Estradiol and Spironolactone Plasma Pharmacokinetics Among Brazilian Transgender Women Using HIV Pre-Exposure Prophylaxis: Analysis of Potential Interactions

Event-driven PrEP beyond cisgender men who have sex with men

Despite advancements in existing antiretroviral-based prevention strategies, including daily oral, locally acting, and injectable options, there is a pressing need for more inclusive and flexible event-driven pre-exposure prophylaxis (PrEP) strategies for all. Event-driven or intermittent dosing of PrEP in populations beyond cisgender men who have sex with men would offer a promising alternative by fitting prevention into the diverse lifestyles of affected populations and thereby advancing health equity. Evidence from PrEP clinical trials, pharmacokinetic studies, modelling studies, and real-world observational research suggests that event-driven PrEP could be a flexible and inclusive option, yet optimal dosing has not been established across sex and gender spectrums. To advance PrEP equity through inclusivity, studies on event-driven PrEP should include people across the gender spectrum. Real-world demonstration studies and simulation studies of optimal dosing strategies are needed. While awaiting further evidence, clinical providers can offer shared decision making and counselling on available data to include event-driven dosing as an option, especially when daily oral, locally acting, or injectable PrEP are not acceptable or preferred methods. Wider access to diverse PrEP options for all populations fosters a more inclusive and effective global HIV prevention strategy.

Bidirectional pharmacokinetics of doravirine, tenofovir, and feminizing hormones in transgender women (IDentify): A randomized crossover trial

Transgender women may have concerns of drug interactions between feminizing hormone therapy (FHT) and antiretrovirals, leading to nonadherence. This randomized, three-period crossover, open-label, phase I trial assessed the effects of doravirine (DOR) and tenofovir disoproxil fumarate (TDF) on the pharmacokinetics (PKs) of estradiol, spironolactone, and total testosterone and vice versa in healthy transgender women. Volunteers were randomized 1:1 into two sequences containing three treatment groups (DOR, lamivudine [3TC], and TDF alone; estradiol, spironolactone, and placebo; and DOR/3TC/TDF, estradiol, and spironolactone). Eight subjects enrolled in the study and six had completed all study periods. The geometric mean ratios for DOR area under the concentration-time curve from zero to last measured concentration (AUC0-last ), maximum concentration (Cmax ), and concentration at 24 h (C24 ) were similar. However, tenofovir (TFV) AUC0-last , Cmax , and C24 moderately increased by 14%-38%. Last, estradiol AUC0-last , Cmax , and C24 were increased by 10%-13%. Whereas most 90% confidence intervals did not meet the bioequivalence bounds of 80%-125%, the point estimates fell within the intervals. Log-transformed DOR, TFV, and estradiol PK parameters computed with and without co-administration were not statistically different (p > 0.05). There were no serious adverse events. There is not a clinically significant impact of FHT on DOR/TFV PKs. Similarly, there is no observed impact on estradiol PKs and total testosterone following use of DOR/3TC/TDF.