Two novel vaginal microbicides (polystyrene sulfonate and cellulose sulfate) inhibit Gardnerella vaginalis and anaerobes commonly associated with bacterial vaginosis

Atomic force microscopy characterization of polyethylene terephthalate grafting with poly(styrene sulfonate)

Polyethylene terephthalate (PET) is widely used to elaborate biomaterials and medical devices in particular for long-term implant applications but tuning their surface properties remains challenging. We investigate surface functionalization by grafting poly(sodium 4-styrene sulfonate, PNaSS) with the aim of enhancing protein adhesion and cellular activity. Elucidating the topography and molecular level organization of the modified surfaces is important for understanding and predicting biological activity. In this work, we explore several grafting methods including thermal grafting, thermal grafting in the presence of Mohr's salt, and UV activation. We characterize the different surfaces obtained using atomic force microscopy (AFM), contact angle (CA), and x-ray photoelectron spectroscopy (XPS). We observe an increase in the percentage of sulfur atoms (XPS) that correlates with changes in (CA), and we identify by AFM characteristic features, which we interpret as patches of polymers on the PET surfaces. This work demonstrates tuning of biomaterials surface by functionalization and illustrates the capability of AFM to provide insights into the spatial organization of the grafted polymer.

Cat flu: Broad spectrum polymeric antivirals

Feline herpesvirus type 1 (FHV-1) and feline calicivirus (FCV) are considered as main causes of feline upper respiratory tract disease and the most common clinical manifestations include rhinotracheitis, conjunctivitis, and nasal/facial ulcerations. While the primary infection is relatively mild, secondary infections pose a threat to young or immunocompromised cats and may result in a fatal outcome. In this study, we made an effort to evaluate antiviral potency of poly(sodium 4-styrenesulfonates) (PSSNa) as potent FHV-1 and FCV inhibitors for topical use. Mechanistic studies showed that PSSNa exhibits a different mechanism of action depending on target species. While PSSNa acts directly on FHV-1 particles blocking their interaction with the host's cell and preventing the infection, the antiviral potency against FCV is based on inhibition at late stages of the viral replication cycle. Altogether, PSSNa polymers are promising drug candidates to be used in the treatment and prevention of the viral upper respiratory tract disease (URTD), regardless of the cause.

A Synthetic, Small, Sulfated Agent Is a Promising Inhibitor of Chlamydia spp. Infection in vivo

Chlamydia is the most frequently reported sexually transmitted bacteria causing 2.9 million infections annually in the United States. Diagnosis, treatment, and sequelae of chlamydial disease cost billions of dollars each year in the United States alone. Considering that a heparin sulfate-like cell surface receptor is involved in Chlamydia infections, we reasoned that sulfated and sulfonated mimics of heparin sulfate would be useful in topical prophylactic prevention of Chlamydia. In this study, we tested a small, synthetic sulfated agent sulfated pentagalloyl glucoside (SPGG) and three synthetic sulfonated polymers PSS and SPS with average molecular weight in the range of 11 to 1000 kDa for inhibition against Chlamydia. Infection of HeLa cells with C. muridarum or C. trachomatis in the presence of increasing concentrations of SPGG or sulfonated polymers were quantified by immunofluorescence of Chlamydia inclusions. To determine whether in vitro pre-treatment of SPGG inhibits infection of C. muridarum, HeLa monolayers were incubated with SPGG-containing media, and then infected with Chlamydia. Our in vitro results show that SPGG pre-treatment inhibits Chlamydia infection in a dose-dependent manner. In addition, we further determined if SPGG treatment has an inhibitory effect during infection, therefore cell monolayers were infected with C. muridarum in the concurrent presence of SPGG. Our results show that SPGG inhibits C. muridarum infection with an IC50 at 10 μg/ml levels. We also tested the inhibitory effect of synthetic polymers PSS and SPS against Chlamydia and found inhibition of C. muridarum and C. trachomatis infections with IC50 ranging from 0.3 to 0.8 μg/ml. SPGG, PSS, and SPS inhibit formation of Chlamydia inclusions in a concentration-dependent manner. For evaluation of in vivo efficacy of the most effective agent in blocking C. muridarum, SPGG, we intravaginally pre-treated mice with SPGG before infection with C. muridarum. Cervical swabs were collected post-infection to quantify Chlamydia inclusions in vitro. Our in vivo data show that the SPGG-treated group has a statistically significant reduction of infection compared to the no-treatment control. Overall, our results show that SPGG could serve as a promising topical inhibitor for preventing Chlamydia infection.

Bacterial vaginosis: An insight into the prevalence, alternative treatments regimen and it's associated resistance patterns

Bacterial Vaginosis (BV) is a complex polymicrobial infection of vagina that shifts the paradigms of vaginal flora from lactobacilli to opportunistic pathogens. BV is catagorized by greyish white discharge, pH greater than 4.5. It results in the preterm labor, abortion, pelvic inflammatory disorders, post cesarean infections. BV is associated with Sexually Transmitted Diseases (STDs) or immune deficiency disorders like Human Immunodeficiency Virus, Human Papilloma Virus, Herpes Simplex Virus 1 and 2, and Neisseria gonorrhoeae. The prevalence rate is about 21.2 million (29.2%) worldwide. BV is more frequent in black females as compared to white females, independent of geographical distribution. Globally, BV is treated with the current recommended antibiotic therapy including Metronidazole and Clindamycin. The recurrence rates are 76% and occur within 06 months of treatment due to antibiotic resistance against pathogenic bacteria and their biofilms. The antibiotic resistance is a global health issue which directs the attentions towards other treatments. One of these is the treatment of sex partners, thus helping to stop the recurrence rates in females. However, this method does not show any positive results. Probiotic therapy is an incorporation of Lactobacilli orally or intravaginally for the recolonization of healthy microbes. This therapy has exhibited promising results but some studies revealed that Probiotic therapy does not control the recurrence rate. The other methods are in trials period and none of them are used clinically or commercially available for the treatment. The thermoplastic polyurethane (TPU) intravaginal rings contain lactic acid and metronidazole showed promising results in trials of BV treatment. The vaginal acidifiers are used as an alternative method to maintain the vaginal pH but the process of douching is a major limitation. The activated charcoal is used to treat BV patients in clinical trials showed decrease in the pH with only 3.1% loss of lactobacilli. Phage therapy is a reemerging field to overcome the bacterial resistance. They are host specific and easier to handle. They can be used naturally, synthetically; phage cocktails and phage-antibiotics combination can be used. Phages show auspicious results for the treatment of bacterial infections as compared to antibiotics as they also treat biofilms. This is one of the promising therapy in future to treat infections with no side effects. Phage therapy can be used in pharmaceuticals according to Food and Drug Administration (FDA) guidelines. Taken together, it is suggested that large funding is required by pharmaceutical sector or government for further investigation of bacteriophages to be used against BV pathogenesis.

Toxicity analysis of poly(sodium-4-styrenesulfonate) coated graphene on HMEC-1 cells under dynamic conditions mimicking blood flow

Functionalized graphene shows lower toxicity towards cells cultured in a dynamic culture as compared with in a static culture compared with other carbon nanomaterials, including MWCNTs and carbon black, due to the lateral-size effect and dispersion behavior.

Design, synthesis and thermal behaviour of a series of well-defined clickable and triggerable sulfonate polymers

In the printing industry, the exploitation of triggerable materials that can have their surface properties altered on application of a post-deposition external stimulus has been crucial for the production of robust layers and patterns.

In vivo evaluation of a mucoadhesive polymeric caplet for intravaginal anti-HIV-1 delivery and development of a molecular mechanistic model for thermochemical characterization

CONTEXT AND OBJECTIVE

The aim of this study was to develop, characterize and evaluate a mucoadhesive caplet resulting from a polymeric blend (polymeric caplet) for intravaginal anti-HIV-1 delivery.

MATERIALS AND METHODS

Poly(lactic-co-glycolic) acid, ethylcellulose, poly(vinylalcohol), polyacrylic acid and modified polyamide 6, 10 polymers were blended and compressed to a caplet-shaped device, with and without two model drugs 3'-azido-3'-deoxythymidine (AZT) and polystyrene sulfonate (PSS). Thermal analysis, infrared spectroscopy and microscopic analysis were carried out on the caplets employing temperature-modulated DSC (TMDSC), Fourier transform infra-red (FTIR) spectrometer and scanning electron microscope, respectively. In vitro and in vivo drug release analyses as well as the histopathological toxicity studies were carried out on the drug-loaded caplets. Furthermore, molecular mechanics (MM) simulations were carried out on the drug-loaded caplets to corroborate the experimental findings.

RESULTS AND DISCUSSION

There was a big deviation between the Tg of the polymeric caplet from the Tg's of the constituent polymers indicating a strong interaction between constituent polymers. FTIR spectroscopy confirmed the presence of specific ionic and non-ionic interactions within the caplet. A controlled near zero-order drug release was obtained for AZT (20 d) and PSS (28 d). In vivo results, i.e. the drug concentration in plasma ranged between 0.012-0.332 mg/mL and 0.009-0.256 mg/mL for AZT and PSS over 1-28 d.

CONCLUSION

The obtained results, which were corroborated by MM simulations, attested that the developed system has the potential for effective delivery of anti-HIV-agents.

Polyethylene glycol-based hydrogels for controlled release of the antimicrobial subtilosin for prophylaxis of bacterial vaginosis

Current treatment options for bacterial vaginosis (BV) have been shown to be inadequate at preventing recurrence and do not provide protection against associated infections, such as that with HIV. This study examines the feasibility of incorporating the antimicrobial peptide subtilosin within covalently cross-linked polyethylene glycol (PEG)-based hydrogels for vaginal administration. The PEG-based hydrogels (4% and 6% [wt/vol]) provided a two-phase release of subtilosin, with an initial rapid release rate of 4.0 μg/h (0 to 12 h) followed by a slow, sustained release rate of 0.26 μg/h (12 to 120 h). The subtilosin-containing hydrogels inhibited the growth of the major BV-associated pathogen Gardnerella vaginalis with a reduction of 8 log10 CFU/ml with hydrogels containing ≥15 μg entrapped subtilosin. In addition, the growth of four common species of vaginal lactobacilli was not significantly inhibited in the presence of the subtilosin-containing hydrogels. The above findings demonstrate the potential application of vaginal subtilosin-containing hydrogels for prophylaxis of BV.

Polyanionic candidate microbicides accelerate the formation of semen-derived amyloid fibrils to enhance HIV-1 infection

Polyanionic candidate microbicides, including cellulose sulfate, carrageenan, PRO 2000, were proven ineffective in preventing HIV-1 transmission and even cellulose sulfate showed increased risk of HIV acquisition in the Phase III efficacy trials. Semen plays critical roles in HIV-1 sexual transmission. Specifically, amyloid fibrils formed by fragments of prostatic acidic phosphatase (PAP) in semen termed semen-derived enhancer of virus infection (SEVI) could drastically enhance HIV-1 infection. Here we investigated the interaction between polyanions and PAP248-286, a prototype peptide of SEVI, to understand the possible cause of polyanionic candidate microbicides to fail in clinical trials. We found anionic polymers could efficiently promote SEVI fibril formation, most likely mediated by the natural electrostatic interaction between polyanions and PAP248-286, as revealed by acid native PAGE and Western blot. The overall anti-HIV-1 activity of polyanions in the presence or absence of PAP248-286 or semen was evaluated. In the viral infection assay, the supernatants of polyanions/PAP248-286 or polyanions/semen mixtures containing the free, unbound polyanionic molecules showed a general reduction in antiviral efficacy, while the pellets containing amyloid fibrils formed by the polyanion-bound PAP248-286 showed aggravated enhancement of viral infection. Collectively, from the point of drug-host protein interaction, our study revealed that polyanions facilitate SEVI fibril formation to promote HIV-1 infection, thus highlighting a molecular mechanism underlying the failure of polyanions in clinical trials and the importance of drug-semen interaction in evaluating the anti-HIV-1 efficacy of candidate microbicides.

Role of heparan sulfate in sexually transmitted infections

Cell surface heparan sulfate (HS), a polysaccharide composed of alternating uronic acid and glucosamine residues, represents a common link that many sexually transmitted infections (STIs) require for infection. Variable modifications within the monomeric units of HS chains together with their unique structural conformations generate heterogeneity, which expands the ability of HS to bind a diverse array of host and microbial proteins. Recent advances made in the field of glycobiology have critically enhanced our understanding of HS and its interactions with microbes and their significance in important human diseases. The role of HS has been elaborated for several STIs to include those caused by herpes simplex virus, human immunodeficiency virus, human papillomavirus, and Chlamydia. In addition, gonorrhea, syphilis, and yeast infections are also dependent on the presence of HS on human target cells. Critical steps such as pathogen adhesion or binding to host cells followed by internalization to enhance intracellular survival and possible spread to other cells are mediated by HS. In addition, HS guided cell signaling plays a role in the development of angiogenesis and inflammation associated with many STIs. Past and ongoing investigations are providing new push for the development of HS-mimetics and analogs as novel prevention strategies against many different STIs. This review article summarizes the significance of HS in STIs and describes how emerging new products that target HS can be used to control the spread of STIs.

Microbicides: a new hope for HIV prevention

Human immunodeficiency virus (HIV), causative agent of acquired immunodeficiency syndrome (AIDS), is a global health concern. To control its transmission, safe sex has been proposed as one of the strategies. Microbicides- intravaginal/intrarectal topical formulations of anti-HIV agents have also been proposed to prevent HIV transmission. Microbicides would provide protection by directly inactivating HIV or preventing the attachment, entry or replication of HIV in susceptible target cells as well as their dissemination from target cells present in semen or the host cells lining the vaginal/rectal wall to other migratory cells. Microbicides must be safe, effective following vaginal or rectal administration, and should cause minimal or no genital symptoms or inflammations following long-term repeated usage. However, a safe and efficacious anti-HIV microbicide is not yet available despite the fact that more than 60 candidate agents have been identified to have in vitro activity against HIV, several of which have advanced to clinical testing. Nonetheless, proof-of-concept of microbicides has been established based on the results of recent CAPRISA 004 clinical trials. In this article, the trends and challenges in the development of effective and safe microbicides to combat HIV transmission are reviewed.

Novel vaginal microflora colonization model providing new insight into microbicide mechanism of action

Several broad-spectrum microbicides, including cellulose sulfate (CS), have passed conventional preclinical and phase I clinical safety evaluation and yet have failed to protect women from acquiring HIV-1 in phase II/III trials. Concerns have been raised that current preclinical algorithms are deficient in addressing the complexity of the microflora-regulated vaginal mucosal barrier. We applied a novel microflora-colonized model to evaluate CS and hydroxyethylcellulose (HEC), which is used as a "universal placebo" in microbicide trials. Cervicovaginal epithelial cultures were colonized with normal vaginal microflora isolates representing common Lactobacillus species used as probiotics (L. acidophilus and L. crispatus) or Prevotella bivia and Atopobium vaginae, most prevalent in the disturbed microflora of bacterial vaginosis (BV). At baseline, all strains maintained constant epithelium-associated CFUs without inducing cytotoxicity and apoptosis. CS selectively reduced epithelium-associated CFUs and (to a lesser extent) planktonic CFUs, most significantly affecting L. crispatus. Inducing only minor changes in sterile epithelial cultures, CS induced expression of innate immunity mediators (RANTES, interleukin-8 [IL-8], and secretory leukocyte protease inhibitor [SLPI]) in microflora-colonized epithelia, most significantly potentiating effects of bacteria causing BV. In the absence of CS, all bacterial strains except L. acidophilus activated NF-κB, although IL-8 and RANTES levels were increased by the presence of BV-causing bacteria only. CS enhanced NF-κB activation in a dose-dependent manner under all conditions, including L. acidophilus colonization. HEC remained inert. These results offer insights into possible mechanisms of CS clinical failure. The bacterially colonized cervicovaginal model reveals unique aspects of microflora-epithelium-drug interactions and innate immunity in the female genital tract and should become an integral part of preclinical safety evaluation of anti-HIV microbicides and other vaginal formulations.

IMPORTANCE

This report provides experimental evidence supporting the concept that the vaginal microflora regulates the epithelial innate immunity in a species- and strain-specific manner and that topically applied microbicides may alter both the bacterial and epithelial components of this homeostatic interaction. Our data also highlight the importance of differentiating the effects of biomedical interventions on epithelium-associated versus conventional planktonic bacterial growth when assessing vaginal mucosal health and immunity.

Bacterial vaginosis: Etiology and modalities of treatment-A brief note

A large women population of the world is suffering from a vaginal infection commonly known as bacterial vaginosis. The disease is associated with the decrease in the lactobacilli count in the vagina. Till date, there is a lack of full proof treatment modalities for the cure of the disease. The treatment includes the use of antimicrobials and/or acidifying agents and probiotics, either separately or in combination. This note discusses about the etiology and the various present-day modalities of treatment of bacterial vaginosis.

HIV sexual transmission and microbicides

Pathogens often rely on the contacts between hosts for transmission. Most viruses have adapted their transmission mechanisms to defined behaviours of their host(s) and have learned to exploit these for their own propagation. Some viruses, such as HIV, the human papillomavirus (HPV), HSV-2 and HCV, cause sexually transmitted infections (STIs). Understanding the transmission of particular viral variants and comprehending the early adaptation and evolution is fundamental to eventually inhibiting sexual transmission of HIV. Here, we review the current understanding of the mechanisms of sexual transmission and the biology of the transmitted HIV. Next, we present a timely overview of candidate microbicides, including past, ongoing and future clinical trials of HIV topical microbicides.

Feasibility of Repurposing the Polyanionic Microbicide, PPCM, for Prophylaxis against HIV Transmission during ART

HIV-serodiscordant couples wishing to conceive often seek assisted reproduction, during which spermatozoa from infected men are washed to minimize the risk of HIV transmission to partner and fetus. We sought to improve this method by adding a microbicide, PPCM, as an HIV prophylactic. HIV-1 (BaL) inhibition by PPCM appears irreversible and independent of added Ca²⁺. Without added Ca²⁺, PPCM (≤10 mg/mL, ≤90 min), a stimulus of Ca²⁺-dependent acrosomal loss, has no effect on sperm motility, forward progression, or acrosomal status. PPCM-treated (10 mg/mL) sperm retain their ability to acrosome react when Ca²⁺ is added. Sperm DNA integrity/function is unaffected by PPCM (≤10 mg/mL). Adding PPCM (5 mg/mL, 30 min) to washing media reduces infectivity (viral antigen p24 and RNA) of ex-vivo HIV-infected semen by 3-4 Logs compared with washing alone. Sperm washing with appropriate extracellular Ca²⁺ levels and PPCM is significantly more effective than washing alone at reducing HIV infectivity.

The last decade of microbicide clinical trials in Africa: from hypothesis to facts

Microbicide clinical trials have dominated biomedical HIV prevention research in the past decade. Two generations of microbicides have gone through large-scale human clinical trials. Candidate microbicides assessed in clinical trials in Africa have fallen into the categories of surfactants, polyanionic entry inhibitors, or vaginal milieu protectors. These include compounds such as nonoxynol-9, SAVVY, cellulose sulphate, Carraguard, PRO 2000, and BufferGel. Disappointingly, none of the products have shown efficacy against HIV. Each successive trial has benefited from the lessons learned in preceding trials. The trials have provided important lessons in basic, clinical, social, and behavioural science. More importantly, we have learned that the concept of a vaginally inserted product for HIV prevention is acceptable by women. We have now reached an end of an era of clinical testing with non-HIV-specific microbicides and move forward to testing novel strategies of antiretroviral therapeutic products such as preexposure prophylaxis (PrEP) for HIV prevention. PrEP for vaginal administration in various formulations is being tested to continue our commitment to providing more HIV prevention options to millions of women worldwide.

Investigation of the physicochemical and physicomechanical properties of a novel intravaginal bioadhesive polymeric device in the pig model

The purpose of this study was to develop and evaluate the bioadhesivity, in vitro drug release, and permeation of an intravaginal bioadhesive polymeric device (IBPD) loaded with 3'-azido-3'-deoxythymidine (AZT) and polystyrene sulfonate (PSS). Modified polyamide 6,10, poly(lactic-coglycolic acid), polyacrylic acid, polyvinyl alcohol, and ethylcellulose were blended with model drugs AZT and PSS as well as radio-opaque barium sulfate (BaSO4) and then compressed into caplet devices on a tableting press. One set of devices was coated with 2% w/v pentaerythritol polyacrylic acid (APE-PAA) while another remained uncoated. Thermal analysis was performed on the constituent polymers as well the IBPD. The changes in micro-environmental pH within the simulated human vaginal fluid due to the presence of the IBPD were assessed over a period of 30 days. Textural profile analysis indicated that the bioadhesivity of the APE-PAA-coated devices (3.699 +/- 0.464 N; 0.0098 +/- 0.0004 J) was higher than that of the uncoated devices (1.198 +/- 0.150 N; 0.0019 +/- 0.0001 J). In addition, BaSO4-facilitated X-ray imaging revealed that the IBPD adhered to pig vaginal tissue over the experimental period of 30 days. Controlled drug release kinetics was obtained over 72 days. During a 24-h permeation study, an increase in drug flux for both AZT (0.84 mg cm(-2) h(-1)) and PSS (0.72 mg cm(-2) h(-1)) was realized up to 12 h and thereafter a steady-state was achieved. The diffusion and dissolution dynamics were mechanistically deduced based on a chemometric and molecular structure modeling approach. Overall, results suggested that the IBPD may be sufficiently bioadhesive with desirable physicochemical and physicomechanical stability for use as a prolonged intravaginal drug delivery device.

Differential Sensitivity of Lactobacillus spp. to Inhibition by Candidate Topical Microbicides

Preclinical evaluation of vaginal microbicides includes screening against lactobacilli. However, there is no consensus regarding the species to be tested. This study was carried out to determine if results with one species would apply to other species, and to evaluate the utility of turbidometry as a screening tool. One current (PPCM; previously designated sulfuric acid-modified mandelic acid, SAMMA) and two former (cellulose sulfate, CS; and polystyrene sulfonate, PSS) candidate microbicides were evaluated. Bacterial growth was measured turbidometrically and by direct cell count. No microbicide affected Lact. gasseri, measured by either method. Apparent inhibition of Lact. jensenii by CS, PSS, and PPCM, and of Lact. crispatus by CS, occurred with turbidometric measurement. This was not substantiated with direct cell count. PSS and PPCM inhibited Lact. crispatus and Lact. acidophilus with both methods. These findings agree with results from vaginal isolates, which included Lact. gasseri, jensenii, acidophillus, crispatus, rhamnosis, casei, and paracasei. We conclude that sensitivities of similar lactobacilli to at least three microbicides are different. A single species is inadequate for screening vaginal products. Turbidometric evaluation is a sensitive, but not specific, screening method. We recommend that this method be used to screen candidate microbicides against several species of prevalent Lactobacillus species as an initial measure of microbicide safety evaluation.

Vaginal microbicides and the prevention of HIV transmission

Worldwide, nearly half of all individuals living with HIV are now women, who acquire the virus largely by heterosexual exposure. With an HIV vaccine likely to be years away, topical microbicide formulations applied vaginally or rectally are being investigated as another strategy for HIV prevention. A review of preclinical and clinical research on the development of microbicides formulated to prevent vaginal HIV transmission yielded 118 studies: 73 preclinical and 45 clinical. Preclinical research included in-vitro assays and cervical explant models, as well as animal models. Clinical research included phase I and II/IIb safety studies, and phase III efficacy studies. Whereas most phase I and phase II clinical trials have found microbicide compounds to be safe and well tolerated, phase III trials completed to date have not demonstrated efficacy in preventing HIV transmission. Topical microbicides are grouped into five classes of agents, based on where they disrupt the pathway of sexual transmission of HIV. These classes include surfactants/membrane disruptors, vaginal milieu protectors, viral entry inhibitors, reverse transcriptase inhibitors, and a fifth group whose mechanism is unknown. The trajectory of microbicide development has been toward agents that block more specific virus-host cell interactions. Microbicide clinical trials face scientifically and ethically complex issues, such as the choice of placebo gel, the potential for viral resistance, and the inclusion of HIV-infected participants. Assessment of combination agents will most likely advance this field of research.

Polyanionic drugs and viral oncogenesis: a novel approach to control infection, tumor-associated inflammation and angiogenesis

Polyanionic macromolecules are extremely abundant both in the extracellular environment and inside the cell, where they are readily accessible to many proteins for interactions that play a variety of biological roles. Among polyanions, heparin, heparan sulfate proteoglycans (HSPGs) and glycosphingolipids (GSLs) are widely distributed in biological fluids, at the cell membrane and inside the cell, where they are implicated in several physiological and/or pathological processes such as infectious diseases, angiogenesis and tumor growth. At a molecular level, these processes are mainly mediated by microbial proteins, cytokines and receptors that exert their functions by binding to HSPGs and/or GSLs, suggesting the possibility to use polyanionic antagonists as efficient drugs for the treatment of infectious diseases and cancer. Polysulfated (PS) or polysulfonated (PSN) compounds are a heterogeneous group of natural, semi-synthetic or synthetic molecules whose prototypes are heparin and suramin. Different structural features confer to PS/PSN compounds the capacity to bind and inhibit the biological activities of those same heparin-binding proteins implicated in infectious diseases and cancer. In this review we will discuss the state of the art and the possible future development of polyanionic drugs in the treatment of infectious diseases and cancer.

A review of current intravaginal drug delivery approaches employed for the prophylaxis of HIV/AIDS and prevention of sexually transmitted infections

The objective of this review is to describe the current status of several intravaginal anti-HIV microbicidal delivery systems these delivery systems and microbicidal compounds in the context of their stage within clinical trials and their potential cervicovaginal defence successes. The global Human Immuno-Deficiency Virus (HIV) pandemic continues to spread at a rate of more than 15,000 new infections daily and sexually transmitted infections (STIs) can predispose people to acquiring HIV infection. Male-to-female transmission is eight times more likely to occur than female-to-male transmission due to the anatomical structure of the vagina as well as socio-economic factors and the disempowerment of women that renders them unable to refuse unsafe sexual practices in some communities. The increased incidence of HIV in women has identified the urgent need for efficacious and safe intravaginal delivery of anti-HIV agents that can be used and controlled by women. To meet this challenge, several intravaginal anti-HIV microbicidal delivery systems are in the process of been developed. The outcomes of three main categories are discussed in this review: namely, dual-function polymeric systems, non-polymeric systems and nanotechnology-based systems. These delivery systems include formulations that modify the genital environment (e.g. polyacrylic acid gels and lactobacillus gels), surfactants (e.g. sodium lauryl sulfate), polyanionic therapeutic polymers (e.g. carageenan and carbomer/lactic acid gels), proteins (e.g. cyanovirin-N, monoclonal antibodies and thromspondin-1 peptides), protease inhibitors and other molecules (e.g. dendrimer based-gels and the molecular condom). Intravaginal microbicide delivery systems are providing a new option for preventing the transmission of STIs and HIV.

A randomized controlled safety trial of the diaphragm and cellulose sulfate microbicide gel in sexually active women in Zimbabwe

BACKGROUND

Cellulose sulfate (CS) is an antimicrobial and contraceptive agent. We assessed its safety when used alone or with the diaphragm in Harare, Zimbabwe.

STUDY DESIGN

This was a randomized controlled safety trial with three arms: diaphragm with 6% CS gel vs. diaphragm with KY gel vs. CS gel alone. Participants were instructed to use their study products before every sex act for a period of 6 months. Safety end points were assessed monthly by questionnaires and urinanalysis and bimonthly by clinical examinations, colposcopy, wet mounts and gram stains.

RESULTS

One hundred nineteen monogamous women were enrolled (28% HIV+) and 105 (88%) completed the study. No urinary tract infections were diagnosed during the study; 81.4% women had symptoms and/or signs of genital irritation considered at least possibly related to the gel or device, and 41.5% had changes in vaginal flora. There were no statistically significant differences between treatment groups in safety end points. All six women with deep epithelial disruption were diaphragm users, and all such findings were on the external genitalia. Of those, 4 had herpetic ulcers which were unrelated to products use.

CONCLUSIONS

Cellulose sulfate appeared safe when used for 6 months alone or with a diaphragm.

Safety trial of the vaginal microbicide cellulose sulfate gel in HIV-positive men

OBJECTIVE

Cellulose sulfate (CS) is a promising vaginal microbicide. Because men will be exposed to the microbicide when engaging in vaginal intercourse, safety and acceptability need to be assessed in men.

DESIGN

This randomized double-blind phase I study assessed the safety and acceptability of seven consecutive daily doses of CS versus KY Jelly in 36 HIV-positive men.

RESULTS

No new or worsening of existing genital findings were observed during the follow-up examination. Mild genital symptoms were reported in 42% of CS users (itching, burning, tingling, testicular pain, dysuria, and warm or cold feeling) and 8% of KY Jelly users.

CONCLUSION

CS gel applied to the penis was well tolerated in this HIV-positive male population. The itching and burning symptoms were not severe and can be explained by the preservative benzyl alcohol present in the CS gel.

South Africa's experience of the closure of the cellulose sulphate microbicide trial

The researchers who conducted the cellulose sulphate microbicide trial share the lessons they learned from the trial's early closure.

Microbicide drug candidates to prevent HIV infection

25 years after the first HIV/AIDS cases emerged in 1981, the disease continues to spread worldwide, with about 15 000 new infections every day. Although highly active antiretroviral therapy (HAART) has greatly reduced the rate of HIV infection, and the spread of the epidemic, this effect has largely been seen in developed countries. More than 90% of HIV-infected people live in developing countries, most of whom do not have access to this treatment. The development of efficient, widely available, and low-cost microbicides (gels and creams can be applied topically before sex) to prevent sexually transmitted HIV infections should be given high priority. We review different categories of microbicide drugs and lead compounds, their mechanism of action, current status of development, and progress in phase III trials.

Microbicides: a new frontier in HIV prevention

Microbicides are products that can be applied to vaginal or rectal mucosal surfaces with the goal of preventing, or at least significantly reducing, the transmission of sexually transmitted infections (STIs) including HIV-1. Despite more than two decades of HIV-1 vaccine research, there is still no efficacious HIV-1 vaccine, and the scientific community appears skeptical about the short or long-term feasibility of developing a vaccine that has the ability to induce sterilizing immunity against HIV-1. In this setting, microbicide research has gathered momentum. Currently, 16 candidate microbicides are in clinical development and five products are being evaluated in large-scale Phase 2B/3 effectiveness studies. Initial data from these trials will be available within the next 2-3 years, and it is feasible that there could be one or more licensed microbicides by the end of the decade. The first generation of surfactant microbicides had a non-specific mechanism of action. However, subsequent candidate microbicides have been developed to target specific steps in the process of viral transmission. The purpose of this article is to provide an overview of microbicide development and an update on the candidate pipeline.

Vaginal distribution of two volumes of the novel microbicide gel cellulose sulfate (2.5 and 3.5 mL)

This was a blinded crossover study to determine the in vivo distribution of 2.5 and 3.5 mL of 6% cellulose sulfate gel. This potential vaginal microbicide was mixed with dilute gadolinium chelate and inserted into the vagina. Magnetic resonance imaging was performed at baseline and repeated after 5, 20, 35 and 50 min with subjects either resting or ambulating between data acquisitions. Use of 2.5 mL with no ambulation gave low linear spread (53.1% of vaginal length) and surface contact (61.7%) at 50 min. Using 3.5 mL of gel with ambulation improved linear spread (84.5%) and surface contact (85.9%) of the gel in the same time interval without significant leakage. Most linear spreading took place in the first 5 min after insertion, although lateral spreading continued to increase with time especially when ambulation took place. Leakage and gel was not a significant problem at either volume.

Development and characterization of bioadhesive vaginal films of sodium polystyrene sulfonate (PSS), a novel contraceptive antimicrobial agent

PURPOSE

Polystyrene sulfonate (PSS) is a novel noncytotoxic antimicrobial contraceptive agent. A gel formulation of PSS was found safe for vaginal administration in phase I clinical trials. The purpose of the current study was to develop and evaluate novel bioadhesive vaginal film formulations of PSS.

METHODS

PSS films were prepared by solvent evaporation and optimized for various physical, mechanical, and aesthetic properties. Further, films were evaluated for various biological activities and safety.

RESULTS

Vaginal films containing 300 mg PSS per unit have been developed, using generally regarded as safe (GRAS) listed excipients. The films are colorless, transparent, thin, soft, and tough, dissolve rapidly in physiologic fluid to form a smooth, viscous and bioadhesive solution that could be retained in the vagina for prolonged intervals. Sperm function inhibition (hyaluronidase and cervical mucus penetration) and antimicrobial activities against human immunodeficiency virus (HIV) and herpes simplex virus (HSV) by PSS films were found comparable to PSS. Also, films did not inhibit normal vaginal microflora (Lactobacillus) and were noncytotoxic as indicated by negligible sperm immobilization and cytotoxicity to host cell assays.

CONCLUSIONS

Rapidly dissolving bioadhesive vaginal film formulation of PSS with desired physical, mechanical, aesthetic, and biological properties is a suitable candidate vaginal microbicide for prevention of sexually transmitted disease (STDs) and is ready for toxicological and clinical evaluation.

Single and multiple exposure tolerance study of polystyrene sulfonate gel: a phase I safety and colposcopy study

OBJECTIVES

To evaluate symptoms and signs of genital irritation, vaginal leakage and acceptability of polystyrene sulfonate (PSS), which is being studied as a vaginal contraceptive and microbicide.

METHODS

Forty-nine women applied 2.5 mL of either 5% PSS, 10% PSS, PSS vehicle, or Conceptrol (a marketed spermicidal product containing 4% nonoxynol-9) for 6 consecutive days.

RESULTS

All women completed the study except one in the Conceptrol group who experienced vaginal symptoms after her first use and was discontinued. After both the first use and after all uses, irritation was seen among more women in the Conceptrol group than in the PSS groups, reaching statistical significance with regard to any evidence of irritation, signs of irritation and product-related irritation. There were no adverse events that were serious, unexpected and related to product use in any group. The 5% concentration of PSS may be preferable in terms of leakage and acceptability.

CONCLUSION

The results suggest that PSS has a safety profile comparable to that of the marketed nonoxynol-9 product, Conceptrol, and appears to be associated with less genital irritation.

Contraception by Ushercell™ (cellulose sulfate) in formulation: duration of effect and dose effectiveness

This study evaluated contraception by formulated Ushercell, a uniquely high-molecular-weight form of cellulose sulfate, in the rabbit. Variables included (1) dose effectiveness, (2) duration of effectiveness, and (3) formulation excipients. Vaginally applied carboxymethyl-cellulose-based Ushercell gel is contraceptive. A 6% gel is active for at least 18 h; partial activity is observed for at least 24 h. With an application-insemination interval of 0.5 h, Ushercell as low as 0.1% is contraceptive. Contraception is incomplete with 2% Ushercell and an application-insemination interval of 24 h. Ushercell formulations containing a relatively high concentration of Carbopol are ineffective contraceptives, whether the gel is applied before insemination or is premixed with spermatozoa before insemination. Contraceptive activity is restored in Ushercell formulations with lower Carbopol content. This study shows that formulated Ushercell is an effective, long-lasting contraceptive and, hence, is bioavailable when vaginally applied. Activity is dependent on the type and relative concentration of formulation excipients. These data support a projected successful outcome of further clinical trials.

Recommendations for the Nonclinical Development of Topical Microbicides for Prevention of HIV Transmission: An Update

The development of methods to prevent HIV infection is critical to curbing the rising epidemic. Topical microbicides represent a potential new strategy for reduction of HIV transmission. The purpose of this article is to update and expand upon the nonclinical recommendations of a previously published document on the development of microbicides prepared by the International Working Group on Microbicides. The nonclinical studies discussed here represent general concepts and regulatory considerations that are pertinent to the development of topical microbicides for prevention or reduction of HIV transmission. Essential early steps in product development include the determination of antiviral activity, cytotoxicity, mechanism of action, pathways to resistance, and cross-resistance to approved drugs. Other parameters to consider include activity against vaginal microflora and pathogens that cause sexually transmitted diseases. Before and during clinical trials, nonclinical data on toxicology and pharmacokinetics should be obtained. Finally, product quality issues, including microbicide formulation characteristics, interaction with other products, and stability, should be addressed.

Vaginal microbicides and teenagers

PURPOSE OF REVIEW

Sexually active teens are at significant risk from sexually transmitted infections and girls and women bear the greatest burden of these infections. New methods, such as vaginal microbicides, would provide female controlled options. Microbicides are currently in development and thus it is timely to discuss the progress made and factors that may influence acceptability for teens.

RECENT FINDINGS

Microbicide development presents many challenges, and several different potential mechanisms of action are being explored. There is interest in these products from women and men, and specific preferences are being investigated. Adolescents, due to reproductive system immaturity, developing cognitive abilities and the psychosocial context of their relationships, present a special set of challenges in efforts to foster microbicide use.

SUMMARY

Vaginal microbicides are on the horizon. Further study into teen issues is required to develop successful strategies for marketing and encouraging adolescent use of microbicides.

Surface area of the human vagina as measured from vinyl polysiloxane casts

Sixty-two vinyl polysiloxane casts from subjects in the lying, supine position were measured for surface area with five shapes: conical, parallel sides, heart, slug, and pumpkin seed being included. The surface areas ranged from 65.73 to 107.07 cm(2) with a mean of 87.46 cm(2) and a standard deviation of 7.80 cm(2). There were no significant differences in surface area among the shape groups. And no correlations with surface area were found by parity or by rod length, introital diameter, posterior length of casts as measured with string, or greatest width and greatest depth of casts. 70% of the casts had a surface area of 84.50 cm(2) or above, and 90% had a surface area of 77.72 cm(2) or above. Variation within the interquartile range (75th to 25th percentile) was +/-5.2% of the median.

Review of cytologic criteria of bacterial vaginosis: examination of 2,841 Papanicolaou-stained vaginal smears

To review the cytologic criteria used in the diagnosis of bacterial vaginosis cases [Bv (+)], 2,841 Papanicolaou-stained vaginal smears were examined cytologically. Clue cells and other cytologic findings were observed in 94 of 2,841 (3.30%) vaginal smears. To detect Bv(+) cases, 94 vaginal smears were screened again. Clue cells, profuse free cocci among cornified type epithelial cells, absence of PMNLs, and vaginal Lactobacilli were detected in 43 of 94 (45.74%). The observation of free cocci which resembled a nebulous appearance was detected first in this study. These four cytologic criteria strongly suggested Bv(+) cases (n = 43). Although clue cells were seen in 51 of 94 (54.25%) vaginal smears, due to the presence of abundant PMNLs, metaplastic cells, vaginal Lactobacilli, and some infectious agents, mainly Trichomonas vaginalis and yeasts, they were considered bacterial vaginosis negative [Bv(-)]. It was postulated that 51 vaginal smears might be aerobic vaginitis. In conclusion, if vaginal smears contain profuse PMNLs, some infectious agents, and metaplastic cells, and even clue cells have been observed they are not accepted as Bv(+) cases.