Lack of microbial proliferation and phototoxic potential of a new matrix patch for estradiol delivery.

OBJECTIVES

To examine the potential of a new matrix system developed for estradiol delivery to cause microbial proliferation under the occluded site or to cause acute phototoxicity reactions.

METHODS

Twenty healthy post-menopausal women participated in a microbial proliferation study and 11 in a phototoxicity study. Both studies were single centre, single blind and placebo controlled. Microbial proliferation was assessed by quantitative counts of the total aerobic bacterial population and of eight individual species before patch application and after removal following a 4 day application period on the abdomen. Acute phototoxicity potential was assessed following an 8 h application period on the abdomen by irradiating the application site after patch removal with ultra violet A radiation and visible light and evaluating the sites for up to 48 h post irradiation. Non-irradiated active and placebo patches on the other side of the abdomen served as controls.

RESULTS

Total aerobic bacterial populations both before and after the matrix patch application period were low as expected for dry skin. Separate counts of microbial species were also low and did not change in any meaningful or consistent manner after patch application. In the phototoxicity study, mild erythema was observed in some patients at 0, 0.5 and 24 h post patch removal with no differences between irradiated and non-irradiated sites.

CONCLUSIONS

These two studies demonstrate that a new matrix patch developed for estradiol delivery does not promote microbial proliferation under the occluded patch site or cause acute phototoxicity following removal.