The MTN-008 trial was the first multi-dose study conducted to evaluate the safety of a microbicide gel (2:1 randomized to tenofovir 1% or hydroxycellulose (HEC) placebo gel) during pregnancy. The study aim was to evaluate safety, tolerability and pharmacokinetics of the study products. Procedures included daily gel administration, with Day 0 and Day 6 in clinic, and Days 1-5 at home. Because pregnancy may pose unique challenges to consistent gel use and acceptability, evaluation of adherence and acceptability was a secondary objective of the trial. The study enrolled healthy, HIV-negative, pregnant women aged 18-40 in Pittsburgh, PA and Birmingham, AL, USA in 2 consecutive groups: cohort 1 was 37-39 weeks gestation, cohort 2 was 34-36 weeks. Ninety-one women completed the study (45 and 46 in each cohort, respectively) and were evaluable per protocol. Adherence was evaluated using self-reports: participants completed a web-based computer-assisted self-interview (CASI) at Days 0 and 6 about gel attitudes and behaviors. At Day 6 trained research staff conducted a short interviewer-administered questionnaire with both structured and open-ended questions. Frequencies of quantitative data were tabulated in SAS and descriptive statistics are presented; open-ended textual data were summarized by a behavioral scientist experienced in qualitative analysis. Participants reported generally neutral perceptions of gel characteristics. A small number of women (7-8%) reported pain (6/90), other physical discomfort (7/90), or mental discomfort (7/90) associated with the process of applicator insertion. About 5% reported the same for the gel itself. Two-thirds (61/90) thought the gel was runny, many complained of bothersome gel leakage and several cited this reason for not inserting a full dose. The majority were not worried the gel would cause problems for their pregnancy or babies. Ninety-seven percent (83/86) said they would use the gel in the future if they were pregnant, and 90% (81/90) when nonpregnant. Self-reported adherence was high with 88% (79/90) reporting daily gel use on both the computerized and interviewer-administered questionnaires. The majority (67/90) reported no difficulty with daily use. However, drug was undetectable (<0.31 ng/mL) among 45% (27/60; 95% CI 32-58%) of the women on active product prior to observed dosing at Day 6. The most common reason for reported nonuse (N = 6) was forgetting. Study gel was generally acceptable, but many complained of a runny consistency (61/90) and leakage (83/90). No frequent or strong concerns about the effects of the study gel on the pregnancy/fetus were reported. Self-reported adherence to study gel self-administered at home for 5 days was high, however plasma drug levels suggest actual use may have been considerably lower. Findings from this study can provide insights relevant to use of other antiretroviral-based, vaginally-inserted HIV prevention methods during pregnancy.
Keywords: Breastfeeding; HIV prevention; Microbicide; Pregnant; Tenofovir.