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

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.

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.

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%.

Applicator assay modifications render the test safe and suitable for use in clinical trials.