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.