Brief Report: Urine Emtricitabine and Tenofovir Concentrations Provide Markers of Recent Antiretroviral Drug Exposure Among HIV-Negative Men Who Have Sex With Men.

BACKGROUND: Urine provides a minimally invasive specimen that may allow for development of rapid tests to detect antiretroviral drugs and provide opportunities to improve individual adherence. This study sought to determine whether urine could provide a biomarker of adherence for currently approved pre-exposure prophylaxis and HIV treatment regimens. METHODS: Urine and blood were collected from 34 HIV-negative men who have sex with men aged 18-49 years, enrolled in a clinical trial comparing 2 antiretroviral regimens. Specimens were collected 4 and 24 hours after a single oral dose of tenofovir disoproxil fumarate (TDF)/emtricitabine (FTC) (n = 10) or tenofovir alafenamide (TAF)/FTC/cobicistat (COBI)/elvitegravir (EVG) (n = 8), or after 4 and 10 days of daily oral TDF/FTC (n = 9) or TAF/FTC/COBI/EVG (n = 7). Tenofovir (TFV), FTC, and EVG were measured by high-performance liquid chromatography-mass spectrometry. RESULTS: Median urine FTC concentrations at 4 and 24 hours were similar between men receiving TDF/FTC (4 hours 147 µg/mL; 24 hours 10 µg/mL) and men receiving TAF/FTC/COBI/EVG (4 hours 333 µg/mL, P = 0.173; 24 hours 13 µg/mL, P = 0.681). Median urine TFV concentrations were lower among men receiving TAF/FTC/COBI/EVG (4 hours 1.2 µg/mL; 24 hours 0.8 µg/mL) compared with men receiving TDF/FTC (4 hours 17 µg/mL, P < 0.001; 24 hours 7 µg/mL, P = 0.001). Urine TFV concentrations remained reduced among men receiving TAF/FTC/COBI/EVG compared with men receiving TDF/FTC after daily dosing. EVG was not consistently measurable in urine. CONCLUSIONS: High urine FTC and TFV concentrations could provide an indication of adherence to daily oral dosing with TDF or TAF-based regimens used for treatment and prevention.

Simultaneous determination and validation of emtricitabine, rilpivirine and tenofovir from biological samples using LC and CE methods.

A combination of antiretroviral agents is frequently used in effective treatment of the human immunodeficiency virus infection. In this study, two different separation methods are presented for the simultaneous determination of emtricitabine, rilpivirine and tenofovir from raw materials and urine samples. Developed liquid chromatography and capillary electrophoresis methods were thoroughly optimized for high analytical performances. Optimization of multiple variables at the same time by performing a minimum number of experiments was achieved by the Box-Behnken design, which is an experimental design in response surface methodology, in capillary electrophoresis. The results of the experimental design ensure minimum analysis time with well-separated analytes. Separation conditions, such as different stationary phases, pH level, organic modifiers and temperatures in liquid chromatography method, were also optimized. In particular, among stationary phases, the core-shell column especially enhanced the effectiveness of separation in liquid chromatography. Both methods were fully validated and applied to real samples. The main advantage of the developed methods is the separation of the drug combination in a short time with high efficiency and without any time-consuming steps.

Two-dimensional LC-MS/MS determination of antiretroviral drugs in rat serum and urine.

A simple, rapid, reliable and highly sensitive on-line two-dimensional reversed-phase liquid chromatography-tandem mass spectrometric (2D-LC/MS/MS) method to determine antiretroviral drugs viz., abacavir (ABC), nevirapine (NVP) and indinavir (IDV) in rat serum and urine was developed and validated. The analytes were extracted on-line from rat serum and urine by a restricted access material (RAM) column and back-flushed into the reversed-phase C18 column for separation by LC. Detection was carried out by ESI-MS/MS. The developed method showed good selectivity, accuracy and precision for quantification of the antiretroviral drugs in rat serum and urine. Quantification limits for abacavir and nevirapine were 4.0 ng ml(-1), whereas for indinavir 4.7 ng ml(-1). The calibration graphs were linear in the range of 4-50 ng ml(-1)for abacavir, nevirapine and indinavir. The method was successfully applied to study the pharmacokinetics of antiretroviral in rats.

A novel probe drug interaction study to investigate the effect of selected antiretroviral combinations on the pharmacokinetics of a single oral dose of maraviroc in HIV-positive subjects.

AIMS: Maraviroc (UK-427 857), an antagonist of the CCR5 receptor with potent anti-HIV activity, was recently approved for use in treatment-experienced patients infected with CCR5-tropic HIV-1. The aim of this study was to evaluate the effect of selected commonly used antiretroviral therapy (ART) combinations on the pharmacokinetics of a single oral dose of maraviroc 300 mg in HIV-positive subjects compared with historical controls. METHODS: In this study, four cohorts of HIV-positive patients (n = 8 each) receiving one of the following combination therapies were recruited: cohort 1--efavirenz + Combivir (lamivudine/zidovudine); cohort 2--efavirenz + didanosine + tenofovir; cohort 3--nevirapine + lamivudine + tenofovir; cohort 4--Kaletra (lopinavir/ritonavir) + stavudine + lamivudine. Subjects continued on their prescribed ART and also received a single oral dose of maraviroc 300 mg. Serial blood samples and urine for determination of maraviroc pharmacokinetics were collected over 12 h postdose. Plasma pharmacokinetic parameters from this study were compared with historical data generated in HIV-positive subjects receiving maraviroc monotherapy in a Phase IIa study. RESULTS: A total of 29 subjects were recruited (eight each in cohorts 1-3, and five in cohort 4). The geometric mean ratios for AUC(12) and C(max) for each treatment group compared with maraviroc monotherapy were: 47% and 67% (cohort 1); 48% and 76% (cohort 2); 101% and 154% (cohort 3); and 265% and 180% (cohort 4), respectively. T(max) was similar in all treatment groups. Mean values for renal clearance ranged from 8.2 l h(-1) (cohort 1) to 13.2 l h(-1) (cohort 4). There were no renal clearance data collected in the comparator study. CONCLUSIONS: The results of this study support those previously seen in healthy volunteer studies that showed that efavirenz reduces maraviroc exposure, whereas lopinavir/ritonavir increases maraviroc exposure. These data also suggest that nevirapine does not lead to a clinically significant effect on maraviroc pharmacokinetics.