Introduction Concerns over potential drug‐drug interactions (DDI) between feminizing hormone therapy (FHT) and pre‐exposure prophylaxis (PrEP) have hampered uptake and adherence of PrEP among transgender women (TGW). To determine DDI between FHT and PrEP, we measured the pharmacokinetic (PK) parameters of blood plasma estradiol (E2) and tenofovir (TFV) in Thai TGW. Methods Twenty TGW who never underwent orchiectomy and had not received injectable FHT within six months were enrolled between January and March 2018. FHT (E2 valerate and cyproterone acetate) were prescribed to participants at baseline until week 5, and then from week 8 until the end of study. Daily PrEP (tenofovir disoproxil fumarate/emtricitabine) was initiated at week 3 and continued without interruption. Intensive E2 PK parameters and testosterone concentration at 24 hours (C24) were measured at weeks 3 (without PrEP) and 5 (with PrEP), and intensive TFV PK parameters were measured at weeks 5 (with FHT) and 8 (without FHT). Results Median (interquartile range) age, body mass index, and creatinine clearance were 21.5 (21–26) years, 20.6 (19.0‐22.4) kg/m2, and 116 (101‐126.5) mL/min, respectively. The geometric mean (%CV) of area under curve from time zero to 24 hours (AUC0‐24), maximum concentration (Cmax), and C24 of E2 at weeks 3 and 5 were 775.13 (26.2) pg h/mL, 51.47 (26.9) pg/mL, and 15.15 (42.0) pg/mL; and 782.84 (39.6), 55.76 (32.9), and 14.32 (67.4), respectively. The geometric mean (%CV) of TFV AUC0‐24, Cmax, and C24 at weeks 5 and 8 were 2242.1 (26.5) ng h/mL, 353.9 (34.0) ng/mL, and 40.9 (31.4) ng/mL; and 2530.2 (31.3), 311.4 (30.0), and 49.8 (29.6), respectively. The geometric mean of TFV AUC0‐24 and C24 at week 5 were significantly less than that at week 8 by 12% (p = 0.03) and 18% (p < 0.001), respectively. There were no significant changes in E2 PK parameters and median C24 of bioavailable testosterone between week 3 and week 5. Conclusions Our study demonstrated lower blood plasma TFV exposure in the presence of FHT, suggesting that FHT may potentially affect PrEP efficacy among TGW; but E2 exposure was not affected by PrEP. Further studies are warranted to determine whether these reductions in TFV are clinically significant. Clinical Trial Number: NCT03620734.

Introduction HIV testing coverage remains low among men who have sex with men (MSM) and transgender women (TGW). We studied characteristics of Thai MSM and TGW who chose online and/or offline platforms for HIV counselling and testing and the feasibility of integrating online technologies and HIV self‐testing to create service options.MethodsFrom December 2015 to June 2017, MSM and TGW enrolled from Bangkok Metropolitan Region and Pattaya could choose between: 1 offline HIV counselling and testing (Offline group), 2 online pre‐test counselling and offline HIV testing (Mixed group), and 3 online counselling and online, supervised, HIV self‐testing (Online group). Sociodemographic data, risk behaviour and social network use characteristics were collected by self‐administered questionnaires. Logistic regression models identified covariates for service preferences.ResultsOf 472 MSM and 99 TGW enrolled, 202 self‐selected the Offline group, 158 preferred the Mixed group, and 211 chose the Online group. The Online group had the highest proportion of first‐time testers (47.3% vs. 42.4% vs. 18.1%, p < 0.001) and reported highest HIV prevalence (15.9% vs. 13.0% vs. 3.4%, p = 0.001) as compared to Offline and Mixed groups, respectively. Having tested for HIV twice or more (OR 2.57, 95% CI 1.03 to 6.41, p = 0.04) increased the likelihood to choose online pre‐test counselling. Being TGW (OR 6.66, 95% CI 2.91 to 15.25, p < 0.001) and using social media from four to eight hours (OR 2.82, 95% CI 1.48 to 5.37, p = 0.002) or >8 hours (OR 2.33, 95% CI 1.05 to 5.16, p = 0.04) increased selection of online, supervised, HIV self‐testing. Providers primarily used smartphones (79.2%) and laptops (37.5%) to deliver online services. Self‐testing strip image sharpness and colour quality were rated “good” to “excellent” by all providers. Most participants (95.1%) agreed that online supervision and HIV self‐testing guidance offered were satisfactory and well delivered.ConclusionsOnline HIV services among MSM and TGW are feasible in Thailand and have the potential to engage high proportions of first‐time testers and those with high HIV prevalence. When designing public health interventions, integrating varied levels of online HIV services are vital to engage specific sections of MSM and TGW populations in HIV services.Clinical Trial NumberNCT03203265