Wallace, Andrea, Aaron Teitelbaum, Livia Wan, Laura Guichard, Robin A. Maguire, and David M. Phillips. "Determining the feasibility of utilizing the microbicide applicator usage assay in clinical trials."

Abstract

INTRODUCTION: Subjects' adherence to use of study product is a major concern in microbicide clinical trials. We have previously described an assay that tests whether single-use microbicide applicators have been exposed to the vagina. The assay involves spraying the applicator with the dye Trypan blue, which stains dried vaginal mucus. In order to integrate the assay into our Phase 3 trial, three key elements needed to be considered: (1) Subjects would be returning applicators only when they returned to the clinic for quarterly visits. Therefore the dye would need to be reactive with the dried mucus for up to 4 months. (2) All of a subject’s applicators are usually returned in the same bag, which could theoretically cause cross-contamination between inserted and noninserted applicators. And (3) The Trypan blue dye, like most histological dyes, is carcinogenic. This poses a potential safety hazard to the technicians performing the assay.

METHODS: Applicators that had been vaginally inserted by a study subject were placed in the same bag with noninserted applicators. As a control, some inserted applicators were bagged individually. Study bags containing applicators were stored for at least 4 months and to increase the likelihood of cross-contamination, bags were shaken daily during the storage period. To alleviate the use of a hazardous dye, a number of nontoxic food dyes were screened. Four judges independently scored the applicators.

RESULTS: The dye was reactive to all applicators that had been inserted after the storage period and there was no evidence of cross-contamination. The four independent judges distinguished inserted from noninserted applicators, which had been stored in the same bag, with 97% accuracy. This compared to an accuracy of 99.5% of applicators that were stored individually. A 0.05% aqueous solution of the nontoxic dye, Blue No. 1 Granular Food Dye was determined to have the same reactive properties as the Trypan blue and was thus substituted. The four independent judges correctly identified 20 applicators as inserted or noninserted with 100% accuracy.

CONCLUSIONS: The study demonstrates that the assay is safe and feasible for implementation in the clinical setting.

Microbicides 2006

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This page updated 3 April 2006

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