DDI Study: Pilot Study Results


DDI Study: Pilot Study Results

Despite tremendous advances in the care of trans women living with HIV, there are still unknowns. For example, it is unknown if taking feminizing hormone therapy (FHT) and antiretroviral medications (ART) together will affect the drug level (causing an increase or decrease) of either of these medications.

This is what we call a drug-drug interaction (DDI).


Since we do not know the possible effects of taking both medications at the same time, some trans women living with HIV have sometimes felt they have to choose between taking FHT and ART, despite needing or desiring both.

Studies have also shown that healthcare providers may not prescribe FHT to trans women who are living with HIV, causing trans women to stop taking their ART medications or take black market hormones without medical direction, which often result in severe side effects and medical risk.

We are carrying out a larger study to see if such drug-drug interactions exist between FHT and ART. Before conducting this larger study, we carried out a pilot (small) study to:

  • Gain a better understanding of estradiol levels found in the blood over an 8 hour period.
  • Determine the best time to measure estradiol levels – essentially trying to figure out when estradiol concentrations are highest in the blood.
  • To gain feedback on a new questionnaire (FEM-SQ) that we created to measure participant satisfaction with FHT.

Our pilot study compared estradiol concentrations among 15 trans women living with and without HIV. Estradiol concentrations were similar between trans women living with HIV and trans women living without HIV. This means that there is a low chance of relevant drug-drug interactions between FHT and ART.

In the larger study, we will enroll 15 trans women living with HIV, 15 cis women living with HIV and 15 transwomen living without HIV.

We will see if we discover similar findings with this bigger population - meaning transwomen can be assured that both their FHT and ART medications can be safely taken together!



Version 1: 28 Sep 2022

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