Assessment of Drug-drug Interactions Between Feminizing Hormone Therapy and Emtricitabine/Tenofovir Alafenamide Concomitantly for Pre-exposure Prophylaxis Among Transgender Women

  • End date
    Oct 1, 2022
  • participants needed
  • sponsor
    Thai Red Cross AIDS Research Centre
Updated on 25 January 2021


Recent studies have showed that there were significant drug-drug interactions (DDI) from feminizing hormone therapy (FHT) towards emtricitabine/tenofovir disoproxil fumarate (F/TDF)-based pre-exposure prophylaxis (PrEP) among transgender women (TGW). New strategies for PrEP among TGW who use FHT are urgently needed. Because tenofovir alafenamide (TAF) can achieve higher intracellular TFV-DP levels with lower tenofovir plasma concentrations, it is promising that both plasma TFV and intracellular TFV-DP levels might not be significantly affected by FHT. The current study aims to determine the pharmacokinetics DDI between FHT and F/TAF-based PrEP among TGW.


Two full pharmacokinetic (PK) measurements will be performed. Samples collected will include: plasma for estradiol (E2), emtricitabine (FTC), tenofovir (TFV), and tenofovir alafenamide (TAF) measurement; and peripheral blood mononuclear cells (PBMC) for emtricitabine-triphosphate (FTC-TP) and tenofovir-diphosphate (TFV-DP) intracellular quantification.

Condition Drug interaction, drug interactions, drug-drug interaction
Treatment Estradiol valerate 2 mg, cyproterone acetate 25 mg
Clinical Study IdentifierNCT04590417
SponsorThai Red Cross AIDS Research Centre
Last Modified on25 January 2021


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Inclusion Criteria

Is your age between 18 yrs and 40 yrs?
Are you male?
Do you have Drug interaction?
Do you have any of these conditions: drug-drug interaction or Drug interaction or drug interactions?
Thai nationality
Age 18-40 years old
Transgender women
Body mass index 18.5-24.9 kg/m2
Calculated creatinine clearance (CrCl) 60 mL/min, as estimated by the Cockcroft-Gault equation
Alanine aminotransferase (ALT) 2.5 x ULN
Signed the informed consent form

Exclusion Criteria

Known history of allergy to hormonal component to be used in the study
Male-to-female transgender who underwent orchiectomy
Use of pre-exposure prophylaxis or post-exposure prophylaxis in the past 30 days
Use of injectable FHT in the past 3 months
Evidence of current hepatitis B virus infection (HBV) - i.e. hepatitis B surface antigen (HBsAg) positive
Evidence of current hepatitis C virus infection (HCV) - i.e. HCV antibody positive
Current use of any of the following
Anticonvulsants: carbamazepine, felbamate, oxcarbazepine, phenytoin, phenobarbital, primidone or topiramate
Herbs: gingko biloba, St John's wort or milk thistle
Anti-infective agents: azole antifungals, macrolides, griseofulvin, protease inhibitors, rifampicin or rifabutin
Participant-reported active rectal infection requiring treatment
History of gastrointestinal tract surgery that alter gastrointestinal tract and/or drug absorption
Alcohol or drug use that, in the opinion of the investigator, would interfere with completion of study procedures
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