Comparative estrogen exposure from compounded transdermal estradiol creams and Food and Drug Administration-approved transdermal estradiol gels and patches.

OBJECTIVE

The aim of this study was to evaluate the amount of estrogen exposure associated with the use of compounded transdermal estradiol (E2) creams and compare it with estrogen exposure associated with the use of Food and Drug Administration (FDA)-approved transdermal E2 patches and gels.

METHODS

This was a retrospective cohort study that used clinical laboratory data collected from January 1, 2016, to December 31, 2019. Participants were first divided into three groups: postmenopausal women on no menopausal hormone therapy (n = 8,720); postmenopausal women using either a transdermal E2 patch, gel, or cream (n = 1,062); and premenopausal women on no hormonal therapy (n = 16,308). The postmenopausal menopausal hormone therapy group was further subdivided by formulation (patch [n = 777], gel [n = 132], or cream [n = 153]) and dose range (low, mid, or high). The Jonckheere-Terpstra trend test was used to determine if there was a dose-dependent trend in urinary E2 with increasing dose of compounded E2 cream (dose categories for E2 cream subanalysis, <0.5 mg [n = 49], ≥0.5-≤1.0 mg [n = 50], ≥1.0-≤1.5 mg [n = 58], and >1.5-≤3.0 mg [n = 46]). Urinary E2 and other characteristics were compared across formulations (within each dose range) using Kruskal-Wallis one-way analysis of variance.

RESULTS

A dose-dependent, ordered trend existed for urinary E2 with increasing doses of compounded E2 cream (urinary E2 medians [ng/mg-Cr], 0.80 for <0.5 mg, 0.73 for ≥0.5-≤1.0 mg, 1.39 for ≥1.0-≤1.5 mg, and 1.74 for >1.5-≤3.0 mg; Jonckheere-Terpstra trend test, P < 0.001). Significant differences in urinary E2 concentrations were observed in all three dose ranges (Kruskal-Wallis one-way analysis of variance, P = 0.013 for low dose, P < 0.001 for mid dose, P = 0.009 for high dose). Comparison of E2 concentrations of compounded creams to E2 concentrations obtained with similar doses of FDA-approved patches and gels showed that the creams had significantly lower values than the patches and gels.

CONCLUSIONS

Estrogen exposure from compounded transdermal E2 creams increases in a dose-dependent manner; however, the amount of estrogen exposure associated with compounded creams is significantly lower than estrogen exposure associated with FDA-approved transdermal E2 patches and gels. Clinicians should be aware of the direction and magnitude of these potential differences in estrogen exposure when encountering women who have either previously used or are currently using compounded E2 creams.