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Leung E, Cottrell ML, Sykes C, White N, Kashuba ADM, Dumond JB. A multicompartment population PK model to predict tenofovir and emtricitabine mucosal tissue concentrations for HIV prevention. CPT Pharmacometrics Syst Pharmacol 2023; 12:1922-1930. [PMID: 37814498 PMCID: PMC10725258 DOI: 10.1002/psp4.13042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 08/02/2023] [Accepted: 08/28/2023] [Indexed: 10/11/2023] Open
Abstract
A priori use of mathematical modeling and simulation to predict outcomes from incomplete adherence or reduced frequency dosing strategies may mitigate the risk of clinical trial failure with HIV pre-exposure prophylaxis regimens. We developed a semi-physiologic population pharmacokinetic model for two antiretrovirals and their active intracellular metabolites in three mucosal tissues using pharmacokinetic data from a phase I, dose-ranging study. Healthy female volunteers were given a single oral dose of tenofovir disoproxil fumarate (150, 300, or 600 mg) or emtricitabine (100, 200, or 400 mg). Simultaneous co-modeling of all data was performed on a Linux cluster. A 16 compartment, bolus input, linear kinetic model best described the data, containing 986 observations in 23 individuals across three matrices and four analytes. Combined with a defined efficacious concentration target in mucosal tissues, this model can be used to optimize the dose and dosing frequency through Monte-Carlo simulations.
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Affiliation(s)
- Erick Leung
- Division of Pharmacotherapy and Experimental TherapeuticsUniversity of North Carolina UNC Eshelman School of PharmacyChapel HillNorth CarolinaUSA
- Present address:
Certara, Inc.PrincetonNew JerseyUSA
| | - Mackenzie L. Cottrell
- Division of Pharmacotherapy and Experimental TherapeuticsUniversity of North Carolina UNC Eshelman School of PharmacyChapel HillNorth CarolinaUSA
| | - Craig Sykes
- Division of Pharmacotherapy and Experimental TherapeuticsUniversity of North Carolina UNC Eshelman School of PharmacyChapel HillNorth CarolinaUSA
| | - Nicole White
- University of North Carolina School of MedicineChapel HillNorth CarolinaUSA
| | - Angela D. M. Kashuba
- Division of Pharmacotherapy and Experimental TherapeuticsUniversity of North Carolina UNC Eshelman School of PharmacyChapel HillNorth CarolinaUSA
- University of North Carolina School of MedicineChapel HillNorth CarolinaUSA
| | - Julie B. Dumond
- Division of Pharmacotherapy and Experimental TherapeuticsUniversity of North Carolina UNC Eshelman School of PharmacyChapel HillNorth CarolinaUSA
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Scott RK, Yu Y, Marzinke MA, Coleman JS, Hendrix CW, Bies R. Clinical trial simulation to evaluate tenofovir disoproxil fumarate/emtricitabine HIV pre-exposure prophylaxis dosing during pregnancy. FRONTIERS IN REPRODUCTIVE HEALTH 2023; 5:1224580. [PMID: 37830105 PMCID: PMC10565828 DOI: 10.3389/frph.2023.1224580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Accepted: 09/04/2023] [Indexed: 10/14/2023] Open
Abstract
Objective To evaluate upward-adjustment of tenofovir disoproxil fumarate (TDF)/emtricitabine (FTC) pre-exposure prophylaxis (PrEP) dosing during pregnancy in order to maintain target plasma concentrations associated with HIV protection. Design Population pharmacokinetic (PK) modeling and clinical trial simulation (CTS). Material and methods We developed population pharmacokinetic models for TFV and FTC using data from the Partners Demonstration Project and a PK study of TDF/FTC among cisgender women by Coleman et al., and performed an in-silico simulation. Pregnancy-trimester was identified as a significant covariate on apparent clearance in the optimized final model. We simulated 1,000 pregnant individuals starting standard daily oral TDF/FTC (300 mg/200 mg) prior to pregnancy. Upon becoming pregnant, simulated patients were split into two study arms: one continuing standard-dose and the other receiving double standard-dose throughout pregnancy. Results Standard-dose trough TFV concentrations were significantly lower in pregnancy compared to pre-pregnancy, with 34.0%, 43.8%, and 65.1% of trough plasma concentrations below the lower bound of expected trough concentrations presumed to be the protective threshold in the 1st, 2nd, and 3rd trimesters, respectively. By comparison, in the simulated double-dose group, 10.7%, 14.4%, and 27.8% of trough concentrations fell below the estimated protective thresholds in the 1st, 2nd, and 3rd trimesters, respectively. The FTC trough plasma concentration during pregnancy was also lower than pre-pregnancy, with 45.2% of the steady-state trough concentrations below the estimated protective trough concentrations of FTC. In the pregnancy-adjusted double-dose group, 24.1% of trough plasma concentrations were lower than protective levels. Conclusions Our simulation shows >50% of research participants on standard dosing would have 3rd trimester trough plasma TFV concentrations below levels associated with protection. This simulation provides the quantitative basis for the design of prospective TDF/FTC studies during pregnancy to evaluate the safety and appropriateness of pregnancy-adjusted dosing.
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Affiliation(s)
- Rachel K Scott
- Women's Health Research, MedStar Health Research Institute, Washington, DC, United States
| | - Yifan Yu
- Department of Pharmaceutical Sciences, University of Buffalo, Buffalo, NY, United States
| | - Mark A Marzinke
- Division of Clinical Pharmacology, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Jenell S Coleman
- Department of Gynecology and Obstetrics, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Craig W Hendrix
- Division of Clinical Pharmacology, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Robert Bies
- Department of Pharmaceutical Sciences, University of Buffalo, Buffalo, NY, United States
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3
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Hughes JP, Williamson BD, Krakauer C, Chau G, Ortiz B, Wakefield J, Hendrix C, Amico KR, Holtz TH, Bekker LG, Grant R. Combining information to estimate adherence in studies of pre-exposure prophylaxis for HIV prevention: Application to HPTN 067. Stat Med 2022; 41:1120-1136. [PMID: 35080038 PMCID: PMC8881405 DOI: 10.1002/sim.9321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 12/29/2021] [Accepted: 12/30/2021] [Indexed: 11/11/2022]
Abstract
In trials of oral HIV pre-exposure prophylaxis (PrEP), multiple approaches have been used to measure adherence, including self-report, pill counts, electronic dose monitoring devices, and biological measures such as drug levels in plasma, peripheral blood mononuclear cells, hair, and/or dried blood spots. No one of these measures is ideal and each has strengths and weaknesses. However, accurate estimates of adherence to oral PrEP are important as drug efficacy is closely tied to adherence, and secondary analyses of trial data within identified adherent/non-adherent subgroups may yield important insights into real-world drug effectiveness. We develop a statistical approach to combining multiple measures of adherence and show in simulated data that the proposed method provides a more accurate measure of true adherence than self-report. We then apply the method to estimate adherence in the ADAPT study (HPTN 067) in South African women.
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Affiliation(s)
- James P Hughes
- Department of Biostatistics, University of Washington, Seattle, Washington, USA.,Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA
| | - Brian D Williamson
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA.,Kaiser Permanente Washington Health Research Institute, Seattle, Washington, USA
| | - Chloe Krakauer
- Department of Biostatistics, University of Washington, Seattle, Washington, USA.,Kaiser Permanente Washington Health Research Institute, Seattle, Washington, USA
| | - Gordon Chau
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA
| | - Brayan Ortiz
- Modeling and Optimization, Amazon, Bellevue, Washington, USA
| | - Jon Wakefield
- Department of Biostatistics, University of Washington, Seattle, Washington, USA
| | - Craig Hendrix
- School of Medicine, Johns Hopkins University, Baltimore, Maryland, USA
| | - K Rivet Amico
- School of Public Health, University of Michigan, Ann Arbor, Michigan, USA
| | - Timothy H Holtz
- Division of HIV/AIDS Prevention, Centers for Disease Control and Prevention, Atlanta, Georgia, USA.,Thailand Ministry of Public Health-U.S. Centers for Disease Control and Prevention Collaboration, Nonthaburi, Thailand.,Office of AIDS Research, National Institutes of Health, Bethesda, Maryland, USA
| | - Linda-Gail Bekker
- The Desmond Tutu HIV Centre, University of Cape Town, Cape Town, South Africa
| | - Robert Grant
- Gladstone Institutes, University of California, San Francisco, San Francisco, California, USA.,San Francisco AIDS Foundation, San Francisco, California, USA
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4
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Tenofovir Plasma Concentration from Preexposure Prophylaxis at the Time of Potential HIV Exposure: a Population Pharmacokinetic Modeling and Simulation Study Involving Serodiscordant Couples in East Africa. Antimicrob Agents Chemother 2019; 63:AAC.00446-19. [PMID: 31182536 PMCID: PMC6658796 DOI: 10.1128/aac.00446-19] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Accepted: 06/03/2019] [Indexed: 01/26/2023] Open
Abstract
The Partners Demonstration Project was a prospective, open-label, implementation science-driven study of preexposure prophylaxis (PrEP) among heterosexual HIV serodiscordant couples in Kenya and Uganda. Adherence data were collected using the Medication Event Monitoring System (MEMS), and time of sexual activity was collected using the mobile phone short message service (SMS). Two plasma samples were collected at a single study visit. We integrated adherence, pharmacokinetics, and SMS data using a population pharmacokinetic (PopPK) model to simulate tenofovir plasma concentrations from PrEP at the time of sexual activity. In the first stage of this analysis, we used data from the current study to update a prior PopPK model of tenofovir (TFV) developed with data from the Partners PrEP Study (a phase III clinical trial). The second stage involved simulating plasma concentrations at the time of sexual activity using empirical Bayes estimates (EBEs) derived from the final model. In addition, EBEs from a previously published parent metabolite model of TFV (MTN-001, an open-label 3-way crossover study in healthy women) was used to simulate tenofovir diphosphate (TFV-DP) concentrations. We estimated percent PrEP "coverage" as the number of reported sexual events during which simulated concentrations were above an a priori threshold concentrations associated with a high degree of protection from HIV infection: plasma TFV of >40 ng/ml and peripheral blood mononuclear cell (PBMC) TFV-DP concentration of >36 fmol/million cells. The levels of coverage were 72% for TFV and 81% for TFV-DP. These levels are consistent with a high degree of protection against HIV acquisition in this study of a pragmatic delivery model for antiretroviral-based HIV prevention.
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Kaufman AS, Morrison A. Patterns of non-adherence to oral antiretroviral medication: frequencies of consecutively missed doses. Patient Prefer Adherence 2019; 13:389-394. [PMID: 30880923 PMCID: PMC6417850 DOI: 10.2147/ppa.s192153] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
PURPOSE The therapeutic effect of a once-daily oral drug will be maintained if there are no occurrences of consecutively missed doses that exceed the duration of the drug's effect. The durations of effect of antiretroviral drugs are typically in the range of 1-4 days. Here, we report the observed frequencies of ≥2, ≥3, and ≥4 consecutively missed doses for patients taking a once-daily oral antiretroviral drug for HIV infection. PATIENTS AND METHODS Medication Event Monitoring System (MEMS) data were extracted from an electronic database of MEMS records, for a 30-day period for 555 patients taking once-daily oral HIV drug therapy. We recorded the number of days with missed doses and occurrences of ≥2, ≥3, or ≥4 consecutively missed doses. Distributions of the observed frequencies of ≥2, ≥3, and ≥4 consecutively missed doses as a proportion of number of missed doses were compared to calculated random distributions using the Wilcoxon signed-rank test. RESULTS The frequencies of 0, 1, and ≥2 missed daily doses were 0.279, 0.312, and 0.409, respectively. The frequencies of ≥2, ≥3, and ≥4 consecutively missed doses were 0.184, 0.110, and 0.065, respectively. The probabilities that the observed frequencies of ≥2, ≥3, and ≥4 consecutively missed doses were as expected from random chance were P=0.345, P<0.01, and P<0.01, respectively. CONCLUSION Observed runs of ≥3 and ≥4 consecutively missed doses - and hence loss of therapeutic effect for drugs of duration of action of <3 and <4 days, respectively - occurred more frequently than expected if missed doses were randomly distributed.
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6
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Hendrix CW. HIV Antiretroviral Pre-Exposure Prophylaxis: Development Challenges and Pipeline Promise. Clin Pharmacol Ther 2018; 104:1082-1097. [PMID: 30199098 PMCID: PMC6925668 DOI: 10.1002/cpt.1227] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 08/20/2018] [Indexed: 12/17/2022]
Abstract
The US Food and Drug Administration (FDA) approved oral daily tenofovir/emtricitabine (Truvada) for pre-exposure prophylaxis of human immunodeficiency virus (HIV) infection in 2012 on the basis of two randomized controlled trials (RCTs), one in men who have sex with men (MSM) and another in HIV serodiscordant heterosexual couples. Subsequently, even greater efficacy has been demonstrated in MSM with rapid population-level incidence reductions in some locations. In contrast, studies of antiretroviral pre-exposure prophylaxis (PrEP) in heterosexual women showed only modest or no efficacy, largely attributed to low adherence. The mixed results of antiretroviral-based PrEP bear witness to unique drug development challenges at this complicated intersection of sexual behavior, public health, and drug development. Multiple innovative methods and formulation strategies followed to address unmet medical needs of persons struggling with daily oral PrEP adherence or preference for nonsystemic PrEP options. Clinical pharmacology plays essential roles throughout this PrEP development process, especially in early product development and through pharmacologically informed enhancement and interpretation of clinical trials.
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Affiliation(s)
- Craig W Hendrix
- 1Division of Clinical Pharmacology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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Madrasi K, Chaturvedula A, Haberer JE, Sale M, Fossler MJ, Bangsberg D, Baeten JM, Celum C, Hendrix CW. Markov Mixed Effects Modeling Using Electronic Adherence Monitoring Records Identifies Influential Covariates to HIV Preexposure Prophylaxis. J Clin Pharmacol 2016; 57:606-615. [PMID: 27922719 DOI: 10.1002/jcph.843] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Accepted: 10/14/2016] [Indexed: 02/02/2023]
Abstract
Adherence is a major factor in the effectiveness of preexposure prophylaxis (PrEP) for HIV prevention. Modeling patterns of adherence helps to identify influential covariates of different types of adherence as well as to enable clinical trial simulation so that appropriate interventions can be developed. We developed a Markov mixed-effects model to understand the covariates influencing adherence patterns to daily oral PrEP. Electronic adherence records (date and time of medication bottle cap opening) from the Partners PrEP ancillary adherence study with a total of 1147 subjects were used. This study included once-daily dosing regimens of placebo, oral tenofovir disoproxil fumarate (TDF), and TDF in combination with emtricitabine (FTC), administered to HIV-uninfected members of serodiscordant couples. One-coin and first- to third-order Markov models were fit to the data using NONMEM® 7.2. Model selection criteria included objective function value (OFV), Akaike information criterion (AIC), visual predictive checks, and posterior predictive checks. Covariates were included based on forward addition (α = 0.05) and backward elimination (α = 0.001). Markov models better described the data than 1-coin models. A third-order Markov model gave the lowest OFV and AIC, but the simpler first-order model was used for covariate model building because no additional benefit on prediction of target measures was observed for higher-order models. Female sex and older age had a positive impact on adherence, whereas Sundays, sexual abstinence, and sex with a partner other than the study partner had a negative impact on adherence. Our findings suggest adherence interventions should consider the role of these factors.
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Affiliation(s)
- Kumpal Madrasi
- Department of Pharmacy Practice and Pharmaceutical Sciences, Mercer University, Atlanta, GA, USA.,Orise Fellow, Office of Clinical Pharmacology, CDER, FDA, Silver Spring, MD, USA
| | - Ayyappa Chaturvedula
- Department of Pharmacy Practice and Pharmaceutical Sciences, Mercer University, Atlanta, GA, USA.,Pharmacotherapy, University of North Texas Health Science Center, Fort Worth, TX, USA
| | - Jessica E Haberer
- Center for Global Health, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | | | | | - David Bangsberg
- Center for Global Health, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Jared M Baeten
- Departments of Global Health, Medicine, and Epidemiology, University of Washington, Seattle, WA, USA
| | - Connie Celum
- Departments of Global Health, Medicine, and Epidemiology, University of Washington, Seattle, WA, USA
| | - Craig W Hendrix
- School of Medicine, Johns Hopkins University, Baltimore, MD, USA
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8
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Population Pharmacokinetics of Tenofovir in HIV-1-Uninfected Members of Serodiscordant Couples and Effect of Dose Reporting Methods. Antimicrob Agents Chemother 2016; 60:5379-86. [PMID: 27353269 DOI: 10.1128/aac.00559-16] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Accepted: 06/23/2016] [Indexed: 12/22/2022] Open
Abstract
Antiretroviral preexposure prophylaxis (PrEP) with once-daily dosing of tenofovir and tenofovir-emtricitabine was shown to be effective for preventing HIV-1 infection in individuals who had HIV-1-seropositive partners (the Partners PrEP Study). We developed a population pharmacokinetic model for tenofovir and investigated the impacts of different dose reporting methods. Dosing information was collected as patient-reported dosing information (PRDI) from 404 subjects (corresponding to 1,280 drug concentration records) from the main trial and electronic monitoring-based adherence data collected from 211 subjects (corresponding to 327 drug concentration records) in an ancillary adherence study. Model development was conducted with NONMEM (7.2), using PRDI with a steady-state assumption or using PRDI replaced with electronic monitoring records where available. A two-compartment model with first-order absorption was the best model in both modeling approaches, with the need for an absorption lag time when electronic monitoring-based dosing records were included in the analysis. Age, body weight, and creatinine clearance were significant covariates on clearance, but only creatinine clearance was retained in the final models per stepwise selection. Sex was not a significant covariate on clearance. Tenofovir population pharmacokinetic parameter estimates and the precisions of the parameters from the two final models were comparable with the point estimates of the parameters, differing from 0% to 35%, and bootstrap confidence intervals widely overlapped. These findings indicate that PRDI was sufficient for population pharmacokinetic model development in this study, with a high level of adherence per multiple measures.
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Hendrix CW, Andrade A, Bumpus NN, Kashuba AD, Marzinke MA, Moore A, Anderson PL, Bushman LR, Fuchs EJ, Wiggins I, Radebaugh C, Prince HA, Bakshi RP, Wang R, Richardson P, Shieh E, McKinstry L, Li X, Donnell D, Elharrar V, Mayer KH, Patterson KB. Dose Frequency Ranging Pharmacokinetic Study of Tenofovir-Emtricitabine After Directly Observed Dosing in Healthy Volunteers to Establish Adherence Benchmarks (HPTN 066). AIDS Res Hum Retroviruses 2016; 32:32-43. [PMID: 26414912 PMCID: PMC4692123 DOI: 10.1089/aid.2015.0182] [Citation(s) in RCA: 152] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Oral preexposure prophylaxis (PrEP) trials report disparate efficacy attributed to variable adherence. HPTN 066 was conducted to establish objective, quantitative benchmarks for discrete, regular levels of adherence using directly observed dosing of tenofovir (TFV) disoproxil fumarate (TDF)/emtricitabine (FTC). Healthy, HIV-uninfected men and women were randomized to one of four oral regimens of fixed-dose TDF 300 mg/FTC 200 mg tablet for 5 weeks with all doses observed: one tablet weekly (one/week), one tablet twice weekly (two/week), two tablets twice weekly (four/week), or one tablet daily (seven/week). Trough serum TFV and FTC, peripheral blood mononuclear cell (PBMC), and CD4(+) TFV-diphosphate (TFV-DP) and FTC-triphosphate (FTC-TP) concentrations were determined throughout dosing and 2 weeks after the last dose. Rectosigmoidal, semen, and cervicovaginal samples were collected for drug assessment at end of dosing and 2 weeks later in a subset of participants. The 49 enrolled participants tolerated the regimens well. All regimens achieved steady-state concentrations by the second dose for serum TFV/FTC and by 7 days for PBMC TFV-DP/FTC-TP. Steady-state median TFV-DP predose concentrations demonstrated dose proportionality: one/week 1.6 fmol/10(6) PBMCs, two/week 9.1, four/week 18.8, seven/week, 36.3. Further, TFV-DP was consistently quantifiable 2 weeks after the last dose for the ≥4/week regimens. Adherence benchmarks were identified using receiver operating characteristic curves, which had areas under the curve ≥0.93 for all analytes in serum and PBMCs. Intersubject and intrasubject coefficients of variation (%CV) ranged from 33% to 63% and 14% to 34%, respectively, for all analytes in serum and PBMCs. Steady-state PBMC TFV-DP was established earlier and at lower concentrations than predicted and was the only analyte demonstrating predose concentration dose proportionality. Steady-state daily dosing serum TFV and PBMC TFV-DP was consistent with highly effective PrEP clinical trials. HPTN 066 provides adherence benchmarks for oral TFV/FTC regimens to assist interpreting study outcomes.
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Affiliation(s)
| | | | | | - Angela D. Kashuba
- University of North Carolina-Chapel Hill, Chapel Hill, North Carolina
| | | | | | | | | | | | | | | | - Heather A. Prince
- University of North Carolina-Chapel Hill, Chapel Hill, North Carolina
| | | | - Ruili Wang
- University of North Carolina-Chapel Hill, Chapel Hill, North Carolina
| | | | | | | | - Xin Li
- SCHARP, Seattle, Washington
| | | | - Vanessa Elharrar
- National Institutes of Health Division of AIDS, Rockville, Maryland
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10
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Burns RN, Hendrix CW, Chaturvedula A. Population pharmacokinetics of tenofovir and tenofovir-diphosphate in healthy women. J Clin Pharmacol 2015; 55:629-38. [PMID: 25581815 PMCID: PMC5008110 DOI: 10.1002/jcph.461] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Accepted: 01/01/2015] [Indexed: 01/01/2023]
Abstract
The objective of this analysis was to develop and qualify a population pharmacokinetic model describing plasma tenofovir (TFV) concentrations and tenofovir‐diphosphate (TFV‐DP) concentrations in peripheral blood mononuclear cell (PBMC) in healthy women volunteers from the MTN‐001 clinical trial, an open label 3‐way crossover study of oral tenofovir disoproxil fumarate 300 mg tablet, TFV 1% vaginal gel, or both. TFV pharmacokinetics were best described by a 2‐compartment, first‐order absorption/elimination model with absorption lag time. TFV was linked to PBMC TFV‐DP by first‐order uptake with first‐order elimination. An adherence adjustment was included to account for nonadherence by explicitly modeling a bioavailability parameter on the previous day's dose. The final model included weight as a covariate on central compartment volume (Vc) with estimates as follows: absorption rate constant (Ka) 9.79 h−1, absorption lag time 0.5 hours, Vc 385.71–2.16*(73‐WT(kg)), and apparent TFV clearance of 56.7 L/h ((K20 + K24)*Vc). TFV‐DP's half‐life was 53.3 hours. All diagnostic plots and bootstrap confidence intervals were acceptable. Model validation was conducted using simulations compared to data from the MTN‐001 oral + vaginal period and other clinical trial data. The resulting model closely predicted the disposition of TFV and TFV‐DP when compared to healthy participant data from another clinical trial.
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Affiliation(s)
- Rebecca N Burns
- Department of Pharmaceutical Sciences, Mercer University College of Pharmacy, Atlanta, GA, USA
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