Baseline Predictors of High Adherence to a Coitally Dependent Microbicide Gel Based on an Objective Marker of Use: Findings from the Carraguard Phase 3 Trial.

A randomized, placebo-controlled, efficacy trial of Carraguard was unable to demonstrate a reduction in women's risk of HIV infection, which may have been due, in part, to low adherence (gel used in 42 % of vaginal sex acts, on average). A secondary analysis was undertaken to understand baseline factors associated with high adherence (gel used in ≥85 % of sex acts). Women who reported ≥1 vaginal sex act, returned ≥1 opened applicator, and had ≥1 conclusive post-enrollment HIV test (N = 5990) were included. Adherence was estimated as the ratio of average weekly applicator insertions (based on a dye stain assay indicating vaginal insertion)/average weekly sex acts (by self-report). Multivariate logistic regression modeling indicated that coital frequency, site, contraception, and partner age difference had a significant impact on adherence. Women reporting >1 and ≤2 vaginal sex acts per week, on average, were half as likely to be adherent as those reporting 1 vaginal sex act per week or less [adjusted odds ratio (AOR): 0.48; 95 % CI 0.38-0.61]; women from the Western Cape had one-third the odds of being adherent compared to women from KZN (AOR: 0.31; 95 % CI 0.23-0.41); compared to women using injectable contraception, women using any other or no method were more likely to be adherent (AOR: 1.30; 95 % CI 1.04-1.63); and women who had a larger age gap from their partners were more likely to be adherent (AOR: 1.03; 95 % CI 1.01-1.05; p = 0.001). Despite low adherence, overall, 13 % of participants achieved nearly perfect adherence, indicating a potential niche for a coitally dependent microbicide. More research is needed on the impact of sexual patterns and HIV risk perception on product acceptability and adherence to improve counseling in ongoing trials and when products are eventually introduced.

Effect of sexual intercourse on the absorption of levonorgestrel after vaginal administration of 0.75 mg in Carraguard gel: a randomized, cross-over, pharmacokinetic study.

BACKGROUND: The Population Council studied a pre-coital contraceptive microbicide vaginal product containing levonorgestrel (LNG) as active component and Carraguard gel as a vehicle (Carra/LNG gel) for couples who engage in occasional unplanned intercourse. The objective of this study was to evaluate the effect of sexual intercourse after vaginal application of Carra/LNG gel on serum levels of LNG in women and to assess LNG absorption by the male partner. STUDY DESIGN: This was a randomized, cross-over, pharmacokinetic study including an abstinence arm and an arm in which couples engaged in sexual intercourse between 2 and 4 h after gel application. In each study arm, each woman received a single application of Carra/LNG gel (0.75 mg in 4 mL gel) followed by serial blood samples taken at 0, 1, 2, 4, 8, 24 and 48 h after gel application for LNG measurements. In the intercourse arm, LNG was measured in blood samples taken from the male partner before intercourse and at 4, 8 and 24 h after gel application in the female partner. RESULTS: Time concentration curves for serum LNG levels showed a mean C(max) of 7.8+/-5.5 and 8.3+/-5.7 nmol/L, a mean T(max) of 6.2+/-5.9 and 7.5+/-5.7, and comparable area under the curve for the intercourse and abstinence arm, respectively. Pharmacokinetic parameters presented large variability between subjects, but excellent reproducibility within each subject. LNG was undetectable in 10 out of 12 male partners. CONCLUSION: Sexual intercourse does not appear to interfere with vaginal absorption of LNG after application of a Carra/LNG gel. A vaginal pre-coital contraceptive gel is feasible.

Efficacy of Carraguard for prevention of HIV infection in women in South Africa: a randomised, double-blind, placebo-controlled trial.

BACKGROUND: Female-initiated HIV-prevention options, such as microbicides, are urgently needed. We assessed Carraguard, a carrageenan-based compound developed by the Population Council, for its efficacy and long-term safety in prevention of HIV infection in women. METHODS: We undertook a randomised, placebo-controlled, double-blind trial in three South African sites in sexually-active, HIV-negative women, aged 16 years and older. 6202 participants, who were randomly assigned by a block randomisation scheme to Carraguard (n=3103) or placebo (methylcellulose [n=3099]), were instructed to use one applicator of gel plus a condom during each vaginal sex act. Participants were followed up for up to 2 years. Visits every 3 months included testing for HIV presence and pregnancy, pelvic examinations, risk reduction counselling, and treatment for curable sexually transmitted infections and symptomatic vaginal infections. The primary outcome was time to HIV seroconversion. Analysis was in the efficacy population (a subset of the intention-to-treat population, excluding participants for whom efficacy could not be assessed). This study is registered with ClinicalTrials.gov, number NCT00213083. FINDINGS: For the primary outcome (time to HIV seroconversion) we analysed 3011 women in the Carraguard group and 2994 in the placebo group. HIV incidence was 3.3 per 100 woman-years (95% CI 2.8-3.9) in the Carraguard group (134 events) and 3.8 per 100 woman-years (95% CI 3.2-4.4) in the placebo group (151 events), with no significant difference in the distribution of time to seroconversion (p=0.30). The covariate-adjusted hazard ratio was 0.87 (95% CI 0.69-1.09). Rates of self-reported gel use (96.2% Carraguard, 95.9% placebo) and condom use (64.1% in both groups) at last sex acts were similar in both groups. On the basis of applicator testing, however, gel was estimated to have been used in only 42.1% of sex acts, on average (41.1% Carraguard, 43.1% placebo). 1420 (23%) women in the intention-to-treat population had adverse events (713 Carraguard, 707 placebo), and 95 (2%) women had adverse events that were related to gel use (48 Carraguard, 47 placebo). Serious adverse events occurred in 72 (2%) women in the Carraguard group and 78 (3%) in the placebo group, only one of which was considered possibly related to gel use (placebo group). INTERPRETATION: This study did not show Carraguard's efficacy in prevention of vaginal transmission of HIV. No safety concerns were recorded.

Microbicide product development.

PURPOSE OF REVIEW: The purpose of this overview is to summarize the essential parameters needed to establish a sound microbicide development strategy. RECENT FINDINGS: In recent years more comprehensive regulatory guidelines that are applicable to microbicides have been developed. Additionally, the US Food and Drug Administration have begun providing specific guidance for microbicide development. SUMMARY: Microbicide product development has been aided in recent years by new regulatory guidance that helps to establish a stepwise development strategy. Developing comprehensive profiles for three key criteria - quality, safety and efficacy - are essential for preparation of an investigational new drug application that will allow proceeding into clinical development to establish microbicide proof-of-concept.

Effect of a single vaginal administration of levonorgestrel in Carraguard gel on the ovulatory process: a potential candidate for "dual protection" emergency contraception.

OBJECTIVE: The study was conducted to evaluate the effect of Carraguard vaginal gel containing 0.75 mg of levonorgestrel (CARRA/LNG gel) administered in a single dose at different stages of follicle development over subsequent follicle rupture and hormonal levels. METHOD: Randomized, blinded, cross-over study comparing the effects of a single administration of CARRA/LNG gel or Carraguard (CARRA) gel. Twenty-four healthy women were enrolled in two centers. The gels were administered when the follicle had reached diameters of 12-14, 15-17 and > or =18 mm in eight women each. Volunteers were followed for one treatment, one washout cycle and a second treatment cycle. Follicle rupture or nonrupture was assessed by transvaginal ultrasound. Luteinizing hormone, estradiol and progesterone levels were measured daily for 5 days following treatment, and three times per week until menses. RESULTS: No follicular rupture within the 5-day period following administration was observed in 74% and 30% of the CARRA/LNG and CARRA gel treatment cycles, respectively, while ovulation was documented in 4% and 61%, respectively. The overall proportion of cycles with lack of follicular rupture or ovulatory dysfunction (follicle rupture preceded by an inadequate LH surge) was 96% for CARRA/LNG and 39% in the CARRA gel cycles. CONCLUSION: Single vaginal administration of 0.75 mg LNG in CARRA gel in the late follicular phase is effective for interfering with the ovulatory process.

Determining the feasibility of utilizing the microbicide applicator compliance assay for use in clinical trials.

INTRODUCTION: Participant's adherence to use of study product is a major concern in microbicide clinical trials, which can impact on proving product efficacy. In a previously described assay, single-use microbicide applicators exposed to the vagina were tested by spraying the applicator with trypan blue dye, resulting in vaginal mucus staining on inserted applicators. As subjects in our Phase 3 trials return applicators only at quarterly visits, often mixing inserted and not-inserted applicators together in the same bag, cross-contamination could confound results. In addition, trypan blue is carcinogenic and thus potentially hazardous to technicians spraying daily. METHODS: Applicators that were exposed to the vagina were placed in the same bag as unexposed applicators and shaken daily for up to 4 months. Validation was carried out in three clinical sites in South Africa. RESULTS: Trypan blue was replaced with FD&C Blue #1 granular food dye. Cross-contamination did not occur, nor did the length of time affect reaction to dye. In South Africa, the assay was validated with an accuracy of over 95%. CONCLUSION: Applicator assay modifications render the test safe and suitable for use in clinical trials.

Pharmacokinetic study to compare the absorption and tolerability of two doses of levonorgestrel following single vaginal administration of levonorgestrel in Carraguard gel: a new formulation for "dual protection" contraception.

OBJECTIVE: The study was conducted to assess levonorgestrel (LNG) serum levels achieved after a single administration of two different doses of Carraguard vaginal gel containing LNG (CARRA/LNG), designed for use as microbicide and contraceptive for potential dual protection. MATERIALS AND METHODS: This was a randomized double-blind pharmacokinetic study conducted in 12 subjects enrolled at two centers. Each subject received a single vaginal administration of CARRA/LNG containing either 0.75 or 1.5 mg LNG per 4 mL of gel on Days 10-12 of the menstrual cycle. LNG serum levels were measured at 0, 1, 2, 4, 8 and 12 h after administration and for the following 7 days. LH and progesterone (for a preliminary evaluation of effect on the ovarian function) as well as SHBG were measured in the daily samples. RESULTS: Serum LNG maximum concentrations (Cmax) were 14.1+/-2.1 and 11.7+/-2.7 nmol/L and Tmax was 12.0 and 6.0 h for the low and high dose, respectively, with large intersubject variability within the first 48 h. Mean levels at 96 h were 10% of Cmax. Differences in AUC between both doses were not statistically significant. SHBG levels decreased approximately 25% by Day 4 after administration. Luteal activity was observed in 3/6 and 5/6 of the subjects in the low- and high-dose group, respectively. CONCLUSION: This study demonstrates that the CARRA/LNG gel can sustain elevated serum levels of the contraceptive steroid for up to 96 h after a single application. The serum levels attained with the 0.75-mg formulation are in the range expected to perturb the ovulatory process as observed in some subjects. The lack of correlation between the administered dose and serum concentrations of the steroid may be related to a rate-limiting absorption of LNG from the vaginal mucosa. The results reported here suggest that the CARRA/LNG formulation has good potential to become a dual-protection method, possibly preventing conception and sexually transmitted infections.

Carrageenan/MIV-150 (PC-815), a combination microbicide.

OBJECTIVE: The objective of this article is to study the effect of PC-815, a novel combination microbicide containing carrageenan and the nonnucleoside reverse transcriptase inhibitor (NNRTI) MIV-150, in blocking HIV-1 and HIV-2 infections in vitro as compared with Carraguard alone. GOAL: The goal of this study was to develop a combination microbicide that is more efficacious than Carraguard against HIV-1 and HIV-2. STUDY DESIGN: The microtiter syncytial assay was used to evaluate: 1) the antiviral and virucidal activity of MIV-150 against HIV-1MN; 2) the additive effect of MIV-150 when combined with carrageenan; and 3) a possible interference of seminal fluid in the antiviral activity of these compounds. RESULTS: MIV-150 effectively inactivated free virus. Combination of MIV-150 and Carraguard demonstrated an additive antiviral effect. Seminal fluid had no effect on the antiviral activity of MIV-150 or Carraguard. The average concentration that blocks 50% of infection (EC50) for PC-815 was approximately 10 times stronger than Carraguard for the different clinical isolates used in the study. CONCLUSION: Theoretically, PC-815 is likely to be a more efficacious microbicide than Carraguard.

Lubricants containing N-9 may enhance rectal transmission of HIV and other STIs.

It has been shown that men who have sex with men actively seek lubricants that contain nonoxynol-9 (N-9) because they believe that N-9 may help to prevent infection by HIV. However, indirect evidence suggests that N-9 may actually enhance infection. Microscopic examination of rectal lavage and biopsy specimens collected at different time points following rectal application of a lubricant containing 2% N-9 showed rapid exfoliation of the rectal epithelium. Because the rectal epithelium protects target cells in the submucosa from HIV, we conclude that lubricants containing N-9 should be avoided during rectal sex.

Assay for establishing whether microbicide applicators have been exposed to the vagina.

OBJECTIVES: To develop an accurate, rapid, and inexpensive method for verifying vaginal applicator use. GOAL: To develop a method for assessing compliance in microbicide clinical trials. STUDY DESIGN: Single use Microlax applicators containing a placebo formulation either were or were not exposed to the vagina. Three assays were developed to determine whether the applicators had been used vaginally. RESULTS: Blinded examiners were able to discern 63% of the time whether or not applicator tips had been exposed to the vagina. Optical density (to measure lactobacilli), increased in media exposed to used applicators but not in media exposed to unused applicators. When tips of applicators were stained with trypan blue, used applicators could be distinguished easily from unused applicators. CONCLUSION: Staining of applicator is accurate, simple, rapid, and inexpensive. This method could be be used in clinical settings in the developing world. Dying applicator tips could prove useful in excluding non-compliant subjects, analyzing data, or developing social intervention strategies to improve compliance.

The Development of Microbicides for Clinical Use to Prevent Sexually Transmitted Diseases.

Approximately 60 vaginal microbicides are under development for the prevention of HIV/AIDS and other sexually transmitted pathogens. The history and current status of the field are discussed with emphasis on the lessons learned from recent clinical trials, along with an emphasis on the mechanisms involved in the sexual transmission of HIV and how this information influences microbicide development. Additionally, the current status of in vitro and animal systems used for evaluating microbicide efficacy, as well as the challenges involved in developing more appropriate and practical assays, are discussed. Also discussed are the challenges that face the microbicide product development field in meeting US Food and Drug Administration requirements regarding product safety and stability.