina. These findings suggest that the 2P23 gel is an excellent candidate for further development as a safe and effective pre-exposure prophylactic microbicide for the prevention of HIV transmission.

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.

Vaginal washing and lubrication among female sex workers in the Mexico-US border region: implications for the development of vaginal PrEP for HIV prevention

Background

To assess the potential acceptability and inform the development of behaviorally-congruent vaginal douche- or gel-based HIV pre-exposure prophylaxis (PrEP) products, we examined vaginal washing and lubrication practices among female sex workers (FSWs) in Tijuana and Ciudad Juarez, two northern Mexico cities bordering the United States (US).

Methods

Two hundred and ninety-five HIV-negative FSWs (145 Tijuana; 150 Ciudad Juarez) enrolled in a behavioral HIV prevention intervention trial completed surveys assessing vaginal washing and lubrication practices, as well as motivators and barriers to performing each practice. Logistic regression was used to identify potential predictors of each practice in the past month.

Results

In the past month, vaginal washing was performed by 56 and 22% of FSWs in Tijuana and Ciudad Juarez (p <  0.0001), respectively, while vaginal lubrication was performed by 64 and 45% of FSWs in Tijuana and Ciudad Juarez (p = 0.001), respectively. Vaginal washing was positively associated with living in Tijuana (adjusted odds ratio [AOR] = 4.35, 95% confidence interval [CI]: 2.60–7.30), older age (AOR = 1.04 per year, 95% CI: 1.01–1.06), and vaginal lubrication (AOR = 2.99, 95% CI: 1.67–5.35), while it was negatively associated with being born in the same state as the study site (AOR = 0.50, 95% CI: 0.31–0.82), earning a monthly income ≥3500 pesos (AOR = 0.53, 95% CI: 0.28–1.00), and hazardous alcohol consumption (AOR = 0.56, 95% CI: 0.33–0.95). Vaginal lubrication was positively associated with living in Tijuana (AOR = 2.21, 95% CI: 1.37–3.54) and vaginal washing (AOR = 2.91, 95% CI: 1.64–5.18), while it was negatively associated with being born in the same state as the study site (AOR = 0.47, 95% CI: 0.29–0.75).

Conclusions

The moderate and high prevalence of vaginal washing and lubrication, respectively, suggest behaviorally-congruent, multi-purpose, vaginal douche- and gel-based PrEP products that simultaneously address FSWs’ needs and prevent HIV infection may be acceptable to many FSWs along the Mexico-US border. Future product development and implementation should also consider the link between vaginal washing and lubrication to ensure existing practices do not undermine vaginal PrEP product effectiveness.

Trial registration

ClincialTrials.gov (NCT02447484).

Electronic supplementary material

The online version of this article (10.1186/s12889-018-5946-z) contains supplementary material, which is available to authorized users.

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.

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

For human immunodeficiency virus (HIV) prevention, microbicides or drugs delivered as quick-dissolving films may be more acceptable to women than gels because of their compact size, minimal waste, lack of an applicator, and easier storage and transport. This has the potential to improve adherence to promising products for preexposure prophylaxis. Vaginal films containing IQP-0528, a nonnucleoside reverse transcriptase inhibitor, were evaluated for their pharmacokinetics in pigtailed macaques. Polymeric films (22 by 44 by 0.1 mm; providing 75% of a human dose) containing IQP-0528 (1.5%, wt/wt) with and without poly(lactic-co-glycolic acid) (PLGA) nanoparticle encapsulation were inserted vaginally into pigtailed macaques in a crossover study design (n = 6). With unencapsulated drug, the median (range) vaginal fluid concentrations of IQP-0528 were 160.97 (2.73 to 2,104), 181.79 (1.86 to 15,800), and 484.50 (8.26 to 4,045) μg/ml at 1, 4, and 24 h after film application, respectively. Median vaginal tissue IQP-0528 concentrations at 24 h were 3.10 (0.03 to 222.58) μg/g. The values were similar at locations proximal, medial, and distal to the cervix. The IQP-0528 nanoparticle-formulated films delivered IQP-0528 in vaginal tissue and secretions at levels similar to those obtained with the unencapsulated formulation. A single application of either formulation did not disturb the vaginal microflora or the pH (7.24 ± 0.84 [mean ± standard deviation]). The high mucosal IQP-0528 levels delivered by both vaginal film formulations were between 1 and 5 log higher than the in vitro 90% inhibitory concentration (IC90) of 0.146 μg/ml. The excellent coverage and high mucosal levels of IQP-0528, well above the IC90, suggest that the films may be protective and warrant further evaluation in a vaginal repeated low dose simian-human immunodeficiency virus (SHIV) transmission study in macaques and clinically in women.

Animal and human mucosal tissue models to study HIV biomedical interventions: can we predict success?

Introduction

Preclinical testing plays an integral role in the development of HIV prevention modalities. Several models are used including humanized mice, non-human primates and human mucosal tissue cultures.

Discussion

Pharmaceutical development traditionally uses preclinical models to evaluate product safety. The HIV prevention field has extended this paradigm to include models of efficacy, encompassing humanized mice, non-human primates (typically Asian macaques) and human mucosal tissue (such as cervical and colorectal). As our understanding of the biology of HIV transmission improves and includes the influence of human behaviour/biology and co-pathogens, these models have evolved as well to address more complex questions. These three models have demonstrated the effectiveness of systemic (oral) and topical use of antiretroviral drugs. Importantly, pharmacokinetic/pharmacodynamic relationships are being developed and linked to information gathered from human clinical trials. The models are incorporating co-pathogens (bacterial and viral) and the effects of coitus (mucosal fluids) on drug distribution and efficacy. Humanized mice are being tailored in their immune reconstitution to better represent humans. Importantly, human mucosal tissue cultures are now being used in early clinical trials to provide information on product efficacy to more accurately characterize efficacious products to advance to larger clinical trials. While all of these models have made advancements in product development, each has limitations and the data need to be interpreted by keeping these limitations in mind.

Conclusions

Development and refinement of each of these models has been an iterative process and linkages to data generated among each of them and from human clinical trials are needed to determine their reliability. Preclinical testing has evolved from simply identifying products that demonstrate efficacy prior to clinical trials to defining essential pharmacokinetic/pharmacodynamic relationships under a variety of conditions and has the potential to improve product selection prior to the initiation of large-scale human clinical trials. The goal is to provide researchers with ample information to make conversant decisions that guide optimized and efficient product development.

The potential of HIV-1 nanotherapeutics: from in vitro studies to clinical trials

Since its discovery almost three decades ago, HIV-1 has grown into the most aggressive pandemic of modern time. Following the implementation of combination antiretroviral therapy, the pathological outcome of HIV infection has substantially improved. However, combination antiretroviral therapy is limited by several factors including, long-term toxicity, serious side effects and complex dosing regimens, and so on. In this regard, researchers have directed their attention toward enhancing current treatment strategies and/or developing alternative HIV-1 therapeutics. In recent years, this attention has fixated on nanomedicine-based anti-HIV therapeutics (HIV-1 nanotherapeutics). In the present study, we have reviewed several HIV-1 nanotherapeutics that have shown success at the preclinical level and/or Phase I/II clinical trials. We also discuss the possible benefits of these nanomedicine-based approaches and their future outlook.