Assessment of Drug-drug Interactions Between Masculinizing Hormone Therapy and Antiretroviral Agents Concomitantly for Pre-exposure Prophylaxis Among Transgender Men

Institute of HIV Research and Innovation (IHRI)

There are currently no published studies addressing drug-drug interactions (DDI) between masculinizing hormone therapy (MHT) and pre-exposure prophylaxis (PrEP) among transgender men (TGM). This could lead to concerns and subsequent prioritizing MHT over PrEP among TGM. Because tenofovir alafenamide (TAF) can achieve higher intracellular tenofovir diphosphate (TFV-DP) levels with lower tenofovir plasma concentrations, it is promising that both plasma tenofovir (TFV) and intracellular TFV-DP levels might not be significantly affected by MHT. The current study aims to determine the pharmacokinetics (PK) DDI between MHT and daily PrEP among TGM.

Inclusion Criteria:

1. Thai nationality
2. Age 18-40 years old
3. Female-to-Male transgender individual
4. HIV-negative
5. Body mass index 18.5-24.9 kg/m2
6. Negative urine pregnancy test
7. Calculated creatinine clearance (CrCl) ≥60 mL/min, as estimated by the Cockcroft-Gault equation
8. Alanine aminotransferase (ALT) ≤2.5 x ULN
9. Signed the informed consent form

Exclusion Criteria:

1. Known history of allergy to hormonal component to be used in the study

2. Use of pre-exposure prophylaxis or post-exposure prophylaxis in the past 30 days

3. Use of injectable MHT in the past 3 months

4. Evidence of current hepatitis B virus infection (HBV) - i.e. hepatitis B surface antigen [HBsAg] positive

5. Evidence of current hepatitis C virus infection (HCV) - i.e. HCV antibody positive

6. History of myocardial infarction or coronary artery disease

7. Current use of any of the following:

   • Anticonvulsants: carbamazepine, oxcarbazepine, phenytoin, or phenobarbital
   • Herbs: gingko biloba, St John's wort or milk thistle
   • Anti-infective agents: protease inhibitors, rifampicin or rifabutin

8. History of gastrointestinal tract surgery that alter gastrointestinal tract and/or drug absorption

9. Alcohol or drug use that, in the opinion of the investigator, would interfere with completion of study procedures