Cellulose sulfate: tolerance and acceptability of penile application

Gellan gum macrobeads loaded with naproxen: The impact of various naturally derived polymers on pH-dependent behavior

Aims

After oral administration, naproxen generates several side-effects related to stomach malfunction. Undoubtedly, the enteric dosage forms with naproxen can be considered as safer. Moreover, since it has been evidenced that development and growth of colorectal cancer is related to the presence of cyclooxygenase, naproxen is investigated in terms of the tumor prevention. The aim of the present work was to formulate and evaluate the properties of novel naproxen-loaded macrobeads, made on the basis of low-acyl gellan gum and its blends with carrageenans, guar gum, cellulose sulfate, and dextran sulfates.

Method

Seven formulations were prepared by ionotropic gelation. The morphology of the dried beads was evaluated by scanning electron microscopy. The next step focused on Raman spectroscopy and thermal analysis of naproxen, polymers, and the beads. Next, the swelling behavior was examined in three acceptor fluids at pH = 1.2; 4.5, and 7.4. The beads were evaluated regarding naproxen content and encapsulation efficiency. The last stage of the work concerned the drug release studies.

Results

Addition of any other polysaccharide than gellan resulted in flattening of the beads upon drying. Differential scanning calorimetry confirmed the crystalline form of naproxen. Raman spectra showed that no apparent interactions occurred. In the acidic environment, all the beads revealed the tendency to absorb water. The beads swelled to the greatest extent at pH = 4.5. Naproxen was released from the beads at a varied rate. At pH = 7.4, the most prolonged release was observed for the beads containing carrageenans.

Conclusions

We have proved that blending of gellan with various polysaccharides can change the pH-dependent properties of the beads loaded with naproxen. We believe that the information enclosed in the paper will be of particular importance regarding the development and characteristics of novel oral dosage forms based on natural polymers.

Topical microbicides and HIV prevention in the female genital tract

Worldwide, HIV disproportionately affects women who are often unable to negotiate traditional HIV preventive strategies such as condoms. In the absence of an effective vaccine or cure, chemoprophylaxis may be a valuable self-initiated alternative. Topical microbicides have been investigated as one such option. The first generation topical microbicides were non-specific, broad-spectrum antimicrobial agents, including surfactants, polyanions, and acid buffering gels, that generally exhibited contraceptive properties. After extensive clinical study, none prevented HIV infection, and their development was abandoned. Second generation topical microbicides include agents with selective mechanisms of antiviral activity. Most are currently being used for, or have previously been explored as, drugs for treatment of HIV. The most advanced of these is tenofovir 1% gel: the first topical agent shown to significantly reduce HIV infection by 39% compared to placebo. This review summarizes the evolution of topical microbicides for HIV chemoprophylaxis, highlights important concepts learned, and offers current and future considerations for this area of research.

A randomized male tolerance study of dapivirine gel following multiple topical penile exposures (MTN 012/IPM 010)

Dapivirine (DPV) is a nonnucleoside reverse transcriptase inhibitor with a favorable safety profile following vaginal application. A penile tolerance study was conducted prior to further development of DPV as a candidate vaginal microbicide. Twenty-four circumcised and 24 uncircumcised (N=48) healthy HIV-negative male participants aged 18 years or older were randomized 2:1:1 to apply DPV 0.05% gel, matched placebo gel, or universal placebo gel, respectively, to their penis once daily for 7 sequential days. The safety, acceptability, and pharmacokinetic profile of DPV 0.05% gel were assessed by the presence of Grade 2 or higher genitourinary adverse events (AEs) and systemic AEs, a behavioral questionnaire, and pharmacokinetic plasma blood draw, respectively, at the final clinic visit (FCV). There were no Grade 2 genitourinary AEs in 47 participants completing the FCV. One participant in the DPV arm failed to attend the FCV. There were 13 AEs reported; all were Grade 1 except one Grade 2 corneal laceration unrelated to study product. Participants liked the gel to a moderate extent, yet 72% reported they would be "very likely" to use a gel like the one they used in the study every time they have intercourse. DPV was detectable in plasma in all 23 DPV arm study participants at the FCV. On average, the circumcised participants' DPV concentrations were 54% of those in uncircumcised participants (p=0.07). Topical seven-day penile application of DPV 0.05% gel was locally and systemically safe, was acceptable to male participants, and resulted in systemic exposure to the drug.

Toward early safety alert endpoints: exploring biomarkers suggestive of microbicide failure

Several microbicides, including nonoxynol-9 (N-9) and cellulose sulfate (CS), looked promising during early trials but failed in efficacy trials. We aimed to identify Phase I mucosal safety endpoints that might explain that failure. In a blinded, randomized, parallel trial, 60 healthy premenopausal sexually abstinent women applied Universal HEC placebo, 6% CS or 4% N-9 gel twice daily for 13½ days. Endpoints included immune biomarkers in cervicovaginal lavage (CVL) and endocervical cytobrushes, inflammatory infiltrates in vaginal biopsies, epithelial integrity by naked eye, colposcopy, and histology, CVL anti-HIV activity, vaginal microflora, pH, and adverse events. Twenty women enrolled per group. Soluble/cellular markers were similar with CS and placebo, except secretory leukocyte protease inhibitor (SLPI) levels decreased in CVL, and CD3(+) and CD45(+) cells increased in biopsies after CS use. Increases in interleukin (IL)-8, IL-1, IL-1RA, and myeloperoxidase (MPO) and decreases in SLPI were significant with N-9. CVL anti-HIV activity was significantly higher during CS use compared to N-9 or placebo. CS users tended to have a higher prevalence of intermediate Nugent score, Escherichia coli, and Enterococcus and fewer gram-negative rods. Most Nugent scores diagnostic for bacterial vaginosis were in N-9 users. All cases of histological inflammation or deep epithelial disruption occurred in N-9 users. While the surfactant N-9 showed obvious biochemical and histological signs of inflammation, more subtle changes, including depression of SLPI, tissue influx of CD45(+) and CD3(+) cells, and subclinical microflora shifts were associated with CS use and may help to explain the clinical failure of nonsurfactant microbicides.

Women's Autonomy and Informed Consent in Microbicides Clinical Trials

ACHIEVING RESPECT FOR PERSONS is problematic in settings with concepts of autonomy that differ from Western values. For international research, women's autonomy to consent to participation is an increasingly contentious issue. We present data from ancillary studies conducted in preparation for a clinical trial testing the safety and efficacy of topical microbicides, used to prevent HIV infection. These ancillary studies were conducted in seven countries, using qualitative research methods to collect data from female and male community members, and their health care professionals and community leaders. Our findings indicate that by working at the level of the community, couple and individual, researchers may be able to take steps to increase women's ability to make their own independent decisions about participating in research. This approach may, in turn, improve both the conduct and outcomes of research.

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.

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.

Disruption of tight junctions by cellulose sulfate facilitates HIV infection: model of microbicide safety

BACKGROUND

The lack of biomarkers that are predictive of safety is a critical gap in the development of microbicides. The present experiments were designed to evaluate the predictive value of in vitro models of microbicide safety.

METHODS

Changes in the epithelial barrier were evaluated by measuring transepithelial electrical resistance (TER) after exposure of human epithelial cells to candidate microbicides in a dual-chamber system. The significance of observed changes was addressed by challenging cultures with human immunodeficiency virus (HIV) and measuring the ability of virus to cross the epithelium and infect target T cells cultured in the lower chamber.

RESULTS

Exposure to nonoxynol-9 (N-9) or cellulose sulfate (CS), but not 9-[2-(phosphonomethoxy)propyl]adenine (also referred to as tenofovir) or PRO2000, resulted in a rapid and sustained reduction in TER and a marked increase in HIV infection of T cells cultured in the lower chamber. Moreover, CS triggered nuclear factor kappaB activation in peripheral blood mononuclear cells and increased HIV replication in chronically infected U1 cells.

CONCLUSIONS

Epithelial barrier disruption and enhanced viral replication may have contributed to the increased risk of HIV acquisition observed in phase 3 trials of N-9 and CS. Expansion of in vitro safety testing to include these models would provide a more stringent preclinical assessment of microbicide safety and may prove to be more predictive of clinical outcomes.

Safety evaluation of 1% tenofovir gel in healthy men

This study was conducted to determine the safety of tenofovir (TFV) gel, a potential microbicide, following seven consecutive daily penile applications. Eighteen circumcised and 18 uncircumcised healthy men were randomly assigned to TFV gel versus K-Y Jelly in a 2:1 ratio within circumcision group. TFV gel or K-Y Jelly was applied onto the penis at bedtime and washed off 6-10 hours later. Safety was assessed by reported symptoms, findings and laboratory tests. Three of 24 (13%) men in the TFV group reported mild genital symptoms compared with two of 11 (18%) men in the K-Y group. Few mild genital findings were observed and no significant systemic toxicities were reported or observed. TFV gel applied to the penis for seven days was well tolerated locally and systemically and it is unlikely that male partners exposed to small amounts of TFV gel will experience significant genital or systemic toxicity.

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.

Effectiveness of cellulose sulfate vaginal gel for the prevention of HIV infection: results of a Phase III trial in Nigeria

Background

This trial evaluated the safety and effectiveness of 6% cellulose sulfate vaginal gel in preventing male-to-female vaginal transmission of HIV, gonorrhea and chlamydial infection.

Methods

This Phase III, double-blind, randomized, placebo-controlled trial was conducted between November 2004 and March 2007 in Lagos and Port Harcourt, Nigeria. We enrolled 1644 HIV-antibody negative women at high risk of HIV acquisition. Study participants were randomized 1∶1 to cellulose sulfate or placebo and asked to use gel plus a condom for each act of vaginal intercourse over one year of follow-up. The participants were evaluated monthly for HIV, gonorrhea and chlamydial infection, and for adverse events.

Results

The trial was stopped prematurely after the data safety monitoring board of a parallel trial concluded that cellulose sulfate might be increasing the risk of HIV. In contrast, we observed fewer infections in the active arm (10) than on placebo (13), a difference that was nonetheless not statistically significant (HR = 0.8, 95% CI 0.3–1.8; p = 0.56). Rates of gonorrhea and chlamydial infection were lower in the CS group but the difference was likewise not statistically significant (HR = 0.8, 95% CI 0.5–1.1; p = 0.19 for the combined STI outcome). Rates of adverse events were similar across study arms. No serious adverse events related to cellulose sulfate use were reported.

Conclusions

Cellulose sulfate gel appeared to be safe in the evaluated study population but we found insufficient evidence that it prevented male-to-female vaginal transmission of HIV, gonorrhea or chlamydial infection. The early closure of the trial compromised the ability to draw definitive conclusions about the effectiveness of cellulose sulfate against HIV.

Trial Registration

ClinicalTrials.gov NCT00120770

Lack of effectiveness of cellulose sulfate gel for the prevention of vaginal HIV transmission

BACKGROUND

Women make up more than 50% of adults living with human immunodeficiency virus (HIV) infection or the acquired immunodeficiency syndrome (AIDS) in sub-Saharan Africa. Thus, female-initiated HIV prevention methods are urgently needed.

METHODS

We performed a randomized, double-blind, placebo-controlled trial of cellulose sulfate, an HIV-entry inhibitor formulated as a vaginal gel, involving women at high risk for HIV infection at three African and two Indian sites. The primary end point was newly acquired infection with HIV type 1 or 2. The secondary end point was newly acquired gonococcal or chlamydial infection. The primary analysis was based on a log-rank test of no difference in the distribution of time to HIV infection, stratified according to site.

RESULTS

A total of 1398 women were enrolled and randomly assigned to receive cellulose sulfate gel (706 participants) or placebo (692 participants) and had follow-up HIV test data. There were 41 newly acquired HIV infections, 25 in the cellulose sulfate group and 16 in the placebo group, with an estimated hazard ratio of infection for the cellulose sulfate group of 1.61 (P=0.13). This result, which is not significant, is in contrast to the interim finding that led to the trial being stopped prematurely (hazard ratio, 2.02 [corrected]; P=0.05 [corrected]) and the suggestive result of a preplanned secondary (adherence-based) analysis (hazard ratio, 2.02; P=0.05). No significant effect of cellulose sulfate as compared with placebo was found on the risk of gonorrheal infection (hazard ratio, 1.10; 95% confidence interval [CI], 0.74 to 1.62) or chlamydial infection (hazard ratio, 0.71; 95% CI, 0.47 to 1.08).

CONCLUSIONS

Cellulose sulfate did not prevent HIV infection and may have increased the risk of HIV acquisition. (ClinicalTrials.gov number, NCT00153777; and Current Controlled Trials number, ISRCTN95638385.)

Acceptability of tenofovir gel as a vaginal microbicide by US male participants in a Phase I clinical trial (HPTN 050)

We studied the acceptability of tenofovir gel among HIV-infected and uninfected men who were exposed to it during vaginal intercourse. The gel was found to be highly acceptable to most men, the large majority indicating they would probably use it in the future if they were concerned about HIV and the product were available. Men liked the gel's transparency and odorless qualities, although reactions to its viscosity were more varied. Men acknowledged women's rights to self-determination concerning HIV-prevention, yet considered that women's covert use of the product was more acceptable in the context of 'one-night-stands' than in stable relationships, for which dialogue on protection measures was preferred. Restrictions to couples' habitual sexual repertoire and the protocol requirement to use condoms resulted in complaints. Microbicide trials that do not require condom use from men who don't typically use them may provide a more accurate assessment of acceptability. Consistent microbicide use may be contingent on its ease of incorporation into typical sexual practices, type of sexual partnership and contextual issues.

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.

Safety and acceptability of 6% cellulose sulfate vaginal gel applied four times per day for 14 days

BACKGROUND

Six percent cellulose sulfate (CS) is a vaginal gel that has been in development as a microbicide.

STUDY DESIGN

This was a single-center, multi-dose, Phase I, placebo-controlled, randomized, fully masked study conducted in Yaoundé, Cameroon, and involving sexually active women at low risk for sexually transmitted infections (STIs).

METHODS

The study assessed the effect of CS and K-Y Jelly applied vaginally four times per day, for 14 consecutive days, on genital epithelial disruption, candidiasis and bacterial vaginosis (BV). Acceptability of the products was also assessed. Twenty-seven women were enrolled in each treatment group.

RESULTS

Two (7.4%) of the women in each group developed genital epithelial disruption. One (3.7%) of the women in each group developed candidiasis, and one (3.7%) of the K-Y users developed BV. One (3.7%) of the CS users said she would not buy her product for pregnancy prevention but would for STI prevention. All the remaining women indicated they would buy their product for both indications.

CONCLUSION

The results suggest that the safety and acceptability of 6% CS gel are comparable to that of K-Y Jelly.

Safety and acceptability of cellulose sulfate as a vaginal microbicide in HIV-infected women

OBJECTIVES

Few studies of topical microbicides have assessed their safety in HIV-infected women. We conducted this study to evaluate the safety and acceptability of 6% cellulose sulfate (CS) gel as a vaginal microbicide in sexually abstinent and active HIV-infected women.

METHODS

Fifty-nine HIV-infected women were enrolled in a randomized double-blind placebo-controlled study comparing 6% CS to placebo gel used for 14 days. Sexually abstinent women applied gel once or twice daily and sexually active women used gel once daily.

RESULTS

CS gel was safe with no reported severe or life-threatening adverse events (AE). Thirty-nine (66%) of the participants experienced urogenital AE judged as probably or possibly related to gel. The majority (51%) of these participants reported only mild events. Fewer women (62%) who used CS experienced urogenital AE than those assigned to placebo gel (70%) (P = 0.59). Eleven (19%) women experienced intermenstrual bleeding judged to be probably or possibly related to gel use (four in the CS and seven in the placebo gel group). There was no increase in AE by frequency of gel use or sexual activity with the exception of abdominal/pelvic pain which was noted more frequently with twice daily use among sexually abstinent women. Women and men found the gel highly acceptable.

CONCLUSIONS

This Phase I study demonstrated that CS vaginal gel was safe, well tolerated and acceptable by HIV-infected women and their male partners. Thus, further development of CS is warranted as a potential method to prevent HIV transmission and acquisition.

Fourteen-day safety and acceptability study of 6% cellulose sulfate gel: a randomized double-blind Phase I safety study

BACKGROUND

Topical microbicides against the human immunodeficiency virus (HIV) 1 that are nonirritating to the female genital epithelium are urgently needed to slow the heterosexual spread of HIV infection. Products that are also effective contraceptives provide additional benefits. Cellulose sulfate (CS) is a noncytotoxic antifertility agent that exhibits in vitro antimicrobial activity against sexually transmitted pathogens, including HIV.

METHODS

We performed a multicenter, Phase I, placebo-controlled, randomized study to evaluate the genital toxicity of CS. Two cohorts of healthy women used 3.5 ml of 6% CS gel or 3.5 ml of K-Y Jelly, vaginally, bid, for 14 days. The first cohort was sexually abstinent, and the second cohort was sexually active.

RESULTS

CS was associated with only a slightly higher odds ratio (OR) of symptoms of minor urogenital irritation compared to the inactive lubricant K-Y Jelly (OR=2.02, 95% confidence interval=0.90-4.53). In addition, there were minor shifts in some genital flora, but there was no evidence of greater inflammation as evidenced by few colposcopic findings, decreased influx of polymorphonuclear cells and minimal changes in proinflammatory cytokines. Moreover, both products appeared acceptable to most women. Product leakage was identified as more of a problem in sexually abstinent women, but less so in women using the product for sexual intercourse, as would be the case in actual practice.

CONCLUSION

CS was safe for twice-daily use for 14 days. CS is appropriate for future studies in effectiveness trials.

Prioritizing prevention of HIV and sexually transmitted infections: first-generation vaginal microbicides

PURPOSE OF REVIEW

As the HIV/AIDS pandemic continues unabated, novel control measures for the spread of HIV and other sexually transmitted infections are urgently needed. Topical microbicides are designed to prevent transmission of sexually transmitted infections when applied vaginally. The microbicides discussed in this review may provide a new opportunity for decreasing the spread of HIV and other sexually transmitted infections.

RECENT FINDINGS

Epidemiological studies suggest a synergistic relationship between HIV and sexually transmitted infections, particularly between HIV and genital herpes infection. Compounds have been developed to block transmission of HIV-1 and herpes simplex virus, as well as Neisseria gonorrhoea and Chlamydia trachomatis. Several of these compounds have advanced to clinical trials as candidate microbicides. Candidate compounds fall into the following categories: detergents or surfactants that inactivate viral particles, anionic polymers that block attachment of virus to target cells, vaginal acid-buffering agents that maintain a protective vaginal pH, and antiretroviral drugs specific for HIV. Evaluation of the safety of topical microbicides remains problematic. Clinical experiences indicate that current models to assess safety in vitro and in vivo may be insufficient to assess the safety of vaginal microbicides. A critical direction of future studies is to identify which assay(s) provide surrogate laboratory markers of safety that correlate with clinical outcomes.

SUMMARY

The spread of HIV, and its increasing burden of disease in women, necessitates the development of novel prophylactic strategies. Topical microbicides offer women an empowering preventative option but require vigorous testing for safety and effectiveness.

Male tolerance of ACIDFORM gel

BACKGROUND

ACIDFORM gel is being studied as a vaginal contraceptive and microbicide. This study was conducted to make certain that males will not be subjected to an unacceptable risk of penile irritation as a result of exposure to the product in future studies.

METHODS

This was a randomized, double-masked, single-center Phase I study in circumcised and uncircumcised men to assess penile irritation, safety and acceptability of seven consecutive doses of ACIDFORM gel compared with K-Y Jelly Personal Lubricant. Each participant was instructed to apply 2 mL of the study product to his penis at bedtime, to wash it off 6-10 h later and to record any symptoms on a diary card. At the follow-up visit, a genital examination was performed and participants were asked about adverse events (AEs) and completed an acceptability questionnaire.

RESULTS

Of the 36 men enrolled, 2 out of 24 (8.3%) ACIDFORM gel users and 5 out of 12 (41.7%) K-Y Jelly users reported genital symptoms. Genital examination findings were observed in 2 out of 24 (8.3%) ACIDFORM gel users and in 1 out of 12 (8.3%) K-Y Jelly users. All product-related AEs were considered mild except for two in the K-Y Jelly group. Both products were acceptable.

CONCLUSION

ACIDFORM gel applied to the penis for seven consecutive days appears to be at least as safe and well-tolerated as the marketed lubricant K-Y Jelly among healthy low-risk men.

Expanded Phase I safety and acceptability study of 6% cellulose sulfate vaginal gel

BACKGROUND

An expanded Phase I trial was performed to assess the safety and acceptability of 6% cellulose sulfate gel (CS) in comparison with K-Y Jelly.

METHODS

Sexually abstinent (cohort I) and sexually active (cohort II) women in India, Nigeria and Uganda applied 3.5 ml of either 6% CS gel or K-Y Jelly for seven consecutive days. Safety was assessed by symptoms and signs (including colposcopy) of genital irritation, review of adverse events, and by changes in vaginal health as assessed by microscopy.

RESULTS

One hundred and eighty women (90 on CS and 90 on K-Y Jelly) were enrolled. Baseline characteristics of women in both gel groups were similar. In cohort I, six (14%) women on CS and 12 (27%) on K-Y Jelly reported genital symptoms, two (in K-Y Jelly group) of whom withdrew from the study. New colposcopy findings or findings showing deterioration were detected in four (9%) women on CS and nine (21%) women on K-Y Jelly in cohort I. Two women on CS and three on K-Y Jelly in cohort II reported genital symptoms. Five women (11%) in each gel group in cohort II had new colposcopy findings or findings showing deterioration. The differences between the gel groups were not statistically significant. The majority of women had no problem with their assigned product.

CONCLUSION

A vaginal application of 6% cellulose sulfate twice daily for seven consecutive days is as safe and well tolerated as a similar regimen of K-Y Jelly. Further development of 6% CS for prevention of HIV and pregnancy is recommended.

Male tolerance study of 1% C31G

BACKGROUND

C31G is being studied as a vaginal contraceptive and microbicide. This study was conducted to ensure that male partners of the women in future trials of C31G will not be subjected to an undue risk of penile irritation.

METHODS

This was a randomized, double-blinded, single-center Phase I study in circumcised and uncircumcised men to assess penile irritation, safety and acceptability of seven consecutive daily doses of 1.0% C31G compared with a marketed spermicide, Extra Strength Gynol II(R) (3% nonoxynol-9) (ES Gynol II). Each participant was instructed to apply the study product to his penis at bedtime, to wash it off 6-10 h later, and to record any symptoms on a diary card. At the follow-up visit, a genital examination was performed and participants were again asked about adverse events and to complete an acceptability questionnaire.

RESULTS

Of the 36 men enrolled, 12.5% of C31G users and 16.7% of Extra Strength Gynol II users reported product-related adverse events (AEs). All product-related AEs were considered mild by the investigator, except for one in the ES Gynol II group. Both products were acceptable.

CONCLUSION

The manner in which the products were used in this study is not the route by which men will be exposed to such products in actual use, and results should be considered in this light. Based on the observations in this study, C31G appears to be at least as safe and acceptable for male penile exposure as the marketed product ES Gynol II.

Clinical microbicide research: an overview

At the end of 2003, 42 million people were HIV infected and the epidemic continues to spread, despite the availability and effectiveness of male condoms. For many women negotiating condom use is not feasible. Therefore there is an urgent need for a female controlled method for HIV prevention. This article gives an overview of the clinical research done with microbicides, chemicals with the potential to prevent an HIV infection. In the 1990s most research was done with spermicides, mainly nonoxynol-9. Since the results of the COL-1492 trial became available, new products were evaluated and some of them are now in phase III trials.

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.

Anti-HIV-1 activity of anionic polymers: a comparative study of candidate microbicides

BACKGROUND

Cellulose acetate phthalate (CAP) in soluble form blocks coreceptor binding sites on the virus envelope glycoprotein gp120 and elicits gp41 six-helix bundle formation, processes involved in virus inactivation. CAP is not soluble at pH < 5.5, normal for microbicide target sites. Therefore, the interaction between insoluble micronized CAP and HIV-1 was studied. Carbomer 974P/BufferGel; carrageenan; cellulose sulfate; dextran/dextrin sulfate, poly(napthalene sulfonate) and poly(styrene-4-sulfonate) are also being considered as anti-HIV-1 microbicides, and their antiviral properties were compared with those of CAP.

METHODS

Enzyme linked immunosorbent assays (ELISA) were used to (1) study HIV-1 IIIB and BaL binding to micronized CAP; (2) detect virus disintegration; and (3) measure gp41 six-helix bundle formation. Cells containing integrated HIV-1 LTR linked to the beta-gal gene and expressing CD4 and coreceptors CXCR4 or CCR5 were used to measure virus infectivity.

RESULTS

1) HIV-1 IIIB and BaL, respectively, effectively bound to micronized CAP. 2) The interaction between HIV-1 and micronized CAP led to: (a) gp41 six-helix bundle formation; (b) virus disintegration and shedding of envelope glycoproteins; and (c) rapid loss of infectivity. Polymers other than CAP, except Carbomer 974P, elicited gp41 six-helix bundle formation in HIV-1 IIIB but only poly(napthalene sulfonate), in addition to CAP, had this effect on HIV-1 BaL. These polymers differed with respect to their virucidal activities, the differences being more pronounced for HIV-1 BaL.

CONCLUSIONS

Micronized CAP is the only candidate topical microbicide with the capacity to remove rapidly by adsorption from physiological fluids HIV-1 of both the X4 and R5 biotypes and is likely to prevent virus contact with target cells. The interaction between micronized CAP and HIV-1 leads to rapid virus inactivation. Among other anionic polymers, cellulose sulfate, BufferGel and aryl sulfonates appear most effective in this respect.