Plasma and intracellular pharmacokinetics of tenofovir disoproxil fumarate and emtricitabine in transgender women receiving feminizing hormone therapy

Drug-drug interactions between gender-affirming hormone therapy and antiretrovirals for treatment/prevention of HIV

Transgender persons face a greater burden of HIV compared to cisgender counterparts. Concerns around drug-drug interactions (DDIs) have been cited as reasons for lower engagement in HIV care and lower pre-exposure prophylaxis (PrEP) uptake among transgender populations. It is therefore imperative for hormone therapy, PrEP and antiretroviral therapy providers to understand the DDI potential between these therapies. Studies of tenofovir disoproxil fumarate (TDF)/emtricitabine (FTC) PrEP with feminizing hormone therapies (FHTs) show reduced plasma tenofovir concentrations, but intracellular concentrations of tenofovir-diphosphate are not reduced. Efficacy of PrEP is expected to be maintained despite this interaction. Masculinizing hormone therapies have no effect on tenofovir concentrations but may increase FTC to a nonclinically relevant extent. No interactions between FHT and cabotegravir or tenofovir alafenamide have been demonstrated. Administration of TDF/FTC PrEP has no effect on hormone levels in transmen or transwomen. PrEP is expected to be effective and safe in transpersons and should be provided to high-risk individuals regardless of gender affirming hormone use. Enzyme inducing/inhibiting antiretroviral therapy may decrease or increase, respectively, the concentrations of FHT and masculinizing hormone therapy. Unboosted integrase inhibitors or enzyme neutral non-nucleoside reverse transcriptase inhibitors are not expected to affect and are not affected by gender affirming hormones and can be considered in transmen and transwomen. Overlapping toxicities including weight gain, dyslipidaemia, cardiovascular disease and bone density effects should be considered, and antiretroviral modifications can be made to minimize toxicities. Interactions between supportive care medications should be assessed to avoid chelation interactions and hyperkalaemia.

No observed bidirectional effect between tenofovir diphosphate concentrations and gender-affirming hormone concentrations among transgender persons switching from tenofovir disoproxil fumarate/emtricitabine to tenofovir alafenamide/emtricitabine for HIV pre-exposure prophylaxis

AIMS

Many transgender and gender diverse (TGD) individuals have expressed concerns about the potential for oral pre-exposure prophylaxis to affect hormonal concentrations achieved from taking gender-affirming hormone therapy (GAHT). The purpose of this study was to understand the bidirectional effects between hormone and intraerythrocytic tenofovir diphosphate concentrations when switching from tenofovir disoproxil fumarate/emtricitabine (TDF/FTC) to tenofovir alafenamide/emtricitabine (TAF/FTC) in TGD users/nonusers of GAHT.

METHODS

The study evaluated stored blood samples and dried blood spot cards from TGD adults without HIV who took ≥12 weeks of TDF/FTC and then switched to ≥12 weeks of TAF/FTC for pre-exposure prophylaxis.

RESULTS

Thirty-nine individuals met the study inclusion criteria. Regardless of sex assigned at birth and the use of GAHT, there were no significant differences in hormone concentrations when individuals taking GAHT were taking TDF/FTC and then switched to TAF/FTC. Further, there was no significant difference in intraerythrocytic tenofovir diphosphate concentrations between users and nonusers of GAHT.

CONCLUSION

There are no bidirectional effects between hormone and intraerythocytic tenofovir diphosphate concentrations when switching from TDF/FTC to TAF/FTC in TGD users/nonusers of GAHT.

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.

Gender Affirming Hormones Do Not Affect the Exposure and Efficacy of F/TDF or F/TAF for HIV Preexposure Prophylaxis: A Subgroup Analysis from the DISCOVER Trial

Purpose

Transgender women are disproportionately affected by HIV and are underutilizing preexposure prophylaxis (PrEP). The lower uptake of PrEP by transgender women may be, in part, owing to the perception that taking PrEP may lower the efficacy of gender-affirming hormone therapy (GAHT) or to provider concerns that GAHT may lower the efficacy of PrEP.

Methods

DISCOVER was a randomized, double-blind, noninferiority trial comparing emtricitabine (FTC, F) and tenofovir alafenamide (F/TAF) versus emtricitabine and tenofovir disoproxil fumarate (F/TDF) as PrEP among transgender women and cisgender men who have sex with men (MSM). This nested substudy of the DISCOVER trial compared the exposure of the active intracellular metabolites of FTC and tenofovir (TFV), FTC triphosphate (FTC-TP) and TFV diphosphate (TFV-DP), in peripheral blood mononuclear cells (PBMC) among transgender women receiving GAHT versus MSM within the F/TAF and F/TDF groups.

Results

Our results demonstrate that TFV-DP and FTC-TP levels in PBMC were comparable between transgender women on GAHT and MSM receiving F/TAF, and between transgender women on GAHT and MSM receiving F/TDF. TFV-DP concentrations remained above the EC90 of 40 fmol/106 cells across all groups. No clinically significant drug-drug interactions of GAHT were observed with either F/TAF or F/TDF in this subanalysis.

Conclusions

These findings are consistent with the clinical pharmacology of GAHT, FTC, TDF, and TAF reported in previous studies, and support the continued use of F/TAF and F/TDF for PrEP in transgender women.

Clinicaltrials.gov registration number: NCT02842086.

Oestradiol concentrations in trans women with HIV suppressed on unboosted integrase inhibitor regimens versus trans women without HIV taking oral oestradiol: a pilot study

BACKGROUND

Feminizing hormone therapy (FHT) is essential to many trans women. Concern about negative drug interactions between FHT and ART can be an ART adherence barrier among trans women with HIV.

OBJECTIVES

In this single-centre, parallel group, cross-sectional pilot study, we measured serum oestradiol concentrations in trans women with HIV taking FHT and unboosted integrase strand transfer inhibitor (INSTI)-based ART versus trans women without HIV taking FHT.

METHODS

We included trans women with and without HIV, aged ≥18 years, taking ≥2 mg/day of oral oestradiol for at least 3 months plus an anti-androgen. Trans women with HIV were on suppressive ART ≥3 months. Serum oestradiol concentrations were measured prior to medication dosing and 2, 4, 6 and 8 h post-dose. Median oestradiol concentrations were compared between groups using Wilcoxon rank-sum tests.

RESULTS

Participants (n = 8 with HIV, n = 7 without) had a median age of 32 (IQR: 28, 39) years. Among participants, the median oral oestradiol dose was 4 mg (range 2-6 mg). Participants had been taking FHT for a median of 4 years (IQR: 2, 8). Six trans women with HIV were taking bictegravir/emtricitabine/tenofovir alafenamide and two were taking dolutegravir/abacavir/lamivudine. All oestradiol concentrations were not significantly different between groups. Eleven (73%) participants had target oestradiol concentrations in the range 200-735 pmol/L at C4h (75% among women with HIV, 71% among those without HIV).

CONCLUSIONS

Oestradiol concentrations were not statistically different in trans women with HIV compared with those without HIV, suggesting a low probability of clinically relevant drug-drug interactions between FHT and unboosted INSTI-based ART.

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

BACKGROUND AND OBJECTIVE

An important barrier to HIV prevention among transgender women (TGW) is the concern that oral pre-exposure prophylaxis (PrEP) negatively affects the efficacy of feminizing hormone therapy (FHT). We aimed to assess the impact of PrEP on FHT pharmacokinetics (PK) among TGW from Brazil.

METHODS

We performed a drug-drug interaction sub-study among TGW enrolled in a daily oral PrEP demonstration study (PrEParadas, NCT03220152). Participants had a first PK assessment (PK1) 15 days after FHT (estradiol valerate 2-6 mg plus spironolactone 100-200 mg) initiation and then started PrEP (tenofovir disoproxil fumarate 300 mg/emtricitabine 200 mg). A second PK evaluation was performed 12 weeks later (PK2). Blood samples were collected prior and after the directly observed dosing (0, 0.5, 1, 2, 4, 6, 8, and 24 hours). Pharmacokinetic parameters of estradiol, spironolactone, and metabolites were estimated by non-compartmental analysis (Monolix 2021R2, Lixoft®) and compared as geometric mean ratios (GMRs, 90% confidence interval [CI]).

RESULTS

Among 19 TGW who completed the substudy, median age was 26 years (interquartile range: 23-27.5). Estradiol area under the plasma concentration-time curve (AUCτ) and trough concentrations did not differ between PK1 and PK2 evaluations (GMR [90% CI]: 0.89 [0.76-1.04] and 1.06 [0.94-1.20], respectively). Spironolactone and canrenone AUCτ were statistically lower at PK2 than PK1 (0.76 [0.65-0.89] and 0.85 [0.78-0.94], respectively). Canrenone maximum concentration was also lower at PK2 than PK1 (0.82 [0.74-0.91]).

CONCLUSION

Estradiol PK was not influenced by PrEP concomitant use. The small differences observed in some spironolactone and canrenone PK parameters should not prevent the concomitant use of estradiol-based FHT and PrEP.

TRIAL REGISTRATION

This trial (NCT03220152) was registered on July 18, 2017.

Inclusion of Transgender and Gender Diverse People in Phase III Trials: Examples from HIV Pharmacologic Prevention Studies

Although at least 25 million adults are transgender worldwide, few phase III clinical trials have enrolled transgender and gender diverse (TGD) people. HIV is the only therapeutic area to include TGD people intentionally in phase III randomized clinical trials during the development of certain newer HIV pharmacologic prevention interventions. Pharmacologic assessments for HIV prevention efficacy in TGD populations are important, as there may be specific considerations for product use and potential interactions with hormone therapies. Herein, we summarize ongoing and completed phase III HIV trials that included TGD people as part of the study population, we examine investigators' strategies for recruiting and engaging TGD priority populations in these phase III trials, and we comment on the implications of these studies for prioritizing TGD populations in clinical pharmacology research within the phase III clinical trial landscape.

Barriers to uptake of PrEP across the continuum among transgender women: A global scoping review

BACKGROUND

Although preexposure prophylaxis (PrEP) has demonstrated high efficacy for HIV prevention, rates of PrEP uptake remain low among the transgender population, especially in transgender women (TGW). We conducted this scoping review to assess and characterize barriers to PrEP use along the PrEP care continuum among TGW.

METHODS

We conducted this scoping review by searching studies in Embase, PubMed, Scopus, and Web of Science. Eligibility criteria included: reporting a PrEP related quantitative result among TGW; peer-reviewed and published in English between 2010-2021.

RESULTS

Globally, high willingness (80%) to use PrEP was found, yet uptake and adherence (35.4%) were low. TGW experiencing hardship, including poverty, incarceration, and substance use, were associated with higher odds of PrEP awareness but lower odds of PrEP use. Structural and social barriers such as stigma, medical mistrust, and perceived racism can be important barriers for PrEP continuation. High social cohesion and hormone replacement therapy were associated with greater odds of awareness. In addition, our study confirmed prior research showing that PrEP does not lower feminizing hormone levels in TGW.

CONCLUSIONS

Significant demographic factors among TGW that are associated with PrEP engagement. It is imperative to focus on TGW as a population with independent needs, requiring specific PrEP care guidelines and tailored resource allocation, that fully considers individual-, provider-, and community/structural-level barriers and facilitators. The present review also indicates that combining PrEP care with GAHT or broader gender-affirmation care may facilitate PrEP use.

Gender-Affirming Hormone Pharmacokinetics Among Adolescent and Young Adult Transgender Persons Receiving Daily Emtricitabine/Tenofovir Disoproxil Fumarate

Transgender persons have an increased vulnerability to HIV infection yet have not been well-represented in past clinical trials for pre-exposure prophylaxis (PrEP). Because of this, there are few data available to understand whether gender-affirming hormone concentrations are influenced by PrEP agents in transgender men (TM) and transgender women (TW). The objective of this study was to compare gender-affirming hormone concentrations with versus without emtricitabine (F, FTC)-tenofovir disoproxil fumarate (TDF). TM and TW without HIV, aged 15-24 years, were enrolled for 1 month of directly observed daily F/TDF. Participants were required to be receiving a stable hormone dose (estradiol or testosterone) for at least 1 month or three consecutive doses, whichever was longer, before enrollment and willing to continue the same dose. Intensive pharmacokinetic (PK) sampling for gender-affirming hormones was collected before and 2-3 weeks after daily F/TDF. Serum estradiol and total testosterone were determined by liquid chromatography-tandem mass spectrometry; free testosterone by equilibrium dialysis. Maximum concentrations (Cmax) and area under the curve (AUClast) were log-transformed and compared between baseline and on F/TDF using geometric mean ratios (GMRs) with 95% confidence intervals (CIs). Twenty-five TW and 24 TM were enrolled (median age: 20 and 21 years, respectively). In TW, estradiol Cmax (GMR [95% CI]: 0.85 [0.65-1.11]) and AUClast (GMR [95% CI]: 0.87 [0.73-1.03]) were comparable on F/TDF versus baseline. In TM, similar comparability was observed for PrEP versus baseline including total testosterone Cmax (GMR [95% CI]: 0.91 [0.80-1.03]) and AUClast (GMR [95% CI]: 0.91 [0.81-1.04]) and free testosterone Cmax (GMR [95% CI]: 0.89 [0.74-1.07]) and AUClast (GMR [95% CI]: 0.88 [0.74-1.03]). Estradiol and testosterone exposures in young TW and TM did not significantly differ on F/TDF versus baseline. These findings should reassure patients and providers that F/TDF can be used as PrEP without concern for altering gender-affirming hormone PK. ClinicalTrials.gov (NCT03652623).

Pharmacokinetics of Emtricitabine/Tenofovir Disoproxil Fumarate Among Transgender Adolescents and Young Adults Without HIV Receiving Gender Affirming Hormones

The transgender community has expressed concerns regarding drug-drug interactions between HIV-pre-exposure prophylaxis (PrEP) and gender-affirming hormones. In this study, we evaluated emtricitabine (F, FTC)/tenofovir (TFV) disoporoxil fumarate (TDF) pharmacokinetics (PK) among adolescent and young adult transgender persons receiving gender-affirming hormone therapy (GAHT). This was a prospective, observational study among transgender women (TW) and men (TM) without HIV, 15-24 years of age, receiving GAHT (estradiol with/without spironolactone, or testosterone). Participants received 1 month of directly observed daily F/TDF. Weekly convenience blood samples were collected for plasma TFV and FTC, and intracellular TFV-diphosphate (TFV-DP) and FTC-triphosphate (FTC-TP) in peripheral blood mononuclear cells (PBMC) and dried blood spots (DBS). After 2-3 weeks of F/TDF dosing, intensive PK sampling was conducted. PK parameters were estimated using noncompartmental methods. Data were log-transformed and compared between TM and TW, and to historical data among cisgender adults. Plasma TFV exposures were similar between TM and TW [geometric mean ratio (GMR); confidence interval (95% CI): 1.06 (0.89-1.28)], whereas FTC plasma exposures were 21% higher in TM versus TW (95% CI: 1.07-1.38). TFV-DP in PBMC and DBS and FTC-TP in DBS did not differ between TM versus TW after controlling for creatinine clearance (CrCl), but FTC-TP in PBMC remained 46% (95% CI: 1.15-1.86) higher in TM versus TW. All PK exposures were within expected ranges based on historical studies. TM had higher FTC exposures compared with TW, but overall plasma and intracellular exposures for both drugs were within the range of historical studies, suggesting high PrEP efficacy will be retained in adolescent and young adult transgender persons. Registered at ClinicalTrials.gov (NCT03652623).

Impact of feminizing hormone therapy on tenofovir and emtricitabine plasma pharmacokinetics: a nested drug-drug interaction study in a cohort of Brazilian transgender women using HIV pre-exposure prophylaxis

OBJECTIVES

Potential interactions between feminizing hormone therapy (FHT) and pre-exposure prophylaxis (PrEP) may be a barrier to PrEP use among transgender women (TGW). We aimed to assess the impact of FHT on PrEP plasma pharmacokinetics (PK) among TGW.

METHODS

This was a PK substudy of the effects of FHT on tenofovir disoproxil fumarate/emtricitabine nested to a trans-specific PrEP demonstration study (NCT03220152). Participants were assigned to receive PrEP only (noFHT) or standardized FHT (sFHT; oestradiol valerate 2-6 mg plus spironolactone 100-300 mg) plus PrEP for 12 weeks, after which they could start any FHT (aFHT). Short- and long-term PK assessment occurred at Weeks 12 and 30-48, respectively (plasma samples prior and 0.5, 1, 2, 4, 6, 8 and 24 h after dose). Non-compartmental PK parameters of tenofovir and emtricitabine were compared as geometric mean ratios (GMRs) between noFHT and PrEP and FHT (sFHT at short-term PK; aFHT at long-term PK) participants.

RESULTS

No differences in tenofovir and emtricitabine plasma PK parameters were observed between the short-term PK of noFHT (n = 12) and sFHT participants (n = 18), except for emtricitabine Cmax [GMR: 1.15 (95% CI: 1.01-1.32)], or between noFHT short-term PK and aFHT long-term PK (n = 13). Most participants were on oestradiol valerate 2 mg at the short-term PK (56%) and 4 mg at the long-term PK (54%). Median (IQR) oestradiol levels were 56.8 (43.2-65.4) pg/mL at short-term PK (sFHT) and 44.8 (24.70-57.30) pg/mL at long-term PK (aFHT). No participants in this analysis seroconverted during the study.

CONCLUSIONS

Our results indicate no interaction of FHT on tenofovir levels, further supporting PrEP use among TGW using FHT.

Barriers and Facilitators to HIV Pre-Exposure Prophylaxis Uptake, Adherence, and Persistence Among Transgender Populations in the United States: A Systematic Review

HIV pre-exposure prophylaxis (PrEP) is highly effective at preventing HIV; however, PrEP use among transgender individuals remains low. We conducted a systematic review to identify barriers and facilitators to PrEP uptake, adherence, and persistence among transgender individuals in the United States. We conducted a literature search in PubMed and CINAHL databases in March 2021 and followed PRISMA guidelines. Studies were eligible if they were published in a peer-reviewed journal and reported interest, uptake, adherence, and/or persistence of PrEP use among transgender individuals. Articles that did not disaggregate results for transgender participants were excluded. Data from included articles were coded using content analysis and narratively synthesized using a framework matrix. We screened 254 unique articles published after US Food and Drug Administration approval of PrEP, and 33 articles were included in the review. Five themes were identified in the literature, including (1) PrEP concentrations were lower among individuals taking feminizing hormones, but the difference did not appear clinically significant; (2) concerns regarding interactions between gender-affirming hormone therapy and PrEP remain a large barrier; (3) PrEP initiation may facilitate increased self-advocacy and self-acceptance; (4) lack of trust in medical institutions impacts PrEP uptake; and (5) social networks have a significant influence on PrEP knowledge, interest, and adherence. Additional research is needed involving transgender men and nonbinary persons, and efforts to improve PrEP persistence among the transgender community are needed. Training health care providers to provide inclusive and affirming care is perhaps one of the strongest areas for intervention to increase PrEP uptake and persistence.

Population pharmacokinetics of tenofovir, emtricitabine and intracellular metabolites in transgender women

Aims

Transgender women (TGW) have been underrepresented in trials and use gender‐affirming hormonal therapies (GAHT) that may alter renal function by significantly increasing creatinine clearance. Population pharmacokinetic (popPK) models and simulations would aid in understanding potential differences in emtricitabine/tenofovir disproxil fumarate (F/TDF) parent–metabolite concentrations in TGW on GAHT when compared to cisgender men (CGM) not exposed to GAHT.

Methods

Pharmacokinetic (PK) data from a Phase 1, open‐label clinical trial with directly observed therapy of daily F/TDF consisting of 8 TGW and 8 CGM was utilized for model building. PopPK analysis was performed using nonlinear mixed effects modelling (NONMEM 7.5.0). Covariates of body weight, creatinine clearance, and gender were evaluated. Final models were subjected to Monte Carlo simulations to compare drug exposure following once daily and on‐demand (IPERGAY 2 + 1 + 1) dosing of F/TDF.

Results

Tenofovir (TFV) and emtricitabine PK were best described by a 2‐compartment model, first‐order absorption/elimination with absorption lag time. Parent models were linked to their metabolites by first order formation and elimination. Creatinine clearance was a significant covariate influencing clearance in both models. Simulations demonstrated that at least 2, weekly 2 + 1 + 1 cycles of on‐demand dosing in TGW on GAHT is necessary for TFV‐diphosphate to reach similar exposure after the initial week of on‐demand dosing in CGM not on GAHT.

Conclusion

PopPK models of TFV, emtricitabine and intracellular metabolites in TGW were established. Dose simulations revealed that TGW should be treated for at least 2 weeks to have comparable exposures to CGM.

Higher colorectal tissue HIV infectivity in cisgender women compared with MSM before and during oral preexposure prophylaxis

OBJECTIVE

The objective of this study was to compare HIV-negative cisgender women (CGW) with MSM for mucosal tissue differences in pharmacokinetics, HIV infectivity and cell phenotype.

DESIGN

A substudy of HPTN 069/ACTG A5305, 48-week study of three oral candidate preexposure prophylaxis regimens: maraviroc, maraviroc/emtricitabine and maraviroc/tenofovir disoproxil fumarate (TDF) compared with a TDF/emtricitabine control group.

METHODS

Plasma, peripheral blood mononuclear cells and cervical and colorectal tissue biopsies were collected at Baseline (no drug), Week 24 and 48 (on drug), and Week 49 (1-week postdrug). Drug concentrations were assessed in all matrices. HIV infectivity was assessed using tissue biopsy 'explants' challenged with HIV ex vivo followed by HIV p24 measurement. Flow cytometry evaluated colorectal cell phenotype.

RESULTS

Thirty-seven CGW and 54 MSM participated. CGW's colorectal explant p24 was higher than MSM before (0.31 log10, P = 0.046), during (1.01-1.19 log10, P = 0.016) and one week after (0.61 log10, P = 0.011) study drug dosing. Pooling regimens, cervical explant p24 did not differ among visits. CGW had higher plasma maraviroc and colorectal tissue tenofovir diphosphate and lower colorectal tissue emtricitabine (all P < 0.005) compared with MSM. Each study drug's cervical tissue concentrations were more than 10-fold below paired colorectal concentrations (P < 0.001). Cell phenotype sex differences included 4% higher CD38+/CD8+ cells at baseline and 3-7% higher CD69+/CD8+ cells throughout Weeks 24-49 in CGW compared with MSM (P < 0.05).

CONCLUSION

Colorectal explants in CGW demonstrated greater HIV infectivity than MSM with and without study drugs. Small differences in adherence, drug concentration and colorectal tissue flow cytometry cannot fully explain this difference.

Pharmacotherapy considerations in transgender individuals living with human immunodeficiency virus

Pharmacotherapy considerations are often a concern for transgender individuals who are living with human immunodeficiency virus (HIV) due to concerns for drug-drug interactions between their hormone and antiretroviral therapies. Many of the first-line therapies offered to patients for the management of HIV have reduced concerns for safety, resistance, and drug-drug interactions. In this review, we highlight common medications and important considerations for caring for transgender people living with HIV.

Hepatocytic transcriptional signatures predict comparative drug interaction potential of rifamycin antibiotics

Current strategies to treat tuberculosis (TB) and co-morbidities involve multidrug combination therapies. Rifamycin antibiotics are a key component of TB therapy and a common source of drug–drug interactions (DDIs) due to induction of drug metabolizing enzymes (DMEs). Management of rifamycin DDIs are complex, particularly in patients with co-morbidities, and differences in DDI potential between rifamycin antibiotics are not well established. DME profiles induced in response to tuberculosis antibiotics (rifampin, rifabutin and rifapentine) were compared in primary human hepatocytes. We identified rifamycin induced DMEs, cytochrome P450 (CYP) 2C8/3A4/3A5, SULT2A, and UGT1A4/1A5 and predicted lower DDIs of rifapentine with 58 clinical drugs used to treat co-morbidities in TB patients. Transcriptional networks and upstream regulator analyses showed FOXA3, HNF4α, NR1I2, NR1I3, NR3C1 and RXRα as key transcriptional regulators of rifamycin induced DMEs. Our study findings are an important resource to design effective medication regimens to treat common co-conditions in TB patients.

Drug Interactions with Gender-Affirming Hormone Therapy: Focus on Antiretrovirals and Direct Acting Antivirals

INTRODUCTION

Gender-affirming care may include hormonal therapy to attain desired health outcomes in transgender (trans) individuals. To provide safe, affirming medical care for trans patients, health care providers must identify and manage drug-drug interactions (DDIs) between gender affirming hormonal therapy (GAHT) and other medication therapies.

AREAS COVERED

This review summarizes available data on DDIs between GAHT and antiretrovirals (ARVs) or hepatitis C direct acting antivirals (DAAs). Potential pharmacokinetic and pharmacodynamic DDIs are predicted based on GAHT, ARV, and DAA pharmacology and adverse event profiles. Clinical management strategies are discussed.

EXPERT OPINION

GAHT may be involved in pharmacokinetic and/or pharmacodynamic DDIs. Certain ARV classes (non-nucleoside reverse transcriptase inhibitors, protease inhibitors) may alter GAHT disposition, whereas selected ARVs (unboosted integrase inhibitors, doravirine, or rilpivirine) may have less impact on GAHT. DAAs may interact with GAHT, but the clinical relevance is unclear. ARV- and/or DAA-associated side effects (including depression, cardiovascular disease, hyperlipidemia) are important to consider in the clinical management of trans patients. Clinicians must evaluate potential DDIs and overlapping side effects between ARVs, DAAs and GAHT when providing care for trans patients.