Tenofovir concentrations in dried blood spots are not associated with the use of gender-affirming hormones, a small trial of directly observed PrEP among transgender men and women found.
The iBrEATHe study, published in Clinical Infectious Diseases, included in its final analysis 24 transgender men taking testosterone and 23 transgender women taking estradiol, with 38% of the women also taking spironolactone. Tenofovir diphosphate concentrations were compared between these two groups and with historical cisgender controls (17 women, 15 men). All participants took directly observed emtricitabine/tenofovir (Truvada) as PrEP for four weeks.
Tenofovir levels were comparable between trans women and trans men as well as between trans women and cis men, but were lower (by a mean of 23%) in trans men compared to cis women. Previously, the iPrEx trial had shown lower tenofovir concentrations in transgender women compared to MSM, but the trial was based on self-reported adherence, not DOT.
One limitation of the current study was the time frame, since it takes eight weeks to achieve steady-state tenofovir concentrations. That said, study data indicated that trans men, trans women, and cis men participating in the study were all on course to reach the necessary threshold of active drug at eight weeks. Further, the researchers found that tenofovir did not alter serum hormone levels among trans women or trans men.
Taken together, these results support current PrEP dosing recommendations for trans men and women—as well as messaging to the transgender community about the lack of interaction between hormones and tenofovir, study authors concluded.
In a related commentary, Douglas S. Krakower, M.D., of Beth Israel Deaconess Medical Center in New York argued that anti-stigma interventions among health care professionals and inclusion of genderqueer communities were also required. “If researchers and clinicians can develop and deliver PrEP in ways that meet the needs of transgender populations, then PrEP can be a cornerstone in the effective and equitable response to HIV that we need,” Krakower wrote.