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  18th International Workshop on
Clinical Pharmacology of Antiviral Therapy
June 14-17, 2017
Chicago, Ill.C
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Drug-Carrying Adherence Sensor Does Not Alter Levels of TDF/FTC
  18th International Workshop on Clinical Pharmacology of Antiviral Therapy, June 14-17, 2017, Chicago
Mark Mascolini
An adherence-tracking ingestible sensor (IS) added to a capsule containing standard tenofovir/emtricitabine (TDF/FTC, Truvada) did not alter levels of the two antiretrovirals. IS technology is cleared by the FDA and could offer a reliable means to monitor drug-taking adherence.
Adherence (steady pill taking) is essential for treatment of HIV infection and for prevention via pre-exposure prophylaxis (PrEP). Truvada remains the only agent licensed for PrEP in populations at high risk of HIV infection. The IS system involves a tiny sensor particle (a 1 x 1 x 0.45 mm microchip) added to a drug, an ingestion-recording monitor patch worn on the torso of the pill taker, and a remote mobile device that allows continuous real-time monitoring of drug ingestion. The eventual goal is to coformulate the sensor with the drugs. Researchers from the University of California, San Diego and Stanford University conducted this study to see if the ingestible sensor changed the pharmacokinetics of tenofovir or emtricitabine in Truvada.
This single-arm open-label study involved 60 HIV-negative adults starting or continuing Truvada PrEP. On study day 14, a subset of 12 people took an observed dose of the sensor-carrying capsule (IS-Truvada) while fasting and had samples collected for drug-level testing before the dose and 2, 4, 6, 8, and 24 hours after. On study day 15, participants returned to standard Truvada and had samples collected before the dose and 2 and 4 hours after an observed dose. The primary objective of the study was to compare the 2-hour concentration (C2) of tenofovir and emtricitabine--a surrogate for maximum concentration (Cmax)--and the 4-hour concentration (C4) in IS-Truvada and standard Truvada.
For emtricitabine, geometric mean ratios of median C2 and C4 for IS-Truvada/standard Truvada were 0.96 (95% confidence interval [CI] 0.87 to 1.12) and 0.94 (95% CI 0.90 to 1.04). For tenofovir, geometric mean ratios at C2 and C4 were 1.04 (95% CI 0.89 to 1.16) and 0.99 (95% CI 0.87 to 1.12). These results indicated that, 2 and 4 hours after dosing, the components of IS-Truvada reached levels equivalent to those of standard Truvada.
Other pharmacokinetic values for tenofovir and emtricitabine in IS-Truvada were in line with published values from previous studies. For emtricitabine, median time to maximum concentration (Tmax) was 2 hours, 24-hour area under the concentration-time curve (AUC0-24) 10,916 ng*h/mL, clearance 195 L/hour, and half-life 6.7 hours. Median tenofovir values were 2 hours for Tmax, 2706 ng*h/mL for AUC0-24, 59 L/hour for clearance, and 17 hours for half-life.
The researchers proposed that "this IS technology will allow for definitive determination of medication ingestion times to accurately assess adherence while not altering the pharmacokinetics of emtricitabine or tenofovir." Future studies will evaluate patient acceptance of wearing the monitor patch.
1. Hanan N, Benson C, Schooley R, et al. Pharmacokinetics of co-encapsulated Truvada with ingestible sensor to assess adherence. 18th International Workshop on Clinical Pharmacology of Antiviral Therapy, June 14-17, 2017, Chicago. Abstract O_14.