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

Non-Hormonal Contraception

While hormonal contraceptives are efficacious and available in several forms for women, perception of safety and concern over side effects are a deterrent for many. Existing non-hormonal contraceptives include permanent sterilization, copper intrauterine devices (IUDs), chemical/physical barriers such as spermicides and condoms, as well as traditional family planning methods including withdrawal and the rhythm method. Individuals who wish to retain their fertility in the future can achieve highest adherence and efficacy with long-acting, reversible contraceptives (LARCs), though there is only one, the copper IUD, that is non-hormonal. As rates of unintended pregnancies remain high with existing contraceptive options, it is becoming increasingly attractive to develop novel pregnancy prevention methods for both women and men. Non-hormonal contraceptives can target a variety of critical reproductive processes discussed here. This review focuses on identified non-hormonal contraceptive targets and subsequent drug candidates in development.

Antiviral activities of four marine sulfated glycans against adenovirus and human cytomegalovirus

Broad-spectrum antivirals are more needed than ever to provide treatment options for novel emerging viruses and for viruses that lack therapeutic options or have developed resistance. A large number of viruses rely on charge-dependent non-specific interactions with heparan sulfate (HS), a highly sulfated glycosaminoglycan (GAG), for attachment to cell surfaces to initiate cell entry. As such, inhibitors targeting virion-HS interactions have potential to have broad-spectrum antiviral activity. Previous research has explored organic and inorganic small molecules, peptides, and GAG mimetics to disrupt virion-HS interactions. Here we report antiviral activities against both enveloped (the herpesvirus human cytomegalovirus) and non-enveloped (adenovirus) DNA viruses for four defined marine sulfated glycans: a sulfated galactan from the red alga Botryocladia occidentalis; a sulfated fucan from the sea urchin Lytechinus variegatus, and a sulfated fucan and a fucosylated chondroitin sulfate from the sea cucumber Isostichopus badionotus. As evidenced by gene expression, time of addition, and treatment/removal assays, all four novel glycans inhibited viral attachment and entry, most likely through interactions with virions. The sulfated fucans, which both lack anticoagulant activity, had similar antiviral profiles, suggesting that their activities are not only due to sulfation content or negative charge density but also due to other physicochemical factors such as the potential conformational shapes of these carbohydrates in solution and upon interaction with virion proteins. The structural and chemical properties of these marine sulfated glycans provide unique opportunities to explore relationships between glycan structure and their antiviral activities.

Recent advances on anti-HIV vaginal delivery systems development

A review of the recent outcomes regarding technologies to prevent vaginal transmission of HIV, mainly by using antiretroviral (ARV) drugs formulated as microbicides. An introduction about the HIV transmission mechanisms by the vaginal route is included, together with the recent challenges faced for development of successful microbicide products. The outcomes of clinical evaluations are mentioned, and the different formulation strategies studied to-date, with the requirements, advantages, disadvantages and limitations of each dosage-form type, are presented. Finally, the recent attempts to apply various types of nanotechnologies in order to develop advanced microbicide-products and overcome existing limitations, are discussed.

Application and removal of polyanionic microbicide compounds enhances subsequent infection by HIV-1

Background

Continued efforts are being directed toward the development of microbicides that will be used to reduce or eliminate the risk of HIV-1 sexual transmission. Unfortunately, clinical trials involving polyanion-containing microbicide formulations, including Carraguard (λ-carrageenan [LC]) and Ushercell (cellulose sulfate [CS]) demonstrated that these products were ineffective and may have, in some circumstances, increased the risk of HIV-1 infection. These findings prompted reassessments of the in vitro activities of these agents to determine whether variables that can affect agent safety and efficacy had been overlooked during preclinical testing. One such variable is product retention and loss following topical application.

Results

In the present studies involving an HIV-1-susceptible cell line and primary human immune cells, product loss was mimicked by introducing and then removing polyanionic compounds prior to HIV-1 infection. In these in vitro "washout" experiments, LC and CS significantly enhanced HIV-1 infection, despite potent antiviral activity when introduced simultaneously with the virus. The presence and magnitude of this effect were dependent on compound identity and concentration; target cell; interval between compound removal and virus challenge; and coreceptor usage. Levels of enhancement (relative to controls) were considerable, exceeding a 200% increase (CS) in P4-R5 MAGI cells and a 300% increase (LC) in human peripheral blood mononuclear cells.

Conclusions

These studies, which demonstrate significant increases in HIV-1 infection subsequent to application and removal of LC and CS, support plausible explanations for the failures of microbicides formulated from these compounds. Detailed studies are now underway to determine the mechanism responsible for this enhancement effect and to assess the potential contribution of this effect to the clinical failures of these agents.

The rise and fall of polyanionic inhibitors of the human immunodeficiency virus type 1

Infection by the human immunodeficiency virus type 1 (HIV-1) is an ordered, multistep process involving binding and entry, reverse transcription, integration, viral gene transcription, translation, processing, and finally assembly. Numerous therapeutic and preventive compounds, which are currently available for clinical use or are under preclinical and clinical development, act on at least one of these steps. Polyanionic HIV-1 inhibitors comprise a family of compounds that are generally considered entry inhibitors. The main mechanism of anti-HIV-1 activity associated with these compounds involves electrostatic interactions with HIV-1 glycoprotein 120 that ultimately prevent binding of the virus to target cells. A number of these compounds have been considered for systemic use and for use as microbicides, which are products designed to prevent sexual HIV-1 transmission. These compounds have been studied extensively using in vitro assays of activity, cytotoxicity, and mechanism of action, ex vivo models of HIV-1 transmission, and animal models of in vivo efficacy and toxicity. Three of these polyanionic compounds - cellulose sulfate, carrageenan, and PRO 2000 - were advanced into clinical trials of microbicide safety and efficacy. Although phase I and phase II clinical trials showed these compounds to be safe and well tolerated, none of the phase III trials provided any evidence that these compounds were effective against heterosexual HIV-1 transmission. Furthermore, clinical and in vitro results suggest enhancement of HIV-1 infection in the presence of polyanionic compounds. We discuss the preclinical development of polyanionic HIV-1 inhibitors, the clinical trials of polyanionic compounds used systemically and as topical vaginal microbicides, and the prospects for the future development of these compounds as inhibitors of HIV-1 infection.

Clinical evaluation of microbicide formulations

The clinical evaluation of microbicide formulations presents variable and interacting challenges. Specific domains of acceptability, pharmacokinetics, and toxicity interact with each other to potentially inhibit or enhance a microbicide's efficacy. Each of these is further influenced by application and use parameters in the relative presence (or absence) of vaginal and/or seminal fluids, ultimately impacting effectiveness. Historically, acceptability of formulation and use parameters, and their concomitant behavioral influences, have been considered separately from pharmacokinetics and toxicity. While independent evaluation of these elements is necessary in some respects, we must acknowledge that this approach is not sufficient for the successful development of microbicides. Each needs to be considered in an integrated clinical evaluation strategy. This article presents the rationale for such an approach. This article forms part of a special supplement covering two presentations on clinical evaluation of microbicides from the symposium on "Recent Trends in Microbicide Formulations" held on 25 and 26 January 2010, Arlington, VA.

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.

Safety, tolerability, and pharmacokinetics of SPL7013 gel (VivaGel): a dose ranging, phase I study

OBJECTIVES

To evaluate safety, tolerability and systemic pharmacokinetics of escalating doses of SPL7013 Gel in healthy women.

DESIGN

: Randomized, double-blind, placebo-controlled dose-escalation trial.

METHODS

Thirty-seven healthy women were randomized to receive 3.5 g of 0.5% (N = 8), 1% (N = 8), or 3% (N = 9) SPL7013 Gel or placebo gel (N = 12), applied vaginally once daily for 7 consecutive days. Genital toxicity was determined by interview, physical examination, assessment of vaginal microflora and colposcopy. Systemic toxicity was determined by nongenital adverse events (AEs) and laboratory assessments. Plasma was collected for pharmacokinetic analysis.

RESULTS

Genital AEs considered potentially product-related were all mild and reported by 5 (20%) women receiving SPL7013 Gel and 2 (17%) women receiving placebo gel. The most common were abdominal pain or discomfort, with no reports of vaginal burning or malodour, or genital-tract pain. There were no clinically significant colposcopic findings, including of genital inflammation or epithelial disruption. Lower concentrations of normal lactobacillary flora occurred during SPL7013 Gel and placebo gel use, with a decrease in anaerobes in the SPL7013 Gel groups. There were no reported cases of bacterial vaginosis, and lactobacilli returned to predose levels in most women after treatment. All nongenital AEs were of mild or moderate severity, expect for a severe tension headache in a woman receiving placebo. There was no absorption of SPL7013 into the systemic circulation.

CONCLUSIONS

SPL7013 Gel applied vaginally once daily for 7 days at concentrations of 0.5% to 3% was safe and well tolerated in healthy, sexually abstinent women, with no evidence of systemic toxicity or absorption.

Development of topical microbicides to prevent the sexual transmission of HIV

Women comprise almost 50% of the population of people living with HIV and the majority of these women contracted the virus through sexual transmission in monogamous relationships in the developing world. In these environments, where women are not empowered to protect themselves through the negotiation of condom use, effective means of preventing HIV transmission are urgently needed. In the absence of an approved and effective vaccine, microbicides have become the strategy of choice to provide women with the ability to prevent HIV transmission from their infected partners. Topical microbicides are agents specifically developed and formulated for use in either the vaginal or rectal environment that prevent infection by sexually transmitted infectious organisms, including pathogenic viruses, bacteria and fungi. Although a microbicidal product will have many of the same properties as other anti-infective agents and would be similarly developed through human clinical trials, microbicide development bears its own challenges related to formulation and delivery and the unique environment in which the product must act, as well as the requirement to develop a product that is acceptable to the user. Herein, perspectives based on preclinical and clinical microbicide development experience, which have led to an evolving microbicide development algorithm, will be discussed. This article forms part of a special issue of Antiviral Research marking the 25th anniversary of anti-retroviral drug discovery and development, Vol 85, issue 1, 2010.

The safety of candidate vaginal microbicides since nonoxynol-9: a systematic review of published studies

OBJECTIVE

To gain a greater understanding of published safety data for candidate vaginal microbicides.

DESIGN

A systematic review of human safety trials of candidate vaginal microbicides - agents designed to protect women against HIV and other sexually transmitted infections.

METHODS

Trials were published in peer-reviewed journals, and publication cut-off was August week 4, 2008. Trials of nonoxynol-9 were excluded, as were trials without a control group, trials that enrolled only male participants or reported on the investigation of a product for the treatment of a genital infection.

RESULTS

Twenty-one trials of 11 products, involving 1465 women, satisfied review criteria. Most trials reported on genital epithelial findings and urogenital symptoms and a number reported a range of other local and systemic toxicity endpoints. Trials were generally of short duration (2 weeks or less) with small sample sizes. There were few findings of significant difference between women in active and control arms. Among the products assessed in more than one study, there were significantly more genital findings with intact epithelium in recipients of PRO2000 [relative risk (RR) 1.68, 95% confidence interval (CI) 1.08-2.60] and a lower incidence of bacterial vaginosis in dextrin sulphate recipients (RR 0.61, 95% CI 0.42-0.88). CIs were generally very wide, and most studies were unable to exclude differences of a substantial magnitude between treated and control women.

CONCLUSION

Larger and longer safety studies are necessary to detect clinically important toxicities, including those that indicate a potential increase in HIV risk, and provide assurance that agents are ready for large-scale effectiveness trials.

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 drug delivery systems for HIV prevention

Microbicides have become a principal focus for HIV prevention strategies. The successful design of drug delivery systems for vaginal microbicide drug candidates brings with it a multitude of challenges. It is imperative that the chemical and physical characteristics of the drug candidate and its mechanism of action be clearly understood and considered to successfully deliver and target drug candidates efficiently. In addition, an understanding of the dynamic nature of the vaginal environment, the tissue and innate barriers present, as well as patient preferences are critical considerations in the design of effective microbicide products. Although the majority of drug candidates clinically evaluated to date have been delivered using conventional semisolid aqueous-based gel dosage forms, drug delivery system design has recently been extended to include advanced delivery systems such as vaginal rings, quick-dissolve films, and tablets. Ultimately, it may be necessary to develop multiple dosage platforms for a single active agent to provide users with options that can be used within the constraints of their social environment, personal choice, and environmental conditions.

Vaginal microbicide and diaphragm use for sexually transmitted infection prevention: a randomized acceptability and feasibility study among high-risk women in Madagascar

BACKGROUND

In preparation for a randomized controlled trial (RCT), we conducted a pilot RCT of the acceptability and feasibility of diaphragms and candidate vaginal microbicide for sexually transmitted infection prevention among high-risk women in Madagascar.

METHODS

Participants were randomized to four arms: (1) diaphragm (worn continuously) with Acidform applied in the dome; (2) diaphragm (worn continuously) with placebo gel hydroxyethylcellulose (HEC) in the dome; (3) HEC applied intravaginally before sex; (4) Acidform applied intravaginally before sex. All women were given condoms. Participants were followed weekly for 4 weeks. We fit unadjusted negative binomial regression models with robust variance estimators to generate the proportion of sex acts with casual partners where condoms and experimental study products were used.

RESULTS

Retention was 98% among 192 participants. Experimental product use with casual partners was high, reported in 85%, 91%, 74%, and 81% of sex acts for women in the Acidform-diaphragm, HEC-diaphragm, HEC-alone, and Acidform-alone arms, respectively. However, the proportion reporting product use during 100% of acts with casual partners over the full follow-up period was much lower: 28% to 29% in the gel-diaphragm arms and 6% to 10% in gel-alone arms. Women used condoms in 62% to 67% of sex acts with casual partners, depending on the randomization arm. Participants found diaphragms easy to insert (97%) and remove (96%). Acidform users (with or without the diaphragm) reported more genitourinary symptoms than HEC users (14% vs. 5% of visits).

CONCLUSIONS

A sexually transmitted infection prevention RCT of candidate microbicide with and without the diaphragm appears acceptable and feasible in this population.

Women's anal sex practices: implications for formulation and promotion of a rectal microbicide

To gain insight into practices that may inform formulation and use of rectal microbicides, in-depth interviews were conducted with an ethnically diverse sample of 28 women who engage in anal intercourse. Microbicides are compounds under development to decrease sexually transmitted infections. Most women practiced anal sex in conjunction with vaginal intercourse. Anal sex typically was not preplanned, and few women reported preparation. Condom use was rare. Most women relied on saliva, vaginal fluids, prelubricated condoms, or used no lubrication at last intercourse. Women were uncertain about the amount of lubricant used during sex, with typical estimates of 1 to 2 teaspoons. This may prove challenging to the formulation and promotion of rectal microbicides, as substantially higher amounts may be required. Additional challenges include infrequent use of packaged lubricants, and typical male lubricant application, which may make women's control of rectal microbicides more difficult. Women overwhelmingly expressed interest in rectal microbicides.

Phase I safety trial of two vaginal microbicide gels (Acidform or BufferGel) used with a diaphragm compared to KY jelly used with a diaphragm

OBJECTIVES

To assess the safety and acceptability of 2 vaginal microbicide gels (Acidform and BufferGel) used with a diaphragm compared to KY Jelly used with a diaphragm among low-risk, sexually abstinent women.

STUDY DESIGN

Eighty-one women enrolled in a randomized, masked, phase I safety study using a diaphragm with Acidform, BufferGel, or KY Jelly for 6 to 10 hours nightly for 14 nights. Physical examination, colposcopy, and lab studies were performed after 1 and 2 weeks of use. Diaries and questionnaires were used to assess user acceptability.

RESULTS

Sixty-nine participants (85%) completed the study. Safety and acceptability appeared similar among the 3 study groups and no serious adverse events related to the study products were reported. Adverse events were mild and anticipated.

CONCLUSIONS

Acidform and BufferGel compared to KY Jelly, when used with diaphragm daily for 14 days, appeared to be safe and acceptable in a small study of low-risk abstinent women.

Willingness to use microbicides is affected by the importance of product characteristics, use parameters, and protective properties

BACKGROUND

Along with efficacy, a microbicide's acceptability will be integral to its impact on the pandemic. Understanding Product Characteristics that users find most acceptable and determining who will use which type of product are key to optimizing use effectiveness.

OBJECTIVES

To evaluate psychometrically the Important Microbicide Characteristics (IMC) instrument and examine its relationship to willingness to use microbicides.

RESULTS

Exploratory and confirmatory factor analyses revealed 2 IMC subscales (Cronbach's coefficient alpha: Product Characteristics subscale (alpha = 0.84) and Protective Properties subscale (alpha = 0.89)). Significant differences on Product Characteristics subscale scores were found for history of douching (P = 0.002) and employment status (P = 0.001). Whether a woman used a method to prevent pregnancy or sexually transmitted disease (STD) in the last 3 months (P < 0.001) and whether she used a condom during the last vaginal sex episode (P < 0.001) were significantly related to her rating of the importance of microbicides being contraceptive. Product Characteristics (r = 0.21) and Protective Properties (r = 0.27) subscale scores and whether a microbicide had contraceptive properties (r = 0.24) were all significantly associated (P < 0.001) with willingness to use microbicides.

CONCLUSIONS

Formulation and use characteristics and product function(s) affect willingness to use microbicides and should continue to be addressed in product development. The IMC instrument serves as a template for future studies of candidate microbicides.

Fourteen-day safety and acceptability study of the universal placebo gel

OBJECTIVE

This study evaluated the effect of the so-called universal placebo compared to the polystyrene sulfonate (PSS) placebo on genital irritation.

DESIGN

A single-center, Phase I, randomized, closed-label study was performed to evaluate the genital irritation of microbicide placebo gels. Thirty healthy, sexually abstinent women were randomly assigned to apply 3.5 mL of either the universal placebo or the PSS placebo gel intravaginally twice daily for 14 days.

METHODS

Genital irritation was assessed by signs as seen on pelvic examination and colposcopy and reports of symptoms. Vaginal health was assessed by wet mounts, Gram stains for Nugent score and polymorphonuclear leukocytes, and semiquantitative vaginal cultures. Acceptability was assessed as reported on the follow-up questionnaire.

RESULTS

The universal placebo was less irritating than the PSS placebo with a lower proportion of women experiencing signs and/or symptoms of genital irritation throughout follow-up (36% compared to 80%, p=.0253). The universal placebo was associated with few and mild genital symptoms, few and minor colposcopic findings and good vaginal health with no clinically significant changes in genital flora. Most participants found the feel of the universal placebo gel neutral or pleasant, and all participants found it odorless.

CONCLUSIONS

The universal placebo appeared safe and acceptable when used twice daily for 14 days. The strategy of creating a de novo inert universal placebo is a successful approach. The universal placebo is appropriate for use as a placebo gel in HIV prevention trials with microbicide candidates.

Gels as vaginal drug delivery systems

The vagina has been used as a mucosal drug delivery route for a long time. Its single characteristics can be either limitative or advantageous when drug delivery is considered. Gels are semi-solid, three-dimensional, polymeric matrices comprising small amounts of solid, dispersed in relatively large amounts of liquid, yet possessing more solid-like character. These systems have been used and are receiving a great deal of interest as vaginal drug delivery systems. Gels are versatile and have been used as delivery systems for microbicides, contraceptives, labour inducers, and other substances. Although somewhat neglected in clinical studies, pharmaceutical characterization of vaginal gels is an important step in order to optimize safety, efficacy and acceptability. Indeed, the simple formulation of a gel can lead to different performances of systems containing the same amount of active substances. Therefore, this paper discusses and summarizes current use and research of vaginal drug delivery systems based in gels.

Effects of long-term use of nonoxynol-9 on vaginal flora

OBJECTIVE

Products containing nonoxynol-9 have been used as spermicidal contraceptives for many years, but limited data have been published describing the long-term effects of nonoxynol-9 use on the vaginal microbial ecosystem. This longitudinal study was conducted to examine the effects of nonoxynol-9 on the vaginal ecology.

METHODS

Vaginal swabs were obtained from 235 women enrolled in a randomized clinical trial before initiation of use of 1 of 5 different formulations of nonoxynol-9 for contraception, and up to 3 more samples were gathered over 7 months of use. The swab samples were evaluated in a single laboratory. The prevalence of several constituents of the normal vaginal flora was evaluated. The associations between nonoxynol-9 dosage, formulation, average product use per week, and number of sex acts per week were calculated.

RESULTS

The changes in prevalence of vaginal microbes after nonoxynol-9 use were minimal for each of the different nonoxynol-9 formulations. However, when both nonoxynol-9 concentration and number of product uses are taken into account, nonoxynol-9 did have dose-dependant effects on the increased prevalence of anaerobic gram-negative rods (odds ratio [OR] 2.4, 95% confidence interval [CI] 1.1-5.3), H2O2-negative lactobacilli (OR 2.0, 95% CI 1.0-4.1), and bacterial vaginosis (OR 2.3, 95% CI 1.1-4.7).

CONCLUSION

This study demonstrated that most nonoxynol-9 users experienced minimal disruptions in their vaginal ecology. There were no differences between the different formulations evaluated with respect to changes in vaginal microflora. However, independent of the nonoxynol-9 formulation, there was a dose-dependent effect with increased exposure to nonoxynol-9 on the risk of bacterial vaginosis and its associated flora.

LEVEL OF EVIDENCE

II-2.