Pharmacokinetics of tenofovir alafenamide, emtricitabine, and dolutegravir in a patient on peritoneal dialysis.

INTRODUCTION: Peritoneal dialysis (PD) is an effective renal replacement modality in people with HIV (PWH) with end-stage kidney disease (ESKD), particularly those with residual kidney function. Data on pharmacokinetics (PK) of antiretrovirals in patients on peritoneal dialysis are limited. METHODS: A single-participant study was performed on a 49-year-old gentleman with ESKD on PD and controlled HIV on once daily dolutegravir (DTG) 50 mg + tenofovir alafenamide (TAF) 25 mg / emtricitabine (FTC) 200 mg. He underwent serial blood plasma, peripheral blood mononuclear cell, and urine PK measurements over 24 h after an observed DTG + FTC/TAF dose. RESULTS: Plasma trough (Cmin) concentrations of TAF, tenofovir (TFV), FTC, and DTG were 0.05, 164, 1,006, and 718 ng/mL, respectively. Intracellular trough concentrations of TFV-DP and FTC-TP were 1142 and 11,201 fmol/million cells, respectively. Compared to published mean trough concentrations in PWH with normal kidney function, observed TFV and FTC trough concentrations were 15.5- and 20-fold higher, while intracellular trough concentrations of TFV-DP and FTC-TP were 2.2-fold and 5.4-fold higher, respectively. TFV and FTC urine levels were 20 times lower than in people with normal GFR. CONCLUSIONS: In a single ESKD PWH on PD, daily TAF was associated with plasma TFV and intracellular TFV-DP trough concentrations 15-fold and 2-fold higher than those of people with uncompromised kidney function, potentially contributing to nephrotoxicity. This suggests that TFV accumulates on PD; thus, daily TAF in PD patients may require dose adjustment or regimen change to optimize treatment, minimize toxicity, and preserve residual kidney function.

Mapping Colorectal Distribution of Cell-free and Cell-associated HIV Surrogates Following Simulated Anal Intercourse to Aid Rectal Microbicide Development.

BACKGROUND: Anal sex remains the greatest HIV transmission risk for men who have sex with men and carries substantial population attributable risk among women. Despite a growing array of HIV pre-exposure prophylaxis (PrEP) options, rectal microbicides remain desirable as on demand, non-systemic PrEP. Rectal microbicide product development for PrEP requires understanding the spatiotemporal distribution of HIV infectious elements in the rectosigmoid to optimize formulation development. SETTING: Outpatient setting with healthy research participants. METHODS: Six healthy men underwent simulated receptive anal sex with an artificial phallus fitted with a triple lumen catheter in the urethral position. To simulate ejaculation of HIV-infected semen, autologous seminal plasma laden with autologous blood lymphocytes from apheresis labeled with 111Indium-oxine (cell-associated) and 99mTechnetium-sulfur colloid (cell-free) as HIV surrogates were injected into the rectal lumen through the phallic urethra. Spatiotemporal distribution of each radioisotope was assessed using SPECT/CT over eight hours. Analysis of radiolabel distribution used a flexible principal curve algorithm to quantitatively estimate rectal lumen distribution. RESULTS: Cell-free and cell-associated HIV surrogates distributed to a maximal distance of 15 and 16 cm, respectively, from the anorectal junction (∼19 and ∼20 cm from the anal verge), with a maximal signal intensity located 6 and 7 cm, respectively. There were no significant differences in any distribution parameters between cell-free and cell-associated HIV surrogate. CONCLUSIONS: Cell-free and cell-associated HIV surrogate distribution in the rectosigmoid can be quantified with spatiotemporal pharmacokinetic methods. These results describe the ideal luminal target distribution to guide rectal microbicide development.

Tenofovir Douche as HIV Preexposure Prophylaxis for Receptive Anal Intercourse: Safety, Acceptability, Pharmacokinetics, and Pharmacodynamics (DREAM 01).

BACKGROUND: Despite highly effective HIV preexposure prophylaxis (PrEP) options, no options provide on-demand, nonsystemic, behaviorally congruent PrEP that many desire. A tenofovir-medicated rectal douche before receptive anal intercourse may provide this option. METHODS: Three tenofovir rectal douches-220 mg iso-osmolar product A, 660 mg iso-osmolar product B, and 660 mg hypo-osmolar product C-were studied in 21 HIV-negative men who have sex with men. We sampled blood and colorectal tissue to assess safety, acceptability, pharmacokinetics, and pharmacodynamics. RESULTS: The douches had high acceptability without toxicity. Median plasma tenofovir peak concentrations for all products were several-fold below trough concentrations associated with oral tenofovir disoproxil fumarate (TDF). Median colon tissue mucosal mononuclear cell (MMC) tenofovir-diphosphate concentrations exceeded target concentrations from 1 hour through 3 to 7 days after dosing. For 6-7 days after a single product C dose, MMC tenofovir-diphosphate exceeded concentrations expected with steady-state oral TDF 300 mg on-demand 2-1-1 dosing. Compared to predrug baseline, HIV replication after ex vivo colon tissue HIV challenge demonstrated a concentration-response relationship with 1.9 log10 maximal effect. CONCLUSIONS: All 3 tenofovir douches achieved tissue tenofovir-diphosphate concentrations and colorectal antiviral effect exceeding oral TDF and with lower systemic tenofovir. Tenofovir douches may provide a single-dose, on-demand, behaviorally congruent PrEP option, and warrant continued development. Clinical Trials Registration . NCT02750540.

EVG/COBI/FTC/TAF Bioequivalence Comparing Whole Tablets with Tablets Dissolved in Tap Water.

Medication adherence can be challenging for persons with difficulty swallowing tablets. We investigated the bioequivalence of a dissolved tablet when compared with that of a whole tablet of the fixed-dose combination elvitegravir (EVG)/cobicistat (COBI)/emtricitabine (FTC)/tenofovir (TFV) alafenamide fumarate (TAF). A within-subject fixed-order two-period open-label study was conducted in 12 HIV-negative research participants after obtaining informed consent. Participants took a single dose each of the whole tablet and dissolved tablet under direct observation, separated by a 14-day washout period. The dissolved tablet was prepared by adding one whole EVG/COBI/FTC/TAF tablet to 120 mL tap water and stirring. Both dosage types were taken with a standardized meal. Plasma samples were obtained for 72 h postdose. Plasma EVG, FTC, TAF, and TFV were analyzed with liquid chromatographic-tandem mass spectrometric methods. Peak plasma concentration (Cmax) and the area under the concentration-time curve extrapolated to infinity (AUC0-∞) were estimated using WinNonlin software (v.8.3). The primary outcome was bioequivalence consistent with FDA guidance using the 90% confidence interval or the geometric mean ratio. Of 12 participants, 7 were black (58%) and 5 were white (42%), 4 were women (33%), 8 were men (67%), and the mean age was 43.6 years (23-54). There were no complaints about taste with the dissolved tablet. Bioequivalence was established only for FTC. EVG Cmax and AUC0-∞ were higher by 18% and 12%, respectively, when taking the dissolved compared with the whole tablet. TAF AUC0-∞ and Cmax were both 8% lower, whereas TFV Cmax and AUC0-∞ were 8% and 5% lower, respectively, when taken after dissolution. EVG/COBI/FTC/TAF dissolved rapidly in water and had no unpleasant taste. Increases in EVG and decreases in TAF and TFV concentrations were observed when taking dissolved EVG/COBI/FTC/TAF. These changes were judged to be clinically insignificant. Dissolving EVG/COBI/FTC/TAF in water may be suitable for those with pill swallowing challenges. The trial was registered on (//clinicaltrials.gov NCT03717129).

Interaction of Depot Medroxyprogesterone Acetate and Tenofovir Disoproxil Fumarate/Emtricitabine on Peripheral Blood Mononuclear Cells and Cervical Tissue Susceptibility to HIV Infection and Pharmacokinetics.

BACKGROUND: Depot medroxyprogesterone acetate (DMPA) is a widely used contraceptive method. HIV pre-exposure prophylaxis with emtricitabine and tenofovir disoproxil fumarate (F/TDF) is highly effective in reducing HIV acquisition in women. We sought to determine the impact of DMPA on F/TDF pharmacokinetics and pharmacodynamics. METHODS: Twelve healthy premenopausal cisgender women were enrolled and each completed 4 sequential conditions: (1) baseline, (2) steady-state F/TDF alone, (3) steady-state F/TDF + DMPA, and (4) DMPA alone. Assessments included clinical, pharmacokinetic, viral infectivity (ex vivo challenge of peripheral blood mononuclear cells by X4- and R5-tropic green fluorescent protein pseudoviruses and cervical tissue by HIV BaL ), endocrine, immune cell phenotyping, and renal function. RESULTS: Compared with baseline, F/TDF (± DMPA) significantly decreased both %R5- and X4-infected CD4 T cells and F/TDF + DMPA decreased cervical explant p24 (all P < 0.05). The %R5- and X4-infected CD4 T cells were higher during DMPA alone than during F/TDF periods and lower than baseline (not statistically significant). Cervical explant p24 fell between baseline and F/TDF values (not statistically significant). There were neither statistically significant differences in F/TDF pharmacokinetics, including total or renal clearance of either antiviral drug, nor changes in glomerular filtration rate with the addition of DMPA. There were few immune cell phenotypic differences across conditions. CONCLUSIONS: F/TDF decreased HIV infection in both challenge assays, whereas DMPA alone did not enhance HIV infection in either challenge assay. DMPA did not alter F/TDF pharmacokinetics or renal function.

Hypo-osmolar rectal douche tenofovir formulation prevents simian/human immunodeficiency virus acquisition in macaques.

In spite of the rollout of oral pre-exposure prophylaxis (PrEP), the rate of new HIV infections remains a major health crisis. In the United States, new infections occur predominantly in men having sex with men (MSM) in rural settings where access to PrEP can be limited. As an alternative congruent with MSM sexual behavior, we have optimized and tested tenofovir (TFV) and analog-based iso-osmolar and hypo-osmolar (HOsm) rectal douches for efficacy against rectal simian/human immunodeficiency virus (SHIV) infection of macaques. Single TFV HOsm high-dose douches achieved peak plasma TFV levels similar to daily oral PrEP, while other formulations yielded lower concentrations. Rectal tissue TFV-diphosphate (TFV-DP) concentrations at the portal of virus entry, however, were markedly higher after HOsm douching than daily oral PrEP. Repeated douches led to significantly higher plasma TFV and higher TFV-DP concentrations in rectal tissue at 24 hours compared with single douches, without detectable mucosal or systemic toxicity. Using stringent repeated intrarectal SHIV exposures, single HOsm high-dose douches delivered greater protection from virus acquisition for more than 24 hours compared with oral PrEP. Our results demonstrate a rapid delivery of protective TFV doses to the rectal portal of virus entry as a potential low-cost and safe PrEP alternative.

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.

Multiparametric magnetic resonance imaging to characterize cabotegravir long-acting formulation depot kinetics in healthy adult volunteers.

AIM: Cabotegravir long-acting (LA) intramuscular (IM) injection is being investigated for HIV preexposure prophylaxis due to its potent antiretroviral activity and infrequent dosing requirement. A subset of healthy adult volunteers participating in a Phase I study assessing cabotegravir tissue pharmacokinetics underwent serial magnetic resonance imaging (MRI) to assess drug depot localization and kinetics following a single cabotegravir LA IM targeted injection. METHODS: Eight participants (four men, four women) were administered cabotegravir LA 600 mg under ultrasonographic-guided injection targeting the gluteal muscles. MRI was performed to determine injection-site location in gluteal muscle (IM), subcutaneous (SC) adipose tissue and combined IM/SC compartments, and to quantify drug depot characteristics, including volume and surface area, on Days 1 (≤2 hours postinjection), 3 and 8. Linear regression analysis examined correlations between MRI-derived parameters and plasma cabotegravir exposure metrics, including maximum observed concentration (Cmax ) and partial area under the concentration-time curve (AUC) through Weeks 4 and 8. RESULTS: Cabotegravir LA depot locations varied by participant and were identified in the IM compartment (n = 2), combined IM/SC compartments (n = 4), SC compartment (n = 1) and retroperitoneal cavity (n = 1). Although several MRI parameter and exposure metric correlations were determined, total depot surface area on Day 1 strongly correlated with plasma cabotegravir concentration at Days 3 and 8, Cmax and partial AUC through Weeks 4 and 8. CONCLUSION: MRI clearly delineated cabotegravir LA injection-site location and depot kinetics in healthy adults. Although injection-site variability was observed, drug depot surface area correlated with both plasma Cmax and partial AUC independently of anatomical distribution.

Examining the Safety, Pharmacokinetics, and Pharmacodynamics of a Rectally Administered IQP-0528 Gel for HIV Pre-Exposure Prophylaxis: A First-In-Human Study.

A lubricating microbicide gel designed for rectal and vaginal use would provide a behaviorally congruent strategy to enhance pre-exposure prophylaxis adherence and reduce HIV infection risk. In this study, we report the first-in-human evaluation of such a gel containing 1% IQP-0528, an investigational antiretroviral. Seven HIV-1-negative participants received one 10 mL rectal dose of radiolabeled 1% IQP-0528 gel. We assessed safety; IQP-0528 pharmacokinetics in plasma, and rectal and vaginal tissue; ex vivo local pharmacodynamics (PD); and colorectal distribution. The 1% gel was determined to be safe with one mild event attributed to study product and no effects on rectal tissue histology. All concentrations measured in plasma and vaginal tissue were below the limit of quantitation. Median IQP-0528 concentrations in rectal tissue exceeded the in vitro EC95 against HIV-1 (0.07 ng/mg) by 3-5 h of dosing and remained above this concentration for at least 24 h, despite a 3-log reduction in concentration over this duration of time. Rectal tissue PD-assessed by ex vivo HIV challenge-demonstrated significant p24 antigen reduction 3-5 h postdose compared with baseline (p = .05), but not 24-26 h postdose (p = .75). Single-photon emission computed tomography/computed tomography imaging revealed that product distribution was localized to the rectosigmoid. The IQP-0528 gel possesses desirable features for a topical microbicide including: local safety with no systemic absorption, delivery of locally high IQP-0528 concentrations, and significant reductions in ex vivo HIV infectivity. However, the gel is limited by its rapid clearance and inability to penetrate vaginal tissues following rectal dosing. Clinical Trial Registration number: NCT03082690.

Nimodipine improves cortical efficiency during working memory in healthy subjects.

The L-type calcium channel gene, CACNA1C, is a validated risk gene for schizophrenia and the target of calcium channel blockers. Carriers of the risk-associated genotype (rs1006737 A allele) have increased frontal cortical activity during working memory and higher CACNA1C mRNA expression in the prefrontal cortex. The aim of this study was to determine how the brain-penetrant calcium channel blocker, nimodipine, changes brain activity during working memory and other cognitive and emotional processes. We conducted a double-blind randomized cross-over pharmacoMRI study of a single 60 mg dose of oral nimodipine solution and matching placebo in healthy men, prospectively genotyped for rs1006737. With performance unchanged, nimodipine significantly decreased frontal cortical activity by 39.1% and parietal cortical activity by 42.8% during the N-back task (2-back > 0-back contrast; PFWE < 0.05; n = 28). Higher peripheral nimodipine concentrations were correlated with a greater decrease in activation in the frontal cortex. Carriers of the risk-associated allele, A (n = 14), had a greater decrease in frontal cortical activation during working memory compared to non-risk allele carriers. No differences in brain activation were found between nimodipine and placebo for other tasks. Future studies should be conducted to test if the decreased cortical brain activity after nimodipine is associated with improved working memory performance in patients with schizophrenia, particularly those who carry the risk-associated genotype. Furthermore, changes in cortical activity during working memory may be a useful biomarker in future trials of L-type calcium channel blockers.

Transgender women on oral HIV pre-exposure prophylaxis have significantly lower tenofovir and emtricitabine concentrations when also taking oestrogen when compared to cisgender men.

INTRODUCTION: Oral HIV Pre-Exposure Prophylaxis (PrEP) with tenofovir (TFV) disoproxil fumarate (TDF)/emtricitabine (FTC) is highly effective. Transgender women (TGW) have increased HIV risk, but have been underrepresented in trials. For TGW on oestrogens for gender-affirming hormone treatment (GAHT), TDF/FTC-oestrogen interactions may negatively affect HIV prevention or gender-affirming goals. Our aim was to evaluate any pharmacokinetic drug-drug interaction between GAHT and TDF/FTC. METHODS: We performed a pharmacokinetic study, in an urban outpatient setting in 2016 to 2018, of the effects of GAHT on TFV, FTC and the active forms TFV diphosphate (TFV-DP) and FTC triphosphate (FTC-TP) in eight TGW and eight cisgender men (CGM). At screening, participants were HIV negative. TGW were to maintain their GAHT regimens and have plasma oestradiol concentrations >100 pg/mL. Under direct observation, participants took oral TDF/FTC daily for seven days. At the last dose, blood was collected pre-dose, one, two, four, six, eight and twenty-four hours, and colon biopsies were collected at 24 hours to measure drug concentration. TGW versus CGM concentration comparisons used non-parametric tests. Blood and colon tissue were also obtained to assess kinase expression. RESULTS: Plasma TFV and FTC C24 (trough) concentrations in TGW were lower by 32% (p = 0.010) and 32% (p = 0.038) respectively, when compared to CGM. Plasma TFV and FTC 24-hr area under the concentration-time curve in TGW trended toward and was significantly lower by 27% (p = 0.065) and 24% (p = 0.028) respectively. Peak plasma TFV and FTC concentrations, as well as all other pharmacokinetic measures, were not statistically significant when comparing TGW to CGM. Oestradiol concentrations were not different comparing before and after TDF/FTC dosing. Plasma oestrogen concentration, renal function (estimated creatinine clearance and glomerular filtration rate), and TFV and FTC plasma concentrations (trough and area under the concentration-time curve) were all correlated. CONCLUSIONS: GAHT modestly reduces both TFV and FTC plasma concentrations. In TGW taking GAHT, it is unknown if this reduction will impact the HIV protective efficacy of a daily PrEP regimen. However, the combination of an on demand (2 + 1 + 1) PrEP regimen and GAHT may result in concentrations too low for reliable prevention of HIV infection.

Conceptual Design of a Universal Donor Screening Approach for Vaginal Microbiota Transplant.

The success of fecal microbiota transplant (FMT) in treating recurrent Clostridioides difficile infection has led to growing excitement about the potential of using transplanted human material as a therapy for a wide range of diseases and conditions related to microbial dysbiosis. We anticipate that the next frontier of microbiota transplantation will be vaginal microbiota transplant (VMT). The composition of the vaginal microbiota has broad impact on sexual and reproductive health. The vaginal microbiota in the "optimal" state are one of the simplest communities, dominated by one of only a few species of Lactobacillus. Diversity in the microbiota and the concomitant depletion of lactobacilli, a condition referred to as bacterial vaginosis (BV), is associated with a wide range of deleterious effects, including increased risk of acquiring sexually transmitted infections and increased likelihood of having a preterm birth. However, we have very few treatment options available, and none of them curative or restorative, for "resetting" the vaginal microbiota to a more protective state. In order to test the hypothesis that VMT may be a more effective treatment option, we must first determine how to screen donors to find those with minimal risk of pathogen transmission and "optimal" vaginal microbiota for transplant. Here, we describe a universal donor screening approach that was implemented in a small pilot study of 20 women. We further characterized key physicochemical properties of donor cervicovaginal secretions (CVS) and the corresponding composition of the vaginal microbiota to delineate criteria for inclusion/exclusion. We anticipate that the framework described here will help accelerate clinical studies of VMT.

Development of rectal enema as microbicide (DREAM): Preclinical progressive selection of a tenofovir prodrug enema.

HIV pre-exposure prophylaxis (PrEP) strategies have the potential to prevent millions of incident HIV infections each year. However, the efficacy of PrEP strategies has been plagued by issues of non-adherence, likely because of the difficulty in motivating otherwise healthy people to adhere to treatment regimens that require significant behavioral changes and daily discipline. An alternative approach to PrEP is to focus on strategies that fit in to normal, and even desirable, sexual behaviors, such as the use of cleansing enemas by men who have sex with men (MSM) prior to receptive anal intercourse (RAI). Here, we describe preclinical efforts toward optimizing a tenofovir (TFV)-based enema formulation for rectal PrEP. Using a murine model, we compared the plasma and tissue pharmacokinetics of TFV and various TFV prodrugs, including tenofovir disoproxil fumarate (TDF), tenofovir alafenamide (TAF), and hexadecyloxypropyl tenofovir (CMX157), after dosing as enema formulations with varying osmolality and ion content. We observed that the enema vehicle composition played a more important role than the TFV prodrug properties in achieving rapid and therapeutically relevant tenofovir diphosphate (TFV-DP) concentrations in mouse colorectal tissue. Our results support the next steps, which are further preclinical (non-human primate) and clinical development of a hypo-osmolar TFV enema product for rectal PrEP.

Rectal Douching Practices Associated with Anal Intercourse: Implications for the Development of a Behaviorally Congruent HIV-Prevention Rectal Microbicide Douche.

Tenofovir administration via rectal douching results in higher rectal-mucosa drug concentration than oral administration. Many who engage in receptive anal intercourse (RAI) use cleansing rectal douches. To inform development of a behaviorally-congruent tenofovir douche, 4751 individuals ≥ 18 years-old, born male, from all US states/territories, who engaged in anal intercourse responded to an online survey. Of those who reported RAI in the prior 3 months, 80% douched beforehand, 82% within 1 h, mean 2.9 consecutive applications; 27% douched afterwards, 83% within 1 h, mean 1.7 consecutive applications. Among multidose users, 78% applied doses within 2 min, and 76% retained liquid < 1 min. Most used tap water (89%) in an enema bottle (50%) or rubber bulb (43%), and douched for cleanliness (97%), to avoid smelling bad (65%), and to enhance pleasure (24%). 98% reported high likelihood of using an HIV-prevention douche. An ideal product will protect within a user's typical number of applications, within 1 h, and be dissolvable in tap water.

Fecal Coliform Bacterial Detection to Assess Enema Adherence in HIV Prevention Clinical Studies.

Evaluating the efficacy of any HIV prevention strategy is dependent on ensuring and objectively monitoring adherence to the intervention. Medicated rectal enemas are a potential method for providing topical, episodic HIV prophylaxis during receptive anal intercourse. Assessing adherence to recommended enema dosing regimens is essential in evaluating the utility of this strategy. We utilized fecal coliform bacteria on used enema tips as a marker for enema use. Enema tip coliforms were tested by repurposing a microtiter plate-based water quality test designed to detect fecal contamination of water. Coliform detection occurred with 100% sensitivity and specificity when tips were assayed on day of use. The assay performed well post-7 day sample storage at room temperature, yielding a sensitivity of 80% and specificity of 93%. All (n = 64) samples collected in a subset of the DREAM-01 rectal microbicide enema clinical trial tested positive, even when tips were evaluated > 7 days post-reported use. The coliform-based enema tip assay allows monitoring of adherence in interventions involving rectal enemas in a sensitive, specific and inexpensive manner. The test performs well in clinical trial settings.

MALDI Mass Spectrometry Imaging Reveals Heterogeneous Distribution of Tenofovir and Tenofovir Diphosphate in Colorectal Tissue of Subjects Receiving a Tenofovir-Containing Enema.

Efforts to prevent human immunodeficiency virus (HIV) infection via pre-exposure prophylaxis (PrEP) include the development of anti-HIV drugs as microbicides for topical application to the mucosal sites of infection; however, although understanding the distribution profiles of these drugs in target mucosal tissues is of critical importance to guiding their optimization, data in this regard are largely lacking. With this in mind, we developed a matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) approach to visualize tenofovir (TFV), an HIV nucleotide analog reverse-transcriptase inhibitor under investigation for use as a topical microbicide, and its active metabolite TFV-diphosphate (TFV-DP) in colorectal biopsies obtained from healthy volunteers who received TFV-containing enemas. Application of MALDI MSI resulted in sufficient spatial resolution to visualize both TFV and TFV-DP and revealed heterogeneity in the distribution profiles of both analytes, including the presence of regions in which TFV and TFV-DP were undetectable, in colorectal tissue at two different time points and concentrations. Cell-specific staining for CD4 T and CD11c dendritic cells, which are important to the establishment of HIV infection, demonstrated that the TFV and TFV-DP distributions were independent of these cell types. MALDI MSI of endogenous lipids demonstrated that the heterogeneity observed for TFV and TFV-DP was not a function of tissue composition or processing. These data provide unique insight into the spatial distribution of TFV and TFV-DP in human colorectal tissue. In addition, this work establishes an approach that can be leveraged to directly detect and visualize these clinically important analytes more broadly in tissue.

Short Communication: Specimen Processing Impacts Tissue Tenofovir Pharmacokinetic Measurements.

Antiretroviral drug concentrations at sites of HIV exposure are important drivers that influence the development of HIV pre-exposure chemoprophylaxis strategies and regimens. We assessed the effect of collection method-in the presence or absence of tissue culture medium-on tenofovir (TFV) and tenofovir diphosphate (TFV-DP) concentrations in colonic biopsies. We find significant baseline interbiopsy variation in TFV (38% CV) and TFV-DP (33% CV) concentrations. Incubation in medium leads to a fluid absorption-driven twofold increase in tissue weight with a concomitant 75% decrease in weight-adjusted tissue TFV concentrations 120 min post-incubation. In contrast, adjusted TFV-DP concentrations decrease by only 25% during the same period, with this difference not achieving statistical significance. Although colonic biopsies should be collected in the absence of medium for accurate TFV concentrations, the presence of medium does not significantly impact TFV-DP-dependent pharmacokinetic or pharmacodynamic assays. Appropriate assessment of tissue drug concentrations should account for biopsy collection method and drug mechanism of action.

Hypo-osmolar Formulation of Tenofovir (TFV) Enema Promotes Uptake and Metabolism of TFV in Tissues, Leading to Prevention of SHIV/SIV Infection.

Oral preexposure prophylaxis (PrEP) has been approved for prophylaxis of HIV-1 transmission but is associated with high costs and issues of adherence. Protection from anal transmission of HIV using topical microbicides and methods congruent with sexual behavior offers the promise of improved adherence. We compared the pharmacokinetics (PK) and ex vivo efficacy of iso-osmolar (IOsm) and hypo-osmolar (HOsm) rectal enema formulations of tenofovir (TFV) in rhesus macaques. Single-dose PK of IOsm or HOsm high-dose (5.28 mg/ml) and low-dose (1.76 mg/ml) formulations of TFV enemas were evaluated for systemic uptake in blood, colorectal biopsy specimens, and rectal CD4+ T cells. Markedly higher TFV concentrations were observed in plasma and tissues after administration of the HOsm high-dose formulation than with all other formulations tested. TFV and TFV diphosphate (TFV-DP) concentrations in tissue correlated for the HOsm high-dose formulation, demonstrating rapid uptake and transformation of TFV to TFV-DP in tissues. TFV-DP amounts in tissues collected at 1 and 24 h were 7 times and 5 times higher, respectively (P < 0.01), than the ones collected in tissues with the IOsm formulation. The HOsm high-dose formulation prevented infection in ex vivo challenges of rectal tissues collected at 1, 24, and 72 h after the intrarectal dosing, whereas the same TFV dose formulated as an IOsm enema was less effective.

Comparison of the Pharmacokinetics and Pharmacodynamics of Single-Dose Tenofovir Vaginal Film and Gel Formulation (FAME 05).

OBJECTIVE: Although preexposure prophylaxis with oral tenofovir (TFV) disoproxil fumarate/emtricitabine reduces HIV acquisition rates, poor adherence to and acceptability of daily vaginal gels have led to development of vaginal film formulations to improve adherence and, potentially, to enable episodic use. STUDY DESIGN: In this 2-arm, cross-over study of a fast-dissolving tenofovir film (40 mg) compared with a previously studied semisolid tenofovir 1% gel (40 mg), 10 healthy women received a single vaginal dose of each study product. Clinical, pharmacokinetic, and antiviral assessments were performed over 1 week after dose. RESULTS: Nine of 10 participants experienced mild to moderate adverse effects, similar between products, with no severe adverse events or events attributed to study products. TFV concentrations after film dosing exceeded concentrations after gel dosing in plasma between 8 and 24 hours (P ≤ 0.02). TFV concentrations in cervicovaginal fluid and both TFV and TFV diphosphate concentrations in cervical tissue homogenates were higher after film dosing (all P values < 0.04). The differences ranged from median (interquartile range) 2.9-fold (1.1, 9.0; midvaginal cervicovaginal fluid) to 4.4-fold (2.9, 7.7; plasma). Neither film nor gel demonstrated reduced cervical tissue biopsy infectivity after ex vivo HIV challenge. CONCLUSION: Single-dose tenofovir film demonstrated consistently higher concentrations in plasma and cervicovaginal samples when compared with gel during the first day after dosing. Single-dose cervical tissue TFV-diphosphate concentrations at 5 hours exceeded steady-state concentrations previously reported with daily oral Truvada dosing. Tenofovir film may provide an alternative to tenofovir oral and gel formulations. Clinical efficacy remains to be tested.

Rectal Douching Associated with Receptive Anal Intercourse: A Literature Review.

To inform the development of HIV-prevention rectal douches, we reviewed the scientific literature and online instructional videos on rectal douching associated with receptive anal intercourse (RAI). Up to 88% of men who practice RAI ever have douched, while 43-64% have douched recently. Of them, 87-97% douche before RAI and 13-48% afterwards. Water, occasionally mixed with soap or salt, is used most often, although up to 31% of men use commercial products. Douching is more common among individuals reporting substance use, sexually transmitted infections, or being HIV-infected. Scant literature is available on women's rectal douching practices, but it is apparently less frequent than among men (32 vs. 70%). Videos advise using 2-3 doses of liquid and retaining it for 10-30 s before expelling. These findings can inform the development of a safe and acceptable rectal douche for HIV prevention.